M4.2 Earthquake 119 km W of Castelo Branco, Portugal — October 31, 2021
2021-10-31 19:36:12 UTC (2021-10-31) · approx. 5:36 PM UTC-2 local
On October 31, 2021 at 19:36 UTC, a magnitude 4.2 shallow crustal earthquake struck 119 km W of Castelo Branco, Portugal, at a depth of 10.0 km and coordinates 38.6937°, -30.0633°.
Physical scale: An earthquake of magnitude 4.2 releases seismic energy equivalent to roughly 30 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 476 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
-30.0633°E
Technical Information
Common Questions
How strong was the magnitude 4.2 earthquake near Castelo Branco, Portugal?
The magnitude 4.2 earthquake that struck 119 km W of Castelo Branco, Portugal on October 31, 2021 at 19:36 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 4.2 earthquakes can continue for several days and gradually diminish over time.
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Understanding This Data
Magnitude 4.2 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us7000frh4). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, October 31, 2021). M4.2 Earthquake 119 km W of Castelo Branco, Portugal — October 31, 2021. Retrieved January 14, 2022 from https://www.earthquaketracker.org/earthquakes/event/us7000frh4/