California reviews non-traditional tsunami sources as analogies for future statewide tsunami hazard analyses
Abstract
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 to 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 are incorporated along with existing deterministic inundation models that include local non-subduction sources such as tectonic faults and landslides.
Strike-slip earthquakes typically produce tsunamis smaller than subduction earthquakes and can also trigger tsunamigenic landslides. These smaller tsunamis may not inundate land, but can generate damaging currents within harbors, causing costly damage to infrastructure, boats, and ships. Recent earthquakes from the 28 January '20 M7.7 Cayman Isles and the 14 July '19 M7.3 Halmahera strike-slip earthquakes both produced cm scale tsunami wave heights. South of the Mendocino triple junction, California tectonics are dominated by the San Andreas transform fault system 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 offshore of California. With all these different possibilities (e.g. local/distant, earthquake as natural warning or not) observations from the 2018 tsunamis in Indonesia support the principle that source models should be continuously reviewed and possibly incorporated into tsunami hazard analyses. Also, that education and outreach efforts must be ongoing.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMNH0140005P
- Keywords:
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- 4315 Monitoring;
- forecasting;
- prediction;
- NATURAL HAZARDS;
- 4333 Disaster risk analysis and assessment;
- NATURAL HAZARDS;
- 4341 Early warning systems;
- NATURAL HAZARDS;
- 4564 Tsunamis and storm surges;
- OCEANOGRAPHY: PHYSICAL