M4.0 Earthquake in the Izu Islands, Japan region — October 21, 2023
2023-10-21 21:19:16 UTC (2023-10-21) · approx. 6:19 AM UTC+9 local
On October 21, 2023 at 21:19 UTC, a magnitude 4.0 deep-focus earthquake struck in the Izu Islands, Japan region, at a depth of 390.4 km and coordinates 30.9872°, 138.3983°.
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.
Earthquake Details
138.3983°E
Technical Information
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Common Questions
How strong was the magnitude 4.0 earthquake in the Izu Islands, Japan region?
The magnitude 4.0 earthquake that struck in the Izu Islands, Japan region on October 21, 2023 at 21:19 UTC had a depth of 390.4 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.
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Understanding This Data
Magnitude 4.0 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us6000lh7m). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, October 21, 2023). M4.0 Earthquake in the Izu Islands, Japan region — October 21, 2023. Retrieved December 26, 2023 from https://www.earthquaketracker.org/earthquakes/event/us6000lh7m/