M4.2 Earthquake 135 km NNW of Castelo Branco, Portugal — July 8, 2023
2023-07-08 19:38:02 UTC (2023-07-08) · approx. 5:38 PM UTC-2 local
On July 8, 2023 at 19:38 UTC, a magnitude 4.2 shallow crustal earthquake struck 135 km NNW of Castelo Branco, Portugal, at a depth of 10.0 km and coordinates 39.6005°, -29.4529°.
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
-29.4529°E
Technical Information
Common Questions
How strong was the magnitude 4.2 earthquake near Castelo Branco, Portugal?
The magnitude 4.2 earthquake that struck 135 km NNW of Castelo Branco, Portugal on July 8, 2023 at 19:38 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: us7000kfrb). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, July 8, 2023). M4.2 Earthquake 135 km NNW of Castelo Branco, Portugal — July 8, 2023. Retrieved September 9, 2023 from https://www.earthquaketracker.org/earthquakes/event/us7000kfrb/