Explanipedia

Subduction Zone Earthquake Catalog Separation Tool: Implementation in the USGS 2025 Puerto Rico and U.S. Virgin Islands National Seismic Hazard Model Open

Kirstie L. Haynie, Eric M. Thompson, Michael Hearne, G. P. Hayes, D. R. Shelly , et al. · 2025

The U.S. Geological Survey (USGS) periodically releases updates to National Seismic Hazard Model (NSHM) for the United States and its territories leveraging current scientific knowledge and methodologies to guide public policy, building co…

SURF: An Automated Method for Building Nonplanar 3D Fault Models from Earthquake Hypocenters Open

Travis Alongi, A. J. Elliott, Robert J. Skoumal, D. R. Shelly, Alexandra E. Hatem · 2025

Accurately characterizing 3D fault geometry is vital for improving our understanding of earthquake behavior and informing the development of seismic hazard models. Despite their importance, subsurface fault structures tend to be poorly con…

A Scientific Vision and Roadmap for Earthquake Rupture Forecast Developments, A USGS Perspective Open

Edward H. Field, Alexandra E. Hatem, Bruce E. Shaw, M. T. Page, P. Martín , et al. · 2025

We articulate a scientific vision and roadmap for the development of improved Earthquake Rupture Forecast (ERF) models, which are one of the two main modeling components used in modern seismic hazard and risk analysis. One primary future o…

A Glimpse Into the Future of Tectonic Tremor Monitoring Open

D. R. Shelly · 2025

Tectonic tremor is a weak, long‐duration seismic signal often observed in subduction zones and on some other plate‐bounding faults. Because of tremor's characteristically low amplitude (and low signal‐to‐noise) and lack of clear phase arri…

Divide and conquer: separating the two probabilities in seismic phase picking Open

Yongsoo Park, Alysha D. Armstrong, William L. Yeck, D. R. Shelly, Gregory C. Beroza · 2025

SUMMARY There are two fundamental probabilities in the seismic phase picking process—the probability of the existence of a seismic phase (detection probability) and the probability associated with the phase arrival time estimation (timing …

Long-term dynamics of earthquake swarms in the Yellowstone caldera Open

M. A. Florez, Bing Q. Li, D. R. Shelly, Mia V. Angulo, Jose Sanabria Gomez · 2025

The factors controlling the spatial distribution and temporal evolution of earthquake swarms in volcanic systems remain unclear. We leverage leading-edge deep learning algorithms and a detailed three-dimensional velocity model to construct…

A Northeast‐Dipping Zone of Low‐Frequency Earthquakes at the Southern Edge of Cascadia Subduction Open

D. R. Shelly, Dara E. Goldberg, A. Wech, Amanda M. Thomas · 2025

Tectonic tremor monitoring occasionally detects events in an anomalous zone in southern Cascadia, 50–100 km west of the main tremor band, near the expected southern edge of the subducting Gorda slab at the Mendocino triple junction. To inv…

Surface‐Wave Relocation and Characterization of the October 2023 Tsunamigenic Seismic Unrest Near Sofugan Volcano, Izu Islands, Japan Open

C. A. Deane, J. D. Pesicek, S. G. Prejean, P. S. Earle, D. R. Shelly , et al. · 2025

A moderate‐magnitude earthquake swarm occurred in the remote Izu Islands region of Japan between October 1 and 8, 2023. The swarm included 151 shallow earthquakes cataloged by the U.S. Geological Survey, which notably included a roughly 2.…

The Value of Hyperparameter Optimization in Phase-Picking Neural Networks Open

Yongsoo Park, D. R. Shelly · 2024

The effectiveness of neural networks for picking seismic phase arrival times has been demonstrated through several case studies, and seismic monitoring programs are starting to adopt the technology into their workflows. However, published …

Uncertainty and Spatial Correlation in Station Measurements for mb Magnitude Estimation Open

William L. Yeck, A. T. Ringler, D. R. Shelly, P. S. Earle, H. Benz , et al. · 2024

The body-wave magnitude (mb) is a long-standing network-averaged, amplitude-based magnitude used to estimate the magnitude of seismic sources from teleseismic observations. The U.S. Geological Survey National Earthquake Information Center …

Subduction intraslab-interface fault interactions in the 2022 M w 6.4 Ferndale, California, earthquake sequence Open

D. R. Shelly, Dara E. Goldberg, Kathryn Materna, Robert J. Skoumal, Jeanne L. Hardebeck , et al. · 2024

The Mendocino triple junction—the intersection of the Pacific, North American, and Gorda plates—activates a collection of disparate faults that reconcile Cascadia subduction with San Andreas transform motion. The 20 December 2022 M w 6.4 F…

Examining the Connections Between Earthquake Swarms, Crustal Fluids, and Large Earthquakes in the Context of the 2020–2024 Noto Peninsula, Japan, Earthquake Sequence Open

D. R. Shelly · 2024

Earthquake swarms are most commonly composed of small‐magnitude earthquakes. However, a recent study by Yoshida, Uchida, et al. (2023, https://doi.org/10.1029/2023GL106023 ) analyzed a swarm beneath the Noto Peninsula in Japan that, after …

Making Phase-Picking Neural Networks More Consistent and Interpretable Open

Yongsoo Park, Brent Delbridge, D. R. Shelly · 2024

Improving the interpretability of phase-picking neural networks remains an important task to facilitate their deployment to routine, real-time seismic monitoring. The popular phase-picking neural networks published in the literature lack i…

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 Open

Clara E. Yoon, D. R. Shelly · 2024

Two earthquake sequences occurred a year apart at the Mendocino Triple Junction in northern California: first the 20 December 2021 Mw 6.1 and 6.0 Petrolia sequence, then the 20 December 2022 Mw 6.4 Ferndale sequence. To delineate active fa…

Rapid Source Characterization of the 2023 Mw 6.8 Al Haouz, Morocco, Earthquake Open

William L. Yeck, Alexandra E. Hatem, Dara E. Goldberg, William D. Barnhart, Jessica Thompson Jobe , et al. · 2023

The U.S. Geological Survey (USGS) National Earthquake Information Center (NEIC) estimates source characteristics of significant damaging earthquakes, aiming to place events within their seismotectonic framework. Contextualizing the 8 Septe…

Rapid Characterization of the February 2023 Kahramanmaraş, Türkiye, Earthquake Sequence Open

Dara E. Goldberg, Tuncay Taymaz, Nadine G. Reitman, Alexandra E. Hatem, Seda Yolsal‐Çevikbilen , et al. · 2023

The 6 February 2023 Mw 7.8 Pazarcık and subsequent Mw 7.5 Elbistan earthquakes generated strong ground shaking that resulted in catastrophic human and economic loss across south-central Türkiye and northwest Syria. The rapid characterizati…

Dense geophysical observations reveal a triggered, concurrent multi-fault rupture at the Mendocino Triple Junction Open

William L. Yeck, D. R. Shelly, Kathryn Materna, Dara E. Goldberg, P. S. Earle · 2023

A central question of earthquake science is how far ruptures can jump from one fault to another, because cascading ruptures can increase the shaking of a seismic event. Earthquake science relies on earthquake catalogs and therefore how com…

Different Tectonics, Same Approach: Estimation of source parameters using the Coda Calibration Tool (CCT). Open

Paola Morasca, Kevin Mayeda, Jorge I. Roman-Nieves, D. R. Shelly, Katherine M. Whidden , et al. · 2023

It is well known that the use of different methods (e.g., spectral fitting, empirical Green’s functions) for compiling catalogs of source parameters (e.g., seismic moment, stress drop) can results in significant inconsistencies (Balt…

Fracture‐Mesh Faulting in the Swarm‐Like 2020 Maacama Sequence Revealed by High‐Precision Earthquake Detection, Location, and Focal Mechanisms Open

D. R. Shelly, Robert J. Skoumal, Jeanne L. Hardebeck · 2022

In August of 2020, an earthquake sequence initiated within the Maacama fault zone in northern California, raising questions about its relationship with the larger‐scale fault. To investigate the faulting geometry and its implications for p…

Using Machine Learning Techniques with Incomplete Polarity Datasets to Improve Earthquake Focal Mechanism Determination Open

Robert J. Skoumal, D. R. Shelly, Jeanne L. Hardebeck · 2022

Earthquake focal mechanisms are traditionally produced using P-wave first-motion polarities and commonly require well-recorded seismicity. A recent approach that is less dependent on high signal-to-noise exploits similar waveforms to produ…

S/P Amplitude Ratios Derived from Single-Component Seismograms and Their Potential Use in Constraining Focal Mechanisms for Microearthquake Sequences Open

D. R. Shelly, Robert J. Skoumal, Jeanne L. Hardebeck · 2022

Focal mechanisms, which reflect the sense of slip in earthquakes, provide important constraints for understanding crustal tectonics and earthquake source physics, including the interactions among earthquakes during mainshock–aftershock seq…

Earthquake‐Derived Seismic Velocity Changes During the 2018 Caldera Collapse of Kīlauea Volcano Open

Alicia J. Hotovec‐Ellis, B. Shiro, D. R. Shelly, K. R. Anderson, M. M. Haney , et al. · 2022

The 2018 Kīlauea caldera collapse produced extraordinary sequences of seismicity and deformation, with 62 episodic collapse events which significantly altered the landscape of the summit region. Despite decades of focused scientific studie…

A Big Problem for Small Earthquakes: Benchmarking Routine Magnitudes and Conversion Relationships with Coda Envelope-Derived Mw in Southern Kansas and Northern Oklahoma Open

D. R. Shelly, Kevin Mayeda, Justin Barno, Katherine M. Whidden, Morgan P. Moschetti , et al. · 2021

Earthquake magnitudes are widely relied upon measures of earthquake size. Although moment magnitude (Mw) has become the established standard for moderate and large earthquakes, difficulty in reliably measuring seismic moments for small (ge…

Identification of Low‐Frequency Earthquakes on the San Andreas Fault With Deep Learning Open

Amanda M. Thomas, Asaf Inbal, J. Searcy, D. R. Shelly, Roland Bürgmann · 2021

Low‐frequency earthquakes are a seismic manifestation of slow fault slip. Their emergent onsets, low amplitudes, and unique frequency characteristics make these events difficult to detect in continuous seismic data. Here, we train a convol…

Geodetic Measurements of Slow‐Slip Events Southeast of Parkfield, CA Open

Brent Delbridge, Joshua Carmichael, R. M. Nadeau, D. R. Shelly, Roland Bürgmann · 2020

Tremor and low‐frequency earthquakes are presumed to be indicative of surrounding slow, aseismic slip that is often below geodetic detection thresholds. This study uses data from borehole seismometers and long‐baseline laser strainmeters t…

Anatomy of a Caldera Collapse: Kīlauea 2018 Summit Seismicity Sequence in High Resolution Open

D. R. Shelly, W. A. Thelen · 2019

The 2018 Kīlauea eruption and caldera collapse generated intense cycles of seismicity tied to repeated large seismic ( M w ~ 5) collapse events associated with magma withdrawal from beneath the summit. To gain insight into the underlying d…

Illuminating Faulting Complexity of the 2017 Yellowstone Maple Creek Earthquake Swarm Open

D. R. Shelly, Jeanne L. Hardebeck · 2019

The 2017 Maple Creek earthquake swarm was one of the most prolific swarms to occur in the Yellowstone region in the past few decades, with nearly 2,500 routinely detected earthquakes up to M w 4.4 between June and September 2017. To gain i…

Deep fluid pathways beneath Mammoth Mountain, California, illuminated by migrating earthquake swarms Open

Alicia J. Hotovec‐Ellis, D. R. Shelly, David P. Hill, A. M. Pitt, Philip Dawson , et al. · 2018

Earthquakes beneath a Californian volcano track fluid movement and outline a zone of partial melt in the deep and mid-crust.

Seismic evidence for significant melt beneath the Long Valley Caldera, California, USA Open

A. F. Flinders, D. R. Shelly, Philip Dawson, David P. Hill, Barbara Tripoli , et al. · 2018

A little more than 760 ka ago, a supervolcano on the eastern edge of California (United States) underwent one of North America’s largest Quaternary explosive eruptions. Over this ~6-day-long eruption, pyroclastic flows blanketed the surrou…

Imaging a Crustal Low‐Velocity Layer Using Reflected Seismic Waves From the 2014 Earthquake Swarm at Long Valley Caldera, California: The Magmatic System Roof? Open

Nori Nakata, D. R. Shelly · 2018

The waveforms generated by the 2014 Long Valley Caldera earthquake swarm recorded at station MLH show clear reflected waves that are often stronger than direct P and S waves. With waveform analyses, we discover that these waves are reflect…

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