3.6

M3.6 Earthquake 137 km SSE of Sand Point, Alaska — October 21, 2020

2020-10-21 23:26:43 UTC (2020-10-21) · approx. 12:26 PM UTC-11 local

MagnitudeM3.6(mb)
Time23:26 UTC≈ 12:26 PM UTC-11
Depth24.7 kmshallow crustal
Coordinates54.218°, -159.589°
Felt byNo felt reports
Status✓ Reviewed by USGS

On October 21, 2020 at 23:26 UTC, a magnitude 3.6 shallow crustal earthquake struck 137 km SSE of Sand Point, Alaska, at a depth of 24.7 km and coordinates 54.2182°, -159.5894°.

Physical scale: An earthquake of magnitude 3.6 releases seismic energy equivalent to roughly 3.8 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 184 m — a useful intuition for the size of the slip patch on the fault.

Map showing earthquake epicenter at 54.22°, -159.59°

Earthquake Details

Magnitude
3.6 mb
Depth
24.7 km
shallow crustal
Location
54.2182°N
-159.5894°E

Technical Information

Event ID
us7000c6bn
Event Type
earthquake
Status
✓ Reviewed
Significance
199
Azimuthal Gap
200.0°
Min Station Distance
0.614°
RMS Residual
0.57 sec
Last Updated
2021-01-09 20:05:33 UTC

Common Questions

How strong was the magnitude 3.6 earthquake near Sand Point, Alaska?

The magnitude 3.6 earthquake that struck 137 km SSE of Sand Point, Alaska on October 21, 2020 at 23:26 UTC had a depth of 24.7 km. For context, this was a minor earthquake typically detected only by instruments.

Were there aftershocks?

Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 3.6 earthquakes can continue for several days and gradually diminish over time.

Understanding This Data

Magnitude 3.6 earthquakes are typically only recorded by instruments.

Learn more about magnitude →

Authoritative source: USGS event page (event ID: us7000c6bn). All scientific values on this page are sourced verbatim from the USGS feed.

Cite this page: EarthquakeTracker.org. (2020, October 21, 2020). M3.6 Earthquake 137 km SSE of Sand Point, Alaska — October 21, 2020. Retrieved January 9, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000c6bn/