Observations of Repeating Earthquakes at a Single Seismic Station Near Lake Sapanca

Yıl 2023, Cilt: 23 Sayı: 6, 1533 - 1541, 28.12.2023

Diğdem Acarel

https://doi.org/10.35414/akufemubid.1286692

Öz

The North Anatolian Fault Zone (NAFZ), which forms the plate boundary between Anatolian Plate and Eurasian Plate, is one of the most active transform fault zones in the world. Following two consecutive magnitude M>7 earthquakes in 1999, an intensified monitoring of western portion of NAF is commenced. Dense networks of onshore/offshore seismic, acoustic, geodetic sensors and surface creep and strain sensors were installed. A single seismic sensor among these, which is located at the midpoint of 1999 ruptures, near Lake Sapanca, exhibits some unusual seismic activity. On a fault segment where creep is known to be present, a series of minor seismic events was observed with identical locations and a recurrence time of three years. These events are quite short in duration and highly similar in their waveforms. Using a single station approach, their angle of incidence and back azimuth were found to coincide with the location of two M2.3 and M2.1 events. At this stage, it is not clear whether these events reflect fault creep at seismogenic depth. Nevertheless, these initial observations emphasize the necessity of monitoring this segment more densely, where recurrent minor earthquakes are likely to be observed.

Anahtar Kelimeler

Creep, Lake Sapanca, North Anatolian Fault, Repeating Earthquakes, Single Seismic Station

Proje Numarası

117C009

Sapanca Gölü Yakınında Tek Bir Sismik İstasyonda Tekrarlayan Deprem Gözlemleri

Öz

Kuzey Anadolu Fay Zonu (KAFZ), Anadolu ve Avrasya plakaları arasındaki levha sınırını oluşturur ve dünya üzerindeki en aktif transform faylarından biridir. 1999'da meydana gelen iki M>7 depremin ardından, KAF'ın batı kısmı yoğun bir şekilde izlenmeye başlanmıştır. Karada/denizde yoğun ağlarla sismik, akustik, jeodezik, yüzey kripi ve gerinimi ölçen sensörler kurulmuştur. Bu sensörler arasında, 1999 kırılmalarının merkezinde, Sapanca Gölü yakınlarında bulunan tek bir sismik sensör, bazı olağandışı sismik aktiviteler kaydetmiştir. Krip gözlemlenen bir fay segmentinde, aynı konumlarda, üç yıllık tekrarlama süresi ile küçük sismik olaylar gözlemlenmiştir. Bu olaylar oldukça kısa sürelidir ve dalga formları açısından oldukça benzerdir. Tek istasyon yaklaşımı kullanılarak, bu olayların çıkış açısı ve geri azimut açısının M2.3 ve M2.1 büyüklüğündeki depremlerin konumuna denk geldiği bulunmuştur. Bu aşamada, bu olayların sismojenik derinlikte krip yansıtıp yansıtmadığı belirsizdir. Bununla birlikte, bu ilk gözlemler, tekrarlayan depremler gözlenen bu segmentin daha yoğun bir şekilde izlenmesinin gerekliliğini vurgulamaktadır.

Anahtar Kelimeler

Kuzey Anadolu Fayi, Krip, Sapanca Gölü, Tekrarlayan Depremler, Tek Bir Sismik Istasyon

Destekleyen Kurum

TÜBITAK

Proje Numarası

117C009

Kaynakça

• Altuncu-Poyraz, S.,Teoman M.U., Türkelli, N., Kahraman, M, Cambaz, D., Mutlu, A., Rost, S., Houseman, G.A., Thompson, D.A., Cornwell, A., Utkucu, M., Gülen, L., 2015. New constraints on micro-seismicity and stress state in the western part of the North Anatolian Fault Zone: Observations from a dense seismic array, Tectonophysics, 656, 190–201. https://doi.org/10.1016/j.tecto.2015.06.022.
• Aslan, G., Lasserre, C., Cakir, Z., Ergintav, S., Özarpaci, S., Dogan, U., et al., 2019. Shallow creep along the 1999 Izmit earthquake rupture (Turkey) from GPS and high temporal resolution interferometric synthetic aperture radar data (2011–2017). Journal of Geophysical Research: Solid Earth, 124, 2218–2236. https://doi.org/10.1029/2018JB017022.

• Barka, A., Akyüz, H. S., Altunel, E., Sunel, G., Çakir, Z., Dikbas, A., Yerli, B., Armijo, R., Meyer, B., de Chabalier, J. B., Rockwell, T., Dolan, J., Hartleb, R., Dawson, T., Christofferson, S., Tucker, A., Fumal, T., Langridge, R., Stenner, R., Lettis, W., Bachhuber, J., and Page, W., 2002. The Surface Rupture and Slip Distribution of the 17 August 1999 Izmit Earthquake (M 7.4), North Anatolian Fault, Bulletin of Seismological Society of America, 92, 43-60, https://doi.org/10.1785/0120000841.
• Bohnhoff, M., Dresen, G., Ellsworth, W.L., Ito, H., 2010. Passive seismic monitoring of natural and induced earthquakes: Case studies, future directions and socio-economic relevance, in New Frontiers in Integrated Solid Earth Sci., Int. Yr. Planet Earth, 261-285, eds Cloetingh, S., Negendank, J., Springer, https://doi.org/10.1007/978-90-481-2737-5_7.
• Bohnhoff, M., Bulut, F., Dresen, G., Malin, P. E., Eken, T., Aktar, M., 2013. An earthquake gap south of Istanbul. Nature Communications, 4, 1999. https://doi.org/10.1038/ncomms2999.
• Cakir, Z., Ergintav, S., Ozener, H., Dogan, U., Akoglu, A. M., Meghraoui, M., Reilinger, R., 2012. Onset of aseismic creep on major strike‐ slip faults., Geology, 40 (12), 1115–1118. https://doi.org/10.1130/G33522.1.
• Ergintav, S., R. E. Reilinger, R. Çakmak, M. Floyd, Z. Cakir, U. Doğan, R. W. King, S. McClusky, and H. Özener, 2014. Istanbul’s earthquake hot spots: Geodetic constraints on strain accumulation along faults in the Marmara seismic gap, Geophysical Research Letters, 41, 16, 5783–5788. https://doi.org/10.1002/2014GL060985.
• Frank, W.B., Shapiro, N.M., Husker, A.L., Kostoglodov, V., Campillo, M., 2016. Repeating seismicity in the shallow crust modulated by transient stress perturbations, Geology, 786, 105-110. https://doi.org/10.1016/j.tecto.2016.09.003.
• Havskov, J. and Ottemöller, L., 2010. Location. In Routine Data Processing in Earthquake Seismology, 101-149. The Netherlands: Springer. ISBN: 978-90-481-8696-9. https://doi.org/10.1007/978-90-481-8697-6.
• Hergert, T. and Heidbach, O., 2010. Slip-rate variability and distributed deformation in the Marmara Sea fault system, Nature Geoscience, 3(2), 132–135. https://doi.org/10.1038/ngeo739.
• Hussain, E., Wright, T.J., Walter, R.J., Bekaert, D., Hooper, A., Houseman, G.A., 2016. Geodetic observations of postseismic creep in the decade after the 1999 Izmit earthquake, Turkey: implications for a shallow slip deficit, Journal of Geophysical Research-Solid Earth, 121(4), 2980-3001. https://doi.org/10.1002/2015JB012737.
• Karabulut, H., Schmittbuhl, J., Ozalaybey, S., Lengline ́, O., Komec-Mutlu, A., Durand, V., Bouchon, M., Daniel, G., Bouin, M., 2011. Evolution of the seismicity in the eastern Marmara Sea a decade before and after the 17 August 1999 Izmit earthquake, Tectonophysics, 510, 17– 27. https://doi.org/10.1016/j.tecto.2011.07.009.
• Lockmann A.B., Allen, R.M., 2005. Single station earthquake characterization or early warning, Bulletin of Seismological Society of America, 6, 2029-2039. https://doi.org/10.1785/0120040241.
• Martínez-Garzón, P., Bohnhoff, M., Mencin, D., Kwiatek, G., Dresen, G., Hodgkinson, K., Nurlu, M., Kadirioglu, F.T., Kartal, R.F., 2019. Slow strain release along the eastern Marmara region offshore Istanbul in conjunction with enhanced local seismic moment release. Earth and Planetary Science Letters, 510, 209- 218. https://doi.org/10.1016/j.epsl.2019.01.001.
• Nakamura, Y., 1988. On the Urgent Earthquake Detection and Alarm System (UrEDAS), Proc. 9th World Conference on Earthquake Engineering VII, Tokyo, Japan, 2-9 August 1988, 673-678.
• Savage, J. C., 1990. Equivalent strike-slip earthquake cycles in half-space and lithosphere-asthenosphere earth models, Journal of Geophysical Research, 95, 4873-4879. https://doi.org/10.1029/JB095iB04p04873.
• Schmittbuhl, J., Karabulut, H., Lengline, O., Bouchon, M., 2016. Long- lasting seismic repeaters in the central basin of the main marmara fault, Geophysical Research Letters, 43 (18), 9527-9534 https://doi.org/10.1002/2016GL070505.
• Townsend, B., 2014. Symmetric Triaxial Seismometers. In: Beer, M., Kougioumtzoglou, I., Patelli, E., Au, IK. (eds) Encyclopedia of Earthquake Engineering, 1-19. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-36197-5_194-1.

• Uchida, N and Bürgmann, R., (2019) Repeating earthquakes, Annual Review of Earth and Planetary Sciences, 47(1), 305-332. https://doi.org/10.1146/annurev-earth-053018-060119.
• Uchida, N., 2019. Detection of repeating earthquakes and their application in characterizing slow fault slip, Progress in Earth and Planetary Sciences, 6, 40, https://doi.org/10.1186/s40645-019-0284-z
• Wollin, C., Bohnhoff, M., Vavrycuk, V., Martínez-Garzón, P., 2018. Stress inversion of regional seismicity in the Sea of Marmara region, Turkey. Pure and Applied Geophysics, 176, 1269-1291. https://doi.org/10.1007/s00024-018-1971-1.