Article
Geochemistry & Geophysics
Marlon D. Ramos, Yihe Huang, Thomas Ulrich, Duo Li, Alice-Agnes Gabriel, Amanda M. Thomas
Summary: The Pacific Northwest coast faces earthquake and tsunami hazards from the Cascadia subduction zone, with evidence of previous megathrust earthquakes occurring every few centuries. Research focused on understanding key questions for the next great megathrust event, such as initiation location, conditions for rupture, and expected slip amount. Dynamic rupture simulations and geological analyses are used to explore the sensitivity of earthquake size to slip deficit in the central Cascadia region, providing insights for earthquake and tsunami hazard assessment in similar subduction zones.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
B. Gombert, J. C. Hawthorne
Summary: Slow earthquakes can have varying durations, moments, and slip and propagation speeds. This study examines tremor bursts with durations between 1 and 30 minutes, which are likely driven by short bursts of aseismic slip. Using a coherence-based technique, thousands of tremor bursts beneath Vancouver Island in Cascadia are detected, and 17 of the ruptures are examined. The study finds that tremor migrates at rates of 3-25 m/s, filling a gap in the spectrum of observed slow earthquakes and suggesting the existence of faster slip and propagation in smaller ruptures.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geochemistry & Geophysics
Aaron G. Wech
Summary: The Pacific Northwest Seismic Network has been detecting and locating tectonic tremor in the Cascadia subduction zone for the past 12 years, resulting in a catalog of over 500,000 tremor epicenters. A new methodology for routine tremor detection in the region was presented, with a focus on the southern edge of the subduction zone where a newly identified tremor source was located. The study found differences in tremor activity between northern and southern Cascadia, with the highest energy rates occurring in the north.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geography, Physical
Junki Komori, Masanobu Shishikura, Ryosuke Ando, Yusuke Yokoyama, Yosuke Miyairi
Summary: This study quantitatively evaluated the emergence ages of tectonically uplifted marine terraces in central Japan. A new method was proposed to estimate the emergence ages of the terraces using Bayesian statistics and the temporal distribution of sample ages. The results showed variations in recurrence intervals of terrace-forming earthquakes and provided valuable information for subduction zone research and hazard assessments.
QUATERNARY SCIENCE REVIEWS
(2021)
Article
Geology
Ehsan Kosari, Matthias Rosenau, Sabrina Metzger, Onno Oncken
Summary: Understanding the seismogenic behavior of megathrusts is crucial for predicting seismic hazards in subduction zones. However, the relationship between frictional heterogeneity at depth and upper-plate deformation is not fully understood. Using a seismotectonic model, we found that the frictional locking heterogeneity generates segmented along-strike strain patterns in the short term but less pronounced permanent strain patterns in the long term. Our results suggest that along-strike upper-plate strain patterns can help interpret lateral variations in seismogenic behavior.
Article
Geochemistry & Geophysics
Reid J. Merrill, Michael G. Bostock, Simon M. Peacock, Andrew J. Schaeffer, Steven W. Roecker
Summary: An automatic earthquake detection algorithm was used to analyze seismic waveforms recorded between 2000 and 2020 in southwest British Columbia, revealing a double seismic zone within the Nootka Fault zone (NFZ) and indicating a more northerly trajectory and increased plate curvature compared to the typical subduction zones.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2022)
Article
Geochemistry & Geophysics
Hanaya Okuda, Matt J. Ikari, Alexander Roesner, Katja Stanislowski, Andre Hupers, Asuka Yamaguchi, Achim J. Kopf
Summary: The study conducted experiments with sediment samples from the Nankai Trough in different locations, finding that the friction coefficient is inversely correlated with clay mineral content, with outer prism sediments exhibiting higher coefficients. All samples exhibited velocity-weakening behavior at low velocities, but outer prism and deep inner prism sediments showed velocity strengthening at higher velocities.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
Fred F. Pollitz
Summary: This study presents a fault-based modeling approach to estimate long-term slip rates on more than 1000 active faults in the western United States using a large dataset of GPS velocities. The study highlights the significant impact of time-dependent effects on slip rate estimation.
SEISMOLOGICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Orlando Alvarez, Stefanie Pechuan Canet, Mario Gimenez, Andres Folguera
Summary: Over the past two decades, space geodesy has greatly improved the study of large megathrust earthquakes by accurately mapping rupture areas, slip distribution, and seismic coupling. By modeling gravity gradients and comparing them with coseismic slip models, we have identified mass heterogeneities and their relationship with seismic activity. This research suggests that combining geodetic and seismological data can help identify and monitor areas with higher seismic hazard potential worldwide.
FRONTIERS IN EARTH SCIENCE
(2021)
Review
Astronomy & Astrophysics
Maureen A. L. Walton, Lydia M. Staisch, Tina Dura, Jessie K. Pearl, Brian Sherrod, Joan Gomberg, Simon Engelhart, Anne Trehu, Janet Watt, Jon Perkins, Robert C. Witter, Noel Bartlow, Chris Goldfinger, Harvey Kelsey, Ann E. Morey, Valerie J. Sahakian, Harold Tobin, Kelin Wang, Ray Wells, Erin Wirth
Summary: The Cascadia Subduction Zone has recorded at least 19 great megathrust earthquakes over the past 10,000 years and is a significant geologic environment for understanding natural hazards. Despite uncertainties, exploring models of earthquake recurrence can help in reducing societal impacts and improving scientific knowledge. Integrating diverse datasets and focusing on geological processes may lead to major progress in addressing outstanding questions about CSZ earthquakes.
ANNUAL REVIEW OF EARTH AND PLANETARY SCIENCES, VOL 49, 2021
(2021)
Article
Geochemistry & Geophysics
Elizabeth G. Westby, Andrew Meigs, Chris Goldfinger
Summary: Subduction zones are responsible for some of the most devastating geological events on Earth, including large earthquakes, tsunamis, and volcanic eruptions. The Cascadia subduction zone has experienced these hazards in the past and is predicted to do so in the future. Therefore, it is crucial to have a detailed scientific understanding of the geological forces and processes involved in order to mitigate risks and protect the growing population and infrastructure in the region.
Article
Geosciences, Multidisciplinary
Khurram S. Aslam, Amanda M. Thomas, Diego Melgar
Summary: The study reveals that the orientation of splay faults is a primary control on slip amplitude within the fore-arc of the Cascadia Subduction Zone, with seaward vergent faults accommodating significant slip leading to larger tsunami amplitudes. There is a need to revisit existing approaches to tsunami hazard assessment in Cascadia to include the influence of splay faults.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Geosciences, Multidisciplinary
Wen-Bin Doo, Chung-Liang Lo, Yin-Sheng Huang, Wen-Nan Wu, Shiou-Ya Wang
Summary: In this study, we investigated the spatial variations in crustal structure and strength of plate coupling along the Ryukyu subduction zone using seismic velocity profiles and gravity modeling. The results revealed the presence of less dense and thinner oceanic plateaus and/or submarine ridges subducting in the northern and central parts of the Ryukyu Trench.
GEOSCIENCE LETTERS
(2023)
Article
Geochemistry & Geophysics
Keisuke Yoshida, Naoki Uchida, Hisahiko Kubo, Ryota Takagi, Shiqing Xu
Summary: The development of seafloor seismic observations has enabled the reliable estimation of rupture directivities from offshore earthquakes. The study found that the majority of earthquakes have directional ruptures favoring updip propagation, which may be related to deep aseismic slip and upward fluid migration along the plate interface.
EARTH AND PLANETARY SCIENCE LETTERS
(2022)
Article
Geochemistry & Geophysics
Koji Tamaribuchi, Masashi Ogiso, Akemi Noda
Summary: Shallow slow earthquakes in the Nankai Trough seismogenic zone were studied using a network of cabled ocean-bottom seismometers. The researchers developed a hybrid method to determine tremor hypocenters based on waveforms and traveltimes. They detected over 6,500 tremors, including three major episodes, and found that the tremors were synchronized with slow slip events and correlated with stress heterogeneity on the shallow plate boundary.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)