Browsing by Author "Senturk, Erman"

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Long-Term Ion Hydration Process and Lithosphere-Atmosphere Coupling Following the 2021 Fagradalsfjall Volcanic Eruption Using Remotely Sensed Data
(Elsevier Sci Ltd, 2023) Senturk, Erman; Adil, Muhammad Arqim; Toker, Mustafa; Iban, Muzaffer Can; Akyurek, Ozer
After a series of earthquakes, the Reykjanes peninsula in Iceland faced a volcanic eruption for the first time in 800 years. This vol-canism of the 2021 Fagradalsfjall started on March 19, 2021, and lasted until September 18, 2021. In this study, the vestiges of the mutual interplay of Earth's different geophysical shells due to the local lithospheric changes around the Fagradalsfjall were extensively investi-gated with the help of satellite-based remotely sensed datasets. Firstly, the regional surface deformations caused by the pre-eruption seis-mic activity are determined using interferometric image pairs, and horizontal and vertical displacement rates are analyzed. Secondly, the satellite observations revealed that the land surface temperature of the entire area increased to a maximum of 40 degrees C during the maximum phase of lava discharge by the end of May 2021. Moreover, we observed that the surface mass concentrations of SO2 and CO trace gases started to ascend in parallel with the lava discharge after the initial eruption, where their concentrations were doubled in April before reaching their maximum phases (three to four times more than the initial eruption) in May 2021. The cumulative concentrations of the trace gases in the atmosphere emitted from the Fagradalsfjall volcano pushed the regional atmospheric balance into a non-equilibrium state by creating air ionization through various chemical reactions with other atmospheric gases. These ion clusters underwent an ion hydration process that changed the electric conductivity of the atmospheric boundary layer, which covers the first two kilometers of the atmosphere. Finally, our observations showed a sharp decrease in the atmospheric relative humidity that led to an increase in the atmospheric air temperature due to this ion hydration process. The large ion clusters in the atmospheric boundary layer produced a ver-tical electric field that penetrated over the affected region and brought long-term changes in the ionosphere layer. This unique phe-nomenon of the simultaneous interaction of different geophysical layers was specifically observed during the maximum phase of the lava discharge and increased ion concentrations in the atmosphere. The used data sets cover the first three months of the volcanism, and this interval seemed to be sufficient to reveal the atmospheric traces. Our comprehensive study provides an important contribution to the theory of the coupling of volcanism and the Earth's atmospheric dynamics. (c) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.
New Insight Into the 24 January 2020, Mw 6.8 Elazig Earthquake (Turkey): an Evidence for Rupture-Parallel Pull-Apart Basin Activation Along the East Anatolian Fault Zone Constrained by Geodetic and Seismological Data
(Ist Nazionale Di Geofisica E Vulcanologia, 2021) Irmak, Tahir Serkan; Toker, Mustafa; Yavuz, Evrim; Senturk, Erman; Guvenaltin, Muhammed Ali
In this study, we investigated the main features of the causative fault of the 24 January 2020, M-w, 6.8 Elazig earthquake (Turkey) using seismological and geodetic data sets to provide new insight into the East Anatolian Fault Zone (EAFZ). We first constrained the co-seismic surface deformation and the rupture geometry of the causative fault segment using Interferometric Synthetic Aperture Radar (InSAR) interferograms (Sentinel-1A/B satellites) and teleseismic waveform inversion, respectively. Also, we determined the centroid moment tensor (CMT) solutions of focal mechanisms of the 27 aftershocks using the regional waveform inversion method. Finally, we evaluated the co-seismic slip distribution and the CMT solutions of the causative fault as well as of adjacent segments using the 27 focal solutions of the aftershocks, superimposed on the surface deformation pattern. The CMT solution of the 24 January 2020Elazig earthquake reveals a pure strike-slip focal mechanism, consistent with the structural pattern and left-lateral motion of the EAFZ. The rupture process of the Elazig event indicated that the rupture is started at 12 km around the hypocenter, and then propagated bilaterally along the NE-SW but mainly toward the southwest. The rupture slip has initially propagated toward the southwest (first 10 s) and northeast (4 s), and again toward the southwest (9 s). Maximum displacement is calculated as 1.3 m about 20 km southwest of the hypocenter at 6 km depth (centroid depth). The rupture stopped to down-dip around 20 km depth toward the southwest. The distribution of the slip vectors indicates that the rupture continued mostly through a normal oblique movement. Most of the moment release was released SW of the hypocenter and the rupture reached up to around 50 km. The focal mechanisms of analyzed 27 aftershocks show strike-slip, but mostly normal and normal oblique-slip faulting with an orientation of the tensional axes (NNE-SSW), indicating a normal oblique-slip, "transtensional" stress regime, parallel-subparallel to the strike of the EAFZ, consistent with SW-rupture directivity and coseismic deformation pattern. Finally, based on the co-seismic surface deformation compatible with the distributional pattern of normal focal solutions, normal and normal oblique-slip focals of the aftershocks evidence the rupture-parallel pull-apart basin activation as a segment boundary of the left-lateral strike-slip movement of the EAFZ.