Study of the seismicity rate and Coulomb stress changes associated with the April 9th, 2013 Kaki-Shonbe earthquake (Mw=6.3) and the spatial distribution of aftershocks

Authors

1 M.Sc. Student, School of Earth Sciences, Damghan University, Iran

2 Assistant Professor, School of Earth Sciences, Damghan University, Iran

3 Ph.D. Student, International Institute of Earthquake Engineering and Seismology, Tehran, Iran

Abstract

Nowadays, the effect of an earthquake in triggering of other events in the surrounding areas is completely accepted. This effect in triggering future events and spatial distribution of aftershocks can be explained using the Coulomb stress changes theory. Occurrence of April 9th, 2013 earthquake with moment magnitude of 6.3 in Bushehr province that followed by an aftershock with 5.4 magnitude after 14 hours in its vicinity, convinced us to examine Coulomb stress change theory for this region of Iran related to this event using the Coulomb 3.4 software. We calculated Coulomb stress changes associated with the Kaki-Shonbe earthquake on surrounding faults and investigated the effect of transferred stress on spatial distribution of aftershocks. We also calculated the seismicity rate changes in the study area and investigated its correlation with Coulomb stress changes. For calculation of Coulomb stress changes, we used a half-space with Poison ratio equal 0.25 and shear modulus about of 800 kbar. The effective coefficient of friction in our calculations was 0.4 that is appropriate for these kinds of faults. We also used a number of about 1,100 earthquakes with magnitude more than 4, from 1913 to October 2016, to calculate the seismicity rate changes.
The Kaki-Shonbe Mw 6.3 earthquake occurred on 9 April 2013 (11:53 UTC, 16:23 local time) in the Zagros Simply Folded Belt in south-western Iran and its largest aftershock was triggered after 14 hours. The epicenter location was 20 km northeast of the town of Kaki, and the earthquake resulted 40 fatalities and 860 injured. Reverse slip on two along-strike, southwest dipping fault segments were found by analyzing satellite interferometry data. The main shock rupture initiated at the lower northern end of the larger northwest segment and slip on the smaller southern segment is likely aseismic. At first, to investigate the effect of the Kaki-Shonbeh earthquake on occurred aseismic slip on the southeast fault plane, we calculated the Coulomb stress changes related to this event on this fault plane by applying slips on the parts of causative fault of main shock. Our results showed that the transferred stress on most part of this fault plane is positive especially in the places that experienced aseismic slip. The aseismic displacement on this fault can be due to the displacement on the causative fault of Kaki-Shonbe earthquake and it is acceptable because of the tectonics of the study area and prevailing stress system. Investigation of the effect of Coulomb stress changes on the distribution of aftershocks showed that more than 80 percent of aftershocks have occurred in places where stress changes were positive. In other word, lots of the aftershocks have occurred in places where the transferred stresses due to co-seismic slip on the northwest fault segment and aseismic slip on the southeast fault segment were increased.
We calculated the Coulomb stress changes due to April 9th earthquake and aseismic slip on the southeast segment on the active faults in the study area. The obtained results indicate that the occurred slips on these fault segments increased the stress in some part of the Zagros Mountain Front Fault (MFF), Zagros Fore-deep Fault (ZFF), and the northern part of the Borazjan Fault. Coulomb stress changes due to these slips show a good correlation with calculated seismicity rate changes in the study area. The Borazjan earthquake epicenter, occurred on November 28th, 2013 with moment magnitude of 5.6, is located in the region that both Coulomb stress changes and seismicity rate changes increased and had positive amounts.

Keywords

Main Subjects


آقانباتی، ع.، 1383، زمین‌شناسی ایران، چاپ اول، (697 ص)، انتشارات سازمان زمین‌شناسی و اکتشافات معدنی کشور، تهران.
انصاری‌پور، م. و رضاپور، م.، 1394، تعیین مدل سرعتی برای ناحیۀ بوشهر و تحلیل زمینلرزۀ 3/6 Mw، 2013 کاکی بوشهر، فیزیک زمین و فضا، دوره 41، شماره3، پاییز 1394، صفحة 351-361.
بلورچی، م.، یوسفی، ط.، کارگر، ش.، علیخانزاده، ر.، فرهنگ، آ. و صداقت، م.، 1392، گزارش فوری-مقدماتی زمین‌لرزه شٌنبه استان بوشهر، سازمان زمین شناسی و اکتشافات معدنی کشور، تهران.
حسن‌زاده، ح.، 1381، بررسی لرزه زمین‌ساخت و تغییرات میدان تنش در منطقه قائنات (مدل تنش کولمب). سازمان زمین‌شناسی و اکتشافات معدنی- پژوهشکده علوم زمین، تهران.
عبادی، ر.، زارع، م.، سلگی، ع. و سینائیان، ف.، 1389، مطالعه خطر زمین‌لرزه در محدودۀ جزیرۀ خارک، فصلنامۀ زمین، سال پنجم،1، 22-28.
ملکی آسایش، ب. و حمزه‌لو، ح.، 1393، بررسی تغییر نرخ لرزه خیزی و تنش در شمال غرب ایران، شانزدهمین کنفرانس ژئوفیزیک ایران، 23 تا 25 اردیبهشت ماه 1393، صفحۀ 90-94.
ملکی آسایش، ب. و حمزه‌لو، ح.، 1394، تغییرات تنش کولمب حاصل از زمین‌لرزه‌های ریگان و توزیع پس‌لرزه‌ها، فصلنامه علمی پژوهشی علوم و مهندسی زلزله، سال دوم، شماره دوم، تابستان 1394، صفحۀ 1-10.
یمینی فرد، ف.، تاتار، م.، تقابنی، م.، 1395، تحلیل پس‌لرزه‌های زمین‌لرزه 20/1/92 کاکی بوشهربا بزرگای 3/6=Mw، پژوهشگان بین‌المللی زلزله‌شناسی و مهندسی زلزله،
تهران.
Allen, M. B. and Armstrong, H. A., 2008, Arabia Eurasia collision and the forcing of mid-Cenozoic global cooling, Palaeogeogr. Palaeoclimatol. Palaeoecol, 265, 52–58.
Bachmanov, D. M., Trifonov, V. G., Hessami, Kh. T., Kozhurin, A. I., Ivanova, T. P., Rogozhin, E. A., Hademi, M. C. and Jamali, F. H., 2004, Active faults in the Zagros and central Iran, Tectonophysics, 380, 221-241.
Baker, C., Jackson, J. and Priestley, K., 1993, Earthquakes on the Kazerun Line in the Zagros Mountains of Iran: Strike-slip faulting within a fold-and-thrust belt, Geophys. J. Int., 115, 41–61, doi:10.1111/j.1365-246X.1993.tb05587.x.
Barnhart, W. D. and Lohman, R. B., 2013, Phantom earthquakes and triggered aseismic creep: Vertical partitioning of strain during earthquake sequences in Iran, Geophys. Res. Lett., 40, 819–823, doi:10.1002/grl.50201.
Bayrak, Y., Yadav, R. B. S., Kalafat, D., Tsapanos, T. M., Cinar, H., Singh, A. P., Bayrak, E., Yimaz, S., öcal, F. and Koravos, G., 2013, Seismogenesis and earthquake triggering during the Van (Turkey) 2011 seismic sequence, Tectonophysics, vol. 601, pp. 163-176.
Berberian, M., Petrie, C. A., Potts, D. T., Asghari Chaverdi, A., Dusting, A., Sardari Zarchi, A., Weeks, L., Ghassemi, P. and Noruzi, R., 2014, Archaeoseismicity of the mounds and monuments along the kazerun fault (western zagros, sw iranian plateau) since the chalcolithic period, iranica antiqua, XLIX, doi: 10.2143/IA.49.0.3009238.
Berberian, M., 1995, Master blind thrust faults hidden under the Zagros folds: active basement tectonics and surface morphotectonics, Tectonophysics, 241,193-224.
Elliott, J. R., Bergman, E. A., Copley, A. C., Ghods, A. R., Nissen, E. K., Oveisi, B., Tatar, M., Walters, R. J. and Yamini-Fard, F., 2015, The 2013 Mw 6.2 Khaki‐Shonbe (Iran) Earthquake: Insights into seismic and aseismic shortening of the Zagros sedimentary cover, Earth and Space Science, 2(11), 435-471.
Fakhari, M. D., Axen, G. J., Horton, B. K., Hassanzadeh, J. and Amini, A., 2008, Revised age of proximal deposits in the Zagros foreland basin and implications for Cenozoic evolution of the High Zagros, Tectonophysics, 451, 170–185.
Harris, R. A., 1998, Introduction to special section: Stress triggers, stress shadows, and implications for seismic hazard, J. Geophys. Res., 103, 24,347–24,358.
Hessami, K., Jamali, F. and Tabasi, H., 2003. Major Active Faults map of Iran, Scale 1:2500000, International Institute of Earthquake Engineering and Seismology (IIEES), 1 sheet.
Hessami, K., Koyi, H. A., Talbot, C. J., Tabasi, H. and Shabanian, E., 2001b, Progressive unconformities within an evolving foreland fold thrust belt, Zagros Mountains, J. Geol. Soc. London, 158, 969–981.
IRSC, "Iranian Seismological Center", http://irsc.ut.ac.ir
Jackson, J. A., 1980, Reactivation of basement faults and crustal shortening in orogenic belts", Nature, 283, 343–346, doi:10.1038/283343a0.
Jackson, J. and Fitch, T., 1981, Basement faulting and the focal depths of the larger earthquakes in the Zagros mountains (Iran), Geophys. J.Int., 64, 561–586, doi:10.1111/j.1365-246X.1981.tb02685.x.
Jakson, J. and McKenzie, D. P., 1984, Active tectonic of the Alpine-Himalayan Belt between western Turkay and Pakistan. Geophys. J. Int., 64, 561-586.
King, G. C. P., Stein, R. S. and Lin, J., 1994, Static stress changes and the triggering earthquakes, Bull. Seismol. Soc. Am. Vol. 84, No. 3, pp. 935- 953.
Lin, J. and Stein, R. S., 2004, Stress triggering in thrust and subduction earthquakes and stress interaction between the southern San Andreas and nearby thrust and strike slip faults, J. Geophys. Res., Vol. 109, B02303, doi: 10.1029/2003JB002607.
Maggi, A., Jackson, J. A., Priestley, K. and Baker, C., 2000a, A re-assessment of focal depth distributions in southern Iran, the Tien Shan and northern India: do earthquakes really occur in the continental mantle?. Geophysical Journal International, 143(3), 629–661.
McQuarrie, N. and Hinsbergen, D. J. J., 2013, Retrograde forming the Arabia-Eurasia collision zone: Age of collision versus magnitude of continental subduction, Geology, 41(3), 315–318.
Mouthereau, F., Lacombe, O. and Vergés, J., 2012, Building the Zagros collisional orogen: Timing, strain distribution and the dynamics of Arabia/Eurasia plate convergence, Tectonophysics, 532, 27–60.
Ni, J. and Barazangi, M., 1986, Seismotectonics of the Zagros continental collision zone and a comparison with the Himalayas. Journal of Geophysical Research, 91(B8), pp 8205-8218.
Nissen, E., Ghorashi, M., Jackson, J., Parsons, B. and Talebian, M., 2007b, The 2005 Qeshm Island earthquake (Iran)—A link between buried reverse faulting and surface folding in the Zagros Simply Folded Belt?, Geophys. J. Int., 171, 326–338, doi:10.1111/j.1365-246X.2007.03514.x.
Nissen, E., Tatar, M., Jackson, J. A. and Allen, M. B., 2011, New views on earthquake faulting in the Zagros fold-and-thrust belt of Iran, Geophys. J. Int., 186, 928–944, doi:10.1111/j.1365-246X.2011.05119.x.
Nissen, E., Yamini-Fard, F., Tatar, M., Gholamzadeh, A., Bergman, E., Elliott, J. R., Jackson, J. A. and Parsons, B., 2010, The vertical separation ofmainshock rupture and microseismicity at Qeshm island in the Zagros fold-and-thrust belt, Iran, Earth Planet. Sci. Lett., 296, 181–194,doi:10.1016/j.epsl.2010.04.049.
Okada, Y., 1992, Internal deformation due to shear and tensile faults in a half space. Bulletin of the Seismological Society of America, 82, 1018-1040.
Oveisi, B., Lavé, J. and van der Beek, P., 2007, Rates and processes of active folding evidenced by Pleistocene terraces at the central Zagros front (Iran), in Thrust Belts and Foreland Basins, "Frontiers in Earth Sciences" Series, edited by O. Lacombe et al., Springer-Verlag, New York, 265-285.
Papadimitriou, E., 2002, Mode of strong earthquake recurrence in the central Ionian Islands (Greece): Possible triggering due to Coulomb stress changes generated by the occurrence of previous strong shocks, Bull, Seismol. Soc. Am.,Vol. 92, No.8, PP-3293-3308.
Parsons, T., Stein, R. S., Simpson, R. W. and Reasenberg, P. A., 1999, Stress sensitivity of fault seismicity: A comparison between limited-offset oblique and major strike-slip faults, J. Geophys. Res., 104, 20,183– 20,202.
Radjput, Sh., Gahalaut, V. K. and Sahu, V. K., 2005, Coulomb stress changes and aftershocks of recent Indian earthquakes, Current Science, 8 (4).
Roustaei, M., Nissen, E., Abbassi, M., Gholamzadeh, A., Ghorashi, M., Tatar, M., Yamini-Fard, F., Bergman, E., Jackson, J. and Parsons, B., 2010, The 2006 March 25 Fin earthquakes (Iran)-insights into the vertical extents of faulting in the Zagros Simply Folded Belt, Geophys. J. Int., 181, 1275–1291, doi:10.1111/j.1365-246X.2010.04601.x.
Sherkati, S., Molinaro, M., Frizon de Lamotte, D. and Letouzey, J., 2005, Detachment folding in the Central and Eastern Zagros fold belt (Iran), Journal of structural Geology, 27, 1680-1696.
Stein, R. S., King, C. P. and Lin, J., 1992, Change in failure stress on the southern San Andreas Fault system caused by the 1992 magnitude =7.4 Landers earthquake, Sience, 258, pp. 1328- 1332.
Talebian, M. and Jackson, J., 2004, A reappraisal of earthquake focal mechanisms and active shortening in the Zagros mountains of Iran, Geophys. J. Int., 156, 506–526, doi:10.1111/j.1365-246X.2004.02092.x.
Toda, S. and Stein, R. S., 2003, Toggling of seismicity by the 1997 Kagoshima earthquake couplet: A demonstration of time-dependent stress transfer. Journal of Geophysical Research, 108(B12), 2567, doi:10.1029/2003JB002527.
Toda, S., Stein, R. S., Reasenberg, P. A., Dieterich, H. and Yoshida, A., 1998, Stress transferred by the 1995 MW=6.9 Kobe, Japan, shock: Effect on aftershocks and future earthquake.
Vernant, Ph., Nilforoushan, F., Hatzfeld, D., Abbassi, M. R., Vigny, C., Masson, F., Nankali, H., Martinod, J., Ashtiani, A., Bayer, R., Tavakoli, F. and Chéry, J., 2004, Present-day crustal deformation and plate kinematics in the Middle East constrained by GPS measurements in Iran and northernOman. Geophysical Journal International, 157(1), 381-398.
Walker, R. T., Andalibi, M. J., Gheitanchi, M. R., Jackson, J. A., Karegar, S. and Priestley, K., 2005, Seismological and field observations from the 1990 November 6 Furg (Hormozgan) earthquake: a rare case of surface rupture in the Zagros mountains of Iran, Priestley Geophysical Journal International, 163, 567-579.
Zarifi, Z., Nilfouroushan, F. and Raeesi, M., 2013, Crustal stress map of Iran: insight from seismic and geodetics computations. Pure and Applied Geophysics, 171(7), 1219-1236.