4.2 Magnitude Earthquake Strikes off West Java Coast, Indonesia
A magnitude 4.2 earthquake shook Sukabumi, West Java, on Oct 4, 2026. Authorities confirm no tsunami risk and no immediate reports of structural damage.
SUKABUMI, INDONESIA — A magnitude 4.2 earthquake rattled the southern coast of West Java on Saturday morning, Oct. 4, 2026, prompting residents in coastal areas to briefly evacuate their homes. Indonesia's Meteorology, Climatology, and Geophysical Agency (BMKG) recorded the tremor at 8:31 a.m. local time (WIB), with its epicenter located 61 kilometers south of Sukabumi Regency.
The seismic event occurred at a depth of 36 kilometers. While the epicenter was deep in the Indian Ocean, the tremor was felt across several regions, including the popular coastal town of Pelabuhan Ratu, as well as parts of Cianjur and Cidolog. BMKG confirmed that the quake posed no tsunami risk to the coastal communities.
Impact Across Southern Java
Residents in Pelabuhan Ratu reported experiencing Modified Mercalli Intensity (MMI) levels of II-III, describing the sensation as similar to the vibration of a passing heavy truck. Observations from the field indicated that while some light hanging objects swayed, no structural failures or injuries were reported in the hours following the event. In Cianjur, some locals noted the rattling of window panes, while the tremor in Cidolog was felt more mildly at MMI level II.
The region is part of a complex subduction zone where the Indo-Australian plate shifts beneath the Eurasian plate. Geologists frequently monitor this area, known as the South Java Megathrust zone, due to its high tectonic activity. This morning's event follows a series of other seismic activities recorded across Indonesia earlier on Saturday, including a more significant M6.1 quake in Southwest Sumba.
Monitoring and Safety Protocols
Local authorities from the West Java Regional Disaster Management Agency (BPBD) have maintained a steady watch over the affected districts. Residents have returned to their normal activities, and government officials continue to verify the structural integrity of residential buildings in the southern corridor.
BMKG officials advised the public to remain vigilant but calm, noting that earthquakes of this magnitude rarely result in catastrophic damage. Authorities warned citizens against relying on unverified reports on social media and urged them to monitor official channels for updates. “We advise residents to stay updated through verified information sources and maintain their emergency preparedness kits, including basic medical supplies and lighting,” an agency representative stated.
The area surrounding Sukabumi and Cianjur remains highly sensitive to tectonic shifts. While this weekend's M4.2 event was relatively minor compared to previous destructive quakes in the region, it serves as a persistent reminder of the seismic volatility inherent to the Indonesian archipelago.
