A magnitude 4.6 earthquake struck Indonesia at 19:37 UTC on Wednesday, September 16, 2026, according to data from the United States Geological Survey (USGS). The earthquake's epicentre was located 43 km SE of Madang, Papua New Guinea, at a focal depth of 59.9 km.
Event Details
At a focal depth of 59.9 km, this is classified as a shallow earthquake (0–70 km). Shallow events are typically the most damaging: the seismic energy has less distance to travel before reaching the surface, resulting in stronger and more abrupt ground shaking at the epicentre.
The earthquake registered a magnitude of 4.6 on the moment magnitude scale — the standard measurement used by seismologists worldwide. At this magnitude, the shaking is felt strongly by everyone; minor to moderate damage possible in vulnerable buildings.
Where Did This Earthquake Occur?
Indonesia is located on the Pacific Ring of Fire at the junction of multiple major tectonic plates, including the Indo-Australian, Eurasian, and Pacific plates. With over 17,000 islands along active fault lines and subduction zones, it is among the world's most earthquake-prone nations.
Indonesia experiences thousands of earthquakes each year. Major events in recent decades include the 2004 Indian Ocean earthquake and tsunami (M9.1–9.3), the 2006 Yogyakarta earthquake, and the 2018 Sulawesi earthquake and tsunami. The country has invested heavily in tsunami warning infrastructure since 2004.
What Does Magnitude 4.6 Mean?
Moderate earthquakes are felt by virtually everyone near the epicentre. Strong shaking lasting 10–30 seconds can topple unsecured items, crack plaster, and cause poorly anchored objects to fall. Aftershocks are common following moderate events.
Significant damage can occur to vulnerable structures — particularly unreinforced masonry, old adobe buildings, and poorly maintained older construction. Well-engineered modern buildings are designed to withstand this level of shaking with minimal structural impact, though contents may shift and non-structural elements (ceilings, partitions) can be damaged.
A magnitude 4.6 earthquake releases approximately roughly 500 tonnes of TNT of energy. For comparison, this exceeds the energy released by most conventional explosive events and is sufficient to shift tectonic stress in measurable ways across a wide region.
Safety Guidance
After an earthquake, expect aftershocks. Check yourself and others for injuries. Inspect your surroundings for hazards before moving — broken glass, gas leaks (smell), downed power lines, and structural damage. If you suspect a gas leak, open windows and evacuate without using electrical switches or open flames.
Keep an earthquake emergency kit accessible at home. It should include at least 72 hours of water (4 litres per person per day), non-perishable food, a first aid kit, torch, battery-powered radio, copies of important documents, and essential medications. Reviewing and restocking this kit annually is strongly recommended.
BMKG (Badan Meteorologi, Klimatologi, dan Geofisika) operates Indonesia's earthquake and tsunami warning system. Coastal communities should move to higher ground immediately after strong shaking without waiting for an official warning.
Monitoring and Aftershocks
Seismologists are continuing to monitor the region for aftershocks, which are common following earthquakes of this magnitude. Aftershocks can occur minutes, hours, or even days after the main event and are sometimes strong enough to cause additional damage to already-weakened structures. Residents in the area are advised to remain cautious and follow guidance from local authorities.
Real-time seismic data is being collected by the USGS and contributing regional networks. Updated information will be published as it becomes available. You can track this and all other global seismic activity in real time on our live earthquake map.
The Science of Seismic Monitoring
Modern earthquake detection relies on a global network of seismographs — sensitive instruments that record ground motion in all three dimensions. When an earthquake occurs, the P-waves (primary, compressional waves) arrive first, followed by the slower S-waves (secondary, shear waves), and finally the surface waves that cause the most felt shaking. By comparing arrival times at multiple stations, scientists can triangulate the earthquake's location and calculate its magnitude within minutes of the event.
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