M6.5 Earthquake Rocks Java Sea North of Jakarta, Felt Widely - Tempo.co English
TEMPO.CO, Jakarta - A magnitude 6.5 tectonic earthquake occurred in the Java Sea, about 69 kilometers northeast of the Thousand Islands, Jakarta, on Saturday morning, September 12, 2026. The Meteorology, Climatology, and Geophysics Agency (BMKG) said the earthquake occurred at 4:23 a.m. local time and is not likely to trigger a tsunami.
"The earthquake's epicenter was at a depth of 368 kilometers, classified as a deep-focus earthquake," said Wijayanto, the Director of Earthquake and Tsunami at BMKG, in a statement shared after the earthquake on Saturday morning. According to Wijayanto, the quake was caused by intraslab activity with an oblique-normal movement mechanism.
The strong earthquake did not trigger a tsunami, but its tremors were widely felt. According to the estimated tremor level map and public reports, the strongest earthquake tremors, level IV MMI, were felt in Pandeglang, Lebak, Serang, Sukabumi, Cianjur, and Tanggamus.
At this level, the earthquake was experienced by many people, both indoors and outdoors. It was capable of breaking pottery, rattling windows and doors, and causing walls to creak.
Residents in Tangerang, North Jakarta, and Cilacap also felt the earthquake, which registered at intensity level III MMI. This means that the vibration indoors was comparable to that of a passing truck.
Weaker intensity was felt more widely, covering Bandung, Yogyakarta, Pacitan, Ponorogo, Malang, Bengkulu, Padang, Mentawai, Pariaman, and Solok Selatan. BMKG's monitoring until 5 AM showed no recorded subsequent earthquake activity.
In a separate statement, a member of the Indonesian Disaster Experts Association, Daryono, explained that deep-focus earthquakes (hypocenter more than 300 kilometers) like the one that occurred this morning rarely trigger aftershocks. "The earthquake occurred in the very homogeneous oceanic lithosphere at a depth of hundreds of kilometers; stress release tends to occur totally within a single main event," he said.
He also explained that this earthquake was not triggered by active fault activity, but rather by the breaking of rocks on the Australian Oceanic Plate that extends deep into the Java Sea. The rock deformation process within this subducted plate is what gives it its name: an intra-slab earthquake.
Because of its depth, the wave attenuation spectrum gradually weakens but covers a very wide geographical area (from Sumatra to eastern Java and Kalimantan).
Daryono explained why the epicenter of the earthquake was in the Java Sea north of Jakarta, yet the tremors were stronger and were felt earlier in southern Java, in places such as Sukabumi. "This happened because seismic waves propagate most efficiently through the dense and homogeneous plate slab medium towards the south before spreading to the surface," said the geography doctor who had worked for BMKG and became Director of Earthquake and Tsunami.
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