Shaded Relief and Radar Image with Color as Height
The Bosporus (also spelled Bosphorus) is a strait that connects the Black Sea with the Sea
of Marmara in the center of this view of northwest Turkey, taken during
the Shuttle Radar Topography Mission. The water of the Black Sea at the
top of the image and Sea of Marmara below the center are colored blue in
this image, along with several large lakes. The largest lake, to the
lower right of the Sea of Marmara, is Iznik Lake. The Bosporus (Turkish
Bogazici) Strait is considered to be the boundary between Europe and
Asia, and the large city of Istanbul, Turkey is located on both sides
of the southern end of the strait, visible as a brighter (light green
to white) area on the image due to its stronger reflection of radar.
Istanbul is the modern name for a city with a long history, previously
called Constantinople and Byzantium. It was rebuilt as the capital of
the Roman Empire in 330 A.D. by Constantine on the site of an earlier
Greek city, and it was later the capital of the Byzantine and Ottoman
empires until 1922.
The Gulf of Izmit is the narrow gulf extending to the east (right)
from the Sea of Marmara. The city of Izmit at the end of the gulf was
heavily damaged by a large magnitude 7.4 earthquake on August 17, 1999,
often called the Izmit earthquake (also known as the Kocaeli, Turkey,
earthquake), that killed at least 17,000 people. A previous earthquake
under the Gulf of Izmit in 1754 killed at least 2,000 people. The Izmit
earthquake ruptured a long section of the North Anatolian Fault system
from off the right side of this image continuing under the Gulf of Izmit. Another strand of the North Anatolian Fault system is visible as a sharp linear feature in the topography south of Iznik Lake. Bathymetric surveys show that the North Anatolian Fault system extends beneath and has formed the Sea of Marmara, in addition to the Gulf of Izmit and Iznik Lake. Scientists are studying the North Anatolian Fault system to determine the risk of a large earthquake on the faults close to Istanbul that could kill many more than the 1999 event.
Three visualization methods were combined to produce this image:
shading and color coding of topographic height and radar image intensity.
The shade image was derived by computing topographic slope in the
northwest-southeast direction. Northwest-facing slopes appear dark and
southeast-facing slopes appear bright. Color coding is directly related
to topographic height, with green at the lower elevations, rising
through yellow and brown to white at the highest elevations. The shade
image was combined with the radar intensity image to add detail,
especially in the flat areas.
Elevation data used in this image was acquired by the Shuttle Radar
Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched
on Feb. 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 3-D measurements of the Earth's surface.
To collect the 3-D data, engineers added a 60-meter (approximately
200-foot) mast, installed additional C-band and X-band antennas, and
improved tracking and navigation devices. The mission is a cooperative
project between NASA, the National Geospatial-Intelligence Agency (NGA) of
the U.S. Department of Defense 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: 2x2 degrees (168 by 222 kilometers; 104 by 138 miles)
Location: 40-42 degrees North latitude, 28-30 degrees East longitude
Orientation: North toward the top
Image Data: shaded and colored SRTM elevation model, with SRTM radar
intensity added
Original Data Resolution: SRTM 1 arcsecond
(about 30 meters or 98 feet)
Date Acquired: February 2000 (SRTM)
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