Saturday, April 11, 2020

1989 Loma Prieta Earthquake

The Bay Area was in the midst of a world series, the San Francisco Giants were taking on the Oakland Athletics. Game three of the series was set to take place October 17th at 5:35 pm. It was around five pm when Tim McCarver, a sportscaster, was narrating highlights from game two in a pregame show. Viewers from home, however, were experiencing interruptions in their connections. McCarver repeated himself after being interrupted by shaking before his colleague, Al Michaels, told viewers “I’ll tell you what, we’re having an earth-”, connection was completely lost after that. 
October 17th, 2019 marked the 30 year anniversary of the Loma Prieta Earthquake of 1989. The 6.9 magnitude earthquake occurred at 5:04 pm, caused 63 deaths, more than 3,700 injuries, and billions of dollars in damages. 
The epicenter of the earthquake was 10 miles northeast of Santa Cruz at the Loma Prieta Peak in the Santa Cruz mountains. The heaviest shaking in the Santa Cruz mountains lasted for about 15 seconds, but shaking lasted longer in flatter areas. The earthquake had a modified mercalli intensity IX which classifies the shaking as violent. 
During the earthquake, people recalled seeing a wave coming from the south and heading to the north.  The earthquake damaged 18,300 houses, 2,600 businesses, and 147 businesses were completely destroyed. It also caused an immense amount of damage to freeways and highways. The Upper deck of the Bay Bridge collapsed onto its lower deck. The upper deck of the Cypress Freeway in Oakland collapsed in an instant killing 42 people and injuring many more. 
There were several aftershocks. The first occurred 
2.5 minutes after with a magnitude of 5.3. In the following week there were 20 recorded aftershocks all having around a 4.0 magnitude. In addition to this more than 200 aftershocks with magnitudes of 2.5 or greater were recorded in the following weeks. 
Prior to this Earthquake many predicted that there would be a major earthquake in the near future due to the fact that there hadn’t been one since the 1906 earthquake (an 8.3 magnitude earthquake in San Francisco). Moreover, there had been two foreshocks (earthquakes that occur before a major seismic attack and share a similar location). There was a 5.3 magnitude earthquake in June 1988 and a 5.4 magnitude earthquake in August 1989. 
The Loma Prieta earthquake served as a wake up call for many in the Bay Area and pushed people to emphasize preparedness for earthquakes.




Sources

2 comments:

  1. This blog post was very informative. I wanted to look more into some of the damages from the earthquake. One thing that stood out was the damage to the Bay Bridge. A month after the earthquake, the bridge opened to traffic again. However, tests showed that it needed to be replaced because of the damage. In 2002, replacement of the eastern portion of the bridge began. However, it took over 11 years to finish and was the most expensive public works project in California history, costing a total of over $6.5 billion, which was 25x the estimated $250 million. It is shocking to think such damage could be caused by this earthquake.

    Source: https://en.wikipedia.org/wiki/1989_Loma_Prieta_earthquake#Magnetic_disturbances

    ReplyDelete
  2. This was a really well written blog post. Having only had two earthquakes since the 1906 earthquake many Americans were fearful an earthquake of such large magnitude was going to strike again. The earthquake spread so far that you could feel it all the way in San Diego and Nevada.

    Source: https://www.conservation.ca.gov/cgs/earthquakes/loma-prieta

    ReplyDelete

Note: Only a member of this blog may post a comment.