1892 Vacaville–Winters earthquakes
 Redding
Virginia City
Salinas
Fresno
Coalinga
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| Date | April 19, 1892 |
|---|---|
| Magnitude | 6.4 MLa |
| Epicenter | 38°24′N 122°00′W / 38.4°N 122°WCoordinates: 38°24′N 122°00′W / 38.4°N 122°W |
| Total damage | $225,000–250,000 |
| Max. intensity | IX (Violent) |
| Aftershocks | 6.2 MLa April 21 |
| Casualties | 1 dead |
The 1892 Vacaville–Winters earthquakes occurred in northern California as a large doublet on April 19 and April 21. Measured on a seismic scale that is based on an isoseismal map or the event's felt area, the 6.4 MLa and 6.2 MLa events were assigned a maximum Mercalli intensity of IX (Violent), and affected the North Bay and Central Valley areas. While the total damage was estimated at between $225,000–250,000, one person was killed, but there are no reports on how many people may have been injured. No surface faulting was observed as a result of either strong shocks.
The primary tectonic feature of the region is the strike-slip San Andreas system of faults. From west to east, the Hayward–Rogers Creek Fault Zone and the Concord–Green Valley Faults are the closest to Vacaville and Winters. While the Hayward and Rogers Creek Faults have been given a 32% chance of a M6.7 or greater shock before 2030, the Concord and Green Valley Faults have been assigned a lower probability of 6% each.
Vacaville and Winters both lie to the east of these faults along the low foothills. Multiple investigators have remarked on the potential for blind thrust earthquakes in this area. Wong and Ely specifically labelled it the Coast Range–Sierran Block Boundary Zone and stated that the 1983 Coalinga earthquake (a blind thrust event) occurred within the zone.
Each large shock had a high intensity and was felt over roughly the same geographical area. The area over which the initial shock was felt with an intensity of VIII (Severe) was about 1,100 km2 and the area for the second shock was about 890 km2. The furthest extent that they were felt was from Redding in the north to Salinas and Fresno in the south and to Virginia City, Nevada in the east.
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