Two-Element Keyboard Model of Generation of the Strongest Subduction Earthquakes

2021 ◽  
Vol 496 (1) ◽  
pp. 72-75
Author(s):  
L. I. Lobkovsky ◽  
I. S. Vladimirova ◽  
D. A. Alekseev ◽  
Y. V. Gabsatarov
Keyword(s):  
Subduction Earthquakes

Spectral damping scaling factors for horizontal components of ground motions from subduction earthquakes using NGA-Subduction data

2021 ◽  
pp. 875529302110279
Author(s):  
Sanaz Rezaeian ◽  
Linda Al Atik ◽  
Nicolas M Kuehn ◽  
Norman Abrahamson ◽  
Yousef Bozorgnia ◽  
...  
Keyword(s):  
Ground Motions ◽  
Damping Ratio ◽  
Spectral Shape ◽  
Parametric Models ◽  
Scaling Factors ◽  
Global Models ◽  
Motion Models ◽  
Subduction Earthquakes ◽  
Crustal Earthquakes ◽  
Subduction Zone Earthquakes

This article develops global models of damping scaling factors (DSFs) for subduction zone earthquakes that are functions of the damping ratio, spectral period, earthquake magnitude, and distance. The Next Generation Attenuation for subduction earthquakes (NGA-Sub) project has developed the largest uniformly processed database of recorded ground motions to date from seven subduction regions: Alaska, Cascadia, Central America and Mexico, South America, Japan, Taiwan, and New Zealand. NGA-Sub used this database to develop new ground motion models (GMMs) at a reference 5% damping ratio. We worked with the NGA-Sub project team to develop an extended database that includes pseudo-spectral accelerations (PSA) for 11 damping ratios between 0.5% and 30%. We use this database to develop parametric models of DSF for both interface and intraslab subduction earthquakes that can be used to adjust any subduction GMM from a reference 5% damping ratio to other damping ratios. The DSF is strongly influenced by the response spectral shape and the duration of motion; therefore, in addition to the damping ratio, the median DSF model uses spectral period, magnitude, and distance as surrogate predictor variables to capture the effects of the spectral shape and the duration of motion. We also develop parametric models for the standard deviation of DSF. The models presented in this article are for the RotD50 horizontal component of PSA and are compared with the models for shallow crustal earthquakes in active tectonic regions. Some noticeable differences arise from the considerably longer duration of interface records for very large magnitude events and the enriched high-frequency content of intraslab records, compared with shallow crustal earthquakes. Regional differences are discussed by comparing the proposed global models with the data from each subduction region along with recommendations on the applicability of the models.

Dynamic rupture of subduction earthquakes located near the trench

2021 ◽  
Vol 562 ◽  
pp. 116842
Author(s):  
Cristian Otarola ◽  
Sergio Ruiz ◽  
Carlos Herrera ◽  
Raúl Madariaga ◽  
Cristián Siegel
Keyword(s):  
Dynamic Rupture ◽  
Subduction Earthquakes

Collapse risk of pre-Northridge tall steel moment-resisting frames in the Seattle basin during large-magnitude subduction earthquakes

2021 ◽  
Vol 244 ◽  
pp. 112751
Author(s):  
Carlos Molina Hutt ◽  
Shervin Zahedimazandarani ◽  
Nasser A. Marafi ◽  
Jeffrey W. Berman ◽  
Marc O. Eberhard
Keyword(s):  
Large Magnitude ◽  
Steel Moment Resisting Frames ◽  
Moment Resisting Frames ◽  
Subduction Earthquakes ◽  
Moment Resisting

Ocean-Bottom Strong-Motion Observations in the Nankai Trough by the DONET Real-Time Monitoring System

2018 ◽  
Vol 52 (3) ◽  
pp. 100-108 ◽  
Author(s):  
Takeshi Nakamura ◽  
Narumi Takahashi ◽  
Kensuke Suzuki
Keyword(s):  
Real Time ◽  
Nankai Trough ◽  
Strong Motion ◽  
Deep Ocean ◽  
Disaster Mitigation ◽  
Ocean Bottom ◽  
Source Modeling ◽  
Origin Time ◽  
Subduction Earthquakes ◽  
Sediment Layers

AbstractThe deployment of real-time permanent ocean-bottom seismic and tsunami observatories is significant for disaster mitigation and prevention during the occurrence of large subduction earthquakes near trough areas. On April 1, 2016, a moderate-sized suboceanic earthquake occurred beneath Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET) stations that were recently deployed in deep ocean-bottom areas near the Nankai Trough in southwest Japan. P-waves arrived at the ocean-bottom station within 4 s of the origin time, which was 6 and 13 s earlier than the arrival of P- and S-waves at a land station in the coastal area, respectively; this implies earlier detection of strong motion than at land stations. However, the waveforms are amplified by sediment layers and even contaminated with acceleration offsets at some stations, which would lead to overestimations during source investigations. Such amplification and offset did not occur at a borehole station connected to DONET. The amplifications caused by the sediment layers and the offset were found to have a considerable spatial variation, not only between the DONET stations and land and borehole stations but also among the DONET stations, implying that the amplitude evaluation could be unstable. Therefore, procedures for correcting or suppressing the amplification and offset problem are required for conducting waveform analyses, such as magnitude estimations and source modeling, during large subduction earthquakes.

scholarly journals Landslides Triggered by the 2016 Mw 7.8 Pedernales, Ecuador Earthquake: Correlations with ESI-07 Intensity, Lithology, Slope and PGA-h

Geosciences ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 371 ◽  
Author(s):  
Kervin Chunga ◽  
Franz A. Livio ◽  
Carlos Martillo ◽  
Hernán Lara-Saavedra ◽  
Maria Francesca Ferrario ◽  
...  
Keyword(s):  
Environmental Effects ◽  
Focal Depth ◽  
Lateral Spreading ◽  
Primary Data ◽  
Ground Acceleration ◽  
Epicentral Area ◽  
Coseismic Landslides ◽  
Subduction Earthquakes ◽  
Rupture Plane ◽  
Hilly Region

We provide a dataset of the landslides induced by the 2016 Pedernales megathrust earthquake, Ecuador (Mw 7.8, focal depth of 20 km) and compare their spatial distribution with mapped bedrock lithology, horizontal peak ground acceleration (PGA-h) and the macroseismic intensity based on earthquake-induced environmental effects (ESI-07). We studied 192 coseismic landslides (classified as coherent, disrupted and lateral spreads) located in the epicentral area, defined by the VII to IXESI-07 isoseismals. Based on our findings, lahar deposits, tuffs and volcanoclastic units are the most susceptible to landslides occurrence. Alluvial plains with fluvial loose fine sand are the most susceptible setting for lateral spreading, with a maximum intensity of IXESI-07. The coherent landslides are frequently found in altered shale and siltstone geological units with moderate slopes (8°–16°), with typical intensity ranging between VII and VIIIESI-07. Our analysis draws a typical framework for slope movements triggered by subduction earthquakes in Ecuador. The most dangerous setting is the coastal region, a relatively highly urbanized area located near the epicenter and where liquefaction can trigger massive lateral spreading events. Coherent and disrupted landslides, dominating the more internal hilly region, can be triggered also in moderate slope settings (i.e., less than 10°). Indeed, the regression analysis between seismic intensity, PGA-h and landslide occurrence shows that most of the events occurred at PGA-h values between 0.4 g and 1.2 g, at a distance of 30 to 50 km from the rupture plane. Our database suggests that lithology and hillslope geometry are the main geological/geomorphological factors controlling coseismic landslides occurrence; while the distance from the rupture plane plays a significant role on determining the landslide size. Finally, we underline that coseismically-triggered landslides are among the most common environmental effects occurring during large subduction events that can be effectively used to properly evaluate the earthquake macroseismic field. The landslide inventory we compiled is suitable for assessing the vulnerability of physical environment from subduction earthquakes in Ecuador, and offers a primary data source for future worldwide analysis.

Marine Terraces Reveal Complex Near-Shore Upper-Plate Faulting in the Northern Hikurangi Margin, New Zealand

2020 ◽  
Vol 110 (2) ◽  
pp. 825-849 ◽  
Author(s):  
Nicola J. Litchfield ◽  
Kate J. Clark ◽  
Ursula A. Cochran ◽  
Alan S. Palmer ◽  
Joshu Mountjoy ◽  
...  
Keyword(s):  
New Zealand ◽  
Plate Boundary ◽  
River Mouth ◽  
Seismic Reflection Data ◽  
Subduction Earthquakes ◽  
Reflection Data ◽  
Marine Terraces ◽  
Need To Evaluate ◽  
Near Shore ◽  
Recent Earthquakes

ABSTRACT Recent earthquakes involving multiple fault ruptures highlight the need to evaluate complex coastal deformation mechanisms, which are important for understanding plate boundary kinematics and seismic and tsunami hazards. We compare ages and uplift of the youngest Holocene marine terraces at Puatai Beach and Pakarae River mouth (∼10  km apart) in the northern Hikurangi subduction margin to examine whether uplift is the result of subduction earthquakes or upper-plate fault earthquakes. From stepped platform-cliff morphology, we infer uplift during 2–3 earthquakes and calculate an average uplift-per-event of 2.9±0.5  m at Puatai Beach and 2.0±0.5  m at Pakarae River mouth. Radiocarbon ages from the youngest beach deposit shells on each terrace and a tephra coverbed on one terrace constrain the timing of earthquakes to 1770–1710, 1100–910, and 420–250 cal. B.P. at Puatai Beach, and 1490–1290 and 660–530 cal. B.P. at Pakarae River mouth. The ages differ at each site indicating uplift is neither the result of subduction earthquakes nor single upper-plate fault earthquakes. A reinterpretation of new and existing bathymetry and seismic reflection data, combined with dislocation modeling, indicates that near-shore fault segmentation is more complex than previously thought and ruptures likely involve multiple upper-plate faults. Future updates of the New Zealand National Seismic Hazard Model should revise the northern Hikurangi subduction seismic sources so that rupture does not uplift Puatai Beach and Pakarae River mouth and include new near-shore upper-plate faults as multifault sources.

Sign in / Sign up

Export Citation Format

Share Document