u .s d epa rtn of h i the m9.0 great tohoku earthquake ... · the magnitude 9.0 tohoku earthquake...

Map prepared by U.S. Geological SurveyNational Earthquake Information Center14 March 2011Map not approved for release by Director USGS

EARTHQUAKE SUMMARY MAP XXXU.S. DEPARTMENT OF THE INTERIORU.S. GEOLOGICAL SURVEY

DISCLAIMER

Base map data, such as place names and politicalboundaries, are the best available but may not be current or may contain inaccuracies and thereforeshould not be regarded as having official significance.

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The M9.0 Great Tohoku Earthquake (northeast Honshu, Japan) of March 11, 2011

0 100 20050Kilometers

Tokyo

Shanghai

Seoul

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DATA SOURCES

EARTHQUAKES AND SEISMIC HAZARD USGS, National Earthquake Information Center NOAA, National Geophysical Data Center IASPEI, Centennial Catalog (1900 - 1999) and extensions (Engdahl and Villaseñor, 2002) HDF (unpublished earthquake catalog) (Engdahl, 2003) Global Seismic Hazard Assessment Program

PLATE TECTONICS AND FAULT MODEL PB2002 (Bird, 2003) Finite Fault Model, Gavin Hayes, USGS (2011)

BASE MAP NIMA and ESRI, Digital Chart of the World USGS, EROS Data Center NOAA GEBCO and GLOBE Elevation Models

0 270 540 810 1,080135Miles

Scale

Prepared in cooperation

with the Global Seismographic

Network

Tectonic Setting

Seismic Hazard

Epicentral Region

M7.1 Near the East Coast of Honshu, Japan of March 11th, 2011 11 March 2011 6:25:50 UTC 38.106° N., 144.553° E.Depth 19.7 kmM = 7.1 (USGS)

M9.0 GREAT TOHOKU TECTONIC SUMMARY

The magnitude 9.0 Tohoku earthquake on March 11, 2011, whichoccurred near the northeast coast of Honshu, Japan, resulted fromthrust faulting on or near the subduction zone plate boundarybetween the Pacific and North America plates. At the latitude of thisearthquake, the Pacific plate moves approximately westwards withrespect to the North America plate at a rate of 83 mm/yr, and beginsits westward descent beneath Japan at the Japan Trench. Note thatsome authors divide this region into several microplates that togetherdefine the relative motions between the larger Pacific, North Americaand Eurasia plates; these include the Okhotsk and Amur microplatesthat are respectively part of North America and Eurasia.

The March 11 earthquake was preceded by a series of largeforeshocks over the previous two days, beginning on March 9th witha M 7.2 event approximately 40 km from the epicenter of the March11 earthquake, and continuing with another three earthquakes greaterthan M 6 on the same day.

The Japan Trench subduction zone has hosted nine events ofmagnitude 7 or greater since 1973. The largest of these, a M 7.8earthquake approximately 260 km to the north of the March 11epicenter, caused 3 fatalities and almost 700 injuries in December1994. In June of 1978, a M 7.7 earthquake 35 km to the southwest ofthe March 11 epicenter caused 22 fatalities and over 400 injuries.Large offshore earthquakes have occurred in the same subductionzone in 1611, 1896 and 1933 that each produced devastating tsunamiwaves on the Sanriku coast of Pacific NE Japan. That coastline isparticularly vulnerable to tsunami waves because it has many deepcoastal embayments that amplify tsunami waves and cause greatwave inundations. The M 7.6 subduction earthquake of 1896 createdtsunami waves as high 38 m and a reported death toll of 22,000. TheM 8.6 earthquake of March 2, 1933 produced tsunami waves as highas 29 m on the Sanriku coast and caused more than 3000 fatalities.

The March 11, 2011 earthquake was an infrequent catastrophe. It farsurpassed other earthquakes in the southern Japan Trench of the 20thcentury, none of which attained M8. A predecessor may haveoccurred on July 13, 869, when the Sendai area was swept by a largetsunami that Japanese scientists have identified from written recordsand a sand sheet.

Seismic hazard is expressed as peakground acceleration (PGA) on firmrock, in meters/sec², expected to beexceeded in a 50-yr period with aprobability of 10 percent.

EXPLANATION

M9.0 Great Tohoku

M7.9 Aftershock

M7.2 Foreshock

M7.1 Aftershock

Mag ≥ 7.00 - 69 km

70 - 299

300 - 600

Plate BoundariesSubduction

Transform

Divergent

Others

RELATIVE PLATE MOTIONS

The red vectors represents the motion of the Pacific Plate relativeto the Philippine Plate, and the Philippine Plate relative to theEurasia Plate in the region. The motion of the Pacific Plate isgenerally 60 mm/yr north westward with respect to thePhilippine Plate. The motion of the Philippine Plate is generally44 mm/yr north westward with respect to the Eurasia Plate.

0 250 500 750 1,000125Miles

Scale

REFERENCES

Bird, P., 2003, An updated digital model of plate boundaries: Geochem. Geophys. Geosyst., v. 4, no. 3, pp. 1027- 80.

Engdahl, E.R. and Villaseñor, A., 2002, Global Seismicity: 1900 - 1999, chap. 41 of Lee, W.H.K., and others,eds., International Earthquake and Engineering Seismology, Part A: New York, N.Y., Elsevier Academeic Press, 932 p.

Engdahl, E.R., Van der Hilst, R.D., and Buland, R.P., 1998, Global teleseismic earthquake relocation with improved trav- el times and procedures for depth determination: Bull. Seism. Soc. Amer., v. 88, p. 722-743.

The GEBCO_08 Grid, version 20090202, http://www.gebco.net

1:5,000,000Scale

Significant Earthquakes Mag >= 7.5

Year Mon Day Time Lat Long Dep Mag1901 08 09 1833 40.600 142.300 35 7.51906 01 21 1349 34.000 137.000 350 7.71909 03 13 1429 34.500 141.500 35 7.61915 11 01 0724 38.300 142.900 35 7.51923 09 01 0258 35.405 139.084 35 7.91923 09 02 0246 34.900 140.200 35 7.61927 03 07 0927 35.802 134.924 9.6 7.61931 03 09 0348 40.484 142.664 35 7.71933 03 02 1731 39.224 144.622 35 8.41938 05 23 0718 36.458 141.755 35 7.71938 11 05 0843 37.009 142.045 35 7.91938 11 05 1050 37.108 142.081 35 7.81938 11 06 0853 37.287 142.283 35 7.71944 12 07 0435 33.750 136.000 0 8.11953 11 25 1748 34.034 141.786 35 7.91960 03 20 1707 39.871 143.435 2.1 7.81964 06 16 0401 38.434 139.226 13.1 7.51968 05 16 0049 40.903 143.346 25.8 8.31972 02 29 0923 33.377 140.881 58.8 7.51978 06 12 0814 38.224 142.009 53.3 7.71983 05 26 0300 40.468 139.080 20 7.71994 12 28 1219 40.530 143.403 29.2 7.82011 03 11 0546 38.322 142.369 24.4 8.9

Peak Ground Acceleration in m/sec**2

.2 .4 .8 1.6 2.4 3.2 4.0 4.8

EPICENTRAL REGION

EXPLANATION

M9.0 Great Tohoku

M7.9 Aftershock

M7.2 Foreshock

M7.1 Aftershock

Earthquake Magnitude5.50 - 5.99

6.00 - 6.99

7.00 - 7.99

8.00 - 8.99

9.00 - 9.99

Earthquake Depth0 - 69

70 - 299

300 - 700

Aftershocks

Foreshocks

1:20,000,000

1:20,000,000

EPICENTRAL REGION

PAGER

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Distribution of the amplitude and direction of slip for subfault elements ofthe fault rupture model are determined from the inversion of teleseismicbody waveforms and long period surface waves. Arrows indicate theamplitude and direction of slip (of the hanging wall with respect to thefoot wall); the slip is also colored by magnitude. The view of the ruptureplane is from above. The strike of the fault rupture plane is S19E and thedip is 14 WNW. The dimensions of the subfault elements are 30 km in thestrike direction and 20 km in the dip direction. The rupture surface is 400km along strike and 150 km downdip. The seismic moment release basedupon this plane is 4.04e+29 dyne.cm.

80 mm/yr

Finite Fault Model

Did You Feel It?

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M9.0 Great Tohoku Earthquake of March 11th, 2011 11 March 2011 5:46:23 UTC 38.322° N., 142.369° E.Depth 24.4 kmMw = 9.0 (USGS)

M7.9 Near the East Coast of Honshu, Japan of March 11, 2011 11 March 2011 6:15:40 UTC 36.186° N., 141.192° E.Depth 35 kmMw = 7.9 (USGS)

M7.2 Near the East Coast of Honshu, Japan of March 9, 2011 09 March 2011 2:45:20 UTC 38.424° N., 142.836° E.Depth 32 kmMw = 7.2 (USGS)

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