Spatial-temporal analysis of seismicity before the 2012 Varzeghan, Iran, Mw 6.5 earthquake

In this work, the spatial and temporal variations of seismicity in northwestern Iran have been evaluated with a special focus on seismic precursors of the 11 August 2012 Mw 6.5 Varzeghan earthquake. The precursors are defined by the z-value test and the generalized fractal dimensions of earthquake epicenters. The investigation applies earthquakes that have occurred since 2006 in a region that includes the main shock and collected by the Iranian Seismological Center. In order to eliminate the effect of explosions in the processing, we removed the explosion from the used catalog by using the normalized ratio analysis of daytime to nighttime events. Having done the preprocessing procedures, we removed the events with magnitudes of less than 2.5. As a result of our analysis, a period of seismic quiescence has been identified, which started about 3 years before the Varzeghan main shock. In a nice coincidence with these results, significant changes have been observed in the generalized fractal dimensions and the related spectra prior to the occurrence of the Varzeghan earthquake. The changes indicate that the seismic activities of the studied area have had increasingly dense clustering in space since about mid-2009, which suggests the regional preparedness for the occurrence of the main quake. Furthermore, the analysis did not exhibit any significant seismic quiescence anomaly at the beginning of 2013.

Spatial-temporal analysis of seismicity before the 2012 Varzeghan, Iran, Mw 6.5 earthquake

In this work, the spatial and temporal variations of seismicity in northwestern Iran have been evaluated with a special focus on seismic precursors of the 11 August 2012 Mw 6.5 Varzeghan earthquake. The precursors are defined by the z-value test and the generalized fractal dimensions of earthquake epicenters. The investigation applies earthquakes that have occurred since 2006 in a region that includes the main shock and collected by the Iranian Seismological Center. In order to eliminate the effect of explosions in the processing, we removed the explosion from the used catalog by using the normalized ratio analysis of daytime to nighttime events. Having done the preprocessing procedures, we removed the events with magnitudes of less than 2.5. As a result of our analysis, a period of seismic quiescence has been identified, which started about 3 years before the Varzeghan main shock. In a nice coincidence with these results, significant changes have been observed in the generalized fractal dimensions and the related spectra prior to the occurrence of the Varzeghan earthquake. The changes indicate that the seismic activities of the studied area have had increasingly dense clustering in space since about mid-2009, which suggests the regional preparedness for the occurrence of the main quake. Furthermore, the analysis did not exhibit any significant seismic quiescence anomaly at the beginning of 2013.

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  • Ambraseys NN, Melville CP (1982). A History of Persian Earthquakes. 1st ed. Cambridge, UK: Cambridge University Press.
  • Ashtari Jafari M (2012). Seismicity anomalies of the 2003 Bam, Iran earthquake. J Asian Earth Sci 56: 212–217.
  • Berberian M (1995). Natural Hazards and the First Earthquake Catalogue of Iran, Historical Hazards in Iran Prior to 1900. 1st ed. Tehran, Iran: IIEES.
  • Bowman DD, Ouillon G, Sammis CG, Sornette A, Sornette D (1998). An observational test of the critical earthquake concept. J Geophys Res 103: 24359–24372.
  • Candela T, Renard F, Bouchon M, Brouste A, Marsan D, Schmittbuhl J, Voisin C (2009). Characterization of fault roughness at various scales: implications of three‐dimensional high resolution topography measurements. Pure Appl Geophys 166: 1817–1851.
  • Copley A, Faridi M, Ghorashi M, Hollingsworth J, Jackson J, Nazari H, Oveisi B, Talebian M (2013). The 2012 August 11 Ahar earthquakes: consequences for tectonics and earthquake hazard in the Turkish–Iranian Plateau. Geophys J Int 196: 15–21.
  • De Natale G, Zollo A (1986). Statistical analysis and clustering features of the Phlegraean Fields earthquake sequence (May 1983-May 1984). B Seismol Soc Am 76: 801–814.
  • Dimitriu PP, Scordilis EM, Karacostas VG (2000). Multifractal analysis of the Arnea, Greece seismicity with potential implications for earthquake prediction. Nat Hazards 21: 277– 295.
  • Djamour Y, Vernant P, Nankali HR, Tavakoli F (2011). NW Iran- eastern Turkey present-day kinematics: results from the Iranian permanent GPS network. Earth Planet Sc Lett 307: 27–34.
  • Grassberger P, Procraccia I (1983). Measuring the strangeness of strange attractors. Physica D 9: 189–208.
  • Helmstetter A, Kagan YY, Jackson DD (2007). High resolution, time- independent grid-based forecast for M ≥ 5 earthquakes in California. Seismol Res Lett 78: 78–86.
  • Hentschel HGE, Procraccia I (1983). The infinite number of generalized dimensions of fractals and strange attractors. Physica D 8: 435–444.
  • Hessami K, Pantosti D, Tabassi H, Shabanian E, Abbassi MR, Feghhi K, Solaymani S (2003). Paleoearthquakes and slip rates of the North Tabriz Fault, NW Iran: preliminary results. Ann Geophys 46: 903–915.
  • Hirata T, Imoto M (1991). Multifractal analysis of spatial distribution of micro earthquakes in the Kanto region. Geophys J Int 107: 155–162.
  • Horasan G, Boztepe-Güney A, Küsmezer A, Bekler F, Öğütçü Z, Musaoğlu N (2009). Contamination of seismicity catalogs by quarry blasts: an example from Istanbul and its vicinity, northwestern Turkey. J Asian Earth Sci 34: 90–99.
  • Kagan YY, Jackson DD (1991). Long-term earthquake clustering. Geophys J Int 104: 117–133.
  • Katsumata K (2011). A long-term seismic quiescence started 23 years before the 2011 off the Pacific coast of Tohoku Earthquake (M = 9.0). Earth Planets Space 63: 709–712.
  • King G (1983). The accommodation of large strains in the upper lithosphere of the earth and other solids by self-similar fault systems: the geometrical origin of b-value. Pure Appl Geophys 121: 761–815.
  • Li D, Zhaobi Z, Binghong W (1994). Research into the multifractal of earthquake spatial distribution. Tectonophysics 223: 91–97.
  • Matthews MV, Reasenberg P (1988). Statistical methods for investigating quiescence and other temporal seismicity patterns. Pure Appl Geophys 126: 357–372.
  • Moradi A, Hatzfeld D, Tatar M (2011). Microseismicity and seismotectonics of the North Tabriz fault (Iran). Tectonophysics 506: 22–30.
  • Oncel AO, Wilson T (2002). Space-time correlations of seismotectonic parameters: examples from Japan and from Turkey preceding the Izmit earthquake. B Seismol Soc Am 92: 339–349.
  • Oncel AO, Wilson T (2006). Evaluation of earthquake potential along the Northern Anatolian Fault Zone in the Marmara Sea using comparisons of GPS strain and seismotectonic parameters. Tectonophysics 418: 215–218.
  • Öztürk S (2011). Characteristics of seismic activity in the Western, Central and Eastern parts of the North Anatolian Fault Zone, Turkey: temporal and spatial analysis. Acta Geophys 59: 209–
  • Öztürk S (2013). A statistical assessment of current seismic quiescence along the North Anatolian Fault Zone: earthquake precursors. Austrian J Earth Sci 106: 4–17.
  • Öztürk S, Bayrak Y (2012). Spatial variations of precursory seismic quiescence observed in recent years in the eastern part of Turkey. Acta Geophys 60: 92–118.
  • Öztürk S, Bayrak Y, Çinar H, Koravos GC, Tsapanos TM (2008). A quantitative appraisal of earthquake hazard parameters computed from Gumbel I method for different regions in and around Turkey. Nat Hazards 47: 471–495.
  • Pechmann JC, Kanamori H (1982). Waveforms and spectra of preshocks and aftershocks of the 1979 Imperial Valley, California, earthquake: evidence for fault heterogeneity? J Geophys Res 87: 10579–10597.
  • Polat O, Gök E, Yılmaz D (2008). Earthquake hazard of the Aegean extension region (West Turkey). Turk J Earth Sci 17: 593–614.
  • Reasenberg P (1985). Second order moment of central California seismicity 1969–1982. J Geophys Res 90: 5479–5495.
  • Rezapour M (2005). Magnitude scale in the Tabriz seismic network. J Earth Space Phys 31: 13–21.
  • Smalley RF Jr, Chatelian JL, Turcotte DL, Prevot A (1987). A fractal approach to the clustering of earthquakes: applications to the seismicity of New Hebrides. B Seismol Soc Am 77: 1368–1381.
  • Smith LA (1988). Intrinsic limits on dimension calculations. Phys Lett A 133: 283–288.
  • Sornette A, Dubois J, Cheminde JL, Sornette D (1991). Are sequences of volcanic eruptions deterministically chaotic? J Geophys Res 96: 11931–11945.
  • Sunmonu LA, Dimri VP, Prakash MR, Bansal AR (2001). Multifractal approach to the time series of M ≥ 7.0 earthquake in Himalayan region and its vicinity during 1895–1995. J Geol Soc India 58: 163–169.
  • Telesca L, Lapenna V, Macchiato M (2005). Multifractal fluctuations in seismic inter spike series. Physica A 354: 629–640.
  • Teotia SS, Khattri KN, Roy PK (1997). Multifractal analysis of seismicity of the Himalayan region. Curr Sci India 73: 359–366.
  • Teotia SS, Kumar D (2007). The great Sumatra-Andaman earthquake of 26 December 2004 was predictable even from seismicity data of mb ≥ 4.5: a lesson to learn from nature. Indian J Mar Sci 36: 122–127.
  • Teotia SS, Kumar D (2011). Role of multifractal analysis in understanding the preparation zone for large size earthquake in the North-Western Himalaya region. Nonlinear Proc Geoph 18: 111–118.
  • Tosi P (1998). Seismogenic structure behavior revealed by spatial clustering of seismicity in the Umbria-Marche region (Central Italy). Ann Geophys 41: 215–224.
  • Turcotte DL (1986a). Fractals and fragmentation. J Geophys Res 91: 1921–1926.
  • Turcotte DL (1986b). A fractal model for crustal deformation. Tectonophysics 132: 261–269.
  • Vernant P, Nilforoushan F, Hatzfeld D, Abbassi MR, Vigny C, Masson F, Nankali H, Martinod J, Ashtiani A, Bayer R et al. (2004). Present-day crustal deformation and plate kinematics in the Middle East constrained by GPS measurements in Iran and northern Oman. Geophys J Int 157: 381–398.
  • Wiemer S (2001). A software package to analyze seismicity: ZMAP. Seismol Res Lett 72: 373–382.
  • Wiemer S, Baer M (2000). Mapping and removing quarry blast events from seismicity catalogs, short notes. B Seismol Soc Am 90: 525–530.
  • Wiemer S, Wyss M (1994). Seismic quiescence before the Landers (M=7.5) and Big Bear (6.5) 1992 earthquakes. B Seismol Soc Am 84: 900–916.
  • Wiemer S, Wyss M (2000). Minimum magnitude of completeness in earthquake catalogs: examples form Alaska, the western United States, and Japan. B Seismol Soc Am 90: 859–969.
  • Wu YM, Chiao LY (2006). Seismic quiescence before the 1999 ChiChi, Taiwan Mw7.6 earthquake. B Seismol Soc Am 96: 321–327.
  • Wyss M, Habermann RE (1988). Precursory seismic quiescence. Pure Appl Geophys 126: 319–332.
  • Yılmaz Ş, Bayrak Y, Çınar H (2013). Discrimination of earthquakes and quarry blasts in the eastern Black Sea region of Turkey. J Seismol 17: 721–734.
  • Yılmaz V, Erişoğlu M, Çelik HE (2004). Probabilistic prediction of the next earthquake in the NAFZ (North Anatolian Fault Zone), Turkey. Doğuş Üniversitesi Dergisi 5: 243–250.
  • Zare M (1999). Contribution a l’etdue des mouvements forts en Iran; du catalogie aux lois d’attenuation. PhD, Universite Joseph Fourier, Grenoble, France (in French).