Magnitude 5.6 earthquake — Teluk Dalam, Indonesia

A magnitude 5.6 earthquake struck the Indian Ocean off North Sumatra on 18 August 2026, according to the United States Geological Survey (USGS). The quake was recorded at 06:02 UTC (around 13:02 local time), with its epicentre located roughly 154km south-south-east of Teluk Dalam, a town in the Nias Selatan (South Nias) regency of North Sumatra province. USGS measured the event's depth at approximately 10km, a relatively shallow rupture, with peak ground shaking estimated at a Modified Mercalli Intensity of around 5.4, corresponding to moderate tremors that could plausibly be felt on nearby islands and the Sumatran mainland, though no felt reports had been logged on USGS's "Did You Feel It?" system at the time of review.

USGS's automated PAGER impact model assigned the earthquake a green alert for both fatalities and economic losses, indicating a low likelihood of significant humanitarian or infrastructure impact, consistent with the epicentre's location in open water well away from population centres. Ground-failure assessments were similarly low-level: liquefaction exposure was estimated at only around 57 people, while landslide exposure was negligible, and no tsunami warning was issued. The region lies along the highly active subduction boundary between the Indo-Australian and Sunda plates, an area responsible for some of the most powerful earthquakes on record, including the catastrophic magnitude 9.1 Sumatra–Andaman quake of December 2004 and a further major aftershock-zone rupture near Nias in March 2005; this latest, considerably smaller event is a reminder of the ongoing seismic activity in the region, though it caused no reported damage or casualties.