A Cascadia earthquake of magnitude 9 (M9) would cause shaking, liquefaction, landslides and tsunamis from British Columbia to northern California. The resulting losses would include damaged buildings, bridges and lifelines, as well as thousands of human casualties. At the University of Washington, we’ve started the NSF-funded M9 project, which addresses scientific and engineering challenges in reducing this risk. The shared vision is to reduce the catastrophic risk of a Cascadia M9 earthquake through integrated advances in forecasting, warning and adaptive planning across the social, built and natural environments.
The challenges start by assessing the range of distributions of fault motion and, therefore, the shaking and tsunamis that the Cascadia fault might generate. The project addresses factors not previously considered: the distribution and timing of energy release on the fault, the coherent variation of frequency content of fault motion with fault depth, and the 3D effects of the deep basins along Puget Sound – and will attempt to specify the uncertainty in the estimated motions, which is critical to probabilistic estimation of earthquake impact, including liquefaction, landslides, tsunamis and built infrastructure response.
To inform the development and deployment of earthquake early warning in the U.S., the project includes interview and survey research on the potential effects of messages that provide just a few seconds or minutes of warning. With local communities and agency partners, the project will improve the utility of probabilistic information by comparing how stakeholders interpret (a) single “worst case” hazard scenarios and (b) multiple probabilistic scenarios, and how each type of scenario is then incorporated into community emergency preparedness and long-range planning.
By anticipating probable events and responses over a range of timescales following an earthquake and using this to guide long-term systemic change before the next earthquake occurs, the M9 project will help prevent natural hazards from becoming disasters.