Map prepared by U.S. Geological Survey National Earthquake Information Center 2 October 2009 Map not approved for release by Director USGS EARTHQUAKE SUMMARY MAP XXX U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY DISCLAIMER Base map data, such as place names and political boundaries, are the best available but may not be current or may contain inaccuracies and therefore should not be regarded as having official significance. Sumatra Java Siberut Sipora N Pagai S Pagai Enggano Pini Nias Tanahbala I N D O N E S I A 2004 1797 2005 1833 2000 Jakarta Melaka Negeri Sembilan Selangor Pahang Sumatera Selatan Songkhla Terengganu Perak Kelantan Pulau Pinang Kedah Narathiwat Andaman and Nicobar Islands Yala Perlis Pattani Jawa Tengah Jakarta Raya Jawa Barat Lampung Johor Sumatera Barat Bengkulu Kalimantan Barat Jambi Kalimantan Tengah Singapore Sumatera Utara Aceh Riau 2005 2004 2004 2004 2007 2007 2007 2007 2008 2008 A' A Padang Jambi Bengkulu Tanjungkarang- Telukbetung Alor Setar Kuantan New Port Yala Kota Baharu Pinang Banda Aceh Kuala Terengganu Ipoh Seremban Melaka Johor Baharu Pekanbaru Singapore Semarang Bandung Palembang Kuala Lumpur Medan Narathiwat Kemaman Harbor Pattani Satun Kangar Kuala Lipis Shah Alam 1907 1913 1914 1916 1900 1984 2001 2000 1998 1983 1976 1975 1971 1969 1963 1957 1955 1950 1949 1909 1946 1943 1943 1943 1943 1936 1936 1936 1935 1935 1933 1931 1931 1917 110° 110° 108° 108° 106° 106° 104° 104° 102° 102° 100° 100° 98° 98° 96° 96° 94° 94° 92° 92° 6° 4° 2° 2° 0° 2° 2° 4° 4° 6° 6° PALAWAN TROUGH S U N D A ( J AV A ) TRE N CH A PLATE BURMA PLATE SUNDA PLATE MOLUCCA SEA PLATE BANDA SE AUSTRALIA PLATE SOUTH CHINA SEA JAVA SEA ANDAMAN SEA BAY OF BENGAL Borneo Sumatra Java Lesser Sunda Islands Greater Sunda Islands Sumatra Fault Philippine Fault I N D O N E S I A RI LANKA THAILAND SINGAPORE MALAYSIA CAMBODIA VIETNAM PHILIPPIN BRUNEI MALAYSIA Gulf of Thailand Mid-Indian Basin North Australian Basin inet y Ea s t R i d g e I n v e s t i g a t o r R i d g e Osborn Plateau Celebes Basin 60 mm/yr 1833 2000 2005 2004 1797 120° 120° 110° 110° 100° 100° 90° 90° 10° 10° 0° 0° 10° M7.6 Southern Sumatra, Indonesia, Earthquake of 30 September 2009 0 220 440 660 880 110 Kilometers Palembang Surabaya Quezon City Manila Phnom Penh Davao Medan Kuala Lumpur Singapore Makassar Bandung Semarang Darwin Quang Ngai Kuantan New Port Nakhon Sawan Ubon Ratchathani Pinang Nakhon Ratchasima Saraburi Phra Nakhon Si Ayutthaya Tavoy Play Cu Qui Nhon Samut Prakan Samut Sakhon Siemreab Batdambang Buon Me Thuot Nha Trang Da Lat Port Blair Bien Hoa Phan Thiet Long Xuyen My Tho Vinh Long Can Tho Rach Gia Soc Trang Bac Lieu Nakhon Si Thammarat Songkhla Yala Kota Baharu Alor Setar Kota Kinabalu Banda Aceh Kuala Terengganu Bandar Seri Begawan Ipoh Seremban Melaka Kuching Johor Baharu Manado Pekanbaru Pontianak Samarinda Padang Balikpapan Jambi Palangkaraya Bandjermasin Ambon Bengkulu Kendari Tanjungkarang- Telukbetung Yogyakarta Dili Mataram Kupang Jakarta Bangkok 130° 130° 120° 120° 110° 110° 100° 100° 10° 10° 0° 0° 10° 10° 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, Chen Ji, UC Santa Barbara (2007) BASE MAP NIMA and ESRI, Digital Chart of the World USGS, EROS Data Center NOAA GEBCO and GLOBE Elevation Models 0 410 820 1,230 1,640 205 Kilometers Prepared in cooperation with the Global Seismographic Network Tectonic Setting Seismic Hazard Epicentral Region Southern Sumatra 30 September 2009 10:16:09 UTC 0.788° S., 99.961° E. Depth 80 km Mw = 7.6 (USGS) 45 km (30 miles) WNW of Padang, Sumatra, Indonesia 220 km (135 miles) SW of Pekanbaru, Sumatra, Indonesia 475 km (295 miles) SSW of KUALA LUMPUR, Malaysia TECTONIC SUMMARY The magnitude 7.6 southern Sumatra earthquake of September 30, 2009 occurred as a result of oblique-thrust faulting near the subduction interface plate boundary between the Australian and Sunda plates. At the location of this earthquake, the Australian Plate moves northeast with respect to the Sunda plate at a velocity of approximately 60 mm/yr. On the basis of the currently available fault mechanism information and earthquake depth of 80 km, it is likely that this earthquake occurred within the subducting Australian Plate rather than on the plate interface itself. The recent earthquake was deeper than typical subduction thrust earthquakes that generally occur at depths less than 50 km. The subduction zone surrounding the immediate region of this event has not witnessed a megathrust earthquake in the recent past, rupturing last in an earthquake of M 8.5 or larger in 1797. Approximately 350km to the south, a 250km section of the plate boundary slipped during an Mw 8.4 earthquake in September 2007, while approximately 300km to the north, a 350km section slipped during the Mw 8.7 earthquake of March 2005. In early 2008, the plate boundary updip of today's earthquake was active in a sequence of Mw 5-6 earthquakes. It is not clear how today's earthquake is related to the sequence of megathrust subduction zone events on the shallower section of the plate boundary. Seismic hazard is expressed as peak ground acceleration (PGA) on firm rock, in meters/sec², expected to be exceeded in a 50-yr period with a probability of 10 percent. EXPLANATION Mag ≥ 7.0 0 - 69 km 70 - 299 300 - 600 Plate Boundaries Subduction Transform Divergent Others Andaman Faults Rupture Area (Year) RELATIVE PLATE MOTIONS In the region of this earthquake, the Australia Plate moves north-northwest with respect to the Sunda Plate at about 65 mm/yr. 0 410 820 1,230 1,640 205 Kilometers 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 Significant Earthquakes Mag >= 7.0 Year Mon Day Time Lat Long Dep Mag 1900 01 05 1900 -3.000 102.000 0 7.0 1907 01 04 0519 2.000 94.500 50 7.5 1909 06 03 1840 -2.000 101.000 0 7.2 1913 08 13 0425 -5.500 105.000 75 7.3 1914 06 25 1907 -4.500 102.500 0 7.6 1916 07 27 1152 4.000 96.500 100 7.0 1917 11 04 1203 4.800 96.800 0 7.1 1931 02 10 0634 -5.433 102.458 35 7.1 1931 09 25 0559 -5.178 102.511 35 7.3 1933 06 24 2154 -5.522 104.434 35 7.3 1935 08 03 0110 4.430 96.326 35 7.0 1935 12 28 0235 -0.345 98.147 35 7.8 1936 01 02 2234 -0.279 98.872 35 7.0 1936 08 23 2112 5.296 94.759 35 7.1 1936 09 19 0101 3.648 97.551 35 7.1 1943 04 01 1418 -6.500 105.500 0 7.1 1943 06 08 2042 -1.000 101.000 50 7.2 1943 06 09 0306 -1.000 101.000 50 7.5 1943 11 26 2125 -2.500 100.000 130 7.1 1946 05 08 0520 0.000 99.500 0 7.1 1949 06 24 2238 -6.200 105.700 65 7.0 1950 03 27 2118 -5.900 102.900 0 7.0 1955 05 17 1449 6.738 93.754 29.1 7.2 1957 04 16 0404 -4.504 107.244 600 7.2 1963 12 15 1934 -4.764 108.050 668 7.1 1969 11 21 0205 1.973 94.574 11 7.6 1971 02 04 1533 0.552 98.665 60 7.1 1975 10 01 0330 -4.859 102.145 37.2 7.0 1976 06 20 2053 3.437 96.254 16.2 7.0 1983 04 04 0251 5.724 94.694 94.5 7.0 1984 11 17 0649 0.179 97.959 28.7 7.1 1998 04 01 1756 -0.544 99.217 32 7.0 2000 06 04 1628 -4.762 102.007 34.6 7.9 2001 02 13 1928 -4.933 102.454 34 7.3 2004 07 25 1435 -2.427 103.981 582 7.3 2004 12 26 0058 3.295 95.982 30 9.0 2004 12 26 0421 6.910 92.958 39 7.2 2005 03 28 1609 2.085 97.108 30 8.6 2007 08 08 1705 -5.859 107.419 280 7.5 2007 09 12 1110 -4.438 101.367 34 8.5 2007 09 12 2349 -2.625 100.841 35 7.9 2007 09 13 0335 -2.130 99.627 22 7.0 2008 02 20 0808 2.768 95.964 26 7.4 2008 02 25 0836 -2.486 99.972 25 7.2 Peak Ground Acceleration in m/sec**2 .2 .4 .8 1.6 2.4 3.2 4.0 4.8 EPICENTRAL REGION EXPLANATION Main Shock M6.6 1 Oct 2009 Earthquake Magnitude 5.50 - 5.99 6.00 - 6.99 7.00 - 7.99 8.00 - 8.99 9.00 - 9.99 Earthquake Depth 0 - 69 70 - 299 300 - 700 Sumatra Fault EPICENTRAL REGION Depth (km) Distance (km) A A' -300 -300 -200 -200 -100 -100 0 0 100 100 200 200 -300 -300 -200 -200 -100 -100 0 0 Southern Sumatra 1 October 2009 1:52:47 UTC -2.602° S., 101.702° E. Depth 10 km Mw = 6.6 (USGS) . -300 -300 -200 -200 -100 -100 0 0 100 100 200 200 -300 -300 -200 -200 -100 -100 0 0