scholarly journals Back-propagating rupture evolution within a curved slab during the 2019 Peru intraslab earthquake

2021 ◽  
Author(s):  
Hu Yaping ◽  
Yagi Yuji ◽  
Okuwaki Ryo ◽  
Kousuke Shimizu
Keyword(s):  
Intraslab Earthquake

scholarly journals Basin Resonance and Seismic Hazard for Jakarta, Indonesia

2018 ◽  
Author(s):  
Athanasius Cipta ◽  
Phil Cummins ◽  
Masyhur Irsyam ◽  
Sri Hidayati
Keyword(s):  
Ground Motion ◽  
Seismic Waves ◽  
Response Spectrum ◽  
Capital City ◽  
Earthquake Ground Motion ◽  
Computational Domain ◽  
Near Surface ◽  
Earthquake Scenario ◽  
Design Response Spectrum ◽  
Intraslab Earthquake

We use earthquake ground motion modelling via Ground Motion Prediction Equations (GMPEs) and numerical simulation of seismic waves to consider the effects of site amplification and basin resonance in Jakarta, the capital city of Indonesia. While spectral accelerations at short periods are sensitive to near-surface conditions (i.e., Vs30), our results suggest that, for basins as deep as Jakarta’s, available GMPEs cannot be relied upon to accurately estimate the effect of basin depth on ground motions at long periods (>1 s). Amplitudes at such long periods are influenced by entrapment of seismic waves in the basin, resulting in longer duration of strong ground motion, and interference between incoming and reflected waves as well as focusing at basin edges may amplify seismic waves. In order to simulate such phenomena in detail, a basin model derived from a previous study is used as a computational domain for deterministic earthquake scenario modeling in a 2-dimensional cross-section. A Mw 9.0 megathrust, a Mw 6.5 crustal thrust and a Mw 7.0 instraslab earthquake are chosen as scenario events that pose credible threats to Jakarta, and the interactions with the basin of seismic waves generated by these events were simulated. The highest PGV amplifications are recorded at sites near the middle of the basin and near its southern edge, with maximum amplifications of PGV in the horizontal component of 200% for the crustal, 600% for the megathrust and 335% for the deep intraslab earthquake scenario, respectively. We find that the levels of ground motion response spectral acceleration fall below those of the 2012 Indonesian building Codes's design response spectrum for short periods (< 1 s), but closely approach or may even exceed these levels for longer periods.

scholarly journals An intraslab earthquake at a depth of 100 km in the subducting Cocos plate beneath Nevado de Toluca volcano

2020 ◽  
Vol 59 (1) ◽  
pp. 5-12
Author(s):  
Shri K. Singh ◽  
Xyoli Pérez-Campos ◽  
Víctor Hugo Espindola ◽  
Arturo Iglesias ◽  
Luis Quintanar
Keyword(s):  
Cocos Plate ◽  
Intraslab Earthquake ◽  
Nevado De Toluca

La sismicidad en la placa de Cocos subducida por debajo de México central, definida por sismos moderados y grandes, cesa antes de al frente volcánico activo. No se ha localizado algún sismo intraplaca por debajo de los volcanes Nevado de Toluca y Popocatépetl. En este trabajo se reporta un evento de Mw3.3 a una profundidad de 98 km, a 38 km al oeste del Nevado de Toluca. Este evento provee evidencia, por primera vez, de un sismo en la placa subducida a profundidad de ~100 km por debajo del volcán. Registros de este evento también proveen evidencia de una alta atenución de las ondas de cizalla conforme se propagan a través de la cuña del manto astenosférico. Es posible que la sismicidad intraplaca por debajo de los volcanes activos en México central, a un nivel de M ~3, sea abundante pero que no ha sido documentada en el pasado por la falta de instrumentación en la región.

The Productivity of Cascadia Aftershock Sequences

2021 ◽  
Author(s):  
Joan Gomberg ◽  
Paul Bodin
Keyword(s):  
Pacific Northwest ◽  
Subduction Zones ◽  
Geological Survey ◽  
Clear Correlation ◽  
Seismogenic Fault ◽  
Intermediate Depth ◽  
Aftershock Sequences ◽  
Intraslab Earthquake ◽  
Seismicity Rates ◽  
Background Seismicity

ABSTRACT This study addresses questions about the productivity of Cascadia mainshock–aftershock sequences using earthquake catalogs produced by the Geological Survey of Canada and the Pacific Northwest Seismic Network. Questions concern the likelihood that future moderate to large intermediate depth intraslab earthquakes in Cascadia would have as few detectable aftershocks as those documented since 1949. More broadly, for Cascadia, we consider if aftershock productivities vary spatially, if they are outliers among global subduction zones, and if they are consistent with a physical model in which aftershocks are clock-advanced versions of tectonically driven background seismicity. A practical motivation for this study is to assess the likely accuracy of aftershock forecasts based on productivities derived from global data that are now being issued routinely by the U.S. Geological Survey. For this reason, we estimated productivity following the identical procedures used in those forecasts and described in Page et al. (2016). Results indicate that in Cascadia we can say that the next intermediate depth intraslab earthquake will likely have just a few detectable aftershocks and that aftershock productivity appears to be an outlier among global subduction zones, with rates that on average are lower by more than half, except for mainshocks in the upper plate. Our results are consistent with a clock-advance model; productivities may be related to the proximity of mainshocks to a population of seismogenic fault patches and correlate with background seismicity rates. The latter and a clear correlation between productivities with mainshock depth indicate that both factors may have predictive value for aftershock forecasting.

scholarly journals Source of the 2019 Mw6.9 Banten Intraslab earthquake modelled with GPS data inversion

2021 ◽  
Author(s):  
Satrio Muhammad Alif ◽  
Erlangga Ibrahim Fattah ◽  
Munawar Kholil ◽  
Ongky Anggara
Keyword(s):  
Gps Data ◽  
Data Inversion ◽  
Intraslab Earthquake
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