M4.3 Earthquake 50 km E of Port Alsworth, Alaska — June 13, 2025
2025-06-13 19:17:06 UTC (2025-06-13) · approx. 9:17 AM UTC-10 local
Felt by 97 people across nearby locations.
On June 13, 2025 at 19:17 UTC, a magnitude 4.3 intermediate depth earthquake struck 50 km E of Port Alsworth, Alaska, at a depth of 160.7 km and coordinates 60.1273°, -153.4275°. The earthquake was reported felt by 97 peopleacross nearby locations, with a maximum shaking intensity of Modified Mercalli Intensity (MMI) 3.4 (light).
Physical scale: An earthquake of magnitude 4.3 releases seismic energy equivalent to roughly 43 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 558 m — a useful intuition for the size of the slip patch on the fault.
The epicenter is located in Alaska, a region characterized by Pacific Plate subduction beneath the North American Plate, producing frequent megathrust and crustal earthquakes along the Aleutian arc. The nearest mapped fault system is the Aleutian megathrust. View all earthquakes in Alaska.
Learn more: Magnitude scale · Aftershock sequences
ShakeMap — predicted shaking intensity
Modeled ground-motion intensity contoured on the Modified Mercalli scale (MMI). Computed by the USGS from the moment-tensor solution and regional ground-motion prediction equations.
Source: U.S. Geological Survey ShakeMap. View interactive ShakeMap on USGS
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 97 citizen responses to the USGS Did You Feel It? system. Each colored zone represents the average MMI from reports in that area.
Source: U.S. Geological Survey Did You Feel It?. View on USGS · submit your own report
Earthquake Details
-153.4275°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.3 earthquake near Port Alsworth, Alaska?
The magnitude 4.3 earthquake that struck 50 km E of Port Alsworth, Alaska on June 13, 2025 at 19:17 UTC had a depth of 160.7 km. It was felt by 97 people with maximum shaking intensity of MMI 3.4 (light). For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 60.1273°, -153.4275°, which is 50 km E of Port Alsworth, Alaska. View all earthquakes in Alaska.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.3 earthquakes can continue for several days and gradually diminish over time.
Has Alaska had earthquakes this big before?
The largest recorded earthquake in Alaska was the M9.2 Great Alaska earthquake of March 27, 1964. Today's magnitude 4.3 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: ak0257jjjt29). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, June 13, 2025). M4.3 Earthquake 50 km E of Port Alsworth, Alaska — June 13, 2025. Retrieved August 22, 2025 from https://www.earthquaketracker.org/earthquakes/event/ak0257jjjt29/