subduction earthquakes
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2021 ◽  
Vol 244 ◽  
pp. 112751
Author(s):  
Carlos Molina Hutt ◽  
Shervin Zahedimazandarani ◽  
Nasser A. Marafi ◽  
Jeffrey W. Berman ◽  
Marc O. Eberhard

2021 ◽  
pp. 875529302110279
Author(s):  
Sanaz Rezaeian ◽  
Linda Al Atik ◽  
Nicolas M Kuehn ◽  
Norman Abrahamson ◽  
Yousef Bozorgnia ◽  
...  

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.


2021 ◽  
Vol 1 (2) ◽  
pp. 75-84
Author(s):  
Charlotte Pizer ◽  
Kate Clark ◽  
Jamie Howarth ◽  
Ed Garrett ◽  
Xiaoming Wang ◽  
...  

Abstract Geological records of subduction earthquakes, essential for seismic and tsunami hazard assessment, are difficult to obtain at transitional plate boundaries, because upper-plate fault earthquake deformation can mask the subduction zone signal. Here, we examine unusual shell layers within a paleolagoon at Lake Grassmere, at the transition zone between the Hikurangi subduction zone and the Marlborough fault system. Based on biostratigraphic and sedimentological analyses, we interpret the shell layers as tsunami deposits. These are dated at 2145–1837 and 1505–1283 yr B.P., and the most likely source of these tsunamis was ruptures of the southern Hikurangi subduction interface. Identification of these two large earthquakes brings the total record of southern Hikurangi subduction earthquakes to four in the past 2000 yr. For the first time, it is possible to obtain a geologically constrained recurrence interval for the southern Hikurangi subduction zone. We calculate a recurrence interval of 500 yr (335–655 yr, 95% confidence interval) and a coefficient of variation of 0.27 (0.0–0.47, 95% confidence interval). The probability of a large subduction earthquake on the southern Hikurangi subduction zone is 26% within the next 50 yr. We find no consistent temporal relationship between subduction earthquakes and large earthquakes on upper-plate faults.


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

2021 ◽  
pp. 875529302098197
Author(s):  
Katsuichiro Goda

This study presents trigger design methods and performance evaluations of multi-hazard parametric catastrophe bonds for mega-thrust subduction earthquakes and tsunamis. The catastrophe bonds serve as alternative disaster risk financing tools for insurers and reinsurers as well as municipalities and governments. Two types of parametric catastrophe bond trigger are investigated. A scenario-based method utilizes available earthquake source-based information, such as magnitude and location, whereas a station-intensity-based method can be implemented when seismic and tsunami hazard monitoring systems are in place in a region. The case study results, focusing on wooden buildings in Miyagi Prefecture, indicate that the station-intensity-based trigger methods outperform the scenario-based trigger methods significantly. Incorporating seismic and tsunami hazard information from multiple recording stations results in smaller trigger errors. The station-intensity-based methods are applicable to building portfolios at both municipality levels and regional levels.


Author(s):  
Behzad Hassani ◽  
Gail Marie Atkinson

ABSTRACT We use an equivalent point-source ground-motion model (GMM) to characterize subduction earthquakes (interface and in-slab) in Japan. The model, which is calibrated using the newly published Next Generation Attenuation (NGA) Subduction database (Bozorgnia et al., 2020), provides a useful complement to the more traditional empirical NGA models developed from the same database. The utility of the point-source model approach lies in its ability to aid in the interpretation of observed trends in the data and to guide modifications to the GMM for application to other regions having fewer data. Key trends in the data that are parameterized with the model include: (a) the enrichment of high-frequency amplitudes for in-slab versus interface events, as modeled by a depth-dependent stress parameter, and (b) attenuation attributes that vary with event type and region, including consideration of fore-arc versus back-arc settings. The developed GMMs of this study are applicable for M 4.5–9.2 for interface events, and M 4–8.5 for in-slab earthquakes, for rupture distances (Drup) from 10 to 600 km, and for 100  m/s<VS30<1500  m/s (time-averaged shear-wave velocity in the top 30 m).


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

2020 ◽  
pp. 875529302097097
Author(s):  
Mahdi Bahrampouri ◽  
Adrian Rodriguez-Marek ◽  
Russell A Green

Significant duration of strong shaking quantifies the length of time during which strong earthquake-induced shaking occurs at a given site. Significant duration has multiple applications in Geotechnical and Structural Engineering. However, while multiple ground motion prediction (GMPE) equations for duration exist for shallow crustal tectonic environments, at the time of this publication, there are few published models for predicting significant duration of subduction earthquakes. To address this need and to identify the difference between significant duration of motions resulting from earthquakes in different tectonic regimes, we develop predictive equations for significant duration applicable to interface and intraslab subduction earthquakes and shallow crustal earthquakes in active tectonic regimes using the KiK-net ground motion database. The GMPEs are applicable to earthquakes with M4 to 9. In addition, the influence of earthquake magnitude on duration due to path effects is captured in the proposed relationships. Based on the relationships proposed in this study, we note that the duration of ground motions from subduction earthquakes is longer than those of shallow crustal earthquakes that have similar magnitudes and distances. The predictions of duration for shallow crustal earthquakes in active tectonic regimes developed in this study are consistent with those from previous studies.


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