Topography of Sendai, Japan

The topography surrounding Sendai, Japan is well shown in this combined radar image and topographic view generated with data from NASA's Shuttle Radar Topography Mission (SRTM). On March 11, 2011, a magnitude 8.9 earthquake struck offshore about 130 kilometers (80 miles) east of Sendai, the capital city of Japan's Miyagi Prefecture, generating a tsunami that devastated the low-lying coastal city of about 1 million residents.

The city is centered in the image and lies along the coastal plain between the Ohu Mountains and the Pacific Ocean. The eastern part of the city is a low-lying plains area, with the city center being hilly (the city's official elevation is about 43 meters, or 141 feet). Sendai's western areas are mountainous, with its highest point being Mt. Funagata at an elevation of about 1,500 meters (4,921 feet) above sea level.

According to the U.S. Geological Survey, the earthquake occurred as a result of thrust faulting on or near the subduction zone interface plate boundary between the Pacific and North America plates. At the latitude of this earthquake, the Pacific plate moves approximately westwards with respect to the North America plate at a velocity of 83 millimeters per year. The Pacific plate thrusts underneath Japan at the Japan Trench, and dips to the west beneath Eurasia. The location, depth, and focal mechanism of the March 11 earthquake are consistent with the event having occurred as thrust faulting associated with subduction along this plate boundary.

This image combines a radar image acquired in February 2000 during the SRTM mission, and color-coding by topographic height using data from the same mission. Dark green colors indicate low elevations, rising through yellow and tan, to white at the highest elevations.

Location: 38.25 degrees North latitude, 140.85 degrees East longitude
Orientation: North toward the top
Size: approximately 174 by 160 kilometers (108 by 99 miles)
SRTM Data Acquired: February 2000

Image credit: NASA/JPL/NGA

Harrat Lunayyir, Saudi Arabia

A swarm of thousands of earthquakes that struck the corner of Saudi Arabia nearest to Egypt in 2009 helped reveal that the area is unexpectedly volcanically active. Scientists had largely thought northwest Saudi Arabia was quiet, geologically speaking. Few earthquakes and few volcanic eruptions have been recorded there in the past millennium. However, between April and June 2009, more than 30,000 micro-earthquakes struck an ancient lava field there named Harrat Lunayyir, with 19 earthquakes of magnitude 4 or greater, including one quake that fractured walls at a nearby town. The image was acquired October 8, 2006, covers an area of 57 x 57 km, and is located near 25.2 degrees North latitude, 37.8 degrees East longitude.

Photo credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team