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    Examination of the Earthquake (Samos Island) in Izmir (30.10.2020) by Using Cors-Tr GNSS Observations and InSAR Data
    (Korean Society Of Civil Engineers-Ksce, 2023) Pirti, Atinc; Hosbas, Ramazan Gursel; Yucel, Mehmet Ali
    Izmir, which is one of the biggest cities of Turkey and has the extensive tectonic features of the Western Anatolia region, has been struck in recent years due to its high seismic activity. In particular, the south of Izmir is one of the regions that has high seismic activity in the city, which is constrained by major fault zones. The earthquake of magnitude of a Mw 6.9 occurred 8 km north of Samos Island at a depth of 16 km on 30.10.2020, at 11:51:24 UTC (14:51:24 Local Time (LT)). It occurred on a 40-kilometer-long north-dipping normal fault zone in the Mediterranean between Greece's Samos Island and Turkey's Kusadasi Bay. Following the mainschock, a tsunami with a height of more than 1 meter occurred at Sigacik Bay, south of Izmir, and on the north side of Samos Island. This article focuses on the investigation of the Samos earthquake by utilizing both GNSS data and InSAR images, and the obtained results are given in this paper. GNSS data were processed by using CSRS-PPP Software as static and kinematic modes. After processing the GNSS data, the maximum displacements were observed at CESME and IZMIR CORS-TR points located in the north of the fault. Horizontal movements of 12 cm and 6 cm towards the north were obtained at CESME and IZMIR points, respectively. However, the amount of horizontal movements was less at DIDIM and AYDIN CORS-TR locations, which are located to the south of the fault. In addition to GNSS data, ESA Sentinel-1 SAR data was used in the InSAR procedure, and the displacements were clarified using the unwrapped interferogram. The interferogram revealed a 10 cm uplift in the west of the Island of Samos and a 10 cm subsidence in the Izmir region, on the north side of the fault, based on the InSAR data. The most striking feature of this study is that the earthquake that occurred near the island of Samos was reported by Gansas' study that the 3 GNSS points (SAMO, SAMU, and 093A) on the island of Samos are moving in a south direction and the largest displacement is about 36 centimetres south. However, in our study, the north direction is more prominent as the direction of movement at IZMIR and CESME points. The movement at the DIDIM point supports his work. In other words, the Samos Fault affected the points located in the north and south differently.
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    Investigation of the Mw 7.3 earthquake in Tonga Islands, Pacific Ocean, 11 November 2022
    (Inst Geology & Geography, 2024) Pirti, Atinc; Yucel, Mehmet Ali; Hosbas, Ramazan Gursel
    The Mw 7.3 Tonga earthquake occurred on 11 November 2022 at 19 degrees.288 S and 172 degrees.147 W. It was caused by reverse faulting in the outer rise of the Pacific Plate, about 75 km east of the Tonga Trench. We studied the Tonga earthquake on 11 November 2022 in order to detect a violent eruption of the Tonga submarine volcano in the South Pacific. Submarine volcano eruptions can displace seawater in a number of different ways, potentially triggering tsunamis. The Tonga subduction zone has the highest rate of plate convergence on Earth. It is one of the places with the most earthquakes. However, the recorded thrust events that can be placed with certainty on the plate boundary haven't been stronger than M 8.0, and the area's history suggests that there isn't much seismic coupling along the arc. The modelling of this earthquake based on the assumption that the fault plane dips to the west give dimensions of about 50 x 35 km, with most of the distance down -dipping from the hypocenter. In our study, we used the CSRS-PPP software to process TONGA station data using static and kinematic methods. This study shows the horizontal coordinate differences of the TONGA station (static -kinematic), which range from a few millimetres to about 40 centimetres.
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    Monitoring of Icelandic plate movement with GNSS method and GPS signal jamming effects in Iceland
    (Sciendo, 2023) Pirti, Atinc; Hosbas, Ramazan Gursel; Yucel, Mehmet Ali
    Jamming is electromagnetic radiation or reflection that impairs the function of electronic instruments and equipment or communication tools. Intentionally disrupting or interfering with GPS signals, which are used for positioning, navigation, and timing, known as GPS jamming, is accomplished using a radio frequency emitting device. On January 8, 2022 (the day of a NATO exercise), it was investigated how GPS signal jamming affected the position accuracy at three IGS points in Iceland. The obtained coordinate differences between kinematic processing and static processing reached values of about 0.5-10 meters for the MAYV, and HOFN stations in this study. In addition to GPS signal jamming effect in Iceland, horizontal and vertical velocity fields of the three IGS stations in Iceland covering a twenty-two year period (2000-2022) in this study. According to the obtained results, a motion of about 2cm-2.5cm per year (horizontal) and 0.1cm-2.1cm per year (vertical) was computed at the three IGS stations (HOFN, REYK, and MAYV) located in Iceland.