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X-Band Radar from February 2000 and February 11, 2000
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Crater Highlands, Tanzania
PIA06669
Sol (our sun)
C-Band Imaging Radar, X-Band
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| Title |
Crater Highlands, Tanzania |
| Original Caption Released with Image |
Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Science Mission Directorate, Washington, DC. View Size: 48 kilometers wide (30 miles) by 230 kilometers (140 miles) distance Location: 3 degrees South latitude, 36 degrees East longitude Orientation: View 35° south of west, 15° below horizontal SRTM Data Acquired: February 2000, The Shuttle Radar Topography Mission (SRTM), flown aboard Space Shuttle Endeavour in February 2000, acquired elevation measurements for nearly all of Earth's landmass between 60°N and 56°S latitudes. For many areas of the world SRTM data provide the first detailed three-dimensional observation of landforms at regional scales. SRTM data were used to generate this view of the Crater Highlands along the East African Rift in Tanzania. Landforms are depicted with colored height and shaded relief, using a vertical exaggeration of 2X and a southwestwardly look direction. Lake Eyasi is depicted in blue at the top of the image, and a smaller lake occurs in Ngorongoro Crater. Near the image center, elevations peak at 3648 meters (11,968 feet) at Mount Loolmalasin, which is south of Ela Naibori Crater. Kitumbeine (left) and Gelai (right) are the two broad mountains rising from the rift lowlands. Mount Longido is seen in the lower left, and the Meto Hills are in the right foreground. Tectonics, volcanism, landslides, erosion and deposition -- and their interactions -- are all very evident in this view. The East African Rift is a zone of spreading between the African (on the west) and Somali (on the east) crustal plates. Two branches of the rift intersect here in Tanzania, resulting in distinctive and prominent landforms. One branch trends nearly parallel the view and includes Lake Eyasi and the very wide Ngorongoro Crater. The other branch is well defined by the lowlands that trend left-right across the image (below center, in green). Volcanoes are often associated with spreading zones where magma, rising to fill the gaps, reaches the surface and builds cones. Craters form if a volcano explodes or collapses. Later spreading can fracture the volcanoes, which is especially evident on Kitumbeine and Gelai Mountains (left and right, respectively, lower center). The Crater Highlands rise far above the adjacent savannas, capture moisture from passing air masses, and host rain forests. Over time, streams erode downward toward the level of the adjacent rift, deeply dissecting the volcanic slopes. This is especially evident on the eastern flanks of Mount Loolmalasin (left of center). Landsliding also occurs here. In particular, the small but steep volcanic cone nearest the image center has a landslide scar on its eastern (left) flank, and topographic evidence shows that the associated landslide deposits extend eastward 10 kilometers (6 miles) across the floor of the rift. Such a long run of landslide debris is unusual but is not unique on Earth. Elevation data used in this image were acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the |
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Strait of Gibraltar, Perspec
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PIA03397
Sol (our sun)
C-Band Interferometric Radar
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| Title |
Strait of Gibraltar, Perspective with Landsat Image Overlay |
| Original Caption Released with Image |
Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC. View Size: 46 kilometers (28 miles) wide, 106 kilometers (66 miles) distance Location: 36 degrees North latitude, 5.5 degrees West longitude Orientation: Looking East, 15 degrees down from horizontal, 3X vertical exaggeration Image Data: Landsat Bands 1, 2+4, 3 as blue, green, red respectively Original Data Resolution: 30 meters (99 feet) Date Acquired: February 2000 (SRTM), July 6, 1987 (Landsat), This perspective view shows the Strait of Gibraltar, which is the entrance to the Mediterranean Sea from the Atlantic Ocean. Europe (Spain) is on the left. Africa (Morocco) is on the right. The Rock of Gibraltar, administered by Great Britain, is the peninsula in the back left. The Strait of Gibraltar is the only natural gap in the topographic barriers that separate the Mediterranean Sea from the world's oceans. The Sea is about 3700 kilometers (2300 miles) long and covers about 2.5 million square kilometers (one million square miles), while the Strait is only about 13 kilometers (8 miles) wide. Sediment samples from the bottom of the Mediterranean Sea that include evaporite minerals, soils, and fossil plants show that about five million years ago the Strait was topographically blocked and the Sea had evaporated into a deep basin far lower in elevation than the oceans. Consequent changes in the world's hydrologic cycle, including effects upon ocean salinity, likely led to more ice formation in polar regions and more reflection of sunlight back to space, resulting in a cooler global climate at that time. Today, topography plays a key role in our regional climate patterns. But through Earth history, topographic change, even perhaps over areas as small as 13 kilometers across, has also affected the global climate. This image was generated from a Landsat satellite image draped over an elevation model produced by the Shuttle Radar Topography Mission (SRTM). The view is eastward with a 3-times vertical exaggeration to enhance topographic expression. Natural colors of the scene (green vegetation, blue water, brown soil, white beaches) are enhanced by image processing, inclusion of some infrared reflectance (as green) to highlight the vegetation pattern, and inclusion of shading of the elevation model to further highlight the topographic features. Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data matches the 30-meter (99-feet) resolution of most Landsat images and will substantially help in analyses of the large Landsat image archive. Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, |
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SRTM Data Release for Eurasi
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PIA03398
Sol (our sun)
C-Band Radar, X-Band Radar
| Title |
SRTM Data Release for Eurasia, Index Map and Colored Height |
| Original Caption Released with Image |
The colored regions of this map show the extent of digital elevation data recently released by the Shuttle Radar Topography Mission (SRTM). This release includes data for most of Europe and Asia plus numerous islands in the Indian and Pacific Oceans. SRTM flew on board the Space Shuttle Endeavour in February 2000 and used an interferometric radar system to map the topography of Earth's landmass between latitudes 56 degrees south and 60 degrees north. The data were processed into geographic "tiles," each of which represents one by one degree of latitude and longitude. A degree of latitude measures 111 kilometers (69 miles) north-south, and a degree of longitude measures 111 kilometers or less east-west, decreasing away from the equator. The data are being released to the public on a continent-by-continent basis. This Eurasia segment includes 5,940 tiles, more than a third of the total data set. Previous releases covered North America and South America. Forthcoming releases will include Africa-Arabia and Australia plus an "Islands" release for those islands not included in the continental releases. Together these data releases constitute the world's first high-resolution, near-global elevation model. The resolution of the publicly released data is three arcseconds (1/1,200 of a degree of latitude and longitude), which is about 90 meters (295 feet). European coverage in the current data release stretches eastward from the British Isles and the Iberian Peninsula in the west, across the Alps and Carpathian Mountains, as well as the Northern European Plain, to the Ural and Caucasus Mountains bordering Asia. The Asian coverage includes a great diversity of landforms, including the Tibetan Plateau, Tarin Basin, Mongolian Plateau, and the mountains surrounding Lake Baikal, the world's deepest lake. Mt. Everest in the Himalayas, at 8,848 meters (29,029 feet) is the world's highest mountain. From India's Deccan Plateau, to Southeast Asia, coastal China, and Korea, various landforms place constraints upon land use planning for a great population. Volcanoes in the East Indies, the Philippines, Japan, and the Kamchatka Peninsula form the western part of the "Ring of Fire" around the Pacific Ocean. Many of these regions were previously very poorly mapped due to persistent cloud cover or the inaccessibility of the terrain. Digital elevation data, such as provided by SRTM, are particularly in high demand by scientists studying earthquakes, volcanism, and erosion patterns for use in mapping and modeling hazards to human habitation. But the shape of Earth's surface affects nearly every natural process and human endeavor that occurs there, so elevation data are used in a wide range of applications. In this index map color-coding is directly related to topographic height, with green at the lower elevations, rising through yellow and tan, to white at the highest elevations. The large, very dark green feature in western Asia is the Caspian Sea, which is below sea, level. Blue areas on the map represent water within the mapped tiles, each of which includes shorelines or islands. Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC. Orientation: North toward the top Image Data: Colored SRTM elevation model Date Acquired: February 2000 |
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Mount Ararat, Turkey, Perspe
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PIA03399
Sol (our sun)
C-Band Radar, X-Band Radar
| Title |
Mount Ararat, Turkey, Perspective with Landsat Image Overlay |
| Original Caption Released with Image |
This perspective view shows Mount Ararat in easternmost Turkey, which has been the site of several searches for the remains of Noah's Ark. The main peak, known as Great Ararat, is the tallest peak in Turkey, rising to 5165 meters (16,945 feet). This southerly, near horizontal view additionally shows the distinctly conically shaped peak known as "Little Ararat" on the left. Both peaks are volcanoes that are geologically young, but activity during historic times is uncertain. This image was generated from a Landsat satellite image draped over an elevation model produced by the Shuttle Radar Topography Mission (SRTM). The view uses a 1.25-times vertical exaggeration to enhance topographic expression. Natural colors of the scene are enhanced by image processing, inclusion of some infrared reflectance (as green) to highlight the vegetation pattern, and inclusion of shading of the elevation model to further highlight the topographic features. Volcanoes pose hazards for people, the most obvious being the threat of eruption. But other hazards are associated with volcanoes too. In 1840 an earthquake shook the Mount Ararat region, causing an unstable part of mountain's north slope to tumble into and destroy a village. Visualizations of satellite imagery when combined with elevation models can be used to reveal such hazards leading to disaster prevention through improved land use planning. But the hazards of volcanoes are balanced in part by the benefits they provide. Over geologic time volcanic materials break down to form fertile soils. Cultivation of these soils has fostered and sustained civilizations, as has occurred in the Mount Ararat region. Likewise, tall volcanic peaks often catch precipitation, providing a water supply to those civilizations. Mount Ararat hosts an icefield and set of glaciers, as seen here in this late summer scene, that are part of this beneficial natural process Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC. View Size: 124 kilometers (77 miles) wide, 148 kilometers (92 miles) distance Location: 39.7 degrees North latitude, 44.3, degrees East longitude Orientation: Looking South, 2 degrees down from horizontal, 1.25X vertical exaggeration Image Data: Landsat Bands 1, 2+4, 3 as blue, green, red respectively Date Acquired: February 2000 (SRTM), August 31, 1989 (Landsat) |
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Africa in SRTM 3-D, Anaglyph
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PIA04964
Sol (our sun)
C-Band Interferometric Radar
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| Title |
Africa in SRTM 3-D, Anaglyph of Shaded Relief |
| Original Caption Released with Image |
This stereoscopic shaded relief image shows Africa's topography as measured by the Shuttle Radar Topography Mission (SRTM) in February 2000. Also shown are Madagascar, the Arabian Peninsula, and other adjacent regions. Previously, much of the topography here was not mapped in detail. Digital elevation data, such as provided by SRTM, are in high demand by scientists studying earthquakes, volcanism, and erosion patterns and for use in mapping and modeling hazards to human habitation. But the shape of Earth's surface affects nearly every natural process and human endeavor that occurs there, so elevation data are used in a wide range of applications. The image shown here is greatly reduced from the original data resolution, but still provides a good overview of the continent's landforms. It is best viewed while panning at full resolution while using image display software. The northern part of the continent consists of a system of basins and plateaus, with several volcanic uplands whose uplift has been matched by subsidence in the large surrounding basins. Many of these basins have been infilled with sand and gravel, creating the vast Saharan lands. The Atlas Mountains in the northwest were created by convergence of the African and Eurasian tectonic plates. The geography of the central latitudes of Africa is dominated by the Great Rift Valley, extending from Lake Nyasa to the Red Sea, and splitting into two arms to enclose an interior plateau and the nearly circular Lake Victoria, visible in the right center of the image. To the west lies the Congo Basin, a vast, shallow depression that rises to form an almost circular rim of highlands. Most of the southern part of the continent rests on a concave plateau comprising the Kalahari Basin and a mountainous fringe, skirted by a coastal plain that widens out in Mozambique in the southeast. Specific noteworthy features one may wish to explore in this scene include (1) the Richat Structure in Mauritania, a "bull's eye" geologic structure, (2) the Velingara Ring in Senegal, a possible meteorite impact crater, (3) the delta of the Niger River in Nigeria, (4) the Cameroon Line of volcanoes, crossing Cameroon and extending offshore, (5) long linear mountain ridges crossing the southern end of Africa, (6) Mount Kilimanjaro and neighboring volcanoes in Kenya and Tanzania, (7) the Afar Triangle in Ethiopia, Djibouti, and vicinity, where Earth's crust is being pulled in three directions by tectonic forces, (8) the Dead Sea fault line, between Israel and Jordan, (9) ancient shorelines, inland from the coast of Libya, and (10) vast seas of sand dunes, particularly across the Sahara Desert and much of the Arabian Peninsula. This anaglyph was created by deriving a shaded relief image from the SRTM data, draping it back over the SRTM elevation model, and then generating two differing perspectives, one for each eye. Illumination is from the north (top). When viewed through special glasses, the anaglyph is a, vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter. Elevation data used in this image were acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C. Orientation: North toward the top, Mercator projection Image Data: Shaded SRTM elevation model Date Acquired: February 2000 |
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Richat Structure, Mauritania
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PIA04962
Sol (our sun)
C-Band Interferometric Radar
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| Title |
Richat Structure, Mauritania, Anaglyph, Landsat Image over SRTM Elevation |
| Original Caption Released with Image |
German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C. Size: 174.6 kilometers (108.3 miles) by 112.5 kilometers (69.8 miles) Location: 21.4 degrees North latitude, 12.0 degrees West longitude Orientation: North toward the top Image Data: Landsat band 7 Date Acquired: February 2000 (SRTM), January 13, 1987 (Landsat), The prominent circular feature seen here, known as the Richat Structure, in the Sahara desert of Mauritania, is often noted by astronauts because it forms a conspicuous 50-kilometer-wide (30-mile-wide) bull's-eye on the otherwise rather featureless expanse of the desert. Initially mistaken for a possible impact crater, it is now known to be an eroded circular anticline (structural dome) of layered sedimentary rocks. Extensive sand dunes occur in this region and the interaction of bedrock topography, wind, and moving sand is evident in this scene. Note especially how the dune field generally ends abruptly short of the cliffs as wind from the northeast (upper right) apparently funnels around the cliff, sweeping clean areas near the base of the cliff (particularly at the cliff point to the northwest, upper left, of the Richat Structure). Note also the isolated peak within the dune field. That peak captures some sand on its windward side, but mostly deflects the wind and sand around its sides, creating a sand-barren streak that continues far downwind. To the west (left), a north-south trending bedrock ridge breaks up the sand field, and downwind from the ridge, streaks of dunes occur at certain locations. Upon close inspection, these streaks can be seen to be associated with saddles (low points) along the ridge, where sand preferentially passes over the ridge. This again shows how topographic features control the distribution of sand across the terrain. This anaglyph was created by draping a Landsat reflectance infrared image over an SRTM elevation model, and then generating two differing perspectives, one for each eye. When viewed through special glasses, the anaglyph is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter For vertical scale, note that the prominent cliffs (image center) are about 300 meters (about 1000 feet) tall, the central rings of the Richat structure are about 80 meters (about 260 feet) tall, and the sand dunes rise about 80 meters (about 260 feet) above the adjacent terrain across the center of the image. Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the |
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Western Tibet, Shaded Relief
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PIA04969
Sol (our sun)
C-Band Radar, X-Band Radar
| Title |
Western Tibet, Shaded Relief with Color as Height |
| Original Caption Released with Image |
. This shaded relief with color as height image was generated using topographic data from the Shuttle Radar Topography Mission (SRTM) 3-arcsecond (90-meter, 300 feet) data and from the GTOPO30 data (30 arcseconds, 900 meters, 3000 feet spacing). Elevations vary from about 200 meters (600 feet) in purple shades above sea level in the plains of India to over 7700 meters (25,000 feet) in the Himalayas (white) within this image. Radar data used in this research were acquired by the European Remotes Sensing (ERS) satellites operated by the European Space Agency, which kindly made this data available for research. Research was performed at the Centre for the Observation and Modelling of Earthquakes and Tectonics supported by the U.K. Natural Environment Research Council. Part of this research was performed at the Jet Propulsion Laboratory, California Institute of Technology under contract with the U.S. National Aeronautics and Space Administration. Elevation data used in this image were acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000, and the GTOPO30 data produced by the U.S. Geological Survey Eros Data Center. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, DC. Size: Image width 320 kilometers (200 miles) and height 850 kilometers (530 miles) Location: 35 degrees North latitude, 79 degrees East longitude at center Orientation: North is up, Universal Transverse Mercator projection, zone 44 Resolution: pixel size is 80 x 80 meters (262 x 262 feet) Date Acquired: February 2000 (SRTM), The 5000 meter (16,000 feet) high Tibetan Plateau has been formed by the collision of the Indian subcontinent with central Asia. The topography rises from the Indus-Ganges plains across the Himalayas and into the lower relief central part of the plateau. The north edge of the plateau is the Altyn Tagh and Kun Lun mountain range. North of Tibet is the Takla Makan desert. Two major faults in western Tibet stand out in the topography and satellite imagery. The Karakoram Fault is the straight line running from top left to lower right across this image, through the Karakoram mountains and southern Tibet. The Altyn Tagh Fault is the slightly curved line running along the northern edge of the plateau from top left to top right. Geologist s and geophysicists have long argued about how fast these two faults in western Tibet are moving. In one model, the Tibetan plateau is like a watermelon seed sliding out to the east along these two faults. In another model, Tibet is deforming internally without sliding rapidly sideways. Scientists at the Centre for Observation and Modelling of Earthquakes and Tectonics and at NASA's Jet Propulsion Lab have used interferometric analysis of radar data from the European Remote Sensing satellites and topographic data from the Shuttle Radar Topography Mission to study the faults in western Tibet. The interferometric analysis was performed with software developed at JPL. The results show that the faults in western Tibet, especially the Karakoram Fault, cannot be moving rapidly. This rules out the watermelon seed "extrusion"http://photojournal.jpl.nasa.gov/catalog/PIA04969 model, at least for western Tibet. These results are published in the journal Science, Volume 305, Issue 5681, pages 236-239, July 9, 2004, available at (subscription required for full text): http://www.sciencemag.org/ [ http://photojournal.jpl.nasa.gov/catalog/PIA04969 http://www.sciencemag.org/ ] |
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SRTM Data Release for Africa
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PIA04965
Sol (our sun)
C-Band Interferometric Radar
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| Title |
SRTM Data Release for Africa, Colored Height |
| Original Caption Released with Image |
This color shaded relief image shows the extent of digital elevation data for Africa recently released by the Shuttle Radar Topography Mission (SRTM). This release includes data for all of the continent, plus the island of Madagascar and the Arabian Peninsula. SRTM flew on board the Space Shuttle Endeavour in February 2000 and used an interferometric radar system to map the topography of Earth's landmass between latitudes 56 degrees south and 60 degrees north. The data were processed into geographic "tiles," each of which represents one by one degree of latitude and longitude. A degree of latitude measures 111 kilometers (69 miles) north-south, and a degree of longitude measures 111 kilometers or less east-west, decreasing away from the equator. The data are being released to the public on a continent-by-continent basis. This Africa segment includes 3256 tiles, almost a quarter of the total data set. Previous releases covered North America, South America and Eurasia. Forthcoming releases will include Australia plus an "Islands" release for those islands not included in the continental releases. Together these data releases constitute the world's first high-resolution, near-global elevation model. The resolution of the publicly released data is three arcseconds (1/1,200 of a degree of latitude and longitude), which is about 90 meters (295 feet). Coverage in the current data release extends from 35 degrees north latitude at the southern edge of the Mediterranean to the very tip of South Africa, encompassing a great diversity of landforms. The northern part of the continent consists of a system of basins and plateaus, with several volcanic uplands whose uplift has been matched by subsidence in the large surrounding basins. Many of these basins have been infilled with sand and gravel, creating the vast Saharan lands. The Atlas Mountains in the northwest were created by convergence of the African and Eurasian tectonic plates. The geography of the central latitudes of Africa is dominated by the Great Rift Valley, extending from Lake Nyasa to the Red Sea, and splitting into two arms to enclose an interior plateau and the nearly circular Lake Victoria, visible in the right center of the image. To the west lies the Congo Basin, a vast, shallow depression which rises to form an almost circular rim of highlands. Most of the southern part of the continent rests on a concave plateau comprising the Kalahari basin and a mountainous fringe, skirted by a coastal plain which widens out in Mozambique in the southeast. Many of these regions were previously very poorly mapped due to persistent cloud cover or the inaccessibility of the terrain. Digital elevation data, such as provided by SRTM, are particularly in high demand by scientists studying earthquakes, volcanism, and erosion patterns for use in mapping and modeling hazards to human habitation. But the shape of Earth's surface affects nearly every natural process and human endeavor that occurs there,, so elevation data are used in a wide range of applications. In this index map color-coding is directly related to topographic height, with brown and yellow at the lower elevations, rising through green, to white at the highest elevations. Blue areas on the map represent water within the mapped tiles, each of which includes shorelines or islands. Elevation data used in this image were acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, DC. Orientation: North toward the top, Mercator projection Image Data: Colored SRTM elevation model Date Acquired: February 2000 |
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Nabro and Mallahle Volcanoes
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PIA04953
Sol (our sun)
C-Band Radar, X-Band Radar
| Title |
Nabro and Mallahle Volcanoes, Eritrea and Ethiopia, SRTM Colored Height and Shaded Relief |
| Original Caption Released with Image |
The area known as the Afar Triangle is located at the northern end of the East Africa Rift, where it approaches the southeastern end of the Red Sea and the southwestern end of the Gulf of Aden. The East African Rift, the Red Sea, and the Gulf of Aden are all zones where Earth's crust is pulling apart in a process known as crustal spreading. Their three-way meeting is known as a triple junction, and their spreading creates a triangular topographic depression for which the area was named. Not surprisingly, the topographic effects of crustal spreading are more dramatic in the Afar Triangle than anywhere else upon Earth's landmasses. The spreading is primarily evident as patterns of numerous tension cracks. But some of these cracks provide conduits for magma to rise to the surface to form volcanoes. Shown here are a few of the volcanoes of the Afar Triangle. The larger two are Nabro Volcano (upper right, in Eritrea) and Mallahle Volcano (lower left, in Ethiopia). Nabro Volcano shows clear evidence of multiple episodes of activity that resulted in a crater in a crater in a crater. Many volcanoes in this area are active, including one nearby that last erupted in 1990. This image was created directly from an SRTM elevation model. A shade image was derived by computing topographic slope in the north-south direction. Northern slopes appear bright and southern slopes appear dark. The shade image was then combined with a color coding of topographic height, with green at the lower elevations, rising through yellow, orange, and red, up to purple at the highest elevations. Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC. Size: 35.2 kilometers (21.8 miles) by 22.5 kilometers (14.0 miles) Location: 13.3 degrees North latitude, 41.7 degrees East longitude Orientation: North toward the top Image Data: Shaded and colored SRTM elevation model Date Acquired: February 2000 |
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Cape Town, South Africa, Ana
…
PIA04960
Sol (our sun)
C-Band Interferometric Radar
…
| Title |
Cape Town, South Africa, Anaglyph, Landsat Image over SRTM Elevation |
| Original Caption Released with Image |
Cape Town and the Cape of Good Hope, South Africa, appear on the left (west) of this anaglyph view generated from a Landsat satellite image and elevation data from the Shuttle Radar Topography Mission (SRTM). The city center is located between Table Bay (upper left) and Table Mountain (just to the south), a 1,086-meter (3,563-foot) tall sandstone and granite natural landmark. Cape Town enjoys a Mediterranean climate but must deal with the limited water supply characteristic of that climate. Until the 1890s the city relied upon streams and springs along the base of Table Mountain, then built a small reservoir atop Table Mountain to capture and store rainfall there (visible in this anaglyph when viewed at full resolution). Now the needs of a much larger population are met in part by much larger reservoirs such as seen well inland (upper right) at the Theewaterskloof Dam. False Bay is the large bay to the southeast (lower right) of Cape Town, just around the Cape of Good Hope. It is one of the largest bays along the entire South African coast, but nearby Cape Town has its harbor at Table Bay. False Bay got its name because mariners approaching Cape Town from the east would see the prominent bay and falsely assume it to be the entrance to Cape Town harbor. Similarly, people often mistake the Cape of Good Hope as the southernmost point of Africa. But the southernmost point is actually Cape Agulhas, located just to the southeast (lower right) of this scene. This anaglyph was created by draping a Landsat visible light image over an SRTM elevation model, and then generating two differing perspectives, one for each eye. When viewed through special glasses, the anaglyph is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter. Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C. View Size: 66 kilometers (41 miles) by 134 kilometers (83 miles) Location: 34.2 degrees South latitude, 18.7 degrees East longitude Orientation:, North-northeast at top Image Data: Landsat Bands 1, 2, 3 merged as grey Date Acquired: February 2000 (SRTM), June 13, 2000 (Landsat) |
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Library of Congress Model, P
…
PIA04967
Sol (our sun)
C-Band Radar, X-Band Radar
| Title |
Library of Congress Model, Perspective View |
| Original Caption Released with Image |
The Shuttle Radar Topography Mission (SRTM) has produced the first high-resolution, near-global elevation dataset of Earth. In recognition of this achievement, and as an illustration of the data, the United States Library of Congress now displays a "solid terrain model" of Los Angeles and adjacent mountainous terrain. The model was created by carving a high-density foam block using computer-guided drills that referenced the SRTM dataset. The block was then covered with a Landsat satellite image using computer-guided paint guns that referenced both the Landsat image and the SRTM dataset. The view shown here mimics the actual model on display at the Library of Congress and was generated from the same satellite image and elevation data sets. The model shows the Pacific Ocean and Santa Monica Mountains along the Malibu Coast (lower left), San Fernando Valley (left center), downtown Los Angeles (bottom center), San Gabriel and Pomona Valleys (lower right), San Gabriel Mountains (right center to far right), and part of the Mojave Desert (upper right). Colors are enhanced true color with added topographic shading, and elevation differences are exaggerated 1.5 times. The view is toward the north-northwest. The Los Angeles region was chosen for the Library of Congress model because it illustrates so many ways that topography affects the daily lives of people. The region consists of a coastal plain, inland valleys, mountains up to 3068 meters (10,064 feet), and a desert interior. Topography blocks the landward influence of marine airmasses here such that summer temperatures often differ by 40 degrees Fahrenheit (22 C) across this region at a given moment even at similar elevations. Temperatures also typically cool with rising elevation, and winter storms drop most of their moisture in the mountains, leaving little rainfall for areas further inland, thus creating the deserts. Topography also controls the land use pattern. The mountains are mostly very rugged, which greatly limits urban expansion. Similarly, major transportation routes are limited to a few mountain passes. Water supply to the city and drainage away from it both follow paths largely dictated by topography. Radio, television, and cell phone transmission towers are all sited with topography in mind to maximize coverage. Its climate and scenic mountain surroundings have been a major part of the appeal of the Los Angeles region as it has grown into one of the world's largest cities over the past 150 years. But the topography that has created this environment also results from and leads to significant natural hazards. The tall mountains result from tectonic compression and uplift of Earth's crust along a kink in the San Andreas fault. (The fault is seen here as a straight boundary between the Mojave Desert and the San Gabriel Mountains.) Major earthquakes occur on the San Andreas fault every few centuries. Damaging earthquakes also occur on other faults across the region several times in a, typical human lifespan. Most of these faults were first recognized by their impact upon the topographic pattern. Meanwhile, wildfires are common in the chaparral covered hills and mountains, and topography affects the fire's path (burning more readily upslope) as well as our ability to fight it. After a fire, rainfall from winter storms often strips exposed soil, accumulates it as mudflows in rugged canyons, and dumps it into the adjacent valleys which are now heavily urbanized. Topography is indeed important in the lives of the people of Los Angeles. Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data substantially help in analyzing Landsat images by revealing the third dimension of Earth's surface, topographic height. The Landsat archive is managed by the U.S. Geological Survey's Eros Data Center (USGS EDC). Elevation data used in this image were acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, DC. Size: Block length 120 kilometers (74 miles), block width 60 kilometers (37 miles) Location: 34.2 degrees North latitude, 118.3 degrees West longitude Orientation: View North-Northwest, 1.5 times vertical exaggeration Image Data: Landsat bands 3, 2, 1 as red, green, blue, respectively, plus elevation shading. Date Acquired: February 2000 (SRTM), May 4, 2001 (Landsat) |
|
Cape Town, South Africa, Per
…
PIA04961
Sol (our sun)
C-Band Interferometric Radar
…
| Title |
Cape Town, South Africa, Perspective View, Landsat Image over SRTM Elevation |
| Original Caption Released with Image |
Cape Town and the Cape of Good Hope, South Africa, appear in the foreground of this perspective view generated from a Landsat satellite image and elevation data from the Shuttle Radar Topography Mission (SRTM). The city center is located at Table Bay (at the lower left), adjacent to Table Mountain, a 1,086-meter (3,563-foot) tall sandstone and granite natural landmark. Cape Town enjoys a Mediterranean climate but must deal with the limited water supply characteristic of that climate. Until the 1890s the city relied upon streams and springs along the base of Table Mountain, then built a small reservoir atop Table Mountain to capture and store rainfall there. Now the needs of a much larger population are met in part by much larger reservoirs such as seen here far inland (mid-distance left) at the Theewaterskloof Dam. False Bay is the large bay to the south (right) of Cape Town, just around the Cape of Good Hope. It is one of the largest bays along the entire South African coast, but nearby Cape Town has its harbor at Table Bay. False Bay got its name because mariners approaching Cape Town from the east would see the prominent bay and falsely assume it to be the entrance to Cape Town harbor. Similarly, people often mistake the Cape of Good Hope as the southernmost point of Africa. But the southernmost point is actually Cape Agulhas, located just to the southeast (upper right) of this scene. This Landsat and SRTM perspective view uses a 2-times vertical exaggeration to enhance topographic expression. The back edges of the data sets form a false horizon and a false sky was added. Colors of the scene were enhanced by image processing but are the natural color band combination from the Landsat satellite. Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C. View Size: 66 kilometers (41 miles) wide by 134 kilometers (83 miles) distance Location: 34.2 degrees South latitude, 18.7 degrees East longitude Orientation: View toward east-southeast Image Data: Landsat Bands 1, 2, 3 in blue, green, red Date Acquired: February 2000 (SRTM), June 13, 2000 (Landsat) |
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Portland, Mount Hood, & Colu
…
PIA04966
Sol (our sun)
C-Band Radar, X-Band Radar
| Title |
Portland, Mount Hood, & Columbia River Gorge, Oregon, Perspective View |
| Original Caption Released with Image |
Portland, the largest city in Oregon, is located on the Columbia River at the northern end of the Willamette Valley. On clear days, Mount Hood highlights the Cascade Mountains backdrop to the east. The Columbia is the largest river in the American Northwest and is navigable up to and well beyond Portland. It is also the only river to fully cross the Cascade Range, and has carved the Columbia River Gorge, which is seen in the left-central part of this view. A series of dams along the river, at topographically favorable sites, provide substantial hydroelectric power to the region. This perspective view was generated using topographic data from the Shuttle Radar Topography Mission (SRTM), a Landsat satellite image, and a false sky. Topographic expression is vertically exaggerated two times. Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data substantially help in analyzing Landsat images by revealing the third dimension of Earth's surface, topographic height. The Landsat archive is managed by the U.S. Geological Survey's Eros Data Center (USGS EDC). Elevation data used in this image were acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, DC. Size: View width 88 kilometers (49 miles), View distance 106 kilometers (66 miles) Location: 45.5 degrees North latitude, 122.5 degrees West longitude Orientation: View East-Southeast, 10 degrees below horizontal, 2 times vertical exaggeration Image Data: Landsat Bands 3, 2, 1 as red, green, blue, respectively Date Acquired: February 2000 (SRTM), August 10, 1992 (Landsat) |
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Richat Structure, Mauritania
…
PIA04963
Sol (our sun)
C-Band Interferometric Radar
…
| Title |
Richat Structure, Mauritania, Perspective View, Landsat Image over SRTM Elevation |
| Original Caption Released with Image |
This prominent circular feature, known as the Richat Structure, in the Sahara desert of Mauritania is often noted by astronauts because it forms a conspicuous 50-kilometer-wide (30-mile-wide) bull's-eye on the otherwise rather featureless expanse of the desert. Initially mistaken for a possible impact crater, it is now known to be an eroded circular anticline (structural dome) of layered sedimentary rocks. Extensive sand dunes occur in this region and the interaction of bedrock topography, wind, and moving sand is evident in this scene. Note especially how the dune field ends abruptly short of the cliffs at the far right as wind from the northeast (lower right) apparently funnels around the cliff point, sweeping clean areas near the base of the cliff. Note also the small isolated peak within the dune field. That peak captures some sand on its windward side, but mostly deflects the wind and sand around its sides, creating a sand-barren streak that continues far downwind. This view was generated from a Landsat satellite image draped over an elevation model produced by the Shuttle Radar Topography Mission (SRTM). The view uses a 6-times vertical exaggeration to greatly enhance topographic expression. For vertical scale, note that the height of the mesa ridge in the back center of the view is about 285 meters (about 935 feet) tall. Colors of the scene were enhanced by use of a combination of visible and infrared bands, which helps to differentiate bedrock (browns), sand (yellow, some white), minor vegetation in drainage channels (green), and salty sediments (bluish whites). Some shading of the elevation model was included to further highlight the topographic features. Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C. View Size: 68 kilometers (42 miles) wide by 112 kilometers (69 miles) distance Location: 21.2 degrees North latitude, 11.7 degrees West longitude Orientation: View toward west-northwest Image Data: Landsat Bands 1, 4, 7 in B.G.R. Date Acquired: February 2000 (SRTM), January 13, 1987 (Landsat) |
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Library of Congress Model, A
…
PIA04968
Sol (our sun)
C-Band Radar, X-Band Radar
| Title |
Library of Congress Model, Anaglyph |
| Original Caption Released with Image |
Gabriel Mountains.) Major earthquakes occur on the San Andreas fault every few centuries. Damaging earthquakes also occur on other faults across the region several times in a typical human lifespan. Most of these faults were first recognized by their impact upon the topographic pattern. Meanwhile, wildfires are common in the chaparral covered hills and mountains, and topography affects the fire's path (burning more readily upslope) as well as our ability to fight it. After a fire, rainfall from winter storms often strips exposed soil, accumulates it as mudflows in rugged canyons, and dumps it into the adjacent valleys which are now heavily urbanized. Topography is indeed important in the lives of the people of Los Angeles. Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data substantially help in analyzing Landsat images by revealing the third dimension of Earth's surface, topographic height. The Landsat archive is managed by the U.S. Geological Survey's Eros Data Center (USGS EDC). Elevation data used in this image were acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, DC. Size: Block length 120 kilometers (74 miles), block width 60 kilometers (37 miles) Location: 34.2 degrees North latitude, 118.3 degrees West longitude Orientation: View North-Northwest, 1.5 times vertical exaggeration Image Data: Landsat bands 3, 2, 1 as red, green, blue, respectively, plus elevation shading. Date Acquired: February 2000 (SRTM), May 4, 2001 (Landsat), The Shuttle Radar Topography Mission (SRTM) has produced the first high-resolution, near-global elevation dataset of Earth. In recognition of this achievement, and as an illustration of the data, the United States Library of Congress now displays a "solid terrain model" of Los Angeles and adjacent mountainous terrain. The model was created by carving a high-density foam block using computer-guided drills that referenced the SRTM dataset. The block was then covered with a Landsat satellite image using computer-guided paint guns that referenced both the Landsat image and the SRTM dataset. The view shown here mimics the actual model on display at the Library of Congress and was generated from the same satellite image and elevation data sets. Anaglyph glasses are required to see this view in three-dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter. The model shows the Pacific Ocean and Santa Monica Mountains along the Malibu Coast (lower left), San Fernando Valley (left center), downtown Los Angeles (bottom center), San Gabriel and Pomona Valleys (lower right), San Gabriel Mountains (right center to far right), and part of the Mojave Desert (upper right). Colors are enhanced true color with added topographic shading, and elevation differences are exaggerated 1.5 times. The view is toward the north-northwest. The Los Angeles region was chosen for the Library of Congress model because it illustrates so many ways that topography affects the daily lives of people. The region consists of a coastal plain, inland valleys, mountains up to 3068 meters (10,064 feet), and a desert interior. Topography blocks the landward influence of marine airmasses here such that summer temperatures often differ by 40 degrees Fahrenheit (22 C) across this region at a given moment even at similar elevations. Temperatures also typically cool with rising elevation, and winter storms drop most of their moisture in the mountains, leaving little rainfall for areas further inland, thus creating the deserts. Topography also controls the land use pattern. The mountains are mostly very rugged, which greatly limits urban expansion. Similarly, major transportation routes are limited to a few mountain passes. Water supply to the city and drainage away from it both follow paths largely dictated by topography. Radio, television, and cell phone transmission towers are all sited with topography in mind to maximize coverage. Its climate and scenic mountain surroundings have been a major part of the appeal of the Los Angeles region as it has grown into one of the world's largest cities over the past 150 years. But the topography that has created this environment also results from and leads to significant natural hazards. The tall mountains result from tectonic compression and uplift of Earth's crust along a kink in the San Andreas fault. (The fault is seen here as a straight boundary between the Mojave Desert and the San |
|
Zagros Mountains, Iran, SRTM
…
PIA04955
Sol (our sun)
C-Band Interferometric Radar
…
| Title |
Zagros Mountains, Iran, SRTM Shaded Relief Anaglyph |
| Original Caption Released with Image |
Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C. Size: 98.1 kilometers (60.8 miles) by 148.1 kilometers (91.8 miles) Location: 27.3 degrees North latitude, 54.5 degrees East longitude Orientation: North toward the top Image Data: Shaded SRTM elevation model Date Acquired: February 2000, The Zagros Mountains in Iran offer a visually stunning topographic display of geologic structure in layered sedimentary rocks. This scene is nearly 100 kilometers (62 miles) wide but is only a small part of similar terrain that covers much of southern Iran. This area is actively undergoing crustal shortening, as global tectonics moves Arabia toward Asia. Consequently, layers of sedimentary rock are folding much like a carpet will fold if pushed. The convex upward folds create structures called anticlines, which are prominently seen here. The convex downward folds (between the anticlines) create structures called synclines, which are mostly buried and hidden by sediments eroding off the anticlines. Layers having differing erosional resistance create distinctive patterns, often sawtooth triangular facets, that encircle the anticlines. Local relief between the higher mountain ridges and their intervening valleys is about 1,200 meters (about 4,000 feet). Salt extrusions and salt "glaciers" are another set of geologic features readily evident in the topography. Salt deposits, likely created by the evaporation of an ancient inland sea, were buried by the sediments that now make up the layers of the anticlines and synclines. But salt is less dense than most other rocks, so it tends to migrate upward through Earth's crust in vertical columns called "diapirs". The compressive folding process has probably facilitated the formation of these diapirs, and the diapirs, in turn, are probably enhancing some anticlines by "inflating" them with salt. Where the diapirs reach the surface, the salt extrudes, much like lava from a volcano, and the salt flows. Two prominent salt flows are evident in the same valley, leaking from neighboring anticlines, just north of the scene center. This anaglyph was created by deriving a shaded relief image from the SRTM data, draping it back over the SRTM elevation model, and then generating two differing perspectives, one for each eye. Illumination is from the north (top). When viewed through special glasses, the anaglyph is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter. Elevation data used in this image were acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National |
|
Zagros Mountains, Iran, SRTM
…
PIA04956
Sol (our sun)
C-Band Interferometric Radar
…
| Title |
Zagros Mountains, Iran, SRTM Shaded Relief |
| Original Caption Released with Image |
The Zagros Mountains in Iran offer a visually stunning topographic display of geologic structure in layered sedimentary rocks. This scene is nearly 100 kilometers (62 miles) wide but is only a small part of similar terrain that covers much of southern Iran. This area is actively undergoing crustal shortening, as global tectonics moves Arabia toward Asia. Consequently, layers of sedimentary rock are folding much like a carpet will fold if pushed. The convex upward folds create structures called anticlines, which are prominently seen here. The convex downward folds (between the anticlines) create structures called synclines, which are mostly buried and hidden by sediments eroding off the anticlines. Layers having differing erosional resistance create distinctive patterns, often sawtooth triangular facets, that encircle the anticlines. Local relief between the higher mountain ridges and their intervening valleys is about 1200 meters (about 4000 feet). Salt extrusions and salt "glaciers" are another set of geologic features readily evident in the topography. Salt deposits, likely created by the evaporation of an ancient inland sea, were buried by the sediments that now make up the layers of the anticlines and synclines. But salt is less dense than most other rocks, so it tends to migrate upward through Earth's crust in vertical columns called "diapirs". The compressive folding process has probably facilitated the formation of these diapirs, and the diapirs, in turn, are probably enhancing some anticlines by "inflating" them with salt. Where the diapirs reach the surface, the salt extrudes, much like lava from a volcano, and the salt flows. Two prominent salt flows are evident in the same valley, leaking from neighboring anticlines, just north of the scene center. This shaded relief image was created directly from an SRTM elevation model by computing topographic slope in the north-south direction. Northern slopes appear bright and southern slopes appear dark. Elevation data used in this image were acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C. Size: 98.1 kilometers (60.8 miles) by 148.1, kilometers (91.8 miles) Location: 27.3 degrees North latitude, 54.5 degrees East longitude Orientation: North toward the top Image Data: Shaded SRTM elevation model Date Acquired: February 2000 |
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Gotel Mountains, Nigeria and
…
PIA04954
Sol (our sun)
C-Band Interferometric Radar
…
| Title |
Gotel Mountains, Nigeria and Cameroon, SRTM Shaded Relief plus Height as Brightness |
| Original Caption Released with Image |
River drainage patterns provide clues to the rock types and erosional processes involved in landscape evolution. Here in the Gotel Mountains along the border between Nigeria and Cameroon two distinct and highly contrasting patterns are evident. The lowlands in the northern and northwestern parts of the scene exhibit "dendritic" patterns, while the highlands in the southern and southeastern parts of the scene show "rectangular" and other linear drainage patterns. Dendritic drainage patterns appear almost random. Moving upstream, streams split into smaller and smaller channels, with finer and finer spacing, and they show little preference for map orientation other than to complete the pattern. In contrast, rectangular and other linear drainage patterns show a distinct preference for certain orientations in map view. In this scene, the two major preferred orientations are rotated slightly clockwise of north-south and east-west. Linear drainage patterns usually match the cracking patterns that can occur in relatively hard rocks, including igneous rocks such as granite and basalt. Stream erosion typically follows such lines of weakness in these hard rocks. Meanwhile, the randomness of dendritic patterns indicates that no such cracks nor any other geologic structure controls the erosion where that pattern occurs. Given the above, the topographic pattern in this scene appears to tell us the following about the geology of this location. The lowlands are composed of poorly consolidated (relatively soft) rocks or sediments that are at least 100 meters (330 feet) thick and are "massive" (uniform, with no prominent layering at the observed scale). The randomness of the dendritic patterns further indicates that stream erosion is the only significant dynamic process altering the lowland landscape. Forces such as volcanism and tectonics are not altering these landforms. Meanwhile, the neighboring highlands are composed of crystalline rocks, such as granite, that are very hard (generally resistant to erosion) and probably very old. Sometime through their history these rocks cracked, perhaps when they cooled, perhaps under tectonic stress, or perhaps when pressure upon them was relieved when they were unearthed by erosion. Now at the surface, these cracks are zones of weakness as these hard rocks otherwise resist stream erosion. But while the topographic data gives clues, it does not always provide definitive answers. Are the lowlands made up of soft sediments washed in from elsewhere or are they simply rocks "softened" by weathering (disintegration into sand) in place over time. If the latter, might they in fact have been granite also? The two patterns interfinger geographically, suggesting that the rugged highlands may be evolving into the dendritic lowlands. Weathering products (loose sands) tend to accumulate in place in low relief terrain because erosion there is slow to remove them. Also, granites are typically "massive" and cracking patterns, vanish when the rocks disintegrate. The topographic data indeed provide thought provoking evidence, but definitive answers will require fieldwork or other additional evidence. This image was created directly from an SRTM elevation model. A shade image was derived by computing topographic slope in the north-south direction. Northern slopes appear bright and southern slopes appear dark. The shade image was then merged with a height-as-brightness image, which helps clarify the continuity of the drainage networks. Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C. Size: 144.8 kilometers (89.8 miles) by 131.5 kilometers (81.5 miles) Location: 7 degrees North latitude, 10 degrees East longitude Orientation: North toward the top Image Data: SRTM elevation shaded plus height-as-brightness Date Acquired: February 2000 |
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