Browsing by Author "Shrivastava, Mahesh N."

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    Coseismic slip and afterslip of the 2015 Mw 8.3 Illapel (Chile) earthquake determined from continuous GPS data
    (John Wiley & Sons Ltd., 2016) Shrivastava, Mahesh N.; González, Gabriel; Moreno, Marcos; Chlieh, Mohamed; Salazar, Pablo; Reddy, C.D.; Báez, Juan Carlos; Yanez Carrizo Gonzalo Alejandro; González, Juan; De La Llera Martin Juan Carlos; Pontificia Universidad Católica de Chile. National Research Center for Integrated Natural Disaster Management
    We analyzed the coseismic and early postseismic deformation of the 2015, M-w 8.3 Illapel earthquake by inverting 13 continuous GPS time series. The seismic rupture concentrated in a shallow (<20km depth) and 100km long asperity, which slipped up to 8m, releasing a seismic moment of 3.6x10(21)Nm (M-w=8.3). After 43days, postseismic afterslip encompassed the coseismic rupture. Afterslip concentrated in two main patches of 0.50m between 20 and 40km depth along the northern and southern ends of the rupture, partially overlapping the coseismic slip. Afterslip and aftershocks confined to region of positive Coulomb stress change, promoted by the coseismic slip. The early postseismic afterslip was accommodated similar to 53% aseismically and similar to 47% seismically by aftershocks. The Illapel earthquake rupture is confined by two low interseismic coupling zones, which coincide with two major features of the subducting Nazca Plate, the Challenger Fault Zone and Juan Fernandez Ridge.
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    The 1 April 2014 Pisagua tsunami : observations and modeling
    (2015) Catalán, Patricio A.; Aránguiz, Rafael; González, Gabriel; Tomita, Takashi; Cienfuegos Carrasco, Rodrigo Alberto; González, Juan; Shrivastava, Mahesh N.; Kumagai, Kentaro; Mokrani, Cyril; Cortés, Pablo; Gubler, Alejandra
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    Tracking tsunami propagation and Island's collapse after the Hunga Tonga Hunga Ha'apai 2022 volcanic eruption from multi-space observations
    (2023) Shrivastava, Mahesh N.; Sunil, A. S.; Maurya, Ajeet K.; Aguilera, Felipe; Orrego, Simon; Sunil, P. S.; Cienfuegos, Rodrigo; Moreno, Marcos
    The quantity and accuracy of satellite-geodetic measurements have increased over time, revolutionizing the monitoring of tectonic processes. Global Navigation Satellite System (GNSS) and satellite radar signals provide observations beyond ground deformation, including how earthquake and tsunami processes affect variations in the ionosphere. Here, we study the Hunga Tonga Hunga Ha'apai (HTHH) volcanic eruption 2022 and its associated tsunami propagation with the analysis GNSS derived Total Electron Content (TEC), Synthetic Aperture Radar (SAR) Sentinel-1 data, complemented with tide gauge observations. We utilize GNSS sites data within a similar to 5000 km radius from the volcanic eruption for estimating the ionospheric perturbation as Vertical TEC. We give evidence on the detection of acoustic gravity, internal gravity, and atmospheric Lamb waves signatures in the TEC perturbation. In particular, the internal gravity waves that concentrated in the southwest of Tonga, directly correlates with the observed tsunami propagation direction as accounted by the tide gauge measurements. However, the acoustic gravity wave signature in the TEC is dominant in the north direction suggesting a surface deformation, which could be verified using Sentinel-1A SAR amplitude data. The analysis presented herein shows that within 5 h of the volcanic eruption, the central part of the HTHH island landscape disappeared with the biggest explosion. The unprecedented detail resolved by integrating satellite data yields previously unknown details of the deformation of the 2022 HTHH volcano eruption.