European Geosciences Union General Assembly 2015 Vienna, Austria, 12 - 17 April 2015 Thisposterparticipatesin OSP EARTHQUAKE SWARM IN ARMUTLU PENINSULA, EASTERN , 1 1 1 1 2 2 2 1 Evrim Yavuz , Deniz Çaka , Berna Tunç , T. Serkan Irmak , Heiko Woith , Simone Cesca , Birger-Gottfried Lühr , Şerif Barış est. 2002 Outstanding Student PosterContest 1Kocaeli University, Department of Geophysical Engineering, Kocaeli, Turkey 2Helmholtz Centre Potsdam, GFZ German Research Center for Geosciences, Potsdam, Germany

[email protected] - [email protected] Abstract No: 5099

Introduction Methodology Moment Tensor Solution August 3, 2014 22:22:44 (GMT) -Termal Earthquake (Mw=3.9) Two main fault systems are located in Turkey called North Anatolian Fault Zone (NAFZ) and To determine the earthquake parameters, zSacWin EQ Processing software (Yılmazer, 2002) was The largest earthquake in the swarm activity, which occurred in August 3, 2014 22:22:44 (GMT) UP East Anatolian Fault Zone (EAFZ). NAFZ is dextral and EAFZ is sinistral systems. Active used (Figure 2). Being user-friendly and successful to obtain earthquake parameters are the was solved with ISOLA. Total 6 stations data with different distances and azimuthally distributed N tectonic is controlled by these fault systems, in Turkey. Because of these fault zones, Anatolian advantages of the software. around the event were used for solution. According to the solution, it discriminates a normal DOWN block moves toward the west with the average rate 20-30 mm/yr (McKenzie,1972; Udias et. faulting with sinistral component and Mw=3.9. The fault mechanism (strike=113o dip=50o al.,1989). Marmara Region is located in the north-west part of Turkey, where many earthquakes rake=-55o) is conformable with the Termal Fault. The moment tensor solution and the consistency have been occurred during centuries. The latest destructive earthquakes stroke the region in 1999. of synthetic-observed seismograms are shown in Figure 5 and 6, respectively. On the other hand, Unbroken part of the NAFZ crosses north of the Armutlu Peninsula on east-west direction. This the focal mechanism by obtaining P wave first motion data is in correlation with moment tensor Strike1 : 111 branch has been also located quite close to known as a megacity with its high population, solution (Figure 7). Dip1 : 52 economic and social aspects. A new earthquake cluster of microseismic activity occurred in the MOMENT TENSOR SOLUTION Rake1 : -80 direct vicinity of southeastern of the Yalova-Termal area. Activity started on August 1, 2014 with −−−−−−−−−−−−−−−−−−−−−−−−−−−− HYPOCENTER LOCATION (ESSRC) Strike2 : 275 P series of micro events and continued with Ml=4.1 event on August 3, 2014. Approximately 5000 −−−−−−−−−−−−−−−−−−−−−−−−−− events recorded during August, 2014. Therefore, investigation of the micro-earthquake activity Origin time 20140803 22:22:44.69 Dip2 : 39 Lat 40.6043 Lon 29.1705 Depth 7.3 Rake2 :-103 of the Armutlu Peninsula has become important to understand the relationship between the CENTROID occurrence of micro-earthqaukes and the tectonic structure of the region. −−−−−−−− Trial source number : 7 (Fixed Epicenter inversion) Seismotectonic Settings of Armutlu Peninsula Centroid Lat (N)40.6112 Lon (E)29.1732 P-axis; plunge : 79 Centroid Depth (km) : 4 The Armutlu Peninsula is located southeastern part of the Marmara Region (Figure 1). The Centroid time : +1.05 (sec) relative to origin time azimuth : 65 peninsula is surrounded by two branches of NAFZ and has high micro-earthquake activity. The −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Moment (Nm) : 9.230e+014 T-axis; plunge : 7 region has complex tectonic structure as well as it’s seismic activity. The Armutlu Peninsula is Mw : 3.9 azimuth :-166 thought to be a transition zone of the intra-Pontid Suture Zone or a part of it. Understanding the VOL% :0 DC% :92.6 T relationship between neo-tectonic features, seismic and thermal activity is very important in and CLVD% :7.4 SNR CN FMVAR STVAR ISK Var.red.: (for stations used in inversion):0.84 NaN 4.6 15±18 0.17 Consistent data: 44 around the peninsula. The hottest thermal sources are located in the north (Yalova-Termal) and in Var.red.(for all stations) :0.84 41˚00' Inconsistent data: 4 the western part of the peninsula, called Armutlu vicinity having near surface temperatures Figure 2. Obtaining earthquake parameters with zSacWin program (Yılmazer, 2002). −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− o Strike Dip Rake | Frequency band used in inversion (Hz) 60-70 C. Other geothermal sources known as Gemlik, Orhangazi, Keramet and Soğucak, which 246 51 −124 | 0.07 − 0.08 −− 0.09 − 0.1 Figure 6. Focal mechanism solution by P wave first motion data. o The other software which called ISOLA (Sokos and Zahradnik, 2008, 2013), was used for are located in the south and the east are warmer (water temperatures around 20-30 C) than the 40˚48' Strike Dip Rake | obtaining the moment tensor solution. ISOLA can successfully calculate both regional and local 113 50 −55 | Stations−Components Used−Distance Results and Discussion others. By associating the locations of the thermal sources with regional faults, the relation waveform inversion. The advantage of the software is the graphical interface that provides the −−−−−−−−−−−−−−−−−−−−−− | NS EW Z D(km) P−axis Azimuth Plunge |HYDR + + + 12 There has been high seismic activity observing in the Termal area for several years. Activity between the thermal sources and the north and south branches of the NAFZ can be seen easily 40˚36' ARMT 91 64 |GEMT + + + 19 user with an easy to use environment, rich in graphics and data handling routines. HYDR (Eisenlohr, 1997). T−axis Azimuth Plunge |KRSK + + + 24 increases every end of the summer seasons. The most seismic activity like earthquake swarm GEMT 359 1 |ARMT + + + 26 occurred in August, 2014. In contrast with usage of the thermal water, snow and rain were not Data Seismic Activity KRSK 40˚24' −−−−−−−−−−−−−−−−−−−−−− |ISK + + + 51 enough to feed reservoir of the thermal source in the area last two years. This phenomenon is Because of the investigation of micro-earthquake activity in and around the Armutlu Peninsula is We observed opproximately 5000 events from continious data in the period of earthquake Mrr Mtt Mpp |UNCK + + + 67 −7.389 9.393 −2.004 unavoidable under these conditions. Lacking of the water in the geothermal reservoir causes very important. Armutlu Network (ARNET), installed at the end of 2005 and equipped with sequence. 561 earthquakes are located up to this time and processing of the data still continuing. 40˚12' Mrt Mrp Mtp collapsing underground cavities. Although location of the event on the Termal Fault which is currently 27 active seismic stations operating by Kocaeli University Earth and Space Sciences Located earthquakes are shown in Figure 3 and number of observed events versus julian day is UNCK 0.185 3.424 0.139 Exponent (Nm): 14 sinistral, focal mechanism of the largest event both moment tensor and P wave first motion Research Center (ESSRC) and Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum given in Figure 4. solutions have mostly normal component with some left lateral displacement. Besides that, the 28˚48'29˚00'29˚12' (GFZ). ARNET is a very dense network tool able to record even micro-earthquakes in this region. Figure 4. Number of events versus Figure 5. Moment tensor solution using ISOLA software (Sokos and Zahradnik, 2008, 2013). depth distribution of the events in the area is very shallow, mostly less than 5 km. Briefly, all the Besides that, we used MARSITE project data, includes all data of Kandilli Observatory and julian day distribution. solutions show that the reason of the swarm is mostly geothermal activity. The effect of the Earthquake Research Institute (KOERI), The Scientific and Technological Research Council of Event date−time: 140803_22_22_44.69 Displacement (m). Inversion band (Hz) 0.07 0.08 0.09 0.1 Gray waveforms weren’t used in inversion. Observed tectonic settings can be seen on the focal mechanism solution with some left lateral displacement. Turkey (TUBITAK), Princes Island High Resolution Seismic Network (PIRES) and ARNET in Synthetic Blue numbers are variance reduction This swarm activity indicated the importance of observing geothermal areas with high dense this study (Figure 1). −6 x 10 NS EW Z 26° 26.5° 27° 27.5° 28° 28.5° 29° 29.5° 30° 30.5° 31° seismic networks. Increasing the number of seismic stations for better azimuthal distribution and 2 0.96 0.73 0.74 PHSR getting online data in the geothermal area make solutions more reliable and faster. To do that, 0 HYDR −2 having a new project will be proposed to the governor of Yalova in the future. 41.5° 41.5° −6 CTYL BLACK SEA x 10 2 0.96 0.21 0.77

0 KLYT References CTKS SNLMSLVT GEMT BGKT −2 SILT −6 Eisenlohr, T., 1997. The thermal springs of the Armutlu Peninsula (NW Turkey) and their relocationship geology and tectonic, KKZM CRLT x 10 ALTM SLVM TEPT KAISKVV MYCM 1 0.97 0.70 0.73 Active Tectonics of Northwestern Anatolia-The Marmara Poly-project (eds. C. Schindler & M. Plister), p. 197-228, ETH- 41° 41° OMRT KYSD MARM KURN 0 Zurich KNAL SBT3 BRGZ GOZT KRSK SBT2 POWDNRTHEASYSHTHBYZN HYBL IBBT GARDSCRPFUTBOILHPIER BUYMBASD −1 KRGZ SAKI YNKM SBT4 MRTI −6 HRTX GBZM x 10 SGTM MARMARA SEA 1 McKenzie, D., 1972. Active Tectonics of Mediterranean Region, Geophys. J. R. Astro Soc., vol. 30, p. 109-185. SBT1 RKY SPNC 0.46 0.47 0.64 ERIK 0.5 MADM CFTB SBT5ESNK TSVK KLCM KVKM MRMT ESKM UCKRTRMLSFRN ILYS 0 ARMT SDSN DLMC YLV ARMT BOZMKYNDARKP −0.5 SLMY HYDR ORHG Udias, A., Buforn, E., Ruiz de Gauna, J., 1989. Catalogue of Focal Mechanisms of European Earthquakes, Dep. Geophys., TRNM FSTK 40.5° 40.5° −7 −1 x 10 GEMT GULT KMRM Univ. Complutense, Madrid, p. 274. KRSK GELI KRBG ZYTB ENGR LAP MDNY 5 EDC MSDM ALTN 0.61 0.73 0.99 AVDN KNLM KRCMKCTX YYLC IGDM 0 ISK

BK2 CAVI Yılmazer, M., 2002. Deprem Kaynak Parametrelerinin On-line Belirlenmesi, MSc. thesis, Istanbul University. BZGM CALI YGTL HAMK −5 STBT −7 UNCK x 10 ATIM EREM 5 0.93 0.57 0.74 40° CMHM 40° Sokos, N., E., Zahradnik, J., 2008. ISOLA a Fortran Code and a MATLAB GUI to Perform Multiple-point Source Inversion of NEVM 0

UNCK Seismic Data, Computers & Geosciences, vol. 34, p. 967-977. 26° 26.5° 27° 27.5° 28° 28.5° 29° 29.5° 30° 30.5° 31° −5 0 50 100 150 200 250 0 50 100 150 200 250 0 50 100 150 200 250 Figure 1. General view of the Marmara Region and MARSITE stations. The orange Time (sec) Time (sec) Time (sec) Sokos, E., Zahradnik, J., 2013. Evaluating Centroid-Moment-Tensor Uncertainty in the New Version of ISOLA Software, rectangle is the Armutlu Peninsula and yellow lines are active faults. Figure 3. Earthquake distribution map around the Termal area (locating is in progress). Figure 6. The consistency of synthetic and observed seismograms. Seismological Ress. Lett., vol. 84, p. 656-665, doi: 10.1785/0220130002.