Tectonic Geohazard Sources and Integrated Probabilistic Modeling

Team 1 is focused on studying and modeling the geohazards associated with earthquakes, tsunamis, and landslides to better understand their impacts on infrastructure and coastal communities. Team 1 has two main research goals to support communities resilience to these geohazards, which are being studied across 6 different subgroups.     


Research Goals 

Research Goal 1: Build a data-driven four-dimensional understanding of Cascadia faults, likely slip, tsunamis, ground shaking, landslides, and land level change over all time scales.           

Research Goal 2: Enable comprehensive and probabilistic coastal multi-hazard planning and mitigation by developing coupled earthquake-tsunami simulations and evaluating their impacts on coastal infrastructure.  

Project Locations

Team 1 researchers are working on regional inventories and outputs that cover the coastal Cascadia region – including 3-D seismic simulations, fault maps, and landslide inventories. We are also working on detailed project sites within collaboratory communities, focusing on Tokeland to Taholah, Washington at present.

Projects

Team 1 consists of almost 40 faculty researchers, staff, and students that are exploring the 2 main research goals. To dive deeper into these goals, there are several project subteams that are studying various aspects of geohazards to answer these questions.

Garrison-Laney studying paleotsunami deposits at Discovery Bay, WA. Photo by Brian Atwater, USGS.

Landslides:
The landslides subteam is working to quantify the timing, triggers, and long-term effects of landslides to the landscape within or adjacent to Hub collaboratories. These aims include new landslide mapping and dating, GIS and field analysis for prediction of secondary hazards, such as landslide dams, as well as measuring other geomorphic metrics within Cascadia. We also have ongoing modeling objectives to both forecast future landslides and consider the long-term landscape evolution of the Cascadia region in response to landslides. 

Paleoseismology:
The paleoseismology subteam is working to improve the understanding of the recurrence of large tsunami-generating earthquakes and coastal land level change related to tectonic processes. Geologic evidence from past earthquakes provides essential constraints for earthquake models. This work includes adding high-quality ages for past tsunamis, improving deformation estimates of past earthquakes and tsunamis, and identifying tsunami sources.

Faults:
The faults subteam is working to characterize active faults of the offshore Cascadia Subduction Zone using recent high-resolution active-source seismic imaging. In collaboration with the CAscadia Seismic Imaging Experiment 2021 (CASIE21) science team, we are working to develop an updated model of the megathrust decollement. Through a joint analysis of near-surface and deep seismic images of the Cascadia accretionary wedge, we aim to better understand interactions between shallow fault activity and deeper fault structure. The megathrust decollement and primary splay faults identified by our subteam will be incorporated into Team 1 earthquake and tsunami simulations for Cascadia. 

Ground motion and Tsunamis:
The ground motion and tsunami modeling subteam is working to improve our estimates of earthquake hazards from full and partial margin ruptures on the Cascadia Subduction Zone. New earthquake simulations will use a range of magnitudes, vary the up-dip limit of slip (including splay faulting), and explicitly couple the ground motion and tsunami simulations by using the same earthquake sources. The outcomes of this research will be used to assess time-dependent impacts of ground shaking and tsunami inundation on infrastructure and coastal communities.  New probabilistic hazard assessments will also be developed based on a suite of potential ground motions.

Debris:
The debris modeling subteam is working to better couple tsunami simulations and probabilistic assessments with models to understand the movement of debris.  The goal is to improve hazard mitigation planning, both for immediate life safety (mapping and forecast of the spatial distribution of debris, assessing possible effects on infrastructure, hazardous materials, road closures, etc.) and for long term recovery (estimating the quantity and types of debris that will need to be removed).

Infrastructure Impacts:
The infrastructure impacts subteam is evaluating impacts of various earthquake and tsunami scenarios on infrastructure, starting with the Tokeland to Taholah collaboratory. The infrastructure impacts inform and enable studies of social impacts. To do this work we are developing geospatial inventories of critical infrastructure and developing computational engineering models for predicting their damage in earthquake and tsunami loading.