M5.9 Earthquake 158 km S of Ambon, Indonesia — April 3, 2021
2021-04-03 18:42:01 UTC (2021-04-03) · approx. 3:42 AM UTC+9 local
On April 3, 2021 at 18:42 UTC, a magnitude 5.9 deep-focus earthquake struck 158 km S of Ambon, Indonesia, at a depth of 326.0 km and coordinates -5.1251°, 128.1558°. The USGS PAGER system issued a green alert level for this event, indicating no significant casualties or damage expected. The nearest populated place is Ambon (population 355,596).
Physical scale: An earthquake of magnitude 5.9 releases seismic energy equivalent to roughly 11 kilotons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 7.1 km — a useful intuition for the size of the slip patch on the fault.
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
Nearest Populated Places
ShakeMap — predicted shaking intensity
Modeled ground-motion intensity contoured on the Modified Mercalli scale (MMI). Computed by the USGS from the moment-tensor solution and regional ground-motion prediction equations.
Source: U.S. Geological Survey ShakeMap. View interactive ShakeMap on USGS
Population exposure (USGS PAGER)
Estimated population that experienced each level of shaking. Based on the USGS PAGER rapid impact assessment, which combines ShakeMap output with global population grids.
| Shaking intensity (MMI) | Description | Population exposed |
|---|---|---|
| MMI 3 | weak | 686,129 |
Earthquake Details
128.1558°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 5.9 earthquake near Ambon, Indonesia?
The magnitude 5.9 earthquake that struck 158 km S of Ambon, Indonesia on April 3, 2021 at 18:42 UTC had a depth of 326.0 km. For context, this was a moderate earthquake that could be widely felt.
Where did the earthquake occur?
The earthquake epicenter was located at -5.1251°, 128.1558°, which is 158 km S of Ambon, Indonesia. The nearest populated place is Ambon (population 355,596). View all earthquakes in Indonesia.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 5.9 earthquakes can continue for days to weeks and gradually diminish over time.
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 5.9 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: us6000dysl). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, April 3, 2021). M5.9 Earthquake 158 km S of Ambon, Indonesia — April 3, 2021. Retrieved December 22, 2025 from https://www.earthquaketracker.org/earthquakes/event/us6000dysl/