4.0

M4.0 Earthquake 150 km N of Nago, Japan — July 4, 2021

2021-07-04 22:05:21 UTC (2021-07-04) · approx. 7:05 AM UTC+9 local

MagnitudeM4.0(mb)
Time22:05 UTC≈ 7:05 AM UTC+9
Depth10.0 kmshallow crustal
Coordinates27.970°, 127.847°
Felt byNo felt reports
Status✓ Reviewed by USGS

On July 4, 2021 at 22:05 UTC, a magnitude 4.0 shallow crustal earthquake struck 150 km N of Nago, Japan, at a depth of 10.0 km and coordinates 27.9695°, 127.8472°.

Physical scale: An earthquake of magnitude 4.0 releases seismic energy equivalent to roughly 15 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 347 m — a useful intuition for the size of the slip patch on the fault.

Map showing earthquake epicenter at 27.97°, 127.85°

Earthquake Details

Magnitude
4.0 mb
Depth
10.0 km
shallow crustal
Location
27.9695°N
127.8472°E

Technical Information

Event ID
us6000et8i
Event Type
earthquake
Status
✓ Reviewed
Significance
246
Azimuthal Gap
92.0°
Min Station Distance
1.190°
RMS Residual
0.36 sec
Last Updated
2021-09-10 20:08:13 UTC

Common Questions

How strong was the magnitude 4.0 earthquake near Nago, Japan?

The magnitude 4.0 earthquake that struck 150 km N of Nago, Japan on July 4, 2021 at 22:05 UTC had a depth of 10.0 km. For context, this was a light earthquake commonly felt near the epicenter.

Were there aftershocks?

Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.0 earthquakes can continue for several days and gradually diminish over time.

Understanding This Data

Magnitude 4.0 earthquakes are often felt but rarely cause damage.

Learn more about magnitude →

Authoritative source: USGS event page (event ID: us6000et8i). All scientific values on this page are sourced verbatim from the USGS feed.

Cite this page: EarthquakeTracker.org. (2021, July 4, 2021). M4.0 Earthquake 150 km N of Nago, Japan — July 4, 2021. Retrieved September 10, 2021 from https://www.earthquaketracker.org/earthquakes/event/us6000et8i/