Why does Sulawesi often have earthquakes? Not an ordinary earthquake, often accompanied by powerful tsunami waves.

In 2018, Donggala Regency and Palu City in Central Sulawesi were hit by an earthquake, a few moments later they were hit by a devastating tsunami wave. In early 2021, several areas in Sulawesi were again rocked by a big earthquake. Most recently, last Thursday (21/01/2021) an earthquake measuring 7.2 on the Richter scale had devastated North Sulawesi.

Based on data from the National Disaster Management Agency (BNPB), over a span of 85 years there have been at least 10 major earthquakes in Central Sulawesi province alone. Meanwhile, in 159 years ago, naturalist Alfred Russel Wallace recorded an earthquake in Tomohon, North Sulawesi. At that time, Wallace was doing research in Biology in Sulawesi.

Why does Sulawesi often have earthquakes? Not an ordinary earthquake, it is often accompanied by a devastating tsunami wave, which causes thousands of lives lost and houses destroyed to the ground.

Tsunami and earthquake in Donggala Regency and Palu City in 2018 (Doc. Public Relations of Directorate General of Highways, Ministry of PUPR).

Why Does Sulawesi Often Earthquake?

Of all parts of Indonesia, Sulawesi Island is one of the places most prone to earthquakes. This is because the island is a meeting point for three tectonic plates, namely the Pacific Plate moving westward, the Eurasian Plate moving south-south, and the smaller Philippine Plate.

The confluence of three plates on the island of Sulawesi has caused complex and diverse geological impacts. One of them is the formation of faults that trigger earthquakes. The Meteorology, Climatology and Geophysics Agency (BMKG) noted that currently there are 40 faults scattered throughout Sulawesi Island. Four of them are very active and dangerous.

The four most active faults are the Palu-Koro fault, the Saddang fault, the Gorontalo fault, and the Matano fault. The Palu-Koro fault is the most active in Indonesia. The power of the vibration is enormous, reaching three times that of ordinary fractures. This fault triggered the devastating earthquake and tsunami in Donggala and Palu in 2018.

Earthquake in West Sulawesi in early 2021 (AP Photo / Rudy Akyaksyah).

East Indonesia is prone to earthquakes

30 million years ago, Sulawesi Island was still separated. Some of them stick to the island of Borneo, some on the island of Java. The island of Sulawesi was only formed about 1 million years ago due to the collision of three earth's plates. The collision caused the islands above it to become messy by fractures from the earth's crust.

The area above it was fragmented like crumbs, and each small block moved apart as a result of the squeezing and lashing of the three plates that surrounded it. This theory is written in the book Earthquake: Collection of Articles of Science and Technology TEMPO (2013) written by Dina Anggraeni Sarsito, a lecturer in Earth Sciences and Engineering at the Bandung Institute of Technology.

This is what, according to Dina, makes Eastern Indonesia more prone to earthquake shocks than others. According to Armstrong F. Sompotan, the collision of three plates makes the four arms on the island of Sulawesi have different tectonic processes, as well as forming a very complex geological mosaic unit.

Source – 2021-01-25 04:33:03


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