2.1

M2.1 Earthquake 4km E of Redwood Valley, CADecember 22, 2021

2021-12-22 19:04:40 UTC (2021-12-22) · approx. 11:04 AM UTC-8 local

MagnitudeM2.1(md)
Time19:04 UTC11:04 AM UTC-8
Depth2.6 kmshallow crustal
Coordinates39.269°, -123.160°
Felt by1DYFI response
Status✓ Reviewed by USGS

On December 22, 2021 at 19:04 UTC, a magnitude 2.1 shallow crustal earthquake struck 4km E of Redwood Valley, CA, at a depth of 2.6 km and coordinates 39.2693°, -123.1598°.

Physical scale: An earthquake of magnitude 2.1 releases seismic energy equivalent to roughly 18.6 kg of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 16 m — a useful intuition for the size of the slip patch on the fault.

Map showing earthquake epicenter at 39.27°, -123.16°

Did You Feel It? — community-reported shaking

Aggregated felt-report intensity from 1 citizen response 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 M2.1 earthquake near 4km E of Redwood Valley, CA

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

Earthquake Details

Magnitude
2.1 md
Depth
2.6 km
shallow crustal
Location
39.2693°N
-123.1598°E
Felt Reports
1
DYFI responses
Community Intensity
2.0
CDI from reports

Technical Information

Event ID
nc73667781
Event Type
earthquake
Status
✓ Reviewed
Significance
65
Stations Used
33
Azimuthal Gap
71.0°
Min Station Distance
0.046°
RMS Residual
0.07 sec
Last Updated
2021-12-28 23:19:11 UTC

Common Questions

How strong was the magnitude 2.1 earthquake near Redwood Valley, CA?

The magnitude 2.1 earthquake that struck 4km E of Redwood Valley, CA on December 22, 2021 at 19:04 UTC had a depth of 2.6 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 2.1 earthquakes can continue for several days and gradually diminish over time.

Understanding This Data

Magnitude 2.1 earthquakes are typically only recorded by instruments.

Learn more about magnitude →

Authoritative source: USGS event page (event ID: nc73667781). All scientific values on this page are sourced verbatim from the USGS feed.

Cite this page: EarthquakeTracker.org. (2021, December 22, 2021). M2.1 Earthquake 4km E of Redwood Valley, CADecember 22, 2021. Retrieved December 28, 2021 from https://www.earthquaketracker.org/earthquakes/event/nc73667781/