M4.9 Earthquake near off the coast of Oregon — February 20, 2021
2021-02-20 21:22:34 UTC (2021-02-20) · approx. 12:22 PM UTC-9 local
Felt by 5 people across nearby locations. Aftershock of the M5.3 mainshock.
On February 20, 2021 at 21:22 UTC, a magnitude 4.9 shallow crustal earthquake struck near off the coast of Oregon, at a depth of 10.0 km and coordinates 43.6654°, -128.1423°.
Physical scale: An earthquake of magnitude 4.9 releases seismic energy equivalent to roughly 338 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.4 km — a useful intuition for the size of the slip patch on the fault.
This earthquake is part of an ongoing aftershock sequence following the magnitude 5.3 mainshock that occurred 24 days ago near off the coast of Oregon. Since the mainshock, the USGS has recorded 2 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
The epicenter is located in Oregon, a region characterized by the southern Cascadia Subduction Zone, with additional seismicity from crustal faults in the Willamette Valley. The nearest mapped fault system is the Cascadia Subduction Zone. View all earthquakes in Oregon.
Learn more: Cascadia Subduction Zone · Magnitude scale · Aftershock sequences
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 5 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
-128.1423°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.9 earthquake near off the coast of Oregon?
The magnitude 4.9 earthquake that struck near off the coast of Oregon on February 20, 2021 at 21:22 UTC had a depth of 10.0 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 43.6654°, -128.1423°, which is near off the coast of Oregon. View all earthquakes in Oregon.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.9 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.3 one earlier?
No. This magnitude 4.9 earthquake is an aftershock of the larger magnitude 5.3 mainshock that occurred earlier near off the coast of Oregon. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
Has Oregon had earthquakes this big before?
The largest recorded earthquake in Oregon was the M7.3 offshore Brookings earthquake of November 23, 1873. Today's magnitude 4.9 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: us6000djrq). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, February 20, 2021). M4.9 Earthquake near off the coast of Oregon — February 20, 2021. Retrieved December 22, 2025 from https://www.earthquaketracker.org/earthquakes/event/us6000djrq/