The Brawley Seismic Zone (BSZ), also known as the Brawley fault zone, is a predominantly extensional tectonic zone that connects the southern terminus of the San Andreas Fault

San Andreas Fault

The San Andreas Fault is a continental strike-slip fault that runs a length of roughly through California in the United States. The fault's motion is right-lateral strike-slip...

 with the Imperial Fault in Southern California

Southern California

Southern California is a megaregion, or megapolitan area, in the southern area of the U.S. state of California. Large urban areas include Greater Los Angeles and Greater San Diego. The urban area stretches along the coast from Ventura through the Southland and Inland Empire to San Diego...

. The BSZ is named for the nearby town of Brawley

Brawley, California

Brawley is a city in Imperial County, California, United States. Brawley is located north of El Centro. The population was 24,953 at the 2010 census, up from 22,052 at the 2000 census. The town has a significant cattle and feed industry, and hosts the annual Cattle Call Rodeo. Year-round...

 in Imperial County, California

Imperial County, California

Imperial County is a county located in the Imperial Valley, in the far southeast of the U.S. state of California, bordering both Arizona and Mexico. It is part of the El Centro Metropolitan Area, which encompasses all of Imperial County. The population as of 2000 was 142,361. The county seat is the...

.

Geology

The Brawley seismic zone represents the northernmost extension of the spreading center axis associated with the East Pacific Rise

East Pacific Rise

The East Pacific Rise is a mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate...

 which runs up the axis of the Gulf of California

Gulf of California

The Gulf of California is a body of water that separates the Baja California Peninsula from the Mexican mainland...

 and is in the process of rifting the Baja California Peninsula

Baja California Peninsula

The Baja California peninsula , is a peninsula in northwestern Mexico. Its land mass separates the Pacific Ocean from the Gulf of California. The Peninsula extends from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south.The total area of the Baja California...

 away from the mainland of Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

.

The Salton Buttes

Salton Buttes

The Salton Buttes are a group of five small lava domes in the lower Coachella Valley, in Imperial County, California. The Salton Buttes domes are on the southeast shoreline of the Salton Sea and are associated with the Salton Sea geothermal field within the Salton Trough...

 on the south shore of the Salton Sea

Salton Sea

The Salton Sea is a shallow, saline, endorheic rift lake located directly on the San Andreas Fault, predominantly in California's Imperial Valley. The lake occupies the lowest elevations of the Salton Sink in the Colorado Desert of Imperial and Riverside counties in Southern California. Like Death...

 are on the north margin of the Brawley Seismic Zone and are linked to volcanic and geothermal

Geothermal

Geothermal is related to energy and may refer to:* The geothermal gradient and associated heat flows from within the Earth- Renewable technology :...

 activity within the zone. The Brawley Seismic Zone has been interpreted as an "onshore spreading center" which runs diagonally across the Salton Trough.