Murat Utkucu, Fatih Uzunca, Hatice Durmuş, Süleyman Sami Nalbant, Cengiz İpek, Şefik Ramazanoğlu
{"title":"The Mw = 5.8 2019 Silivri earthquake, NW Türkiye: is it a warning beacon for a big one?","authors":"Murat Utkucu, Fatih Uzunca, Hatice Durmuş, Süleyman Sami Nalbant, Cengiz İpek, Şefik Ramazanoğlu","doi":"10.1007/s00531-023-02359-6","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The September 26, 2019 Silivri earthquake (<i>M</i><sub>W</sub> = 5.8) occurred along the North Anatolian Fault beneath the Marmara Sea and its epicenter was in an identified seismic gap. Coseismic stress calculations demonstrate that the 1999 İzmit earthquake (<i>M</i><sub>W</sub> = 7.4) caused stress increase from 0.057 to 0.114 bars at its hypocenter, depending on the various reported rupture parameters. In addition, over 20 years following the 1999 earthquake, and constituting the main difference from previous studies, viscoelastic postseismic stress computations indicate stress increase from 0.081 to 0.135 bars at the hypocenter. In spite of the positive stress transfer, the 2019 earthquake occurred long after the end of the computed aftershock time span (~ 16 years) of the 1999 earthquake. Plots of the seismicity around selected points within the gap also show that the background seismicity level following the 1999 earthquake was reached in 2003. Therefore, it is suggested that the 2019 earthquake was not an aftershock but rather an independent event, and its occurrence was hastened about 4 years due to stress loading. Further analysis of the seismicity between 1978 and 2020 indicates that the <i>b</i> value increased from a range of 1.0–1.1 to 1.6–1.8 till 2002, then progressively decreased to 0.9–1.0, which is consistent with positive stress transfer. The stress increase ranging from 0.19 to 2.52 bars on the segments within the gap brought forward their seismic cycles about 33 and 2 years from east to west, respectively. These additional clock advances in the seismic cycles due to stress load urgently require risk mitigating actions.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>","PeriodicalId":13845,"journal":{"name":"International Journal of Earth Sciences","volume":"202 S607","pages":""},"PeriodicalIF":1.8000,"publicationDate":"2023-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"International Journal of Earth Sciences","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1007/s00531-023-02359-6","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The September 26, 2019 Silivri earthquake (MW = 5.8) occurred along the North Anatolian Fault beneath the Marmara Sea and its epicenter was in an identified seismic gap. Coseismic stress calculations demonstrate that the 1999 İzmit earthquake (MW = 7.4) caused stress increase from 0.057 to 0.114 bars at its hypocenter, depending on the various reported rupture parameters. In addition, over 20 years following the 1999 earthquake, and constituting the main difference from previous studies, viscoelastic postseismic stress computations indicate stress increase from 0.081 to 0.135 bars at the hypocenter. In spite of the positive stress transfer, the 2019 earthquake occurred long after the end of the computed aftershock time span (~ 16 years) of the 1999 earthquake. Plots of the seismicity around selected points within the gap also show that the background seismicity level following the 1999 earthquake was reached in 2003. Therefore, it is suggested that the 2019 earthquake was not an aftershock but rather an independent event, and its occurrence was hastened about 4 years due to stress loading. Further analysis of the seismicity between 1978 and 2020 indicates that the b value increased from a range of 1.0–1.1 to 1.6–1.8 till 2002, then progressively decreased to 0.9–1.0, which is consistent with positive stress transfer. The stress increase ranging from 0.19 to 2.52 bars on the segments within the gap brought forward their seismic cycles about 33 and 2 years from east to west, respectively. These additional clock advances in the seismic cycles due to stress load urgently require risk mitigating actions.
期刊介绍：
The International Journal of Earth Sciences publishes process-oriented original and review papers on the history of the earth, including
- Dynamics of the lithosphere
- Tectonics and volcanology
- Sedimentology
- Evolution of life
- Marine and continental ecosystems
- Global dynamics of physicochemical cycles
- Mineral deposits and hydrocarbons
- Surface processes.
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