Qualla: 1915 Imperial Valley Earthquakes

1915 Imperial Valley Earthquakes: Introduction

Wed, 01 Apr 2026 00:00:00 GMT

Photo credit Angelsrm, CC BY-SA 4.0. The first shock came at 7:59 in the evening — eleven seconds that stopped clocks, cracked walls, and sent people pouring into the streets of El Centro and Calexico. Then, nearly an hour later, the second earthquake arrived. At 8:57 PM, another magnitude 6.25 shake rolled through the same ground. The people who had gone back inside their weakened buildings were injured. In Mexicali, where the nightlife had barely paused after the first shock, the collapse of walls and falling debris killed six people when the second quake struck. The date was June 22, 1915.

Image: Angelsrm | CC BY-SA 4.0

1915 Imperial Valley Earthquakes: One Hour Apart

Wed, 01 Apr 2026 00:00:00 GMT

Photo credit Mikenorton, CC BY-SA 3.0. What made the 1915 Imperial Valley earthquakes particularly destructive was their sequence. A single large earthquake allows rescuers to begin immediately and allows survivors to understand what they face. Two earthquakes an hour apart create a crueler scenario: the first weakens...

Image: Mikenorton | CC BY-SA 3.0

1915 Imperial Valley Earthquakes: From Calexico to Yuma

Wed, 01 Apr 2026 00:00:00 GMT

Photo credit Mikenorton, CC BY-SA 3.0. The earthquakes' reach extended far beyond the Imperial Valley. The two mainshocks were felt as far north as San Bernardino and Los Angeles, east to Parker and Yuma, Arizona, and south into Ensenada, Mexico, and likely beyond. The worst damage concentrated at El Centro, where los...

Image: Mikenorton | CC BY-SA 3.0

1915 Imperial Valley Earthquakes: The November Earthquake

Wed, 01 Apr 2026 00:00:00 GMT

Photo credit Comisión Mexicana de Filmaciones from México D. F., México, CC BY-SA 2.0. June's twin earthquakes were not 1915's last geological event in the region. On November 21, a magnitude 7.0 earthquake struck Baja California, associated with a rupture on the Cerro Prieto Fault near the volcano of the same name. This larger event caused widespread ground slumpi...

Image: Comisión Mexicana de Filmaciones from México D. F., México | CC BY-SA 2.0

1915 Imperial Valley Earthquakes: A Fault That Doesn't Stop

Wed, 01 Apr 2026 00:00:00 GMT

Photo credit Nzeemin, CC BY-SA 3.0. The Imperial Fault Zone, a 69-kilometer right-lateral strike-slip fault running near Brawley, Imperial, El Centro, Calexico, and Mexicali, has never been a quiet seismic feature. It produced damaging earthquakes again in 1940 and 1979. In 1966, a magnitude 3.6 event caused a surf...

Image: Nzeemin | CC BY-SA 3.0