M4.9 Earthquake 42 km ESE of Tambolaka, Indonesia — September 23, 2025
2025-09-23 19:54:41 UTC (2025-09-23) · approx. 3:54 AM UTC+8 local
Aftershock of the M5.1 mainshock.
On September 23, 2025 at 19:54 UTC, a magnitude 4.9 shallow crustal earthquake struck 42 km ESE of Tambolaka, Indonesia, at a depth of 67.7 km and coordinates -9.6123°, 119.5807°. This earthquake was detected by 81 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 369, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 4.9 releases seismic energy equivalent to roughly 338 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.4 km — a useful intuition for the size of the slip patch on the fault.
This earthquake is part of an ongoing aftershock sequence following the magnitude 5.1 mainshock that occurred 5 days ago 27 km SSE of Tambolaka, Indonesia. Since the mainshock, the USGS has recorded 2 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
The epicenter is located in Indonesia, a region characterized by the convergence of the Indo-Australian, Eurasian, and Philippine Sea plates, forming the Sunda-Banda arc system. The nearest mapped fault system is the Sunda megathrust. View all earthquakes in Indonesia.
Learn more: Magnitude scale · Aftershock sequences
Earthquake Details
119.5807°E
Technical Information
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Common Questions
How strong was the magnitude 4.9 earthquake near Tambolaka, Indonesia?
The magnitude 4.9 earthquake that struck 42 km ESE of Tambolaka, Indonesia on September 23, 2025 at 19:54 UTC had a depth of 67.7 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at -9.6123°, 119.5807°, which is 42 km ESE of Tambolaka, Indonesia. View all earthquakes in Indonesia.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.9 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.1 one earlier?
No. This magnitude 4.9 earthquake is an aftershock of the larger magnitude 5.1 mainshock that occurred earlier 27 km SSE of Tambolaka, Indonesia. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
Has Indonesia had earthquakes this big before?
The largest recorded earthquake in Indonesia was the M9.1 Indian Ocean earthquake of December 26, 2004. Today's magnitude 4.9 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: us6000rcdx). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, September 23, 2025). M4.9 Earthquake 42 km ESE of Tambolaka, Indonesia — September 23, 2025. Retrieved December 6, 2025 from https://www.earthquaketracker.org/earthquakes/event/us6000rcdx/