GEOSTRATA Magazine

Characterization of earthquake ground motion for engineering applications varies from place to place, and the degree of variability, which depends on the application and on the place, is not always intuitive. One would expect, for example, that parts of the globe with frequent earthquakes and dense strong-motion networks (e.g., areas with rich ground motion datasets, such as California) would have developed ground motion models with lower uncertainty than the other parts of the world, where moderate and large earthquakes occur infrequently, and monitoring networks are sparse or have a short history of use. Following that line of thought, one can also expect that stakeholders in metropolitan areas, where seismic networks are more dense than in rural regions, would be able to use the additional ground motion data to refine the ground motion models around these metropolitan areas and reduce the uncertainty further.

Recent major earthquakes have been the drivers of complex multihazard cascading events, such as landslides, that may have been more likely due to weather events like extreme floods or continuous rainfalls. These cascading effects are becoming an increasingly common threat that may be overlooked by geotechnical engineers, who typically focus on assessments of single geohazards in isolation, disregarding potential exacerbation effects from associated hazards that may follow. Recent catastrophic events have brought up the importance of cascading multihazards with vivid examples of human, geostructural, environmental, and socioeconomic impacts with interactions and interplays that need to be studied to eventually advance our codes and standards of practice.

A paradigm shift in seismic code provisions for design against earthquake hazards is a much needed and exciting engineering frontier. Current seismic codes primarily target life-safety performance objectives, but future design standards will aim to move beyond life safety, targeting improved post-earthquake performance to support reoccupancy and recovery of functions within a reasonable time. This new performance state, which moves beyond life safety, is called “functional recovery.” Initial efforts in functional recovery frameworks have focused primarily on buildings and structural engineering considerations. To be effective in implementing functional recovery goals, however, significant efforts to address geotechnical engineering aspects will also be required for buildings, lifelines, geostructures, and critical infrastructure.

The 21st century has seen destructive and deadly earthquakes. Whether in the Indian Ocean, New Zealand, Japan, or most recently in Turkey-Syria, earthquakes from around the globe have demonstrated that failure to predict or anticipate soil behavior can heighten the already devastating effects to people and infrastructure.

Driving across California's San Francisco-Oakland Bay Bridge, Yerba Buena Island appears about midway through, and alongside it sits Treasure Island. Although home to a population of 2,300 people, numerous local companies, a 40-acre campus occupied by the U.S. Department of Labor, and a popular music festival named after it, the island is often an overlooked destination. Located in the second-most densely populated urban area in the U.S., how have these two islands, comprising 575 acres with stunning San Francisco and East Bay views, remained unchanged for the last 80 years? The answers lie in the island's history, geologic composition, and seismic setting.