Geologic Hazards Science Center

Publications

Filter Total Items: 2,056
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Year Published: 2021

Amateur radio operators help fill earthquake donut holes

If you’ve ever seen tall antennas rising from everyday residences in your community and wondered what they are for, it could be that those homes belong to ham radio enthusiasts who enjoy communicating with each other over the airwaves. In addition to having fun with their radios and finding camaraderie, many ham radio operators are also...

Wald, David J.; Quitoriano, Vince; Dully, Oliver

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Year Published: 2021

Electrical conductivity of the lithosphere-asthenosphere system

Electromagnetic geophysical methods image the electrical conductivity of the subsurface. Electrical conductivity is an intrinsic material property that is sensitive to temperature, composition, porosity, volatile and/or melt content, and other physical properties relevant to the solid Earth. Therefore, imaging the electrical structure of...

Naif, Samer; Selway, Kate; Murphy, Benjamin Scott; Egbert, Gary D.; Pommier, Anne

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Year Published: 2021

Forecasting the frequency and magnitude of postfire debris flows across southern California

Southern California has a long history of damaging debris flows after wildfire. Despite recurrent loss, forecasts of the frequency and magnitude of postfire debris flows are not available for the region like they are for earthquakes. Instead, debris flow hazards are typically assessed in a reactive manner after wildfires. Such assessments are...

Kean, Jason W.; Staley, Dennis M.

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Year Published: 2021

Time since burning and rainfall characteristics impact post-fire debris flow initiation and magnitude

The extreme heat from wildfire alters soil properties and incinerates vegetation, leading to changes in infiltration capacity, ground cover, soil erodibility, and rainfall interception. These changes promote elevated rates of runoff and sediment transport that increase the likelihood of runoff-generated debris flows. Debris flows are most common...

McGuire, Luke A.; Rengers, Francis K.; Oakley, Nina S.; Kean, Jason W.; Staley, Dennis M.; Tang, Hui; de Orla-Barile, Marian; Youberg, Ann M.

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Year Published: 2021

Quantifying nuisance ground motion thresholds for induced earthquakes

Hazards from induced earthquakes are a growing concern with a need for effective management. One aspect of that concern is the “nuisance” from unexpected ground motions, which have the potential to cause public alarm and discontent. In this article, we borrow earthquake engineering concepts to quantify the chance of building damage states and...

Schultz, Ryan; Quitoriano, Vince; Wald, David J.; Beroza, Gregory C.

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Year Published: 2021

Coseismic surface displacement in the 2019 ridgecrest earthquakes: Comparison of field measurements and optical image correlation results

A fundamental topic in earthquake studies is understanding the extent to which fault rupture at the surface is localized on primary fault strands as opposed to distributed tens to hundreds of meters away from primary ruptures through off‐fault deformation (OFD) via a combination of discrete secondary faulting and bulk deformation. The 2019...

Gold, Ryan D.; Duross, Christopher; Barnhart, William D.

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Year Published: 2021

Using high sample rate lidar to measure debris-flow velocity and surface geometry

Debris flows evolve in both time and space in complex ways, commonly starting as coherent failures but then quickly developing structures such as roll waves and surges. These processes are readily observed but difficult to study or quantify because of the speed at which they evolve. Many methods for studying debris flows consist of point...

Rengers, Francis K.; Rapstine, Thomas D; Olsen, Michael; Allstadt, Kate; Iverson, Richard M.; Leshchinsky, Ben; Obryk, Maciej; Smith, Joel B.

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Year Published: 2021

Modeling hydrologic processes associated with soil saturation and debris flow initiation during the September 2013 storm, Colorado Front Range

Seven days of extreme rainfall during September 2013 produced more than 1100 debris flows in the Colorado Front Range, about 78% of which occurred on south-facing slopes (SFS). Previously published soil moisture (volumetric water content) observations suggest that SFS were wetter than north-facing slopes (NFS) during the event, which contrasts...

Timilsina, Sujana; Niemann, Jeffrey D.; Rathburn, Sara L.; Rengers, Francis K.; Nelson, Peter A.

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Year Published: 2021

Toward physics-based nonergodic PSHA: A prototype fully-deterministic seismic hazard model for southern California

We present a nonergodic framework for probabilistic seismic‐hazard analysis (PSHA) that is constructed entirely of deterministic, physical models. The use of deterministic ground‐motion simulations in PSHA calculations is not new (e.g., CyberShake), but prior studies relied on kinematic rupture generators to extend empirical earthquake rupture...

Milner, Kevin R.; Shaw, Bruce E.; Goulet, Christine A.; Richards-Dinger, Keith B.; Callaghan, Scott; Jordan, Thomas H.; Dieterich, James H.; Field, Edward H.

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Year Published: 2021

A subset of CyberShake ground-motion time series for response-history analysis

This manuscript describes a subset of CyberShake numerically simulated ground motions that were selected and vetted for use in engineering response-history analyses. Ground motions were selected that have seismological properties and response spectra representative of conditions in the Los Angeles area, based on disaggregation of seismic hazard....

Baker, Jack W.; Rezaeian, Sanaz; Goulet, Christine A.; Luco, Nicolas; Teng, Ganyu

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Year Published: 2021

Evaluation of simulated ground motions using probabilistic seismic demand analysis: CyberShake (ver. 15.12) simulations for Ordinary Standard Bridges

There is a need for benchmarking and validating simulated ground motions in order for them to be utilized by the engineering community. Such validation may be geared towards a specific ground motion simulation method, a target engineering application, and a specific location; the validation presented herein focuses on a bridge engineering...

Fayaz, Jawad; Rezaeian, Sanaz; Zareian, Farzin

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Year Published: 2021

Rapid sensitivity analysis for reducing uncertainty in landslide hazard assessments

One of the challenges in assessing temporal and spatial aspects of landslide hazard using process-based models is estimating model input parameters, especially in areas where limited measurements of soil and rock properties are available. In an effort to simplify and streamline parameter estimation, development of a simple, rapid approach to...

Baum, Rex L.