4.8

M4.8 Earthquake near Gulf of Alaska — October 24, 2020

2020-10-24 17:58:51 UTC (2020-10-24) · approx. 7:58 AM UTC-10 local

Felt by 2 people across nearby locations.

MagnitudeM4.8(mww)
Time17:58 UTC≈ 7:58 AM UTC-10
Depth12.2 kmshallow crustal
Coordinates56.357°, -147.609°
Felt by2DYFI responses
Status✓ Reviewed by USGS

On October 24, 2020 at 17:58 UTC, a magnitude 4.8 shallow crustal earthquake struck near Gulf of Alaska, at a depth of 12.2 km and coordinates 56.3569°, -147.6095°.

Physical scale: An earthquake of magnitude 4.8 releases seismic energy equivalent to roughly 239 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.2 km — 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

Map showing earthquake epicenter at 56.36°, -147.61°

Did You Feel It? — community-reported shaking

Aggregated felt-report intensity from 2 citizen responses to the USGS Did You Feel It? system. Each colored zone represents the average MMI from reports in that area.

USGS DYFI community-reported intensity map for the M4.8 earthquake near Gulf of Alaska

Source: U.S. Geological Survey Did You Feel It?. View on USGS · submit your own report

Earthquake Details

Magnitude
4.8 mww
Depth
12.2 km
shallow crustal
Location
56.3569°N
-147.6095°E
Felt Reports
2
DYFI responses
Community Intensity
2.0
CDI from reports

Technical Information

Event ID
us6000ccph
Event Type
earthquake
Status
✓ Reviewed
Significance
355
Azimuthal Gap
76.0°
Min Station Distance
3.069°
RMS Residual
0.84 sec
Last Updated
2021-01-09 20:05:24 UTC

Common Questions

How strong was the magnitude 4.8 earthquake near Gulf of Alaska?

The magnitude 4.8 earthquake that struck near Gulf of Alaska on October 24, 2020 at 17:58 UTC had a depth of 12.2 km. For context, this was a light earthquake commonly felt near the epicenter.

Where did the earthquake occur?

The earthquake epicenter was located at 56.3569°, -147.6095°, which is near Gulf of Alaska. View all earthquakes in Alaska.

Were there aftershocks?

Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.8 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 4.8 event is significantly smaller than that historical record.

Authoritative source: USGS event page (event ID: us6000ccph). All scientific values on this page are sourced verbatim from the USGS feed.

Cite this page: EarthquakeTracker.org. (2020, October 24, 2020). M4.8 Earthquake near Gulf of Alaska — October 24, 2020. Retrieved January 9, 2021 from https://www.earthquaketracker.org/earthquakes/event/us6000ccph/