Earth Observatory Blog

Submitted on 15 Jan 2021 by:

A moderate earthquake struck western Sulawesi, Indonesia, on 15 January 2021 at approximately 2:28am (SGT). According to the United States Geological Survey, the Mw 6.2 event occurred about 36 kilometres (km) south of Mamuju on the island of Sulawesi at a depth of 18 km.

This event follows a smaller Mw 5.7 foreshock event that occurred approximately 12 hours earlier at about the same location.

Today’s event is due to compressional forces on a fault system that has left a visible record in the topography and geology. However, not many earthquakes have happened on this fault system in the recent past. “The east-dipping thrust fault here is part of an obscure system of faults that extends offshore and is not well studied,” said Dr Kyle Bradley, a Principal...

Submitted on 28 Sep 2019 by:

During the early evening of 28 September 2018, a magnitude-7.5 earthquake struck along the coast of northwestern Sulawesi, Indonesia. This region hosts a famous strike-slip fault system called the Palu-Koro Fault.

Even though this is one of the fastest slipping faults in the world, it has not produced many large earthquakes during historical times. The Palu-Koro Fault was therefore thought to have a high probability of a large and destructive earthquake, and so the occurrence of the 2018 quake in Sulawesi wasn’t very surprising.

However, the landsliding that was triggered by the earthquake turned out to be unexpectedly destructive. Soon after the earthquake, witnesses described entire villages south of Palu City sinking into mud and disappearing, and it was...