Magnitude 6.2 Earthquake off the west coast of Sumatra.

The Indonesian Meteorological, Climatological, and Geophysical Agency recorded a Magnitude 6.2 Earthquake at a depth of about 29 km, off the West coast of Aceh Province, Sumatra, Indonesia slightly after 6.00 pm Western Indonesian Time (slightly after 11.00 am GMT) on Tuesday 31 January 2025. There have been no reports of any damage or casualties following this event, but people have reported feeling  tremors  across Aceh Province and parts of North Sumatra.

The approximate location of the 31 January 2025 Aceh Province Earthquake. USGS.

The Indo-Australian Plate, which underlies the Indian Ocean to the west of Sumatra, is being subducted beneath the Sunda Plate, a breakaway part of the Eurasian Plate which underlies Sumatra and neighbouring Java, along the Sunda Trench, passing under Sumatra, where friction between the two plates can cause Earthquakes. As the Indo-Australian Plate sinks further into the Earth it is partially melted and some of the melted material rises through the overlying Sunda Plate as magma, fueling the volcanoes of Sumatra.

The Subduction zone beneath Sumatra. NASA/Earth Observatory.

This does not happen at a 90° angle, as occurs in the subduction zones along the western margins of North and South America, but at a steeply oblique angle. This means that as well as the subduction of the Indo-Australian plate beneath the Sunda, the two plates are also moving past one-another. This causes rifting within the plates, as parts of each plate become stuck to the other, and are dragged along in the opposing plate's direction. The most obvious example of this is the Sumatran Fault, which runs the length of Sumatra, with the two halves of the island moving independently of one-another. This fault is the cause of most of the quakes on the island, and most of the island's volcanoes lie on it.

The movement of the tectonic plates around Sumatra. NASA/Earth Observatory.

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Sumatran Orangutan found with gunshot wounds in Aceh Province, Indonesia.

A male Sumatran Orangutan, Pongo abelii, has been found with multiple injuries by staff from the Indonesian Natural Resources Conservation Agency while carrying out a patrol in the South Aceh District of Aceh Province, on the island of Sumatra on Thursday 28 November 2019. The Ape, who has been named Paguh by rescuers, was found to have 24 air rifles pellets in his body, and to have been blinded in both eyes. He was taken to the Batu Mbelin Sibolangit Orangutan Rehabilitation Center, run by the Lestari Ecosystem Foundation and PanEco Foundation - Sumatran Orangutan Conservation Programme, where he was treated for his injuries; he is expected to survive, but not to be able to return to the wild.

A male Orangutan named Pugeh who was rescued after  being blinded with airgun pellets last week. EPA.

The Sumatran Orangutan is considered to be Critically Endangered under the terms of the the International Union for the Conservation of Nature's Red List of Threatened Species,with less than 14 000 individuals surviving in the wild,  in a total area of 16 775 km² of forest. They are considered to be at threat from habitat loss and fragmentation, as a result of Indonesia's rapidly expanding Human population and associated development projects, such as mining, road building, and plantation forestry, as well as more directly from poaching. 

X-ray image of Paguh showing airgun pellets within his head. EPA.

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Elephas maximus sumatrensis: Two Sumatran Elephants found dead within a week.

Authorities in Indonesia are investigating after two Sumatran Elephants, Elephas maximus sumatrensis, were found dead within the last week. The first Elephant, a 40-year-old male, was found in a plantation near Bengkalis in Riau Province on Tuesday 19 November 2019, having been decapitated and having its tusks removed. The cause of death of this animal is unclear, as it had no other injuries and was showing no signs of poisoning (it is unlikely that anybody managed to decapitate a living Elephant). The second Elephant was a 25-year-old female found on a timber plantation in Peureulak District, Aceh Province, on Wednesday 20 November. It had been dead for about a week when it was found, and showed no signs of any physical injuries, and authorities are investigating if it may have been poisoned or electrocuted.

Vetenery surgions inspecting a male Elephant found dead on a plantation near Bengkalis in Riau Province, Indonesia, on Tuesday 19 November 2019. AFP.

Many animals will simply flee such incursions, or, if unable to, are likely to end up in the cooking pots of hungry villagers. Elephants, however, are a somewhat different proposition. They are large animals, not used to being challenged by other animals in their home ranges, and typically live in matriarchal herds of up to a hundred, with herds holding large territories, criss-crossed by Elephant trails. A herd of Elephants encountering a new Human construction are unlikely to attempt to go round it, and are quite likely to maximise the damage they cause to show their displeasure. This has become a particular fuel of conflict in Indonesia, where a rapidly expanding Palm Oil industry has intruded on the Elephant's natural environment, and the Elephants have discovered that the fruit of the Oil Palm is an excellent form of food.

Indonesian police officers inspecting a female Elephant found dead on a plantation in Peureulak District on Wednesday 20 November 2019. Cek Mad/Antara Foto/Reuters.

The Sumatran Elephant Elephas maximus sumatrensis, is a subspecies of the Asian Elephant, Elephas maximus, found on the islands of Sumatra and Borneo. The subspecies is considered to be Critically  Endangered in the wild under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species, with less than 2000 individuals thought to be surviving in the wild, fragmented into 20 fragmented populations. The species is threatened by habitat loss due to Human activities and direct hunting for their ivory.

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Sumatran Elephant killed by poachers.

A male Sumatran Elephant, Elephas maximus sumatranus, is believed to have been killed by poachers in Banda Alam District of Aceh Province, Sumatra, Indonesia. The body of the animal, aged about ten years, was found by conservation officials on Friday 16 November 2018. It appeared to have been dead for about a week, and was too badly decomposed to determine the cause of death by physical examination, but its tusks had been removed, which is typically a sign that an Elephant has been killed by poachers. Tissue samples have been taken from the body to analyse for traces of poison, a method that has been used by poachers to kill other Elephants in the area.

A male Sumatran Elephant found dead on 16 November 2018 being examined by a local conservation official. Maulana/Rakyat Aceh.

The Sumatran Elephants is a subspecies of Asian Elephant, Elephas maximus, which was once found across the island of Sumatra, but which is now restricted to 25 fragmented populations, most of which are located outside of conservation areas, a drop from 43 populations in 1985, with the total wild population estimated at 2400-2800 individuals. For this reason the Sumatran Elephant is considered to be Critically Endangered under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

 

The species has been badly impacted by the severe deforestation which has occurred on Sumatra in recent decades, destroying their natural habbitat and brining them into conflict with Humans, where they suffer for being both a threat to crops and a potential source of income due to the high value of their ivory on the illegal market.

 

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Poachers kill tame Elephant in Aceh Province, Sumatra.

A tame Elephant has been killed by poachers in the Serbajadi District of Aceh Province, Sumatra, Indonesia. Bunta, 27, was one of a herd of four Sumatran Elephants, Elephas maximus sumatranus, kept by the Serbajadi Conservation Response Unit in the village of Bunin, and used to help prevent Human-Elephant conflict by warding off wild Elephants approaching agricultural land. He was found dead on Sunday 10 June 2018, having apparently died after consuming Bananas and Mangoes laced with poison, and had subsequently had one tusk removed.

The body of Bunta, a 26-year-old Sumatran Elephant from a herd owned by the Serbajadi Conservation Response Unit Conservation Response Unit, killed by poachers this weekend. Al Mahdi/Antara.

The Sumatran Elephants, Elephas maximus sumatranus, is a subspecies of Asian Elephant, Elephas maximus, which was once found across the island of Sumatra, but which is now restricted to 25 fragmented populations, most of which are located outside of conservation areas, a drop from 43 populations in 1985, with the total wild population estimated at 2400-2800 individuals. For this reason the Sumatran Elephant is considered to be Critically Endangered under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

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Explosion at illegal oil well kills 21 in Aceh Province, Sumatra.

Twenty one people have died and another 42 people have been injured following an explosion at an illegal oil well in the village of Pasir Putih in Aceh Province, Sumatra, on Wednesday 25 April 2018. The well was apparently run by local people from the village, which lies within an area where all legal drilling is controlled by the Indonesian state oil company Pertamina. The operators had apparently drilled own to a depth of about 250 m, when they struck a pocket of pressurised oil which they were unable to control and sprayed freely from the well. This attracted the attention of other people in the village, who gathered to try to collect some of the oil. At some point after this the oil was ignited, causing a major explosion and fire, though accounts of how this happened vary (though there would seem to have been a degree of bad luck involved, as crude oil is not usually easy to ignite).

Flames issuing from an illegal oil well in Passir Putih Village, Aceh Province, on 25 April 2018. Maulana/Antara Foto/Reuters.

The fire destroyed at least five homes and burned for several hours, before eventually being extinguished by teams from the National Disaster Mitigation Agency assisted by specialist fire fighting crews loaned by Pertamina. Authorities in the area are concerned there may still be undiscovered casualties in the village, and are planning to prosecute those responsible for the disaster.

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Magnitude 6.5 Earthquake on the north coast of Sumatra claims over a hundred lives.

The United States Geological Survey recorded a Magnitude 6.5 Earthquake at a depth of 8.2 km, on the north coast of Sumatra, about 16 km to the southeast of the town of Sigli in Aceh Province, slightly after 5.00 am Western Indonesian Time on Wednesday 7 December 2016 (slightly after 10.00 pm on Tuesday 6 December, GMT). So far 102 fatalities have been attributed to this event, which is also thought to have destroyed over 10 000 homes and over 50 mosques, and which was felt across much of northern Sumatra, western Peninsula Malaysia and southern Peninsula Thailand.

Damage to a mosque following the 7 December 2016 Earthquake. Zian Muttaqien/AFP/Getty Images.

The Indo-Australian Plate, which underlies the Indian Ocean to the west of Sumatra, is being subducted beneath the Sunda Plate, a breakaway part of the Eurasian Plate which underlies Sumatra and neighbouring Java, along the Sunda Trench, passing under Sumatra, where friction between the two plates can cause Earthquakes. As the Indo-Australian Plate sinks further into the Earth it is partially melted and some of the melted material rises through the overlying Sunda Plate as magma, fuelling the volcanoes of Sumatra.

The Subduction zone beneath Sumatra. NASA/Earth Observatory.

This does not happen at a 90° angle, as occurs in the subduction zones along the western margins of North and South America, but at a steeply oblique angle. This means that as well as the subduction of the Indo-Australian plate beneath the Sunda, the two plates are also moving past one-another. This causes rifting within the plates, as parts of each plate become stuck to the other, and are dragged along in the opposing plate's direction. The most obvious example of this is the Sumatran Fault, which runs the length of Sumatra, with the two halves of the island moving independently of one-another. This fault is the cause of most of the quakes on the island, and most of the island's volcanoes lie on it.

 The movement of the tectonic plates around Sumatra. NASA/Earth Observatory.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.

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