M5.3 Earthquake 15km SE of Rio Dell, CA — January 1, 2023
2023-01-01 18:35:04 UTC (2023-01-01) · approx. 10:35 AM UTC-8 local
Felt by 1,208 people across a wide area. Maximum shaking intensity MMI 6.9 (very strong).
On January 1, 2023 at 18:35 UTC, a magnitude 5.3 shallow crustal earthquake struck 15km SE of Rio Dell, CA, at a depth of 30.6 km and coordinates 40.4090°, -123.9710°. The earthquake was reported felt by 1,208 peopleacross a wide area, with a maximum shaking intensity of Modified Mercalli Intensity (MMI) 6.9 (very strong). The USGS PAGER system issued a yellow alert level for this event, indicating local impact possible. This earthquake was detected by 37 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 1190, making it one of the most significant global earthquakes in recent days. The nearest populated place is Rio Dell (population 3,368).
Physical scale: An earthquake of magnitude 5.3 releases seismic energy equivalent to roughly 2 kilotons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 3.0 km — a useful intuition for the size of the slip patch on the fault.
The epicenter is located in California, a region characterized by the San Andreas transform fault system, where the Pacific and North American plates slide past each other at roughly 46 mm per year. The nearest mapped fault system is the San Andreas Fault. View all earthquakes in California.
Learn more: San Andreas Fault · Magnitude scale · Aftershock sequences
Nearest Populated Places
What the Shaking Felt Like
At MMI 6.9 (very strong), people in the most strongly affected areas would have experienced: Strong shaking felt by everyone. Heavy furniture may move. Books fall from shelves. Plaster and chimneys may crack. Damage is generally slight in well-built structures.
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 1,208 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
Population exposure (USGS PAGER)
Estimated population that experienced each level of shaking. Based on the USGS PAGER rapid impact assessment, which combines ShakeMap output with global population grids.
| Shaking intensity (MMI) | Description | Population exposed |
|---|---|---|
| MMI 3 | weak | 290,112 |
| MMI 4 | light | 76,080 |
| MMI 5 | moderate | 17,530 |
| MMI 6 | strong | 2,837 |
| MMI 7 | very strong | 2,425 |
Earthquake Details
-123.9710°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 5.3 earthquake near Rio Dell, CA?
The magnitude 5.3 earthquake that struck 15km SE of Rio Dell, CA on January 1, 2023 at 18:35 UTC had a depth of 30.6 km. It was felt by 1,208 people with maximum shaking intensity of MMI 6.9 (very strong). For context, this was a moderate earthquake that could be widely felt.
Where did the earthquake occur?
The earthquake epicenter was located at 40.4090°, -123.9710°, which is 15km SE of Rio Dell, CA. The nearest populated place is Rio Dell (population 3,368). View all earthquakes in California.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 5.3 earthquakes can continue for days to weeks and gradually diminish over time.
Has California had earthquakes this big before?
The largest recorded earthquake in California was the M7.9 Fort Tejon earthquake of January 9, 1857. Today's magnitude 5.3 event is significantly smaller than that historical record.
Actions
Authoritative source: USGS event page (event ID: nc73827571). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, January 1, 2023). M5.3 Earthquake 15km SE of Rio Dell, CA — January 1, 2023. Retrieved January 26, 2026 from https://www.earthquaketracker.org/earthquakes/event/nc73827571/