California Reviews Non-Traditional Tsunami Sources as Analogies for Future Statewide Tsunami Hazard Analyses

Session: Understanding Non-Traditional Seismic Tsunami Hazards
Type: Oral
Date: 4/28/2020
Time: 03:00 PM
Room: 120 + 130
Description: 

In 2018 two deadly non-subduction triggered tsunami in Indonesia reminded tsunami scientists of the importance to consider non-traditional sources while preparing a tsunami hazard assessment. The entire California coast is susceptible to tsunami inundation from either local or distant sources. To meet the needs of coastal residents and visitors and help communities become more resilient, the California Geological Survey (CGS) and the California Governor’s Office of Emergency Services (CalOES) are collaborating to prepare updated statewide tsunami inundation maps for evacuation planning. Informing this process, new probabilistic inundation models based on Pacific Ocean subduction zone sources were incorporated along with existing deterministic inundation models that include local non-subduction sources, such as local faults and landslides.

Strike-slip earthquakes typically produce tsunami smaller than subduction earthquakes and can also trigger tsunamigenic landslides. South of the Mendocino triple junction, California tectonics are dominated by the San Andreas transform fault and, where offshore, these faults and landslide sources contribute to the hazard regionally with a shorter arrival time than for trans-pacific tsunami. While there are no significant volcanoes offshore of California, these sources should be considered in places like the Alaska-Aleutian magmatic arc.

We review non-traditional tsunami sources globally and consider how these analogies may apply to California. In the next few years CGS and CalOES will be preparing probabilistic source models for local sources including tectonic faults and landslides offshore of California. With all these different possibilities (e.g. local/distant, earthquake as natural warning or not), the take away lesson from the 2018 tsunami from the Donggala-Palu Earthquake and the Anak Krakatau volcanic collapse is that source models should be continuously reviewed and education and outreach efforts must be ongoing.

Presenting Author: Jason R. Patton

Authors