U.S. DEPARTMENT OF THE INTERIOR EARTHQUAKE SUMMARY MAP XXX U.S. GEOLOGICAL SURVEY Prepared in cooperation with the Global Seismographic M7.2 offshore Padang, Sumatra, Indonesia Earthquake of 25 February 2008 Network Tectonic Setting Epicentral Region 90° 100° 110° 120° 94° 96° 98° 100° 102° 104° 1E99X0PLANATION T H A I L A N D 1935 Ipoh Mag ≥ 7.0 V I E T N A M P h i l i p p i n e F a u l t Kemaman Harbor C A M B O D I A 0 - 69 km Kuala Lipis B A Y O F 1916 B E N G A L 1941 P H I L I P P7I0N E- S299 4° 4° 1936 DiamondK uBaanrt aann Nd eCwh Pinoort Hills A N D A M A N 300 - 600 M a l a y s i a S E A Gulf 1948 10° of 10° 1976 Medan Thailand 25 February 2008 8:36:35 UTC BURMA 1881 Rupture Zones N PLATE A W H A G 1955 Kuala Lumpur 2.351° S., 100.018° E. S R I L A N K A L U Year of Earthquake A O Shah Alam P R Depth 35 km T 2005 Mw = 7.2 (USGS) SUNDA PLATE 2008 2004 Seremban B R U N E I Felt throughout the Los Angeles Basin area and in much M of southern California. Felt as far away as Las Vegas, A C e l e b e s 1941 2004 L Simeulue A S u m a t r a F a u l t B a s i n Nevada, and Yuma, Arizona. 2008 Y Melaka 2004 S I A I S 1881 1907 2005 A Y 1969 A L A M i d - I n d i a n M 1991 2° 2° 1969 S I N G A P O R E 1861 B a s i n 1907 1996 S 1861 u 1990 1833 0° 1935 m 1938 0° Borneo Johor Baharu a MOLUCCA 2005 tr Plate Boundaries a SEA Singapore 1943 PLATE 1928 1833 2007 I N D O N E S I SAubduction Transform 2007 AUSTRALIA 2000 S u m a t r a PLATE Nias 1971 1914 Greater Sunda Islands Divergent Pekanbaru EPICENTRAL 2007 REGION I 1984 n AUSTRALIA PLATE v Convergent Pini e e Java Lesser Sunda Islands 1946 s g t 0° 0° d i 55 2006 Volcanoes 1936 g i 1943 1935 a mm/yr R t 1994 1998 10° o S 10° t U r N D A 1977 Tanahbala ( S s J AV R A) T R u E N C H m a i d a E 1943 tr g Padang a e y t 1943 N o r t h e 2000 A u s t r a l i a n Siberut n EXPLANATION O s b o r n i B a s i n P l a t e a u N Jambi M7.5 20 Feb 2008 I N D I A N Siberut 1909 Aftershocks 90° I N D I A N 1O00°C E A N 110° 120° 2° O C E A N 2° RELATIVE PLATE MOTIONS Earthquake Magnitude SCALE 1:20,000,000 Sipora Kilometers 4.00 - 5.99 The broad red vector represents the motion of 0 200 400 800 1,200 1,600 1943 the Australia Plate relative to the Sunda Plate 6.00 - 6.99 Sipura in the region. The motion of the Australia N Pagai 1900 Palembang Plate is generally 50 - 60 mm/yr north and 7.00 - 7.99 slightly eastward with respect to the Sunda Plate. 8.00 - 8.99 S Pagai 9.00 - 9.99 Seismic Hazard Bengkulu Ear4t°hquake Depth 4° 80° 90° 100° 110° I N D O N E S I A Vishakhapatnam Vientiane Vinh 0 - 69 1914 Hyderabad Pegu Udon Thani 94° 96° 98° 100° 102° 104° BasseinRangoon Phitsanulok 70 - 299 1:4,000,000 Moulmein Khon Kaen Hue Scale Nakhon Sawan Savannakhet Da Nang 300 - 700 Ubon Ratchathani Nakhon Ratchasima Quang Ngai Kilometers 0 100 200 400 Tavoy Bangkok Play Cu Madras Siemreab Qui Nhon Bangalore Samut SakhonBatdambang Buon Me Thuot Nha Trang Pondicherry Port Blair Phnom Penh Bien HoaHo Chi Minh City My Tho Phan Thiet Cochin Rach Gia Can Tho 10° 10° Madurai Bac Lieu TECTONIC SUMMARY Trivandrum Nakhon Si Thammarat The magnitude 7.2 Kepulauan Mentawai, Indonesia, earthquake of Significant Earthquakes Mag >= 7.5 Colombo Songkhla February 25, 2008 occurred as the result of thrust faulting on the Yala Kota Baharu Year Mon Day Time Lat Long Dep Mag Galle Alor Setar Kota Kinabalu boundary between the Australia and Sunda plates. At the location of this Banda Aceh 1907 01 04 0519 2.000 94.500 50 7.5 Pinang Kuala Terengganu earthquake, the Australia plate moves north-northeast with respect to the Ipoh Bandar Seri Begawan 1914 06 25 1907 -4.500 102.500 0 7.6 Sunda plate at a velocity of about 60 mm/year. The direction of relative Medan 1935 12 28 0235 -0.345 98.147 35 7.8 Kuala Lumpur plate motion is oblique to the orientation of the plate boundary offshore 1943 06 09 0306 -1.000 101.000 50 7.5 Seremban 1969 11 21 0205 1.973 94.574 11 7.6 Melaka of the west coast of Sumatra. The component of plate-motion M7.5 Johor Baharu Singapore Kuching perpendicular to the boundary is accommodated by thrust faulting on the 2004 12 26 0058 3.295 95.982 30 9.0 2005 03 28 1609 2.085 97.108 30 8.6 20 Feb 2008 Pekanbaru offshore plate-boundary, with the Australia plate subducting beneath the Pontianak 2007 09 12 1110 -4.438 101.367 34 8.5 0° 0° Sunda plate. Much of the component of plate motion parallel to the Padang 2007 09 12 2349 -2.625 100.841 35 8.1 Balikpapan plate boundary is accommodated by strike-skip faulting on the Sumatra Jambi 2008 02 20 0308 2.751 95.966 34.3 7.5 Palangkaraya fault, which is inland on Sumatra proper. Palembang NOTE: The earthquake magnitude was changed to 7.2 in April 2008. Bandjermasin PAGER was not updated as it is a product for immediate release following an earthquake. Bengkulu This earthquake continues an episode of unusually high earthquake EPICENTRAL REGION activity that has impacted Sumatra and vicinity in recent years. Previous Tanjungkarang-Telukbetung earthquakes in the series of shocks include the Sumatra –Andaman Jakarta Islands earthquake of December 26, 2004 (M 9.2), the Nias earthquake DATA SOURCES Bandung Surabaya of March 28, 2005 (M 8.6), and the southern Sumatra earthquakes of Yogyakarta EARTHQUAKES AND SEISMIC HAZARD Semarang September 12, 2007 (M 8.4 and 7.9). The earthquake of February 25, Mataram USGS, National Earthquake Information Center REFERENCES Seismic hazard is expressed as peak 2008, occurred within the broad section of the Sumatra subduction zone NOAA, National Geophysical Data Center ground acceleration (PGA) on firm that was spanned by aftershocks of the southern Sumatra earthquakes of IASPEI, Centennial Catalog (1900 - 1999) and Bird, P., 2003, An updated digital model of plate boundaries: 10° rock, in meters/sec², expected to be 10° September 12, 2007. extensions (Engdahl and Villaseñor, 2002) Geochem. Geophys. Geosyst., v. 4, no. 3, pp. 1027- 80. exceeded in a 50-yr period with a HDF (unpublished earthquake catalog) (Engdahl, 2003) probability of 10 percent. Global Seismic Hazard Assessment Program Engdahl, E.R. and Villaseñor, A., 2002, Global Seismicity: 1900 - 1999, chap. 41 of Lee, W.H.K., and others,eds., PLATE TECTONICS AND FAULT MODEL International Earthquake and Engineering Seismology, 80° 90° 100° 110° PB2002 (Bird, 2003) Part A: New York, N.Y., Elsevier Academeic Press, 932 p. SCALE 1:20,000,000 Finite Fault Model, Chen Ji, UC Santa Barbara (2007) DISCLAIMER Kilometers Engdahl, E.R., Van der Hilst, R.D., and Buland, R.P., 1998, 0 200 400 800 1,200 1,600 BASE MAP Global teleseismic earthquake relocation with improved trav- Base map data, such as place names and political NIMA and ESRI, Digital Chart of the World el times and procedures for depth determination: Bull. Seism. Peak Ground Acceleration in m/sec**2 boundaries, are the best available but may not be USGS, EROS Data Center Soc. Amer., v. 88, p. 722-743. current or may contain inaccuracies and therefore NOAA GEBCO and GLOBE Elevation Models should not be regarded as having official significance. Map prepared by U.S. Geological Survey National Earthquake Information Center .2 .4 .8 1.6 2.4 3.2 4.0 4.8 26 September 2008 Map not approved for release by Director USGS.