The "Great San Francisco Earthquake"
Before 1906, the earthquake that occurred on October 21, 1868 was known as "The Great San Francisco Earthquake." The magnitude 6.8 event ruptured approximately 20 miles of the Hayward Fault, from Fremont to Berkeley.
The earthquake struck at 7:53 AM on a Wednesday morning, when many people were beginning their day. It was felt from Monterey to Red Bluff, a distance of over 300 miles.
Damage and Deaths
At least 30 people were killed, and nearly every building in Hayward was damaged or destroyed. In San Francisco, five people died and many adobe and brick buildings collapsed. The newly built San Leandro courthouse was destroyed.
Total damage was estimated at $350,000 in 1868 dollars, a significant sum at the time. Hayward, then a small agricultural town, was particularly hard hit, with almost complete destruction of its business district.
Scientific Significance
The 1868 earthquake was the first to be scientifically studied in California. Geologist Josiah Whitney conducted the first systematic investigation of an earthquake in the state, documenting fault displacement and ground effects.
The surface rupture was clearly visible, with horizontal displacement of several feet observed in multiple locations. This evidence was crucial in early understanding of earthquake mechanics.
Why It Matters Today
The Hayward Fault has an average recurrence interval of approximately 140 years for major earthquakes. Having last ruptured in 1868, the fault is now considered "due" for another major event.
Scientists estimate a 33% probability of a magnitude 6.7 or greater earthquake on the Hayward Fault within the next 30 years. With millions of people now living along the fault, such an event would be catastrophic.