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)