Last updated 2 April 2011
A magnitude 9.0 earthquake occurred at 02:46:23 PM local time on March 11, 2011, near the east coast of Honshu, Japan. Five minutes in duration, it triggered a tsunami of more than 10 m in height, causing immense damage along the northeast coast of Japan.
The UNAVCO community has been in communication with other agencies to stay abreast of needs that UNAVCO can help to fulfill.
The event coordinator is Dr. Frederick Blume (blumeunavco.org).
Letters from Japan
1 April, 2011
Dear UNAVCO Community,
Fatalities and missing due to this disaster are close to 30,000, which is the worst loss since the 1923 Great Kanto Earthquake. Reactors in Fukushima are still in critical condition, which prevents us from relief and survey.
However researchers and satellites are working hard to reveal what's going on. ALOS already made several observations. Unfortunately ScanSAR observation was not successful because of long baselines, but we already processed three strip-map mode images to obtain deformation (click here for link), which impresses us with its scale again. GEONET is recovering owing to devoted efforts of GSI and showing us postseismic evolution.
We continue monitoring the deformation of Japanese Island to understand how this earthquake happened and what we were short of. Sincerely yours,
16 March, 2011
What a huge disaster it has been! It is very regrettable that the number of casualties and missing exceeded 10,000, which is the worst after the World War II. The Japanese Island also suffered from this big shock. Seismicity became higher than before. We had a medium shock near Mt.Fuji last night.
13 March, 2011
Two nights have passed since the devastating disaster. Unbelievably huge damages are being revealed time after time.
Adapted from the USGS Summary
Weeklong aftershock sequence clearly delineates the rupture zone of the M9 Event between the Japan trench and the Honshu Mainland. Created with Jules Verne Voyager tool by Lou Estey (UNAVCO). [View full scale image].
The March 11, 2011, M9.0 earthquake near the east coast of Honshu, Japan, occurred along the subduction zone at the interface between the Pacific and North American tectonic plates.
At this latitude, the Pacific plate moves approximately westwards with respect to the the Okhotsk microplate, which is considered part of the North American plate in the MORVEL 2010 conventions, at a velocity of 83 mm/yr. The Pacific plate thrusts underneath Japan at the Japan Trench, and then dips to the west beneath Eurasia.
The location, depth, and focal mechanism of the March 11 earthquake are consistent with it resulting from thrust faulting associated with subduction along this plate boundary.
The March 11 earthquake was preceded by a series of large foreshocks over the previous two days, beginning on March 9th with an M7.2 event approximately 40 km from the March 11 earthquake, and continuing with a further 3 earthquakes greater than M6 on the same day.
Figure 2 - Preliminary fault model from Geospatial Information Authority of Japan (GSI) showing observed and calculated GPS displacements from select GEONET stations. See http://www.gsi.go.jp/cais/topic110313-index-e.html for further details. [Download PDF].
Figure 3 - Preliminary highly smoothed model of coseismic slip for the 11 March main shock. Red and yellow vectors show horizontal (left) and vertical (right) predicted and observed displacements respectively. The triangulated model geometry follows the megathrust as close as possible. Model derived with a least squares inversion using Laplacian damping, constrained by both GPS displacements and 12 DART buoy tsunami records. GPS offsets are derived from 5 minute epoch time series processed by the ARIA team at JPL and Caltech. Displacements due aftershocks have been isolated and removed. This model was generated by M. Simons, F. Ortega, J. Jiang, A. Sladen, and S. Minson at Caltech Tectonics Observatory as part of the ARIA project. All orginal GEONET RINEX data provided to Caltech by the Geospatial Information Authority (GSI) of Japan. [View full scale image].
Figure 4 - Horizontal displacements based on ARIA version 0.3 position estimated for GEONET stations. Coseismic displacement is shown in red, and the first 8 hours of postseismic motion is shown in blue, including motion caused by aftershocks. Bars at the end of the vectors show 95% error estimate. Solutions courtesy of ARIA team at JPL and Caltech. Direct links to the displacement data, contact information and updates can be found in the Event Forum topic. Animated visualization of the displacements by Ronni Grapenthin (U of Alaska) is available here. All GEONET RINEX data provided to Caltech by the Geospatial Information Authority (GSI) of Japan. [View full scale image].
Figure 5 - A one-meter tsunami first arrives at the Hiratsuka buoy at about 6:35 UTC. It is interesting to note the change in buoy motion at about 5:50 UTC (most visible in the 11-sec running average) which appears to coincide with the arrival of seismic waves. The shown PPP solution was post processed with the real-time global orbit and clock product from the VERIPOS/APEX service. See the GPS Solutions event page for maps and further details, including true realtime solutions for stations further from the epicenter. [View full scale image].
Figure 6 - 5 second GPS coordinate solutions of GEONET station 0171 on the Japanese coast, provided by GPS Solutions. Shown are PPP results post processed using realtime orbit and clock corrections from the VERIPOS/APEX service. Time series shows nearly 5 meters of coseismic displacement and one meter of subsidence. See the GPS Solutions event page for maps and further details, including true realtime solutions for stations further from the epicenter. [View full scale image].
Figure 7 - Post-processed kinematic GPS solution from International GNSS Service station at the Usuda Deep Space Tracking Station in central Japan, 350 km SW of the epicenter. Courtesy of Simon Banville, University of New Brunswick, Canada.[View full scale image].
Figure 8 - Stacked real-time 1 Hz displacement waveforms for more than 100 UNAVCO, USGS/SCIGN,and SIO GPS stations in the southern California region streaming to the California Real Time Network. Courtesy of Yehuda Bock, Brendan Crowell and Diego Melgar of Scripps Orbit and Permanent Array Center. They show the passage of the S-wave at about 1400 seconds and the Love wave at about 2000 seconds after the onset of the M=9.0 Honshu earthquake. Additional details are available in the full pdf presentation. [View full scale image].
Figure 9 - Plots of borehole strainmeter data from British Columbia, Canada show crustal deformation in response to the main shock tsunami that impacted the coast near the sites. B927, located at the end of a long fjord in the town of Port Alberni, shows both a delay and amplification of the peak signals as the tsunami is focused up the fjord (Kathleen Hodgkinson, UNAVCO). [View full scale image]. Click here to see a map of borehole strainmeter locations on Vancouver Island.
Last modified: Thursday, 23-Jul-2015 15:06:30 UTC