The Whittier Fault is a geologic fault

Geologic fault

In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement along the fractures as a result of earth movement. Large faults within the Earth's crust result from the action of tectonic forces...

 located in eastern Los Angeles County

Los Angeles County, California

Los Angeles County is a county in the U.S. state of California. As of 2010 U.S. Census, the county had a population of 9,818,605, making it the most populous county in the United States. Los Angeles County alone is more populous than 42 individual U.S. states...

 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...

, that is one of the two upper branches of the Elsinore Fault Zone

Elsinore Fault Zone

The Elsinore Fault Zone is a large right-lateral strike-slip geological fault structure in Southern California. The fault is part of the trilateral split of the San Andreas fault system and is one of the largest, though quietest faults in Southern California....

, with the Chino Fault

Chino Fault

The Chino Fault is a fault that extends along the eastern Chino Hills range region, from Corona in Riverside County to the Los Serranos, Chino Hills area of San Bernardino County in Southern California.-Geology:...

 the second.

Geology

The Whittier Fault is a 40 kilometres (24.9 mi) right-lateral strike-slip fault that runs along the Chino Hills range

Chino Hills

The Chino Hills are a mountain range on the border of Orange, Los Angeles, and San Bernardino Counties, California, with a small portion in Riverside County...

 between the cities of Chino Hills

Chino Hills, California

Chino Hills is a Los Angeles suburb located in the southwestern corner of San Bernardino County, California, United States. The city borders Los Angeles County on its northwest side, Orange County to its south, and Riverside County to its southeast...

 and Whittier

Whittier, California

Whittier is a city in Los Angeles County, California about southeast of Los Angeles. The city had a population of 85,331 at the 2010 census, up from 83,680 as of the 2000 census, and encompasses 14.7 square miles . Like nearby Montebello, the city constitutes part of the Gateway Cities...

. The fault has a slip rate of 2.5 to 3 mm (0.0984251968503937 to 0.118110236220472 in) per year. It is estimated that this fault could generate a quake of M_W6.0–7.2 on the moment magnitude scale

Moment magnitude scale

The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

.

Whittier Narrows earthquake

In 1987, the Whittier Narrows earthquake

Whittier Narrows earthquake

The 1987 Whittier Narrows earthquake struck the southern San Gabriel Valley and surrounding communities of southern California at 7:42 a.m. on October 1, 1987. The magnitude 5.9 earthquake was originally assigned a magnitude of 6.0 but was revised a few days later when additional data became...

 sequence occurred, with two large earthquakes, a 5.9 and a 5.3, happening within 3 days. No surface rupture happened during the quake, but there has been surface rupture on this fault within the last 10,000 years. The quakes caused US$350 million in damages.