CAREER: Using the Rattlesnake Ridge landslide as a natural laboratory to study repeating earthquake evolution and development of operational repeating signal detectors

Landslides are a significant natural hazard that threaten both human safety and infrastructure. They can cause billions of dollars of damage and thousands of deaths and injuries annually. To reduce the impact of landslides on people and infrastructure it is important to improve our understanding of landslide dynamics and the processes controlling this diversity of behaviors. This CAREER project leverages a unique seismic dataset collected along an active landslide near Yakima in Washington State, the Rattlesnake Ridge landslide. The project will detect and analyze small earthquakes that occurred as the landslide developed and use these to better understand how the landslide evolves and what drives its failure. Because the landslide occurred on land from the Yakama Nation, the project will work closely to inform the Tribal Council and others about results from this research. The project will conduct field trips for students at Heritage University and the Tribal School to understand landslides in the region. The project also supports a graduate student. The Rattlesnake Ridge landslide is a hillslope located in Union Gap, WA that has rapidly destabilized over the last few months. Cracks in the ridge were first identified in late October of 2017 and over a two month period the 3 million cubic meter mass detached from the adjacent hillside and began accelerating downhill. The future behavior of the slide is still uncertain and concerning. This project will perform a comprehensive seismic analysis of data collected from this event. The dataset is rich in small magnitude seismicity. The research plan consists of earthquake detection, location, cross-correlation to determine which events repeat, comparison of the spatiotemporal distribution of seismicity with geodetic data recording slide motion, and local precipitation. The results of this analysis will be synthesized estimate the stresses acting on the slide body and address why the Rattlesnake Ridge landslide is slowing down while other nearly-identical slides in the region have failed catastrophically. Behavior of seismicity at the slide will provide insight into how repeating earthquake sequences on tectonic faults evolve over large displacements, a proxy for long timescales. The results of the analysis will constitute a unique case study that will provide insight into landslide character and failure mechanisms helping to evaluate underlying hazard. This proposal is supported by the Geophysics program, The Tribal Colleges and Universities Program and the Prediction of and Resilience against Extreme Events (PREEVENTS) program. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.