User:Shaquil Noorzay/sandbox

Class Activity 1: Historical Earthquakes

When:
The Loma Prieta earthquake took place on October 17, 1989 at approximately 5:04 PM.

Where:
San Francisco and Monterey Bay regions. The epicenter of the quake was located near Loma Prieta Peak in the Santa Cruz mountains.

Size of the Event:
The earthquake had a magnitude of 6.9 which violently rattled the San Francisco and Monterey Bay regions. The moment magnitude was a 6.9 while the surface wave (s-wave) magnitude was a 7.1.

What Caused the Earthquake:
The crustal rock formation which creates the Pacific and North American plates abruptly slipped as much as 2 meters or 7 feet along their common boundary, the San Andreas fault system.

Proximity to Exposure:
Several surrounding communities were also hit incredible hard such as the Watsonville community and the Marina district. Within Watsonville, 1 in 8 houses were destroyed as a result of the earthquake. In the  Marina district, liquefaction caused several buildings to sink into the ground which in turn caused gas mains and pipes to burst created several wild and uncontrollable fires.

Earthquake Induced Consequences:
Greater than $5 billion in damages. Liquefaction caused by the earthquake under the Marina district caused extensive damage. In order for liquefaction to occur, the underlying soils must be soft and very wet and shaken violently. Liquefaction is a process in which the soil underneath a certain area begins to act as a liquid which basically causes all structures on top to sink into the ground. Because of the collapse of the Marina district, gas mains and pipes burst which in turn sparked fires.

Casualties:
As a result of the earthquake, 67 people were killed, over 3000 people were injured and many other buildings were destroyed.

Aftermath:
San Francisco and other surrounding communities required strict regulations which made it a requirement for unreinforced buildings to be retrofitted and brought to modern day standards and codes.

References:
https://www.history.com/topics/natural-disasters-and-environment/1989-san-francisco-earthquake https://www.conservation.ca.gov/cgs/earthquakes/loma-prieta https://pubs.usgs.gov/dds/dds-29/ https://www.usgs.gov/natural-hazards/earthquake-hazards/science/m69-october-17-1989-loma-prieta-earthquake