Introduction
October 17, 1989, was much like any other day in Northern California, USA. Residents went about their daily lives, completely unaware that a major disaster was looming. At 5:04 PM (pacific daylight time), a magnitude 6.9 earthquake hit the region, causing tragic loss of life, extensive property damage, and bringing the city of San Francisco to a standstill. The quake, known as the Loma Prieta Earthquake, would become a seminal moment of geologic reckoning, forcing changes in preparedness and engineering that continue to reverberate today.
Description of the Event
The Loma Prieta Earthquake was centered in Forest of Nisene Marks State Park approximately 10 mi (16 km) northeast of Santa Cruz and was named for the nearby Loma Prieta Peak in the Santa Cruz Mountains. The quake lasted approximately 15 seconds and was the most powerful to hit the region since the great quake of 1906. The shaking resulted from a slip along the San Andreas Fault – a tectonic boundary known for its seismic activity.
The earthquake caused severe damage and loss of life. It collapsed buildings, bridges, and freeways, most notably a section of the San Francisco-Oakland Bay Bridge and the double-decker section of Interstate 880,, known as the Cypress Street Viaduct. Overall, the destruction led to 63 deaths, thousands of injuries, and left several thousand people homeless.
The Loma Prieta Earthquake’s Impact
The impact of this event went beyond the immediate casualties and physical destruction. The earthquake struck during the warm-up for the third game of the 1989 World Series, between the San Francisco Giants and the Oakland Athletics, resulting in the first and only major delay in the history of the professional baseball championship. The event, being witnessed live on national television, brought the reality of California’s earthquake risks into homes across America.
Moreover, this disaster marked a turning point in American seismic preparedness and engineering. It led to significant changes in policies, standards, and procedures for emergency response, inspired advancements in earthquake engineering, and spurred investment in early warning systems. Building codes were revisited, and aging infrastructure was re-evaluated for seismic resistance, leading to the retrofitting and replacement of many deficient structures.
Interesting Facts for Kids
1. During the Loma Prieta Earthquake, liquefaction (when saturated soil behaves like a liquid) caused a phenomenon called “sand blows” or “earthquake fountains,” where sandy water erupted from cracks in the ground!
2. The earthquake’s energy release was equivalent to 1.25 million tons of TNT — that’s more than 80,000 times the energy released by the atomic bomb dropped on Hiroshima!
Educational Activities for Kids
1. Earthquake in a Box: On a smaller scale, kids can understand how earthquakes work by modelling tectonic plate movements with a simple puzzle.
2. Seismograph Model: Children can learn how the intensity of earthquakes is measured by creating a homemade seismograph using a shoebox, a pen, and some weights.
Conclusion
The Loma Prieta Earthquake was not just a geological disaster but also a profound lesson in humility in the face of nature’s unpredictability. It forever changed the perceptions of risks associated with earthquakes, kick-starting a new era of preparedness and resilience efforts. Even now, three decades later, the day serves as a reminder of the continuous need for vigilance against natural disasters.
References
1. USGS (2020). The M 6.9 Loma Prieta Earthquake of October 17, 1989. https://earthquake.usgs.gov/earthquakes/events/1989lomaprieta/
2. FEMA (2009). Significant Earthquake and Earthquake Sequences. https://www.hsdl.org/?view&did=36687
3. American Geosciences Institute (2017). The Loma Prieta Earthquake: 30 Years Ago. https://www.americangeosciences.org/geotimes/loma-prieta-earthquake-30-years-ago
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