M4.7 Earthquake in the Izu Islands, Japan region — July 12, 2021
2021-07-12 13:48:29 UTC (2021-07-12) · approx. 10:48 PM UTC+9 local
Aftershock of the M5.0 mainshock.
On July 12, 2021 at 13:48 UTC, a magnitude 4.7 shallow crustal earthquake struck in the Izu Islands, Japan region, at a depth of 10.0 km and coordinates 32.0222°, 141.8193°.
Physical scale: An earthquake of magnitude 4.7 releases seismic energy equivalent to roughly 169 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.1 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 5.0 mainshock that occurred 8 days ago in the Izu Islands, Japan region. Since the mainshock, the USGS has recorded 0 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 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
Earthquake Details
141.8193°E
Technical Information
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Common Questions
How strong was the magnitude 4.7 earthquake in the Izu Islands, Japan region?
The magnitude 4.7 earthquake that struck in the Izu Islands, Japan region on July 12, 2021 at 13:48 UTC had a depth of 10.0 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 32.0222°, 141.8193°, which is in the Izu Islands, Japan region. View all earthquakes in Japan.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.7 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.0 one earlier?
No. This magnitude 4.7 earthquake is an aftershock of the larger magnitude 5.0 mainshock that occurred earlier in the Izu Islands, Japan region. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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 4.7 event is significantly smaller than that historical record.
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Authoritative source: USGS event page (event ID: us6000eum6). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, July 12, 2021). M4.7 Earthquake in the Izu Islands, Japan region — July 12, 2021. Retrieved September 17, 2021 from https://www.earthquaketracker.org/earthquakes/event/us6000eum6/