6.5-magnitude earthquake jolts Jakarta’s Thousand Islands, no tsunami

An early morning earthquake shook residents awake across Indonesia’s capital and neighboring islands. The tremor struck at 4:23 a.m. local time in the Java Sea, prompting immediate inspections of vital transport infrastructure and reports of shaking from residential neighborhoods.

Epicenter Depth and Magnitude Revision by BMKG

The Meteorology, Climatology, and Geophysics Agency initially placed the tremor at magnitude 5.9 before revising the magnitude to 6.5 following further analysis. Earthquake and Tsunami Director Dr Wijayanto stated that the earthquake struck at 4.23 am local time, with its epicentre in the Java Sea, 69 kilometres northeast of Jakarta’s Thousand Islands, at a depth of 368 kilometres. Other agency records noted the depth at 376 kilometers.

Because of this deep hypocenter, experts classified the event as an earthquake caused by intraslab activity within tectonic plates. Tsunami modelling results showed that the earthquake had no tsunami potential, with the agency stating regarding the tremor: No tsunami threat. Taking into account the location of the epicentre and the depth of its hypocentre, Dr Wijayanto said in a statement: Taking into account the location of the epicentre and the depth of its hypocentre, the earthquake was a deep earthquake caused by intraslab activity.

“No tsunami threat”

BMKG, Meteorology, Climatology, and Geophysics Agency

The earthquake came less than 10 hours after a magnitude 6.0 quake struck the Banda Sea in eastern Indonesia at 6.56 pm on Friday at a depth of 148 kilometres, with its epicentre 162 kilometres northeast of Southwest Maluku and tremors felt across parts of Maluku.

Shaking Felt Across Java, Sumatra, and the Sunda Strait

While the epicentre remained far offshore in the Java Sea, the depth of the rupture carried seismic energy across distances. Dr Wijayanto said that the strongest tremors from Saturday’s earthquake were reported in parts of Banten and West Java, as well as Tanggamus in southern Sumatra, where the shaking was perceptible by people indoors and could cause windows and doors to rattle. The tremor was felt at IV MMI in large areas of Pandeglang, Lebak, and Serang districts in Banten; Cianjur District in West Java; and Tanggamus District in Lampung, according to agency notes.

Lighter tremors rated at III MMI were felt in Tangerang, Banten; Tanjung Priok, North Jakarta; and Cilacap, Central Java, where residents felt lighter tremors. Dr Wijayanto noted that weaker shaking was reported as far away as Yogyakarta and Malang in Java, and Padang and the Mentawai Islands in western Sumatra.

Some of the strongest tremors were reportedly felt in Pandeglang in Banten, which lies along the Sunda Strait near the Anak Krakatau volcano which experienced renewed eruptive activity last week. However, Dr Wijayanto stated that Saturday’s earthquake was tectonic in origin, with BMKG reporting no aftershocks as of 5 a.m. local time. BMKG advised residents to stay clear of damaged structures and remain calm while the agency continues monitoring the situation.

Commuter Rail Suspensions and Quick Line Resumptions

Transport networks faced brief interruptions as operators initiated safety protocols. KAI Commuter said in a social media post that Commuter Line services were suspended following the earthquake to allow comprehensive inspections of railway tracks.

Services along the Bogor, Cikarang, Rangkasbitung, and Tanjung Priok lines resumed services after inspections were completed at 5.26 am. The Tangerang line followed shortly after, resuming services at 5.45 am.