A 6.7-magnitude earthquake struck Indonesia

At 10:27 a.m. local time on the 16th, a 6.7-magnitude earthquake struck the Sulawesi region of Central Sulawesi province, Indonesia. The epicenter was located approximately 42 kilometers southeast of Palu (0.95°S, 120.10°E).

Key Parameters and Impacts

Focus and Cause: The Indonesian Meteorology, Climatology and Geophysics Agency (BMKG) measured the focal depth at 10 kilometers, while the China Earthquake Networks Center measured it at 20 kilometers, classifying it as a shallow earthquake triggered by the movement of a local active fault.

Tsunami Risk: Indonesian officials determined there was no risk of a tsunami. The China Tsunami Warning Center of the Ministry of Natural Resources assessed that the earthquake might trigger a localized tsunami around the epicenter, but would not affect China’s coast.

On-site Situation: Strong tremors were felt in Palu and other areas. Residents were evacuated to open areas for safety. Some buildings experienced wall collapses and structural damage. As of now, no reports of casualties or major property damage have been received, and relevant departments are continuing to monitor aftershocks.

The Root Cause of Frequent Earthquakes in Indonesia

Indonesia is one of the most seismically active countries in the world, with approximately 13% of global earthquakes occurring within its borders. This is primarily due to its unique geological location:

Indonesia is situated in a key section of the Circum-Pacific Seismic Belt, at the intersection and collision zone of the Eurasian Plate, the Indo-Australian Plate, the Pacific Plate, and the Philippine Sea Plate. The Indo-Australian Plate is subducting northward beneath the Eurasian Plate at a rate of 5-7 centimeters per year, leading to a continuous accumulation and frequent release of crustal stress, resulting in high-density seismic activity.

Major Seismic Tectonic Zones

Sunda Trench (Java Trench)

Stretching 3200 kilometers along Sumatra, Java, Bali, and the southern side of Timor Island, it forms the main boundary of the Indo-Australian Plate subduction and is the origin of Indonesia’s strongest earthquakes. The devastating 2004 Indian Ocean earthquake, measuring 9.1 on the Richter scale, occurred on this subduction zone west of Sumatra.

The Sumatra Strike-Slip Fault

Stretching 1900 kilometers in length, it runs through the interior of Sumatra and bears the horizontal strike-slip component of the subduction zone, frequently triggering moderate to strong earthquakes.

Complex Fault Zone in Eastern Indonesia

Sulawesi, the Maluku Islands, and New Guinea are located in a region of plate tectonics, characterized by a complex and interwoven fault system and highly unstable tectonic activity. This is the core reason for the high frequency of earthquakes in eastern Indonesia. The recent 6.7 magnitude earthquake was located on an active fault zone in Sulawesi.

Core Risk Characteristics of Earthquakes in Indonesia

High Proportion of Shallow-Focused Earthquakes, Strong Direct Destructive Power

Most strong earthquakes in Indonesia are shallow-focused earthquakes with a focal depth of less than 70 kilometers. The energy loss during transmission to the surface is minimal, resulting in a stronger impact on buildings and infrastructure. Densely populated islands like Java and Sumatra are located in areas prone to strong earthquakes, posing a high risk of casualties. Earthquake-Tsunami Linkage Risk is Prominent

Major earthquakes in subduction zones of the southern ocean are highly likely to trigger large-scale transoceanic tsunamis; nearshore strike-slip or thrust earthquakes can also trigger localized tsunamis. The 2018 Palu 7.4 magnitude earthquake was accompanied by a localized tsunami, causing significant casualties.

Earthquake-Volcanic Complex Disasters

Indonesia has the world’s largest number of active volcanoes (over 130). Plate subduction simultaneously drives volcanic activity, and strong earthquakes can trigger anomalies in surrounding volcanoes, creating a superimposed disaster.

Historical Major Earthquake Events

December 2004, 9.1 magnitude earthquake off the coast of Sumatra: The third strongest earthquake in recorded history, triggering an Indian Ocean tsunami that swept through 14 countries, causing over 227,000 deaths, making it one of the most severe tsunami disasters in modern times.

September 2018: A 7.4 magnitude earthquake struck Palu, Central Sulawesi. The epicenter was 10 kilometers deep, accompanied by a local tsunami and widespread soil liquefaction, resulting in over 4,000 deaths and extensive damage to buildings in Palu.

January 2022: A 5.6 magnitude earthquake struck West Java. The epicenter was extremely shallow and occurred in a densely populated area, causing over 600 deaths and widespread collapse of homes.