How did the San Fran 1989 earthquake occur?

Question

Was the earthquake destructive or constructive and how was it caused?

Thanks.

Answer 1

The Loma Prieta earthquake, also known as the Quake of '89 and the World Series Quake, was a major earthquake that struck the San Francisco Bay Area of California on October 17, 1989 at 5:04 p.m. Caused by a slip along the San Andreas Fault, the earthquake lasted approximately 15 seconds and measured 6.9 on the moment magnitude scale (surface-wave magnitude 7.1). The quake killed 63 people throughout northern California, injured 3,757 people and left some 8,000 to 12,000 people homeless.

The epicenter of the quake was in Forest of Nisene Marks State Park in Santa Cruz County, an unpopulated area in the Santa Cruz Mountains (geographical coordinates 37.04° N 121.88° W), approximately 4 km (2-3 miles) north of unincorporated Aptos and approximately 16 km (10 miles) northeast of Santa Cruz.

The quake was named for the nearby Loma Prieta Peak which lies 8 km (5 miles) to the northeast in Santa Clara County.

Answer 2

The Loma Prieta earthquake, also known as the Quake of '89 and the World Series Quake, was a major earthquake that struck the San Francisco Bay Area of California on October 17, 1989 at 5:04 p.m. Caused by a slip along the San Andreas Fault, the earthquake lasted approximately 15 seconds and measured 6.9 on the moment magnitude scale (surface-wave magnitude 7.1).[2] The quake killed 63[3] people throughout northern California, injured 3,757 people and left some 8,000[4] to 12,000 people homeless.[5]

The earthquake occurred during the warm up for the third game of the 1989 World Series, coincidentally featuring both of the Bay Area's Major League Baseball teams, the Oakland Athletics and the San Francisco Giants. This was the first major earthquake in America to be broadcast on live television.The epicenter of the quake was in Forest of Nisene Marks State Park in Santa Cruz County, an unpopulated area in the Santa Cruz Mountains (geographical coordinates [show location on an interactive map] 37.04° N 121.88° W), approximately 4 km (2-3 miles) north of unincorporated Aptos and approximately 16 km (10 miles) northeast of Santa Cruz. The quake was named for the nearby Loma Prieta Peak which lies 8 km (5 miles) to the northeast in Santa Clara County.The earthquake caused severe damage throughout the San Francisco Bay Area, most notably in San Francisco and Oakland, but also in many other communities throughout the region, including Alameda, San Mateo, Santa Clara, San Benito County, Santa Cruz, and Monterey counties. Major property damage in the Marina District 60 miles (95 km) from the epicenter resulted from liquefaction of soil used to fill waterfront properties. Other effects included sand volcanoes, landslides, and ground ruptures. 18,306 homes and 2,575 businesses were damaged. In Santa Cruz, close to the epicenter, 40 buildings collapsed, killing at least six people.

Given the distance between the quake's epicenter and some of the worst-hit areas, geologists were surprised at the severity of the resulting damage. Subsequent analysis indicated that the damage was due to the amplification of the earthquake's Seismic waves by waves reflecting off the deep (about 24 km(15 miles)) discontinuities in the Earth's surface.

The quake caused an estimated $6 billion to $13 billion in property damage, becoming one of the most expensive natural disasters in U.S. history at the time. It was the largest earthquake to occur on the San Andreas Fault since the great 1906 San Francisco earthquake. Private donations poured in to aid relief efforts and on October 26, President George H.W. Bush signed a $3.45 billion earthquake relief package for California.