4.9

M4.9 Earthquake 27 km NW of Yonakuni, Japan — March 28, 2021

2021-03-28 06:41:17 UTC (2021-03-28) · approx. 2:41 PM UTC+8 local

MagnitudeM4.9(mb)
Time06:41 UTC≈ 2:41 PM UTC+8
Depth98.8 kmintermediate depth
Coordinates24.608°, 122.775°
Felt byNo felt reports
Status✓ Reviewed by USGS

On March 28, 2021 at 06:41 UTC, a magnitude 4.9 intermediate depth earthquake struck 27 km NW of Yonakuni, Japan, at a depth of 98.8 km and coordinates 24.6079°, 122.7747°.

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.

The epicenter is located in Japan, a region characterized by the intersection of four tectonic plates — Pacific, Philippine Sea, Eurasian, and North American — creating multiple subduction zones. The nearest mapped fault system is the Japan Trench. View all earthquakes in Japan.

Learn more: Magnitude scale · Aftershock sequences

Map showing earthquake epicenter at 24.61°, 122.77°

Earthquake Details

Magnitude
4.9 mb
Depth
98.8 km
intermediate depth
Location
24.6079°N
122.7747°E

Technical Information

Event ID
us6000dx45
Event Type
earthquake
Status
✓ Reviewed
Significance
369
Azimuthal Gap
45.0°
Min Station Distance
0.257°
RMS Residual
0.69 sec
Last Updated
2021-06-08 17:58:52 UTC

Common Questions

How strong was the magnitude 4.9 earthquake near Yonakuni, Japan?

The magnitude 4.9 earthquake that struck 27 km NW of Yonakuni, Japan on March 28, 2021 at 06:41 UTC had a depth of 98.8 km. For context, this was a light earthquake commonly felt near the epicenter.

Where did the earthquake occur?

The earthquake epicenter was located at 24.6079°, 122.7747°, which is 27 km NW of Yonakuni, Japan. View all earthquakes in Japan.

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.

Has Japan had earthquakes this big before?

The largest recorded earthquake in Japan was the M9.1 Tohoku earthquake of March 11, 2011. Today's magnitude 4.9 event is significantly smaller than that historical record.

Authoritative source: USGS event page (event ID: us6000dx45). All scientific values on this page are sourced verbatim from the USGS feed.

Cite this page: EarthquakeTracker.org. (2021, March 28, 2021). M4.9 Earthquake 27 km NW of Yonakuni, Japan — March 28, 2021. Retrieved June 8, 2021 from https://www.earthquaketracker.org/earthquakes/event/us6000dx45/