Japan’s Coastline Before and After the Tsunami
These images show the effects of the tsunami on Japan’s coastline. The image on the left was taken on Sept. 5, 2010; the image on the right was taken on March 12, 2011, one day after an earthquake and resulting tsunami struck the island nation.
Smoke Plume from Industrial Fires in Miyagi Prefecture, Japan
In the aftermath of the massive earthquake that struck northeastern Japan at 2:46 p.m. local time on March 11, 2011, and its subsequent tsunami, several oil refineries and industrial complexes caught fire, including facilities in the Port of Sendai and a petrochemical facility in Shiogama, where a large explosion has been reported. This pair of images, acquired on March 12, 2011 by the Multi-angle Imaging SpectroRadiometer (MISR) instrument aboard NASA’s Terra spacecraft, shows a large smoke plume that appears to be associated either with the Shiogama incident or the Sendai port fires. The presence of clouds makes it difficult to pinpoint the exact origin. The data were obtained at a local time of about 10:30 a.m.
The images are oriented with north at the left and east at the top, and cover an area measuring 85 kilometers by 115 kilometers (53 miles by 71 miles). The left-hand view is a natural-color image from MISR’s nadir (vertical viewing) camera. The large brown smoke plume extends about 85 kilometers (53 miles) southeast from the coastline. To confirm that the brown plume is an airborne feature, the right-hand image is a stereoscopic “anaglyph” created from data in MISR’s red spectral band, and generated by displaying the 46-degree backward view in red and 60-degree backward view in cyan. The separation between the red and cyan images is known as stereo parallax, and is related to the height of the observed features above the surface. Viewing the anaglyph with red-cyan glasses (red filter over the left eye) gives a perception of height. No separation is visible for the coastline, which is at sea level, but the clouds and plume are distinctly elevated. The height of the plume is estimated to be about 2 kilometers (1.2 miles), at a similar altitude as the nearby clouds.
Flooding from Tsunami near Sendai, Japan
NASA’s Terra satellite’s first view of northeastern Japan in the wake of a devastating earthquake and tsunami reveal extensive flooding along the coast. The Moderate Resolution Imaging Spectroradiometer (MODIS) acquired the right image of the Sendai region on March 12, 2011, at 10:30 a.m. The left image, taken by Terra MODIS on February 26, 2011, is provided as a point of reference.
Water is black or dark blue in these images. It is difficult to see the coastline in the March 12 image, but a thin green line outlines the shore. This green line is higher-elevation land that is above water, presumably preventing the flood of water from returning to the sea. The flood indicator on the left image illustrates how far inland the flood extends.
MISR Images Tsunami Inundation Along Japan’s Eastern Coast
The extent of inundation from the destructive and deadly tsunami triggered by the March 11, 2011, magnitude 8.9 earthquake centered off Japan’s northeastern coast about 130 kilometers (82 miles) east of the city of Sendai is revealed in this image pair from the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA’s Terra spacecraft. The new image, shown on the right, was acquired at 10:30 a.m. local time (01:30 UTC) on March 12, 2011 during Terra orbit 59731. For comparison, a MISR image from March 16, 2001, acquired under nearly identical illumination conditions during Terra orbit 6607, is shown on the left.
From top to bottom, each image extends from just north of the Abukuma River (which is about 21 kilometers, or 13 miles, south of Sendai) to south of the town of Minamisoma (population 71,000, located in Japan’s Fukushima Prefecture about 70 kilometers, or 44 miles, south of Sendai), and covers an area of 78 kilometers (48 miles) by 104 kilometers (65 miles). Flooding extending more than 4 kilometers (2.5 miles) inland from the eastern shoreline is visible in the post-earthquake image. The white sand beaches visible in the pre-earthquake view are now covered by water and can no longer be seen. Among the locations where severe flooding is visible is the area around Matsukawa-ura Bay, located just north and east of the image center.
These unique images enhance the presence of water in two ways. First, their near-infrared observations cause vegetated areas to appear red, which contrasts strongly with water. Second, by combining nadir (vertical-viewing) imagery with observations acquired at a view angle of 26 degrees, reflected sunglint enhances the brightness of water, which is shown in shades of blue. This use of observations at different view angles causes a stereoscopic effect, where elevated clouds have a yellow tinge at their top edges and blue tinge at their bottom edges.
Earthquake and Tsunami near Sendai, Japan
On March 11, 2011, at 2:46 p.m. local time (05:46 Universal Time, or UTC), a magnitude 8.9 earthquake struck off the east coast of Japan, at 38.3 degrees North latitude and 142.4 degrees East longitude. The epicenter was 130 kilometers (80 miles) east of Sendai, and 373 kilometers (231 miles) northeast of Tokyo. If the initial measurements are confirmed, it will be the world’s fifth largest earthquake since 1900.
This map shows the location of the March 11 earthquake, as well as the foreshocks (dotted lines) and aftershocks (solid lines). The size of each circle represents the magnitude of the associated quake or shock. The map also includes land elevation data from NASA’s Shuttle Radar Topography Mission and ocean bathymetry data from the British Oceanographic Data Center.
According to the U.S. Geological Survey (USGS), the earthquake occurred at a depth of 24.4 kilometers (15.2 miles) beneath the seafloor. The March 11 earthquake was preceded by a series of large foreshocks on March 9, including an M7.2 event. USGS reported that the earthquakes “occurred as a result of thrust faulting on or near the subduction zone interface plate boundary.”
The March 11 quake sent tsunami waves rushing into the coast of Japan and rippling out across the entire Pacific basin. Crescent-shaped coasts and harbors, such as those near Sendai, can play a role in focusing the waves as they approach the shore. Also, the land elevation is low and flat along much of the Japanese coast west and south of the earthquake epicenter, leaving many areas particularly vulnerable to tsunamis.
The Japan Meteorological Agency reported maximum tsunami heights of 4.1 meters at Kamaishi at 3:21 p.m. (06:21 UTC), 7.3 meters at 3:50 p.m. (06:50 UTC) at the Soma station, and 4.2 meters at 4:52 p.m. (07:52 UTC) at Oarai.
The U.S. Pacific Tsunami Warning Center (PTWC) reported a wave with maximum height of 2.79 meters (9.2 feet) at an observing station at Hanasaki, Hokkaido, at 3:57 p.m. local time (06:57 UTC). Other PTWC reports of tsunami waves include:
1.27 meters (4.2 feet) at 10:48 UTC at Midway Island
1.74 meters (5.7 feet) at 13:72 UTC at Kahului, Maui, Hawaii
1.41 meters (4.6 feet) at 14:09 UTC at Hilo, Hawaii
0.69 meters (2.3 feet) at 15:42 UTC in Vanuatu
1.88 meters (6.2 feet) at 16:54 UTC at Port San Luis, California
2.02 meters (6.6 feet) at 16:57 UTC at Crescent City, California
NASA Radar Image Shows Topography of Sendai, Japan Region
The topography surrounding Sendai, Japan is clearly visible in this combined radar image and topographic view generated with data from NASA’s Shuttle Radar Topography Mission (SRTM) acquired in 2000. 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, while the city center is 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 (3.3 inches) 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.
Japan
This image of Japan from 1999 was taken as part of SeaWiFS, the Sea-viewing Wide Field-of-view Sensor Project. The SeaWiFS Mission, which was part of NASA’s Earth Science Enterprise, was designed to look at our planet from space to better understand it as a system in both behavior and evolution.
