The first of the 2009 Sumatra earthquakes ( id, Gempa bumi Sumatra 2009) occurred on 30 September off the coast of Sumatra,

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

with a moment magnitude of 7.6 at . The epicenter was west-northwest of

Padang Padang () is the capital and largest city of the Indonesian province of West Sumatra. With a Census population of 1,015,000 as of 2022, it is the 16th most populous city in Indonesia and the most populous city on the west coast of Sumatra. Th ...

West Sumatra West Sumatra ( id, Sumatra Barat) is a province of Indonesia. It is located on the west coast of the island of Sumatra and includes the Mentawai Islands off that coast. The province has an area of , with a population of 5,534,472 at the 2020 cen ...

, and southwest of

Pekanbaru Pekanbaru is the capital of Indonesian province of Riau, and a major economic center on the eastern part of Sumatra Island. Its name is derived from the Malay words for 'new market' ('pekan' is market and 'baru' is new). It has an area of , w ...

Riau Riau is a province of Indonesia. It is located on the central eastern coast of Sumatra along the Strait of Malacca. The province shares land borders with North Sumatra to the northwest, West Sumatra to the west, and Jambi to the south. Accord ...

Government A government is the system or group of people governing an organized community, generally a state. In the case of its broad associative definition, government normally consists of legislature, executive, and judiciary. Government ...

and authorities confirmed 1,115 dead, 1,214 severely injured and 1,688 slightly injured. The most deaths occurred in the areas of Padang Pariaman (675),

(313), Agam (80) and Pariaman (37). In addition, around 135,000 houses were severely damaged, 65,000 houses were moderately damaged and 79,000 houses were slightly damaged. An estimated 250,000 families (1,250,000 people) have been affected by the earthquake through the total or partial loss of their homes and livelihoods.http://www.reliefweb.int/rw/rwb.nsf/db900SID/EDIS-7WSKEP

Tectonic setting

Many of Indonesia's islands, including Sumatra, are situated within a zone of high seismic activity known as the

Ring of Fire The Ring of Fire (also known as the Pacific Ring of Fire, the Rim of Fire, the Girdle of Fire or the Circum-Pacific belt) is a region around much of the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur. The Ring ...

. Along the

Sunda megathrust The Sunda megathrust is a fault that extends approximately 5,500 km (3300 mi) from Myanmar (Burma) in the north, running along the southwestern side of Sumatra, to the south of Java and Bali before terminating near Australia. It is a ...

, the

Indo-Australian Plate The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and the surrounding ocean and extends northwest to include the Indian subcontinent and the adjacent waters. It was formed by the fusion of the Indian an ...

is being

subducted Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

beneath the

Eurasian plate The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and ...

. The subduction creates regular earthquakes, many of them of

megathrust Megathrust earthquakes occur at convergent plate boundaries, where one tectonic plate is forced underneath another. The earthquakes are caused by slip along the thrust fault that forms the contact between the two plates. These interplate earthqua ...

type. Specifically the Sumatran segment is currently experiencing a period of increased activity that began with the catastrophic

2004 Indian Ocean earthquake An earthquake and a tsunami, known as the Boxing Day Tsunami and, by the scientific community, the Sumatra–Andaman earthquake, occurred at 07:58:53 local time ( UTC+7) on 26 December 2004, with an epicentre off the west coast of northern Su ...

. Each earthquake of the sequence adds additional stresses to segments of the plate boundary that have not moved recently.

Earthquakes

Because of its depth and the computed

focal mechanism The focal mechanism of an earthquake describes the deformation in the source region that generates the seismic waves. In the case of a fault-related event it refers to the orientation of the fault plane that slipped and the slip vector and ...

, the first earthquake is thought to have resulted from deformation within the mantle of the descending

Australian plate The Australian Plate is a major tectonic plate in the eastern and, largely, southern hemispheres. Originally a part of the ancient continent of Gondwana, Australia remained connected to India and Antarctica until approximately when India broke ...

, rather than from movement on the plate boundary itself. A second event, which measured 6.6 , struck the province of

Jambi Jambi is a province of Indonesia. It is located on the east coast of central Sumatra and spans to the Barisan Mountains in the west. Its capital and largest city is Jambi. The province has a land area of 50,160.05 km2, and a sea area of ...

in central Sumatra, 01:52:29 local time on 1 October 2009 at a depth of , about 46 kilometres south-east of Sungaipenuh. Although it was in the same region, the United States Geological Survey specified that it was not an aftershock, as it was located too far from the initial quake. The second earthquake has been linked to dextral (right-lateral) movement on the Great Sumatran fault, which takes up the

strike-slip In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tecton ...

component of the convergence between the two plates.

Effects

Tremors from the first earthquake were felt in the Indonesian capital, Jakarta,

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

and

Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...

. The management of some high-rise buildings in Singapore evacuated their staff. A

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater exp ...

watch was triggered and there was reports of house damage and fires. Hotels in Padang were destroyed, and communications to the city were disrupted. Local news channel Metro TV reported fires in Padang where residents had run onto the streets as the first quake hit. Teams of rescuers from nearby branches of the National Search and Rescue Agency were deployed to Padang. It was also reported that some water pipes in Padang were broken and there was flooding in the street. There were reports that at least two hospitals and several schools collapsed. There were landslides and collateral debris flows in the hills surrounding Lake Maninjau. The landslide in Gunung Nan Tigo, Padang Pariaman district completely destroyed some villages and caused many fatalities. Landslides also forced some roads to be closed. Padang's

Minangkabau International Airport Minangkabau International Airport ( id, Bandar Udara Internasional Minangkabau), is the principal airport serving the province of West Sumatra on the island of Sumatra, Indonesia. It is located at Ketaping, Padang Pariaman Regency which is ...

suffered minor damage, with parts of the ceiling in the boarding area falling down. The airport reopened on 1 October.

Response

Authorities announced that several

disaster management Emergency management or disaster management is the managerial function charged with creating the framework within which communities reduce vulnerability to hazards and cope with disasters. Emergency management, despite its name, does not actual ...

teams were en route to

although it took several hours for them to reach more remote areas. Rescue workers pulled dozens of survivors from the rubble and rushed them to Djamil Hospital. The hospital itself was overwhelmed with patients, and many patients were treated in tents set up outside the hospital. A man was trapped beneath a flattened hotel for 25 hours with a broken leg before rescue workers pulled him free. The Indonesian military deployed emergency response teams with earth moving equipment to help move rubble and recover trapped victims. Rescue workers and volunteers searched the rubble of a collapsed three-story concrete building, rescuing survivors and recovering bodies while parents of students trapped inside waited nearby. Indonesian villagers used their bare hands to sift through ruins and try to find survivors. On 5 October, Indonesian rescue workers called off their search for trapped survivors and increased efforts to recover bodies, clear rubble, and provide aid to survivors. Indonesian authorities used helicopters to airdrop food and blankets into remote areas, and to bring the wounded from these areas to hospitals.

World Vision In its most general sense, the term "world" refers to the totality of entities, to the whole of reality or to everything that is. The nature of the world has been conceptualized differently in different fields. Some conceptions see the wor ...

Oxfam Oxfam is a British-founded confederation of 21 independent charitable organizations focusing on the alleviation of global poverty, founded in 1942 and led by Oxfam International. History Founded at 17 Broad Street, Oxford, as the Oxford Co ...

IFRC The International Federation of Red Cross and Red Crescent Societies (IFRC) is a worldwide humanitarian aid organization that reaches 160 million people each year through its 192-member National Societies. It acts before, during and after disas ...

, Muslim Charity and Mercy Corps confirmed that they would fly their emergency response teams to the devastated Padang area for rapid assessment of the catastrophe. The Red Cross sought donations to help cover earthquake relief costs. World Vision has also airlifted 2,000 collapsible water containers and will distribute them immediately to the area most affected by earthquake. Additionally World Vision has launched US$1 million appeal for the relief effort. ;Countries that sent aid Below is the table of countries that sent or pledged aid for Indonesia

References

External links

Rescue efforts continue in Indonesia
– On Demand News
Indonesia quake deaths pass 1,000
– ''

BBC News BBC News is an operational business division of the British Broadcasting Corporation (BBC) responsible for the gathering and broadcasting of news and current affairs in the UK and around the world. The department is the world's largest broad ...