HayWired - Earthquake Hazards

Science Center Objects

Hazards Societal Consequences and Risk Communication scientists coauthored several chapters in the Earthquake hazards volume of the HayWired earthquake scenario.

Cover of the HayWired Earthquake Hazards Report

Figure 1 Cover of Scientific Investigations Report for the HayWired Earthquake Scenario for Earthquake Hazards (Public domain.)

The HayWired Earthquake Scenario—Earthquake Hazards is the first volume of U.S. Geological Survey (USGS) Scientific Investigations Report 2017–5013 (fig. 1), which describes the HayWired scenario, developed by USGS and its partners. The HayWired scenario is a hypothetical earthquake sequence that is being used to better understand hazards for the San Francisco Bay region during and after an earthquake of magnitude 7 on the Hayward Fault. The 2014 Working Group on California Earthquake Probabilities calculated that there is a 33-percent likelihood of a large (magnitude 6.7 or greater) earthquake occurring on the Hayward Fault within three decades. A large Hayward Fault earthquake will produce strong ground shaking, permanent displacement of the Earth’s surface, landslides, liquefaction (soils becoming liquid-like during shaking) (fig. 2), and subsequent fault slip, known as afterslip, and earthquakes, known as aftershocks (table 1)

The most recent large earthquake on the Hayward Fault occurred on October 21, 1868, and it ruptured the southern part of the fault. The 1868 magnitude-6.8 earthquake occurred when the San Francisco Bay region had far fewer people, buildings, and infrastructure (roads, communication lines, and utilities) than it does today, yet the strong ground shaking from the earthquake still caused significant building damage and loss of life. The next large Hayward Fault earthquake is anticipated to affect thousands of structures and disrupt the lives of millions of people. Earthquake risk in the San Francisco Bay region has been greatly reduced as a result of previous concerted efforts; for example, tens of billions of dollars of investment in strengthening infrastructure was motivated in large part by the 1989 magnitude 6.9 Loma Prieta earthquake. To build on efforts to reduce earthquake risk in the San Francisco Bay region, the HayWired earthquake scenario comprehensively examines the earthquake hazards to help provide the crucial scientific information that the San Francisco Bay region can use to prepare for the next large earthquake. The HayWired Earthquake Scenario—Earthquake Hazards volume describes the strong ground shaking modeled in the scenario and the hazardous movements of the Earth’s surface that the fault rupture and shaking will activate.

Table of lifeline exposure to coseismic slip in SF Bay region

Table 1. Lifeline exposure to coseismic slip in the San Francisco Bay region, California, for the magnitude-7 mainshock of the HayWired earthquake scenario (Jamie L. Jones, U.S. Geological Survey, written commun., 2016). (Public domain.)

 

Map of the San Francisco region with liquefaction probabilities

Figure 2. Map of the San Francisco Bay region, California, showing liquefaction (soils becoming liquid-like during shaking) probabilities for western Alameda and northern Santa Clara Counties as a result of strong ground shaking during the hypothetical magnitude-7 mainshock of the HayWired earthquake scenario on the Hayward Fault. <, less than; >, greater than. (From Jones and others, this volume.) (Public domain.)