Elsinore Fault Zone: Earthquake Risk, History & Live Activity
The Elsinore Fault Zone is a right-lateral strike-slip fault running about 180 kilometres through Southern California, from the Whittier and Chino faults near Los Angeles southeast past Lake Elsinore toward the Mexican border. It is one of the largest components of the San Andreas plate-boundary system, yet it slips relatively slowly, roughly 4 to 5 millimetres a year, and has been one of the quietest major faults in the region in historical times.
How likely is a large earthquake?
Because the Elsinore Fault moves slowly, its large earthquakes are spaced further apart than those on the neighbouring San Jacinto or San Andreas faults; estimates of the recurrence interval on the main fault are on the order of 250 years or more. UCERF3 (USGS, 2015) includes it in the statewide forecast that gives California a greater than 99 percent chance of a magnitude 6.7 or larger earthquake over 30 years.
The fault's quiet historical record is not evidence of safety. A slow, long-quiet fault can still store enough strain for a magnitude 6.5 to 7 earthquake, and the Elsinore zone passes near growing communities in Riverside, Orange, and San Diego counties.
Live seismic activity near this fault
Counts include M2.5+ events — the smallest size USGS reports consistently worldwide.
| Magnitude | Time (UTC) | Depth | Location |
|---|---|---|---|
| M2.6 | Sep 12, 11:32 UTC | 19 km | 4 km ESE of Inglewood, CA |
| M3.4 | Sep 12, 11:13 UTC | 11 km | 26 km ESE of Avalon, CA |
| M3.0 | Sep 12, 11:11 UTC | 14 km | 25 km ESE of Avalon, CA |
| M2.6 | Sep 12, 11:03 UTC | 10 km | 27 km ESE of Avalon, CA |
| M2.7 | Sep 12, 07:34 UTC | 19 km | 5 km E of Lennox, CA |
| M2.6 | Sep 11, 10:19 UTC | 8 km | 6 km W of Edwards Air Force Base, CA |
| M2.7 | Sep 8, 21:15 UTC | 2 km | 39 km NE of Big Bear City, CA |
| M3.1 | Sep 6, 07:13 UTC | 16 km | 4 km SSE of Compton, CA |
History
The Elsinore zone has produced few large earthquakes in the historical record, with most activity concentrated at its southern continuation across the border.
- 1892 Laguna Salada (M7.1 to 7.2) — a large earthquake on the fault's southern continuation in Baja California.
- 1910 Temescal Valley (M6.0) — the largest event on the main Elsinore fault in the historical record, near Lake Elsinore.
- 2010 El Mayor-Cucapah (M7.2) — struck the Laguna Salada region at the southern end of the system and was felt widely across Southern California.
Frequently asked questions
Is the Elsinore Fault dangerous if it is so quiet?
Yes, in the sense that a long quiet period lets strain accumulate. The Elsinore is capable of a magnitude 6.5 to 7 earthquake, and its slow slip rate means the interval between large events is long, so a lack of recent activity is expected rather than reassuring. Its position near dense parts of Riverside and Orange counties is the main concern.
How does the Elsinore Fault compare to the San Andreas?
Both are right-lateral strands of the same plate-boundary system, but the Elsinore slips far more slowly, about 4 to 5 millimetres a year versus 20 to 35 on the San Andreas, so it produces large earthquakes less often and, on average, somewhat smaller ones. It is still capable of a damaging major earthquake.
Nearby regions
Live counts from the USGS earthquake feeds within 200 km of the fault. Magnitudes and depths are automated readings and may be revised. Not for emergency use.