San Jacinto Fault Zone
Southern California, USA · continental transform · 277.6 km of mapped active fault in 7 traces
unknown as of 7 November 2026.
no baseline good enough to compare against; the catalogue holds too few events on this system to say what normal is
| Window | the last 30.0 days |
|---|---|
| Earthquakes counted | 0 at M4.5 or above |
| Expected in that window | 0.00 |
What this system normally does
From 1995 to 2025 the catalogue holds 7 earthquakes of M4.5 or larger attributable to this system: about 0.23 a year. That figure is what "elevated" on this page is measured against.
Confidence in that rate is low: the catalogue holds too few events here for the average to carry much weight, and this system is never called elevated on the strength of it alone.
The fault itself
| Mapped length | 277.6 km |
|---|---|
| Traces | 7 |
| Tectonic setting | continental transform |
| Slip types | Dextral |
| Depth attributed to it | down to 50.0 km |
| Extent | 33.21 to 34.26 latitude, -117.50 to -116.10 longitude |
Recorded history
NOAA's hazard records hold one significant earthquake attributed to this system since 1918.
The deadliest was the 21 April 1918 magnitude 6.7 earthquake (California: San Jacinto, Hemet), which killed one person.
| Date | What | Where | Toll |
|---|---|---|---|
| 21 April 1918 | magnitude 6.7 earthquake | California: San Jacinto, Hemet | 1 dead, damage under $1 million |
A dash means NOAA recorded no number, not that nobody died. Older entries are fewer because fewer were written down, not because less happened.
Recorded history: NOAA NCEI hazard databases, public domain, retrieved 2026-10-22.
Published rupture probability
USGS, UCERF3 (Fact Sheet 2015-3009) publishes a probability for this system. It is their figure, not ours:
| Probability | 5% |
|---|---|
| For an earthquake of | M6.7 or larger |
| Within | 30 years |
| As of | 2015 |
Read the issuer's own publication
Who to listen to if you live here
California Geological Survey is the agency that tells people on this system what to do. https://www.conservation.ca.gov/cgs/earthquakes (in English)
Other systems in Southern California, USA
Where these numbers come from
Fault geometry, length and segment counts: GEM Global Active Faults Database (GEM GAF-DB), GEM Foundation, https://github.com/GEMScienceTools/gem-global-active-faults Licence: CC-BY-SA-4.0. Figures derived from it here are offered under the same licence. Earthquake counts, magnitudes and depths: United States Geological Survey, public domain. The activity judgement is ours, computed from those two inputs, and is not a statement by either agency.