The 1797 Sumatra earthquake occurred at 22:00 local time on February 10. It was the first in a series of great earthquakes that ruptured part of the Sumatran segment of 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 ...

. It caused a damaging

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 ...

that was particularly severe near Padang, where a 150–200 ton English ship was driven 1 km inland up the Arau River.

Background

The island of Sumatra lies on the

convergent plate boundary A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a ...

between 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 ...

and 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 an ...

. The convergence between these plates is highly oblique near Sumatra, with the displacement being accommodated by near pure dip-slip faulting along the subduction zone, known as the

, and near pure strike-slip faulting along the

Great Sumatran fault The Indonesian island of Sumatra is located in a highly seismic area of the world. In addition to the subduction zone off the west coast of the island, Sumatra also has a large strike-slip fault, the Great Sumatran Fault also known as Semangko ...

. The major slip events on the subduction zone interface are typically of the

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 earthqu ...

type. Historically, great or giant megathrust earthquakes have been recorded in 1797,

1833 Events January–March * January 3 – Reassertion of British sovereignty over the Falkland Islands in the South Atlantic. * February 6 – His Royal Highness Prince Otto Friedrich Ludwig of Bavaria assumes the title His Majesty Othon the ...

, 1861,

2004 2004 was designated as an International Year of Rice by the United Nations, and the International Year to Commemorate the Struggle Against Slavery and its Abolition (by UNESCO). Events January * January 3 – Flash Airlines Flight ...

, 2005 and 2007, most of them being associated with devastating tsunamis. Smaller (but still large) megathrust events have also occurred in the small gaps between the areas that slip during these larger events, in

1935 Events January * January 7 – Italian premier Benito Mussolini and French Foreign Minister Pierre Laval conclude an agreement, in which each power agrees not to oppose the other's colonial claims. * January 12 – Amelia Earhart ...

, 1984, 2000 and 2002.

Damage

The earthquake caused the collapse or damage of many houses. The tsunami surge drove an English sailing ship of 150–200 tons, moored in the Arau River, about 1 km inland, destroying several houses as it went. Smaller boats were driven up to 1.8 km upstream. In Air Manis, the whole town was flooded and the bodies of several people who had climbed trees to escape the surge were found the next day in the branches. Only two fatalities were reported from Padang itself but many more from Air Manis. The

Batu Islands The Batu Islands are an archipelago of Indonesia located in the Indian Ocean, off the west coast of Sumatra, between Nias and Siberut. The three primary islands, of approximately equal size, are Pini, Tanahmasa, and Tanahbala. There are seventy ...

were also reported to be affected.

Characteristics

Earthquake

The shaking at Padang lasted one minute. Reports in 1845 and 1847 said either that this was the strongest earthquake in the memory of the residents of Padang or the strongest for forty years.

Tsunami

The run-up of the tsunami at Padang and the village of Air Manis is estimated to be in the range of 5–10 m. Modelling of tsunami effects using source parameters estimated from the uplift of coral

microatoll A microatoll is a circular colony of coral, dead on the top but living around the perimeter. Growth is mainly lateral, as upward growth is limited by exposure to air. Microatolls may be up to in diameter. They are named for their resemblance to ...

s, provide a reasonable match to the sparse historical records. The tsunami reports for this event are localised around Padang and it has been suggested that the tsunami may have been caused by an underwater landslide triggered by the earthquake.

References

{{Earthquakes in Indonesia Megathrust earthquakes in Sumatra

Sumatra Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...