17:15 〜 18:30
[SIT19-P04] Estimation of postseismic effects of 2013 Okhotsk Sea Mw8.3 deep-focus earthquake
キーワード：earthquake modeling, postseismic displacements, deep-focus earthquake
The strong deep-focus earthquake Mw8.3 occurred beneath the Okhotsk Sea to the west of the Kamchatka Peninsula on 24 May 2013 at a depth of 620 km. This earthquake is the strongest deep-focus event ever instrumentally observed. Seismic shaking was registered at great distances from the epicenter almost over the World.
The earthquake generated surface coseismic displacements that were detected by GNSS-techniques for the first time for a deep-focus event. The regional GNSS-network revealed offsets up to 2 cm in both horizontal and vertical components [Shestakov et al. 2014]. Coseismic displacements affected all north-eastern Asia.
All regional GNSS-stations notable changed their secular movement directions and velocities after the event. Variations have systematic character and could be caused by postseismic processes. In such a case, in opposite to typical postseismic exponentially decaying motion caused by shallow earthquakes, Kamchatka GNSS-stations demonstrate linear postseismic drift.
Coordinate time series of Kamchatka GNSS-sites were carefully analysed for investigation of this effect. Coordinate sequences were divided into two parts – before and after the event. Each component was processed separately.
Obtained sites motion parameters were utilized for modeling by using Visco2.5D software [Pollitz, 2014]. Different sets of slab, crust and mantle rigidity and shape were tested. Finally, reasonable fit between the observed and calculated postseismic displacements was achieved.
References:
Shestakov, N. et al. Modeling of earth crustal coseismic movement initiated by deep-focus Okhotsk sea earthquakes on 24 May 2013, Mw8.3 // Reports of Academy of Sciences. 2014, vol. 457, 4, pp 471-476.
Pollitz, F. Post-earthquake relaxation using a spectral element method: 2.5-D case // Geophysical Journal International. 2014. 19 p.
This work was partially supported by the RFBR grant No. 20-05-00509 and JREX Fellowship.
The earthquake generated surface coseismic displacements that were detected by GNSS-techniques for the first time for a deep-focus event. The regional GNSS-network revealed offsets up to 2 cm in both horizontal and vertical components [Shestakov et al. 2014]. Coseismic displacements affected all north-eastern Asia.
All regional GNSS-stations notable changed their secular movement directions and velocities after the event. Variations have systematic character and could be caused by postseismic processes. In such a case, in opposite to typical postseismic exponentially decaying motion caused by shallow earthquakes, Kamchatka GNSS-stations demonstrate linear postseismic drift.
Coordinate time series of Kamchatka GNSS-sites were carefully analysed for investigation of this effect. Coordinate sequences were divided into two parts – before and after the event. Each component was processed separately.
Obtained sites motion parameters were utilized for modeling by using Visco2.5D software [Pollitz, 2014]. Different sets of slab, crust and mantle rigidity and shape were tested. Finally, reasonable fit between the observed and calculated postseismic displacements was achieved.
References:
Shestakov, N. et al. Modeling of earth crustal coseismic movement initiated by deep-focus Okhotsk sea earthquakes on 24 May 2013, Mw8.3 // Reports of Academy of Sciences. 2014, vol. 457, 4, pp 471-476.
Pollitz, F. Post-earthquake relaxation using a spectral element method: 2.5-D case // Geophysical Journal International. 2014. 19 p.
This work was partially supported by the RFBR grant No. 20-05-00509 and JREX Fellowship.