U.S. DEPARTMENT OF THE INTERIOR EARTHQUAKE …Map prepared by U.S. Geological Survey National...
1
Map prepared by U.S. Geological Survey National Earthquake Information Center 30 July 2004 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. M7.3 Southern Sumatra, Indonesia Earthquake of 25 July 2004 102° 103° 104° 105° 106° 102° 103° 104° 105° 106° 4° 3° 2° 1° 0° 4° 3° 2° 1° 0° M u s i B a n y ua s in Pul a u R i m au Ba ta n gh a r i I n dr a g iri SOUTH CHINA SEA S el a t B e rh a la Lingga Singkep Bangka S e l a t B a ng k a JAVA SEA INDIAN OCEAN Ba ri s a n Epicentral Area Pegunungan 1991 1965 1983 1977 1986 1969 1978 1991 1988 1997 1986 1979 1979 1990 1970 1977 1965 1972 2002 1989 1994 Kaba Pendan Daun, Bukit Belirang-Beriti Aur Uki Baru LAIS Muba Pauh LAHAT Keban Pulan Babat Babat Upang Bajat Pusuk Rukam Djebu Bakit Telus Sipin Selat Bubus Parit Posik Djago Ketan Resum Limau Untal Siabun Betung Lembak Trawas PLABJU Ngulak Radjik Lidung Bangko MUNTOK Sangku Majang Rambat Kelapa Seling Betung Pintas DJAMBI Parits RENGAT Tengki Pinang Kelume Sambau Saisum Mendala Udjamas Bingjai Seangit Keluang Tamiang Pelawan Keludin Tjengal Djangga Teritip Airabik BELINJU Semuguk Pelawan Merlung Simpang Mendaha Serajak Parit 2 Keramat Sebetik Menloda Simpong Sukarame Kantjing Tandjung Bungomas Singnaik Glumbang Mamdiaur Muarabab Bailangu Sukarami Tandjung Mangsang Pamenang Pulauaro Paallima MURATEBO Tandjung Menungul Keritang Seberida Selentai Kelajang Pelangko Merawang Pematang Pebanduk Parit 21 Lunggajan Pagerdewa Siguwaras Embatiang Muaraenim KEPAHIANG Tambangan Kurotidur Kujuagung Dusunbaru Tambangan Indralaja Pagarkaja MUARAAMAN PALEMBANG Ambatjang Sakasuban Medielang Ulakmakam Tanahgaro Tengkalat Batuampar Senjerang Paritatah Sapatluar Bulungkor Belingkas Gunungkaia Pagerdjali BANGKAHULU Sukotjinta Atartulung Tebatogung Gadjahmati Peremoahan Prabumulih Surulangun Sakakemang Tanahrenah MUARAKUMPE Muaradanan Lubukbesar Paritsaman Paritpiapi Sentjalang Rusukbuaja Sungaidaun Rumahampai Tebingsuloh Sungaitepuk Karangradja Talangdjauh Pagergunung Muaroburnai PASARKERKAP PERABUMULIH MUARABELITI Sungairotan Muararengas Batukutjing Muaratalang Karanganjar Subanburung Sungaiselan Renahmangus Hulukandang Puput-bawah Penindjanan Rantaurasau Kampungbaru Kualainuman Lubukkandis Pinangteluk Paritderani Pasirkuning Kualatjukas Sungaiperak Gunungterang Lubukseberuk TEBINGTINGGI Tandjungibul Kepalatjurup Lubuklinggan Talangkubuan Tambangsawah Kotatandjung Muaralengajo Tandjungniur Kotawaringin Puding-basar Diernih-muda Lubukdjoring Pangkalberas MUARATEMBESI Muarakuamang Sungoilandai Lubukkambing Dusunsimambu Kualatjenake Sakeanlosong Tandjungrindu Gunungmerakas Talang Padang Singapurabaru Serdangmenang Talang Gudang Tandjungmarga Pasarmuarapit Teruson-dalam Beringintingi Pondokselapan Lambansigatai Pangkalmenduk Murekeh-besar Bajunglentjin Talangkupilan Pangkallajang Bukitluntjung Butungbedarah Pematangraman Nipahpandjang Pangkalanbalei Tempino-Ketjil Pangkalankasai Tjontjong-laut Umbultandjungan Talanggelumbang Pangkalanlampam Talang Pangeran Teluktenggulang Pangkalangresik Muaropinang-baru Atartulungmumbul Palangpondokduku Paritsungaibutuh Umbulan Padulmanan Talangtebingtenggi Parithadjisam Suri Talang Lambangambir Dusunrantaukelajang 1944 1946 1900 1956 2004 1990 95° 100° 105° 95° 100° 105° 5° 0° 5° 5° 0° 5° SOUTH CHINA SEA INDIAN OCEAN JAVA SEA JAVA SUMATRA S t r a it o f M a lacc a Su n da T re n c h I n v e s t i g a t o r R i d g e Cocos Basin Plate Tectonic Setting Jakarta Singapore Belitung Bangka Kep. Lingga Kep. Riau Kep . Men t a w a i Kuala Lumpur 2004 0 100 200 300 400 50 Kilometers SCALE 1:10,000,000 Mercator Projection RELATIVE PLATE MOTIONS The relative motion of adjacent tectonic plates is depicted on the map by short vectors located at selected points on the plate boundary. In this presentation, one plate (the fixed reference plate) is assum- ed to be rigid. The vector therefore rep- resents the direction of the moving plate relative to the reference plate. The rate of relative motion is labelled next to the vector. The components of the vector perpen- dicular and parallel to the plate margin approximate convergent/divergent and transverse direction of motion between the plates, respectively. As viewed from the fixed plate, an inward directed com- ponent suggests convergence at and near the plate boundary that may be ex- pressed as crustal folding, uplift, thrust faulting, or plate subduction. Similarly, an outward directed component sug- gests plate divergence such as would be expected at a zone of crustal spread- ing. Transcurrent or transform faulting would be expected when the predom- inant vector component is parallel to the plate margin. In this case, the Australia plate in the vi- cinity of Sumatra is moving NNE relative to the reference Sunda plate at a speed ranging between 65 and 70 mm/yr. SOUTHERN SUMATRA, INDONESIA 25 July 2004 14:35:18 UTC 2.412° S., 103.977° E. Depth 576 km (USGS) Mw = 7.3 (HRV) A powerful earthquake shook southern Sumatra and western Java in Indonesia on Sunday evening, 25 July 2004. The state news agency Antara reported that people fled in panic into the streets of Padang, capital of Sumatera Berat Province and that tall buildings in Jakarta swayed. However, no deaths and no major damage were reported. The earthquake was unusual because of its uncommonly great depth. The earthquake was also felt throughout Bali, Lombok, and Singapore. EXPLANATION Main Shock 25 July 2004 Seismicity 1964 - 2002 0 - 69 km 70 - 299 300 - 700 Magnitude Classes 5.0 - 5.9 6.0 - 6.9 7.0 - 7.9 Plate Boundary Continental Rift RL Continental Transform Oceanic Convergent Oceanic Rift Subduction Seismic Hazard 0 - 0.2 m/sec² 0.2 - 0.4 0.4 - 0.8 0.8 - 1.6 1.6 - 3.2 3.2 - 4.1 Volcano Urbanized Area 0 20 40 60 80 10 Kilometers SCALE 1:1,500,000 Mercator Projection 95° 100° 105° 95° 100° 105° 5° 0° 5° 5° 0° 5° SOUTH CHINA SEA INDIAN OCEAN JAVA SEA JAVA SUMATRA S t r a it o f M a lacc a Seismicity 1964 - 2002 Jakarta Singapore Belitung Bangka Kep. Lingga Kep. Riau Kep . Men t a w a i Kuala Lumpur A1 A1' A2 A2' A3 A3' 2004 EXPLANATION Main Shock 25 July 2004 Seismicity 1900 - 2002 0 - 69 km 70 - 299 300 - 700 Magnitude Classes 4.0 - 4.4 4.5 - 4.9 5.0 - 5.4 5.5 - 5.9 6.0 - 6.4 6.5 - 6.9 Volcano Kaba Urbanized Area Populated Place Tamlang Airfield 95° 100° 105° 95° 100° 105° 5° 0° 5° 5° 0° 5° SOUTH CHINA SEA INDIAN OCEAN JAVA SEA JAVA SUMATRA S t r a it o f M a lacc a Generalized Seismic Hazard Jakarta Singapore Belitung Bangka Kep. Lingga Kep. Riau Kep . Men t a w a i Kuala Lumpur 2004 100 km 0 km 100 km 200 km 300 km 400 km 100 km 0 km 100 km 200 km 300 km 400 km 300 km 200 km 100 km 0 km 300 km 200 km 100 km 0 km A1 A1' 100 km 0 km 100 km 200 km 300 km 400 km 100 km 0 km 100 km 200 km 300 km 400 km 300 km 200 km 100 km 0 km 300 km 200 km 100 km 0 km A2 A2' 100 km 0 km 100 km 200 km 300 km 400 km 500 km 100 km 0 km 100 km 200 km 300 km 400 km 500 km 600 km 500 km 400 km 300 km 200 km 100 km 0 km 600 km 500 km 400 km 300 km 200 km 100 km 0 km A3 A3' 2004 Depth Profiles 0 100 200 300 400 50 Kilometers SCALE 1:10,000,000 Mercator Projection 0 100 200 300 400 50 Kilometers SCALE 1:10,000,000 Mercator Projection LARGEST EARTHQUAKES IN THE EPICENTRAL AREA 1900 - 2002 YR MO DY LAT LON DEPTH MAG 1900 1 5 -3.000 102.000 0 7.0 1944 1 5 -3.500 102.000 60 6.8 1946 3 26 -3.000 102.000 0 6.6 1956 4 10 -2.897 102.255 131 6.6 1965 1 28 -2.753 102.472 174.6 5.2 1965 4 3 -3.991 102.282 69.8 5.0 1969 9 15 -3.740 102.592 45.0 5.1 1970 8 1 -3.013 102.311 119.7 5.3 1972 1 26 -2.568 102.425 171.0 5.4 1977 4 4 -2.806 102.187 118.7 5.3 1977 9 5 -3.909 103.696 162.2 5.1 1978 2 5 -3.499 104.217 302.9 5.0 1979 12 15 -3.333 102.577 13.4 6.6 1979 12 18 -3.361 102.313 28.3 5.1 1983 1 3 -3.926 102.885 103.8 5.0 1986 1 29 -3.892 103.444 47.5 5.0 1986 10 9 -3.365 103.038 189.2 5.0 1988 6 15 -3.419 102.097 97.2 5.2 1989 9 30 -1.903 102.214 204.8 5.0 1990 7 1 -3.279 102.045 112.8 5.0 1990 9 26 -3.979 102.306 68.4 5.4 1991 1 26 -3.445 102.645 130.6 5.5 1991 3 5 -3.995 102.310 56.6 5.8 1994 11 22 -1.896 102.594 232.3 5.1 1997 4 22 -3.400 102.026 101.7 5.9 2002 6 16 -2.352 102.484 226.8 5.8 2004 7 25 -2.412 103.977 576 7.3 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. EXPLANATION Main Shock 25 July 2004 Seismicity 1964 - 2002 0 - 69 km 70 - 299 300 - 700 Magnitude Classes 5.0 - 5.9 6.0 - 6.9 7.0 - 7.9 Plate Boundary Continental Rift RL Continental Transform Oceanic Convergent Oceanic Rift Subduction Volcano Urbanized Area 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. DATA SOURCES EARTHQUAKES AND SEISMIC HAZARD USGS, National Earthquake Information Center IASPEI, Centennial Catalog (1900 - 1963) Engdahl, unpublished catalog (1964 - 2002) Global Seismic Hazard Assessment Program PLATE TECTONICS Bird (2003), plate boundaries Smithsonian Institution, Global Volcano Program BASE MAP NIMA and ESRI, Digital Chart of the World USGS, EROS Data Center DISCUSSION The earthquake occurred deep beneath the island of Sumatra, which is one of many islands in the large Indonesian island-arc system. Off the south- west coast of Sumatra, the Australia plate* is being subducted, toward the north-northeast, beneath the Sunda plate at a rate of about 7 cm/yr (see the Plate Tectonic Setting map). At the earth's surface, the boundary between the plates is marked by the 3400 km long Sunda (Java) Trench. The island arc is delin- eated by the Sunda Trench axis, a parallel line of vol- canoes, and zones of intense seismicity. The subduct- ed Australia plate has previously been known to be seismically active to a depth of about 650 km beneath Java, but the 25 July 2004 magnitude 7.3 earthquake is one of the few to occur below 300 km beneath the island of Sumatra. Due to the earthquake's great depth it was felt over a large area, but caused little damage. * Plate names and boundaries are due to Bird (2003)
Transcript of U.S. DEPARTMENT OF THE INTERIOR EARTHQUAKE …Map prepared by U.S. Geological Survey National...
Map prepared by U.S. Geological SurveyNational Earthquake Information Center30 July 2004Map 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.
M7.3 Southern Sumatra, Indonesia Earthquake of 25 July 2004
102° 103° 104° 105° 106°
102° 103° 104° 105° 106°
4°
3°
2°
1°
0°
4°
3°
2°
1°
0°
Musi
Ban
yua sinPulau Rimau
Batanghari
Indragiri
S O U T HC H I N A
S E AS e l a t B e r h a l a
L i n g g a
S i n g k e p
B a n g k a
S e l a t B a n g k a
JAVASEAINDIAN
OCEAN
Barisan
Epicentral Area
Pegunungan
19911965
1983 19771986
1969
19781991
19881997 19861979
19791990
1970
19771965
1972
2002
1989 1994
Jambi
Sumatera Selatan
Riau
Bengkulu
Lampung
Kaba
Pendan
Daun, Bukit
Belirang-Beriti
Aur
Uki
BaruLAIS
Muba
Pauh
LAHAT
Keban
Pulan
BabatBabat Upang
Bajat
PusukRukamDjebu
BakitTelus
Sipin
Selat Bubus
Parit
PosikDjago
Ketan
Resum Limau
Untal
Siabun
Betung
Lembak
Trawas
PLABJU
Ngulak
Radjik
Lidung
Bangko MUNTOKSangku
Majang
RambatKelapaSeling Betung
Pintas
DJAMBI
Parits
RENGAT
TengkiPinang
KelumeSambau
Saisum
Mendala
Udjamas
BingjaiSeangit
Keluang
Tamiang
Pelawan
KeludinTjengal
Djangga
Teritip
Airabik
BELINJUSemuguk Pelawan
Merlung Simpang
Mendaha
Serajak
Parit 2Keramat
Sebetik
Menloda
Simpong
Sukarame
Kantjing Tandjung
Bungomas
Singnaik
Glumbang
MamdiaurMuarabab
Bailangu
Sukarami
Tandjung
Mangsang
Pamenang
Pulauaro
Paallima
MURATEBO
Tandjung
Menungul
Keritang
Seberida
Selentai
KelajangPelangko
MerawangPematangPebanduk
Parit 21
Lunggajan
Pagerdewa
SiguwarasEmbatiang
MuaraenimKEPAHIANG
Tambangan
Kurotidur KujuagungDusunbaru
Tambangan
Indralaja
PagarkajaMUARAAMAN
PALEMBANG
Ambatjang
Sakasuban
Medielang
Ulakmakam
Tanahgaro
Tengkalat
Batuampar
Senjerang
Paritatah
Sapatluar
Bulungkor
Belingkas
Gunungkaia
Pagerdjali
BANGKAHULU
SukotjintaAtartulung
Tebatogung
Gadjahmati
Peremoahan
Prabumulih
Surulangun
SakakemangTanahrenah
MUARAKUMPE
Muaradanan Lubukbesar Paritsaman
Paritpiapi
Sentjalang
RusukbuajaSungaidaun
Rumahampai
Tebingsuloh
Sungaitepuk
KarangradjaTalangdjauhPagergunung Muaroburnai
PASARKERKAP
PERABUMULIH
MUARABELITI
Sungairotan
Muararengas
Batukutjing
MuaratalangKaranganjarSubanburung
Sungaiselan
Renahmangus
Hulukandang
Puput-bawahPenindjanan
Rantaurasau
Kampungbaru
Kualainuman
Lubukkandis
PinangtelukParitderani
PasirkuningKualatjukas
Sungaiperak
Gunungterang
Lubukseberuk
TEBINGTINGGI
TandjungibulKepalatjurup
Lubuklinggan
Talangkubuan
Tambangsawah
Kotatandjung
Muaralengajo
Tandjungniur KotawaringinPuding-basar
Diernih-mudaLubukdjoring Pangkalberas
MUARATEMBESI
Muarakuamang
Sungoilandai
LubukkambingDusunsimambu
Kualatjenake
Sakeanlosong
TandjungrinduGunungmerakas
Talang Padang
Singapurabaru
SerdangmenangTalang Gudang
Tandjungmarga
Pasarmuarapit
Teruson-dalam
Beringintingi
Pondokselapan
Lambansigatai
PangkalmendukMurekeh-besar
Bajunglentjin
Talangkupilan
Pangkallajang
Bukitluntjung
ButungbedarahPematangraman
Nipahpandjang
Pangkalanbalei
Tempino-Ketjil
Pangkalankasai
Tjontjong-laut
Umbultandjungan
Talanggelumbang
PangkalanlampamTalang Pangeran
Teluktenggulang
Pangkalangresik
Muaropinang-baru
Atartulungmumbul
Palangpondokduku
Paritsungaibutuh
Umbulan Padulmanan
Talangtebingtenggi
Parithadjisam Suri
Talang Lambangambir
Dusunrantaukelajang
1944
19461900
1956
2004
1990
95° 100° 105°
95° 100° 105°
5°
0°
5°
5°
0°
5° S O U T HC H I N A
S E A
I N D I A NO C E A N
S I N G A P O R E
M A L A Y S I A
J A V AS E A
I N D O N E S I A
T H A I L A N D
JAVA
S UM
AT
RA
St r a
i t o f Ma l a c c a
Su
nd
a
Tr
en
ch
Inv
es
t ig
at o
r R
i dg
e
C o c o sB a s i n
SUNDA PLATE
AUSTRALIAPLATE
BURMAPLATE
INDIAPLATE
Plate Tectonic Setting
EPICENTRAL AREA
Jakarta
Singapore
BelitungBangka
Kep. Lingga
Kep. Riau
Ke
p. M
e nt a w
a i
Kuala Lumpur
68 mm/yr
65 mm/yr
2004
0 100 200 300 40050
Kilometers
SCALE 1:10,000,000Mercator Projection
RELATIVE PLATE MOTIONS
The relative motion of adjacent tectonicplates is depicted on the map by short vectors located at selected points on the plate boundary. In this presentation, one plate (the fixed reference plate) is assum-ed to be rigid. The vector therefore rep-resents the direction of the moving plate relative to the reference plate. The rate of relative motion is labelled next to the vector.
The components of the vector perpen-dicular and parallel to the plate margin approximate convergent/divergent and transverse direction of motion between the plates, respectively. As viewed from the fixed plate, an inward directed com-ponent suggests convergence at and near the plate boundary that may be ex-pressed as crustal folding, uplift, thrustfaulting, or plate subduction. Similarly, an outward directed component sug-gests plate divergence such as would be expected at a zone of crustal spread-ing. Transcurrent or transform faultingwould be expected when the predom-inant vector component is parallel to theplate margin.
In this case, the Australia plate in the vi-cinity of Sumatra is moving NNE relative to the reference Sunda plate at a speed ranging between 65 and 70 mm/yr.
SOUTHERN SUMATRA, INDONESIA
25 July 2004 14:35:18 UTC2.412° S., 103.977° E.Depth 576 km (USGS)Mw = 7.3 (HRV)
A powerful earthquake shook southern Sumatra and western Javain Indonesia on Sunday evening, 25 July 2004. The state news agencyAntara reported that people fled in panic into the streets of Padang,capital of Sumatera Berat Province and that tall buildings in Jakarta swayed. However, no deaths and no major damage were reported.The earthquake was unusual because of its uncommonly great depth.The earthquake was also felt throughout Bali, Lombok, and Singapore.
EXPLANATIONMain Shock
25 July 2004
Seismicity 1964 - 2002
0 - 69 km
70 - 299
300 - 700
Magnitude Classes
5.0 - 5.9
6.0 - 6.9
7.0 - 7.9
Plate Boundary
Continental Rift
RL Continental Transform
Oceanic Convergent
Oceanic Rift
Subduction
Seismic Hazard
0 - 0.2 m/sec²
0.2 - 0.4
0.4 - 0.8
0.8 - 1.6
1.6 - 3.2
3.2 - 4.1
Volcano
Urbanized Area
0 20 40 60 8010
Kilometers
SCALE 1:1,500,000Mercator Projection
95° 100° 105°
95° 100° 105°
5°
0°
5°
5°
0°
5° S O U T HC H I N A
S E A
I N D I A NO C E A N
S I N G A P O R E
M A L A Y S I A
J A V AS E A
I N D O N E S I A
T H A I L A N D
JAVA
S UM
AT
RA
St r a
i t o f Ma l a c c a
SUNDA PLATE
AUSTRALIAPLATE
BURMAPLATE
INDIAPLATE
Seismicity 1964 - 2002
EPICENTRAL AREA
Jakarta
Singapore
BelitungBangka
Kep. Lingga
Kep. Riau
Ke
p. M
e nt a w
a i
Kuala Lumpur
A1
A1'
A2
A2'
A3
A3'2004
EXPLANATIONMain Shock
25 July 2004
Seismicity 1900 - 2002
0 - 69 km
70 - 299
300 - 700
Magnitude Classes
4.0 - 4.4
4.5 - 4.9
5.0 - 5.4
5.5 - 5.9
6.0 - 6.4
6.5 - 6.9
Volcano
Kaba
Urbanized Area
Populated Place
Tamlang
Airfield
95° 100° 105°
95° 100° 105°
5°
0°
5°
5°
0°
5° S O U T HC H I N A
S E A
I N D I A NO C E A N
S I N G A P O R E
M A L A Y S I A
J A V AS E A
I N D O N E S I A
T H A I L A N D
JAVA
S UM
AT
RA
St r a
i t o f Ma l a c c a
SUNDA PLATE
AUSTRALIAPLATE
BURMAPLATE
INDIAPLATE
Generalized Seismic Hazard
EPICENTRAL AREA
Jakarta
Singapore
BelitungBangka
Kep. Lingga
Kep. Riau
Ke
p. M
e nt a w
a i
Kuala Lumpur
2004
100 km 0 km 100 km 200 km 300 km 400 km
100 km 0 km 100 km 200 km 300 km 400 km
300 km
200 km
100 km
0 km
300 km
200 km
100 km
0 km
A1 A1'
100 km 0 km 100 km 200 km 300 km 400 km
100 km 0 km 100 km 200 km 300 km 400 km
300 km
200 km
100 km
0 km
300 km
200 km
100 km
0 km
A2 A2'
100 km 0 km 100 km 200 km 300 km 400 km 500 km
100 km 0 km 100 km 200 km 300 km 400 km 500 km
600 km
500 km
400 km
300 km
200 km
100 km
0 km
600 km
500 km
400 km
300 km
200 km
100 km
0 km
A3 A3'
2004
Depth Profiles
0 100 200 300 40050
Kilometers
SCALE 1:10,000,000Mercator Projection
0 100 200 300 40050
Kilometers
SCALE 1:10,000,000Mercator Projection
LARGEST EARTHQUAKES IN THE EPICENTRAL AREA 1900 - 2002
YR MO DY LAT LON DEPTH MAG
1900 1 5 -3.000 102.000 0 7.0 1944 1 5 -3.500 102.000 60 6.8 1946 3 26 -3.000 102.000 0 6.6 1956 4 10 -2.897 102.255 131 6.6 1965 1 28 -2.753 102.472 174.6 5.2 1965 4 3 -3.991 102.282 69.8 5.0 1969 9 15 -3.740 102.592 45.0 5.1 1970 8 1 -3.013 102.311 119.7 5.3 1972 1 26 -2.568 102.425 171.0 5.4 1977 4 4 -2.806 102.187 118.7 5.3 1977 9 5 -3.909 103.696 162.2 5.1 1978 2 5 -3.499 104.217 302.9 5.0 1979 12 15 -3.333 102.577 13.4 6.6 1979 12 18 -3.361 102.313 28.3 5.1 1983 1 3 -3.926 102.885 103.8 5.0 1986 1 29 -3.892 103.444 47.5 5.0 1986 10 9 -3.365 103.038 189.2 5.0 1988 6 15 -3.419 102.097 97.2 5.2 1989 9 30 -1.903 102.214 204.8 5.0 1990 7 1 -3.279 102.045 112.8 5.0 1990 9 26 -3.979 102.306 68.4 5.4 1991 1 26 -3.445 102.645 130.6 5.5 1991 3 5 -3.995 102.310 56.6 5.8 1994 11 22 -1.896 102.594 232.3 5.1 1997 4 22 -3.400 102.026 101.7 5.9 2002 6 16 -2.352 102.484 226.8 5.8
2004 7 25 -2.412 103.977 576 7.3
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.
EXPLANATIONMain Shock
25 July 2004
Seismicity 1964 - 2002
0 - 69 km
70 - 299
300 - 700
Magnitude Classes
5.0 - 5.9
6.0 - 6.9
7.0 - 7.9
Plate Boundary
Continental Rift
RL Continental Transform
Oceanic Convergent
Oceanic Rift
Subduction
Volcano
Urbanized Area
Seismic hazard is expressed as peak ground acceleration (PGA) on firm rock,in meters/sec², expected to be exceededin a 50-yr period with a probability of 10 percent.
DATA SOURCES
EARTHQUAKES AND SEISMIC HAZARD USGS, National Earthquake Information Center IASPEI, Centennial Catalog (1900 - 1963) Engdahl, unpublished catalog (1964 - 2002) Global Seismic Hazard Assessment Program
PLATE TECTONICS Bird (2003), plate boundaries Smithsonian Institution, Global Volcano Program
BASE MAP NIMA and ESRI, Digital Chart of the World USGS, EROS Data Center
DISCUSSION
The earthquake occurred deep beneath the island of Sumatra, which is one of many islands in the large Indonesian island-arc system. Off the south-west coast of Sumatra, the Australia plate* is being subducted, toward the north-northeast, beneath the Sunda plate at a rate of about 7 cm/yr (see the PlateTectonic Setting map). At the earth's surface, the boundary between the plates is marked by the 3400 km long Sunda (Java) Trench. The island arc is delin-eated by the Sunda Trench axis, a parallel line of vol-canoes, and zones of intense seismicity. The subduct-ed Australia plate has previously been known to be seismically active to a depth of about 650 km beneath Java, but the 25 July 2004 magnitude 7.3 earthquake is one of the few to occur below 300 km beneath the island of Sumatra. Due to the earthquake's great depth it was felt over a large area, but caused little damage.
* Plate names and boundaries are due to Bird (2003)
