SEPTEMBER 26, 2019 Mw5.8 MARMARA SEA-SILIVRI (ISTANBUL) EARTHQUAKE: ANALYSIS OF GROUND MOTION RECORDS

2020 ◽  
Author(s):  
Seyhan Okuyan Akcan ◽  
Can Zulfikar
Keyword(s):  
Ground Motion ◽  
North Anatolian Fault ◽  
Marmara Region ◽  
Marmara Sea ◽  
The North ◽  
Tectonically Active ◽  
Earthquake Research ◽  
Earthquake Research Institute ◽  
Ground Motion Records ◽  
Almost All

<p>Marmara region located on the western end of the North Anatolian Fault Zone is a tectonically active region in Turkey. There have been frequent severe earthquakes in the region and will continue to occur. There was no serious earthquake in the region after the 1999 Mw7.4 Kocaeli and Mw7.2 Düzce earthquakes. A Marmara Sea offshore earthquake Mw5.8 close to Silivri Town of Istanbul Metropolitan City has occurred on September 26, 2019 daytime at 13:59. The earthquake happened at the coordinate of 40.87N – 28.19E with a depth of 7.0km on the Kumburgaz segment of the North Anatolian Fault line. It was felt in almost all Marmara region. In some settlements in Istanbul City, slight to moderate damages were observed. A foreshock earthquake of Mw4.8 occurred on the same segment on 24 September, 2019. 150 aftershock events ranging from M1.0 to M4.1 have been recorded within the 24 hours after the mainshock. The ground motions have been recorded in the region by the several institutions including AFAD (Disaster and Emergency Management Presidency), KOERI (Kandilli Observatory and Earthquake Research Institute) and IGDAS (Istanbul Gas Distribution Industry and Trade Inc.). The ground motion records and selected parameters have been examined in this study. The ground motion parameters (MMI, PGA, PGV, Sa, Sv, Sd) distribution have been achieved and checked by the recent NGA-West2 ground motion prediction equations (GMPEs); ASK2014, CY2014 and BSSA2014. The compatibility of the GMPEs for a moderate size Marmara Sea earthquake has been examined.</p>

A study of the tectonically active Marmara region, Turkey, using a global positioning system (GPS)

2003 ◽  
Vol 40 (9) ◽  
pp. 1191-1202 ◽  
Author(s):  
U Dogan ◽  
G Lachapelle ◽  
L Fortes ◽  
S Ergintav
Keyword(s):  
Global Positioning System ◽  
Rigid Motion ◽  
North Anatolian Fault ◽  
Marmara Region ◽  
Positioning System ◽  
Tectonic Zone ◽  
The North ◽  
Slip Regime ◽  
Global Positioning ◽  
Tectonically Active

The Marmara region is an active tectonic zone characterized by a transition in the dextral strike-slip regime of the western part of the North Anatolian Fault Zone. The main goal of this paper is to assess the use of global positioning system (GPS) data sets collected during five relatively short time intervals during the period December 2000 – March 2002 to detect potential crustal deformations. To determine if the deformations measured with GPS are real or only a data artifact, a statistical reliability analysis of the solutions is performed. The results indicate that each station has statistically different temporal behavior and significant relative motions. This area is consequently still very active, with significant deformation patterns. Although the average magnitude for our estimated displacement rates with respect to ANKR station, which represents the rigid motion of the Anatolian plate, is in the order of 1.1 cm/year in the south of the North Anatolian Fault, it increases to 2.3 cm/year in the northern part of the area.

A robust seismic structure along the North Anatolian Fault beneath the Central Marmara Sea, and its implication for seismogenesis

2021 ◽  
Author(s):  
Yojiro Yamamoto ◽  
Dogan Kalafat ◽  
Ali Pinar ◽  
Narumi Takahashi ◽  
Remzi Polat ◽  
...  
Keyword(s):  
High Velocity ◽  
Seismic Velocity ◽  
Large Earthquake ◽  
North Anatolian Fault ◽  
Seismic Gap ◽  
Observation Data ◽  
Marmara Region ◽  
Marmara Sea ◽  
Seismic Structure ◽  
The North

<p>The offshore part of the North Anatolian Fault (NAF) beneath the Marmara Sea is a well-known seismic gap for future M > 7 earthquakes in the sense that more than 250 years have passed since the last major earthquake in the Central Marmara region. Here, an assessment on the location of possible asperities to host the expected next large earthquake is done based on the heterogeneities on the seismic velocity structure. Using long-term ocean bottom seismograph (OBS) observation data, seismic tomography and precise hypocenter estimations have been conducted. As a result, about five times more microearthquakes than the events in a land-based catalog has been detected. A comparison with previously published results suggests that the seismicity pattern has not changed during the three years period between Sep. 2014 and Jun. 2017. The obtained velocity model shows strong lateral contrast whose changing points locate at 28.10°E and 28.50°E. The western corner of the area (28.10°E) corresponds to a segmentation boundary where the dip angle of the NAF segments changed. The high velocity zones in the tomographic images are characterized by low seismicity eastward from the segment boundary at 28.10°E. Eastern 28.50°E, the high velocity zone becomes thicker in the depth direction. These zones are interpreted as asperities to be ruptured by the next large earthquake which are possibly accumulating strain since the mainshock rupture associated with the May 1766 Ms7.3 earthquake.</p>

scholarly journals Electrical characterization of the North Anatolian Fault Zone underneath the Marmara Sea, Turkey by ocean bottom magnetotellurics

2013 ◽  
Vol 193 (2) ◽  
pp. 664-677 ◽  
Author(s):  
T. Kaya ◽  
T. Kasaya ◽  
S. B. Tank ◽  
Y. Ogawa ◽  
M. K. Tuncer ◽  
...  
Keyword(s):  
Fault Zone ◽  
Electrical Characterization ◽  
North Anatolian Fault ◽  
Marmara Sea ◽  
Ocean Bottom ◽  
North Anatolian Fault Zone ◽  
The North

Investigation of Land Subsidence in Eastern Thrace (Turkey) using Multi Temporal InSAR

2021 ◽  
Author(s):  
Tohid Nozadkhalil ◽  
Semih Ergintav ◽  
Ziyadin Cakir ◽  
Ugur Dogan ◽  
Thomas R. Walter
Keyword(s):  
Natural Gas ◽  
Ground Motion ◽  
Deformation Source ◽  
Seismic Gap ◽  
Marmara Region ◽  
Marmara Sea ◽  
Gas Extraction ◽  
Triangular Elements ◽  
Natural Gas Extraction ◽  
Thrace Region

<p>Westward migration of M>7 earthquakes along North Anatolian fault with the latest one, Izmit 1999 event, led focus of studies to the seismic gap in the main Marmara fault. For this purpose, the coastal ranges of the Marmara Sea, mainly Istanbul megacity, are renowned for earthquake and ground motion hazards, associated with faulting, landslides and sediment compaction processes. Ground motion associated with man-made activities, however, have been barely studied. The Thrace region of Turkey, some 50 km to the North of the Marmara Sea, expresses pronounced ground motions affecting large areas. We use the Persistent InSAR technique to monitor the Marmara region using Sentinel-1 satellites’ TOPSAR data between 2014 and 2020. Results for both ascending (T131 and T58) and descending (T36) tracks reveals 10 mm/yr rate of subsidence in the Thrace region of Turkey, affecting an area ~15400km² with dimensions of ~110 km by ~140 km. There are two plausible mechanisms for this deformation; (1) excessive pumping of groundwater for agricultural purposes, or (2) natural gas extraction activities taking place in the region. To better understand the observed deformation source, as a first step, we model potential gas extraction by volume change. No piezometric data are available for this region for the time being. Thick sediments including sandstone, reefal carbonates, amongst others, are aimed for gas exploration in the Thrace basin for more than half century. Depth of gas extraction wells and sediment thickness is compiled from previous studies to compare the subsided area with sediment and well depth variations. </p><p>We use  the Poly3D boundary element method to model the surface. Poly3D uses planar triangular elements of constant model to model displacement’s source. Using triangular elements provides models with complex and smooth 3D surfaces avoiding overlaps or gaps, and hence allowing one to construct realistic models. Poly3dinv inverse model applies a fast non-negative/non-positive least squares solver to optimize the solution. We construct a surface enveloping tips of the wells and use it to produce deformation at surface due by allowing opening on it. Small residuals between the observation and model based on opening suggests that deformation is likely caused by natural gas extraction.</p>

Neotectonics of the SW Marmara region, NW Anatolia, Turkey

2006 ◽  
Vol 143 (2) ◽  
pp. 229-241 ◽  
Author(s):  
ÖMER FEYZI GÜRER ◽  
ERCAN SANGU ◽  
MUZAFFER ÖZBURAN
Keyword(s):  
Fault Zone ◽  
Structural Characteristics ◽  
Strike Slip ◽  
North Anatolian Fault ◽  
Marmara Region ◽  
Field Observations ◽  
Extensional Tectonics ◽  
North Anatolian Fault Zone ◽  
The North ◽  
Differential Movement

This study reports on the geometric and structural characteristics of the North Anatolian Fault Zone in the southwest Marmara region. The geometric and kinematic features of the faults in the region are described, based on field observations. In addition, the Neogene and Quaternary basin fill which occupies large areas in the region has been determined, and the tectonic regimes controlling these basins are explained. The neotectonic regime is also explained considering different deformation phases affecting the region. The N–S extension and E–W strike-slip have affected the region possibly since the latest Pliocene–Quaternary. Field observations show that these extensional tectonics around the south Marmara region are related to right strike-slip on the E–W North Anatolian fault zone and the N–S Aegean extensional system. The faults in this zone trend approximately E–W in the eastern part of the region and NE–SW towards the west of the region, indicating that they accommodate rotation in addition to differential movement between adjacent blocks.

Evidence of NW extension of the North Anatolian Fault Zone in the Marmara Sea: a new interpretation of the Marmara Sea (İzmit) earthquake on 17 August 1999

2001 ◽  
Vol 21 (4) ◽  
pp. 183-199 ◽  
Author(s):  
Erkan Gökaşan ◽  
Cem Gazioğlu ◽  
Bedri Alpar ◽  
Zeki Yücel ◽  
Şükrü Ersoy ◽  
...  
Keyword(s):  
Fault Zone ◽  
North Anatolian Fault ◽  
Marmara Sea ◽  
North Anatolian Fault Zone ◽  
Izmit Earthquake ◽  
The North ◽  
New Interpretation

scholarly journals Seismological and Engineering Characteristics of Strong Motion Data from 24 and 26 September 2019 Marmara Sea Earthquakes

2021 ◽  
Author(s):  
Fatma Sevil Malcıoğlu ◽  
Hakan Süleyman ◽  
Eser Çaktı
Keyword(s):  
Ground Motion ◽  
Prediction Models ◽  
Strong Motion ◽  
P Wave ◽  
Corner Frequency ◽  
Marmara Region ◽  
Marmara Sea ◽  
S Wave ◽  
Data Set ◽  
Motion Data

Abstract An MW 4.5 earthquake took place on September 24, 2019 in the Marmara Sea. Two days after, on September 26, 2019, Marmara region was rattled by an MW5.7 earthquake. With the intention of compiling an ample strong ground motion data set of recordings, we have utilized the stations of Istanbul Earthquake Rapid Response and Early Warning System operated by the Department of Earthquake Engineering of Boğaziçi University and of the National Strong Motion Network operated by AFAD. All together 438 individual records are used to calculate the source parameters of events; namely, corner frequency, radius, rupture area, average source dislocation, source duration and stress drop. Some of these parameters are compared with empirical relationships and discussed extensively. Duration characteristics are analyzed in two steps; first, by making use of the time difference between P-wave and S-wave onsets and then, by considering S-wave durations and significant durations. It is observed that they yield similar trends with global models. PGA, PGV and SA values are compared with three commonly used ground motion prediction models. At distances closer than about 60 km observed intensity measures mostly conform with the GMPE predictions. Beyond 60 km their attenuation is clearly faster than those of GMPEs. Frequency-dependent Q models are developed for both events. Their consistency with existing regional models are confirmed.

Analog Seismogram Archives at the Earthquake Research Institute, the University of Tokyo

2020 ◽  
Vol 91 (3) ◽  
pp. 1384-1393 ◽  
Author(s):  
Kenji Satake ◽  
Hiroshi Tsuruoka ◽  
Satoko Murotani ◽  
Kenshiro Tsumura
Keyword(s):  
Strong Motion ◽  
Large Earthquake ◽  
Earthquake Research ◽  
Long Time ◽  
Earthquake Research Institute ◽  
Almost All ◽  
The University ◽  
Large Earthquakes ◽  
Seismograph Network ◽  
Research Institute

Abstract The Earthquake Research Institute (ERI) of the University of Tokyo maintains archives of analog seismograms and mareograms. The main collection is ∼236,000 Japanese historical seismograms recorded at the University of Tokyo (at various buildings and using various instruments around Hongo [Tokyo] with a total of 189,000 records from 1881 to 1993), at the Tsukuba observatory (∼11,000 records from 1921 to 1986), and at the Wakayama seismological network (∼12,650 records from 1928 to 1968). Seismograms recorded by temporal stations at various locations in Japan for several years, typically following large earthquakes, are also included. Different types of instruments were used to record the data. The oldest record from a large earthquake is from the 1891 Nobi earthquake recorded at Hongo on a circular seismogram using an Ewing-type seismograph. Teleseismic seismograms include those from the 1899 Alaska earthquake at Hongo on an Omori-type seismograph. Imamura-type and Omori-type tremometers and strong-motion seismographs had also been used for a long time. While these seismograms were microfilmed by the 1990s, the original smoked paper records have also been archived. Foreign seismogram collections include those from earthquakes in Taiwan between 1904 and 1917 recorded in both Japan and Taiwan and those from the Canadian Seismograph Network between 1981 and 1989. For the Worldwide Standardized Seismograph Network stations, almost all (∼5,000,000) microfilm records at 167 stations from 1963 to 1988 are archived. High-resolution image scanning of analog daily seismograms at the Wakayama microearthquake network is currently being performed, and the scans are provided using Leaflet software so that the users can easily access and enlarge parts of seismograms. The tsunami waveform archive contains ∼3100 records on Japanese tide gauges from large earthquakes between 1911 and 1996. The available data, with dates and types of instruments, can be searched from the database through the website of the ERI.

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