M6.9 October 17, 1989 Loma Prieta Earthquake

Science Center Objects

On October 17, 1989, at 5:04:15 p.m. (PDT), a magnitude 6.9 earthquake severely shook the San Francisco and Monterey Bay regions. The epicenter was located near Loma Prieta peak in the Santa Cruz Mountains, approximately 14 km (9 mi) northeast of Santa Cruz and 96 km (60 mi) south-southeast of San Francisco.

The 1989 Loma Prieta earthquake ended decades of tranquility in the San Francisco Bay region. It was a wakeup call to prepare for the potentially even more devastating shocks that are inevitable in the future. Since 1989, the work of the U.S. Geological Survey and other organizations has improved understanding of the seismic threat in the Bay region, promoted awareness of earthquake hazards, and contributed to more effective strategies to reduce earthquake losses. These efforts will help reduce the impact of future large quakes in the San Francisco Bay region.

                                                                                                                                                     -Robert Page, U.S. Geological Survey

Ground Shaking Animations
To better understand the distribution of shaking from past and anticipated future earthquakes, seismologists have constructed computer models of earthquakes and the resulting ground shaking. This movie shows shaking intensity as the seismic waves travel away from the earthquake epicenter over time.

Tectonic summary, maps and data.

Map showing ground motion and shaking intensity based on instrumental measurements of shaking along with information about local geology and the earthquake’s location and magnitude.

Did You Feel It?
Map of shaking intensity based on 15,000+ reports from citizens who experienced the earthquake.

USGS Professional Papers on Loma Prieta Summaries: 
Four Loma Prieta Earthquake Professional Papers, each containing multiple chapters, document the magnitude 6.9 earthquake that shook the San Francisco and Monterey Bay regions.

  • Professional Paper 1550: Earthquake Occurrence
  • Professional Paper 1551: Strong Ground Motion and Ground Failure
  • Professional Paper 1552: Performance of the Built Environment
  • Professional Paper 1553: Societal Response

Faultline: Remembering Loma Prieta
A personal account of the events unfolding, by Mary K. Miller of the Exploratorium.

1989 Earthquake Reports and Photographs
From the Virtual Museum of the City of San Francisco.