Map prepared by U.S. Geological SurveyNational Earthquake Information Center19 September 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.

Xizang

Uttar Pradesh

Karnali

Seti

Arunachal Pradesh

BheriRapti

GandakiBagmati

Lumbini

Janakpur

SikkimAssam

KosiMechiNarayani

Ha

Bihar

Sagaing

West Bengal

Nagaland

Madhya Pradesh

Rajshahi

Meghalaya

Manipur

Dhaka

Tripura Mizoram

KhulnaChin State

Chittagong

1934

1950

1908

1915

1916

19181923

1930

1932

1934

1936

1938

1943

1947

1951

1952

1954

1988

96°

94°

94°

92°

92°

90°

90°

88°

88°

86°

86°

84°

84°

82°

82°

80°

32°

30°

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26°

26°

24°

22°

EURASIA PLATE

INDIA PLATE

BURMAPLATE

SUNDA PLATEA R A B I A N

S E A

Y E L L O W

S E A

A N D A M A NS E AB A Y O F

B E N G A L

HI M

A L A Y A

T i a n S h a n

K u n j u n M o u n t a i n s

Chan

g Ja

ing

Huan

g H e

A l t y n Ta g h F a u l t

K u n l u n F a u l t

S u m a t r a F a u l t

B A N G L A -D E S H

M Y A N M A R

( B U R M A )

T H A I L A N D

C H I N A

P A K I S T A N

A F G H A N I S T A N

I N D I A

N E P A L

U Z B E K I S TA N

T A J I K I S T A N

K Y R G Y Z S T A N

M A L A Y S I A

C A M B O D I A

V I E T N A M

L A O S

B H U T A N

Gulfof

Thailand

A r a b i a n B a s i n

Cha g o s - L a c c a d i v e P l at e a u

1941

2004

1881

120°110°

100°

100°

90°

90°

80°

80°

70°

70°

40°

30°

30°

20°

20°

10°

M 6.9 India-Nepal Border Region Earthquake of 18 September 2011

0 300100 200Kilometers

TashkentLanzhou

Kabul

Xi'an

LahoreFaisalabad

Chengdu

Wuhan

Chongqing

Nanchang

Changsha

Jaipur Lucknow

Guiyang

Kanpur

Kunming

Dhaka

BhopalAhmadabadCalcutta Chittagong

Nagpur

Hanoi

PuneHyderabad

Rangoon

MadrasBangalore

Ho ChiMinh City

110°

100°

100°

90°

90°

80°

80°

70°

70°

40°

30°

30°

20°

20°

10°

0 500 1,000 1,500250Kilometers

Scale

Prepared in cooperation

with the Global Seismographic

Network

Tectonic Setting

Seismic Hazard

Epicentral Region

TECTONIC SUMMARY

The September 18, 2011 India-Nepal border region earthquakeoccurred near the boundary between the India and Eurasia plates, inthe mountainous region of northeast India near the Nepaleseboarder. Initial analyses suggest the earthquake was complex, likelya result of two events occurring close together in time at depths ofapproximately 20 km beneath the Earth's surface. At the latitude ofthe September 18 earthquake, the India plate converges withEurasia at a rate of approximately 46 mm/yr towards the north-northeast. The broad convergence between these two plates hasresulted in the uplift of the Himalayas, the world's tallest mountainrange. The preliminary focal mechanism of the earthquake suggestsstrike slip faulting, and thus an intraplate source within the upperEurasian plate or the underlying India plate, rather than occurringon the thrust interface plate boundary between the two.

This region has experienced relatively moderate seismicity in thepast, with 18 earthquakes of M 5 or greater over the past 35 yearswithin 100 km of the epicenter of the September 18 event. Thelargest of these was a M 6.1 earthquake in November of 1980, 75km to the southeast.

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.

EXPLANATIONEarthquake Depth

0 - 69 km70 - 299VolcanoesSubductionTransformDivergentOthers

RELATIVE PLATE MOTIONS

The motion of the Inda Plate is generally 40 -50 mm/yr northward with respect to theEurasia Plate.

0 500 1,000 1,500250Kilometers

Scale

1:4,187,252Scale

Earthquakes Mag >= 6.5

Year Mon Day Time Lat Long Dep Mag1901 04 21 0000 29.500 90.100 0 6.81905 02 17 1142 26.000 96.000 0 6.81906 08 31 1457 27.000 97.000 100 6.71908 08 20 0953 32.000 89.000 60 7.01908 12 12 1254 26.500 97.000 0 7.01909 08 04 0000 28.800 90.500 0 6.51911 10 14 2324 31.000 80.500 0 6.81915 12 03 0239 29.500 91.500 0 7.01916 08 28 0639 30.000 81.000 0 7.21918 07 08 1022 24.809 90.725 15 7.51923 09 09 2203 24.943 90.320 35 7.11930 07 02 2103 25.641 90.245 35 7.11931 01 27 2009 25.675 96.755 35 7.61932 08 14 0439 25.765 95.655 143 7.01934 01 15 0843 26.773 86.762 35 8.11934 12 15 0157 31.013 89.080 35 7.11936 05 27 0619 28.345 83.283 35 7.01938 04 14 0116 23.372 94.407 35 6.81938 08 16 0427 22.957 93.884 35 7.11939 05 27 0345 24.461 93.955 46.9 6.81941 01 21 1241 27.339 91.714 15 6.81943 10 23 1723 26.000 93.000 0 7.11944 10 17 1836 31.500 83.500 0 6.81944 10 29 0011 31.500 83.500 0 6.81946 09 12 1517 23.500 96.000 0 7.31946 09 12 1520 23.500 96.000 0 7.71947 07 29 1343 28.500 94.000 0 7.31950 08 15 1409 28.500 96.500 0 8.61951 11 18 0926 30.500 91.500 0 6.81951 11 18 0935 30.500 91.000 0 7.71952 08 17 1602 30.797 91.648 10 7.71954 03 21 2342 24.420 95.104 186 7.41957 07 01 1930 24.308 93.880 78 6.81966 03 06 0215 31.453 80.469 41.1 7.01980 07 29 1458 29.616 81.100 13.8 6.61988 08 06 0036 25.090 95.108 90.5 7.31988 08 20 2309 26.758 86.624 57 6.91991 01 05 1457 23.582 95.878 17.7 7.02008 08 25 1321 30.901 83.520 12 6.72011 09 18 1240 27.723 88.064 19.7 6.9

Peak Ground Acceleration in m/sec**2

.2 .4 .8 1.6 2.4 3.2 4.0 4.8

EPICENTRAL REGION

EXPLANATIONMain Shock

Earthquake Magnitude4.00 - 6.006.01 - 7.007.01 - 8.00

8.01 - 9.00

Earthquake Depth0 - 6970 - 299

1:20,000,000

1:20,000,000

EPICENTRAL REGION

M 6.9 India-Nepal Border Region Earthquake 18 September 2011 12:40:4827.723°N, 88.064°EDepth 19.7 kmMw = 6.9 (USGS)

PAGER

ShakeMap

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.

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)

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

DYFI