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Distinct yet adjacent earthquake sequences near the Mendocino Triple Junction: 20 December 2021 Mw 6.1 and 6.0 Petrolia, and 20 December 2022 Mw 6.4 Ferndale

Two earthquake sequences occurred a year apart at the Mendocino Triple Junction in northern California: first the 20 December 2021 �w 6.1 and 6.0 Petrolia sequence, then the 20 December 2022 �w 6.4 Ferndale sequence. To delineate active faults and understand the relationship between these sequences, we applied an automated deep‐learning workflow to create enhanced and relocated earthquake catalogs
Clara Yoon, David R. Shelly

Data-driven adjustments for combined use of NGA-East hard-rock ground motion and site amplification models

Model development in the Next Generation Attenuation-East (NGA-East) project included two components developed concurrently and independently: (1) earthquake ground-motion models (GMMs) that predict the median and aleatory variability of various intensity measures conditioned on magnitude and distance, derived for a reference hard-rock site condition with an average shear-wave velocity in the uppe
Maria E. Ramos-Sepulveda, Jonathan P. Stewart, Grace Alexandra Parker, Morgan P. Moschetti, Eric M. Thompson, Scott J. Brandenberg, Youssef M A Hashash, Ellen M. Rathje

Stress-driven recurrence and precursory moment-rate surge in caldera collapse earthquakes

Predicting the recurrence times of earthquakes and understanding the physical processes that immediately precede them are two outstanding problems in seismology. Although geodetic measurements record elastic strain accumulation, most faults have recurrence intervals longer than available measurements. Foreshocks provide the principal observations of processes before mainshocks, but variability bet
Paul Segall, Mark V. Matthews, David R. Shelly, Taiyi Wang, Kyle R. Anderson

Satellite Interferometry Landslide Detection and Preliminary Tsunamigenic Plausibility Assessment in Prince William Sound, Southcentral Alaska

Regional mapping of actively deforming landslides, including measurements of landslide velocity, is integral for hazard assessments in paraglacial environments. These inventories are also critical for describing the potential impacts that the warming effects of climate change have on slope instability in mountainous and cryospheric terrain. The objective of this study is to identify slow-moving la

Lauren N. Schaefer, Jinwook Kim, Dennis M. Staley, Zhong Lu, Katherine R. Barnhart

The 2022 Chaos Canyon landslide in Colorado: Insights revealed by seismic analysis, field investigations, and remote sensing

An unusual, high-alpine, rapid debris slide originating in ice-rich debris occurred on June 28, 2022, at 16:33:16 MDT at the head of Chaos Canyon, a formerly glacier-covered valley in Rocky Mountain National Park, CO, USA. In this study, we integrate eyewitness videos and seismic records of the event with meteorological data, field observations, pre- and post-event satellite imagery, and uncrewed
Kate E. Allstadt, Jeffrey A. Coe, Elaine Collins, Francis K. Rengers, Anne Mangeney, Scott M. Esser, Jana Pursley, William L. Yeck, John Bellini, Lance R. Brady

Landslide initiation thresholds in data-sparse regions: Application to landslide early warning criteria in Sitka, Alaska, USA

Probabilistic models to inform landslide early warning systems often rely on rainfall totals observed during past events with landslides. However, these models are generally developed for broad regions using large catalogs, with dozens, hundreds, or even thousands of landslide occurrences. This study evaluates strategies for training landslide forecasting models with a scanty record of landslide-t
Annette Patton, Lisa Luna, Josh J. Roering, Aaron Jacobs, Oliver Korup, Benjamin B. Mirus

How long do runoff-generated debris-flow hazards persist after wildfire?

Runoff-generated debris flows are a potentially destructive and deadly response to wildfire until sufficient vegetation and soil-hydraulic recovery have reduced susceptibility to the hazard. Elevated debris-flow susceptibility may persist for several years, but the controls on the timespan of the susceptible period are poorly understood. To evaluate the connection between vegetation recovery and d
Andrew Paul Graber, Matthew A. Thomas, Jason W. Kean

Bedrock erosion by debris flows at Chalk Cliffs, Colorado, USA: Implications for bedrock channel evolution

Debris flow erosion into bedrock helps to set the pace of mountain denudation, but there are few empirical observations of this process. We studied the effects of debris flows on bedrock erosion using Structure-From-Motion photogrammetry and multiple real-time monitoring measurements. We found that the distribution of bedrock erosion across the channel cross-section could be generalized as an expo
Francis K. Rengers, Jason W. Kean, Jeffrey A. Coe, Megan Hanson, Joel Smith

Ground‐motion variability from kinematic rupture models and the implications for nonergodic probabilistic seismic hazard analysis

The variability of earthquake ground motions has a strong control on probabilistic seismic hazard analysis (PSHA), particularly for the low frequencies of exceedance used for critical facilities. We use a crossed mixed‐effects model to partition the variance components from simulated ground motions of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone. Total variability of si
Grace Alexandra Parker, Morgan P. Moschetti, Eric M. Thompson

Runout model evaluation based on back-calculation of building damage

We evaluated the ability of three debris-flow runout models (RAMMS, FLO2D and D-Claw) to predict the number of damaged buildings in simulations of the 9 January 2019 Montecito, California, debris-flow event. Observations of building damage after the event were combined with OpenStreetMap building footprints to construct a database of all potentially impacted buildings. At the estimated event volum
Katherine R. Barnhart, Jason W. Kean

Forecasting the inundation of postfire debris flows

In the semi-arid regions of the western United States, postfire debris flows are typically runoff generated. The U.S. Geological Survey has been studying the mechanisms of postfire debris-flow initiation for multiple decades to generate operational models for forecasting the timing, location, and magnitude of postfire debris flows. Here we discuss challenges and progress for extending operational
Katherine R. Barnhart, Ryan P Jones, David L. George, Francis K. Rengers, Jason W. Kean

Predicting burn severity for integration with post-fire debris-flow hazard assessment: A case study from the Upper Colorado River Basin, USA

Background: Burn severity significantly increases the likelihood and volume of post-wildfire debris flows. Pre-fire severity predictions can expedite mitigation efforts because precipitation contributing to these hazards often occurs shortly after wildfires, leaving little time for post-fire planning and management.Aim: The aim of this study was to predict burn severity using pre-fire conditions o
Adam Gerhard Wells, Todd Hawbaker, John Kevin Hiers, Jason W. Kean, Rachel A. Loehman, Paul F. Steblein