Earthquake Mapping Update

Hayward Scenario 2012

Project Overview

Residents in many parts of the Bay Area do not have an accurate perception of the risk they face from earthquakes. Several myths common among residents contribute to this perception:

  • “Loma Prieta was a major earthquake and because my home or business wasn’t damaged in that earthquake, it will withstand future earthquakes as well”;
  • “Living in earthquake country means that we experience earthquakes all the time and I don’t perceive earthquakes to be a major threat”, and;
  • “The greatest threat of earthquakes is on the Hayward and San Andreas faults—I don’t live very close to these faults and so I am not at significant risk.”

The goal of this project is to help residents and local government officials to understand that every region of the Bay Area faces significant earthquake risk from both near and far faults, and empower them to take actions to reduce their risk.

Project Outcomes

Using readily available information, we have developed a hazard and risk picture for each county that includes specific vulnerabilities. ABAG has also updated its shaking scenario maps with CISN Scenario ShakeMap products. This effort provides an opportunity to educate residents about the updated hazards in their region. This project performed the following major tasks:

  • Updated earthquake shaking scenarios on the ABAG website. View the new maps.
  • Developed new probabilistic shaking hazard maps for the Bay Area, using 10% chance in 50 years as the risk level, to help residents better understand their risk of shaking within a 50-year time period. View the new map.
  • Developed new explanations of the Modified Mercalli Intensity scale levels to help homeowners understand what types of damage may happen to their homes in a large earthquake. View the revised MMI scale.
  • Identified major sub-regions of the Bay Area and developing a detailed picture of hazard and risk in each sub-region that includes specific hazards and vulnerabilities.
  • Identified the top faults and associated shaking scenarios for the region to help residents understand which faults provide the most risk to their homes.
  • Developed web portal to disseminate scientific information about earthquake hazards and risks in each sub-region of the Bay Area and provide tools to mitigate those hazards and risks. Include specific information about shaking-related risks and ground failures.
  • Summary Report: Sub-Regional Earthquake Hazards and Earthquake Mapping Update, November 2013

This project broke up the Bay Area into nine county sub-regions. A new webpage was developed for each sub-region that includes earthquake information and resources specific to each sub-region, including local ordinances or incentives. Some information on these sub-regional sites is common across all regions, including for example, background on the science of earthquakes and suggestions for mitigating, preparing for, and recovering from earthquakes. The sub-regional pages can be found below:

As part of this project, ABAG also redesigned the Earthquake and Hazards website to better highlight current projects and provide a better user experience.

This project is generously funded by a grant from the USGS Earthquake Hazards Program and will be completed by the end of September 2013.

Last modified: 01.07.2014