The Palu-Koro Fault or Palu-Koro Fault System is a major active NNW-SSE trending left-lateral strike-slip fault zone on the island of

Sulawesi Sulawesi (), also known as Celebes (), is an island in Indonesia. One of the four Greater Sunda Islands, and the world's eleventh-largest island, it is situated east of Borneo, west of the Maluku Islands, and south of Mindanao and the Sulu Ar ...

in Indonesia. It caused the

2018 Sulawesi earthquake and tsunami On 28 September 2018, a shallow, large earthquake struck in the neck of the Minahasa Peninsula, Indonesia, with its epicentre located in the mountainous Donggala Regency, Central Sulawesi. The magnitude 7.5 quake was located away from the prov ...

Geometry

It extends from near Dondowa,

North Luwu Regency North Luwu Regency is a regency of South Sulawesi Province of 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 ...

, in the south, where it links to the WNW-ESE trending Matano Fault. It continues northwards, heading offshore through the Gulf of Palu and passing to the west of the

Minahassa Peninsula The Minahasa Peninsula, also spelled Minahassa, is one of the four principal peninsulas on the Indonesian island of Sulawesi. It stretches north from the central part of the island, before turning to the east and forming the northern boundary of th ...

, before eventually linking with the North Sulawesi Subduction Zone. Although it is a strike slip fault, there are locally normal and thrust features and segments. Near Palu it forms the western side of the Palu Basin, a small

pull-apart basin In geology, a basin is a region where subsidence generates accommodation space for the deposition of sediments. A pull-apart basin is a structural basin where two overlapping (en echelon) strike-slip faults or a fault bend creates an area of cru ...

developed along the fault system.

Regional setting

The fault forms the boundary between two of the major microblocks that form the island, the North Sula Block and the Makassar Block. The current slip rate along the Palu-Koro Fault is estimated to be in the range per year, compared to a long term slip rate of per year over the last 5 million years.

Seismicity

The fault is known to be highly active and several historical earthquakes are thought to have occurred on this zone, in 1905, 1907, 1909, 1927, 1934,

1968 The year was highlighted by protests and other unrests that occurred worldwide. Events January–February * January 5 – "Prague Spring": Alexander Dubček is chosen as leader of the Communist Party of Czechoslovakia. * Januar ...

, 1985 and 1993. From trenching across the fault, three major earthquakes have been identified over the last 2,000 years, suggesting a recurrence interval for major earthquakes of about 700 years. That recurrence interval is insufficient to account for the long-term slip-rate, suggesting that either aseismic creep is important in this fault zone or that other strands have been active, away from the main fault trace.

References

{{DEFAULTSORT:Great Sumatran Fault Seismic faults of Southeast Asia Geology of Indonesia Strike-slip faults Seismic faults of Indonesia Supershear earthquakes