Space-Time Correlations of Seismotectonic Parameters: Examples from Japan and from Turkey Preceding the Izmit Earthquake

Abstract

Analysis of the correlation between fractal attributes of complex seismotectonic variables may offer insights into seismic hazard assessment. The Gutenberg-Richter, moment-magnitude, and moment-source area relations yield a direct fractal relationship among the Gutenberg-Richter b-value, occurrence rate, and the characteristic linear dimension of the fault plane (square root of fault surface area). In contrast, temporal variation in the correlation dimension of epicenters (D C) is found, in several studies, to correlate negatively with the b-value in different regions of the world. Spatial variations between the b-value and D C also tend to oppose each other. In Japan, negative correlations are also observed in the regional scale comparisons of the capacity dimension (D o) of active fault systems and the b-value. However, at local scales, the relationship yields both positive and negative correlation. The occurrence of positive or negative correlation appears to be controlled by different modes of failure within the active fault complex. Spatial variations between the b-value and D C along the Northern Anatolian Fault Zone (NAFZ) suggest that, on average from 1900 to 1992, earthquake magnitudes were higher and epicenters more scattered within the central NAFZ than in its eastern and western segments. Temporal analysis reveals that the relationship between the b-value and D C are nonstationary. Temporal correlations are generally negative. A period of positive correlation is observed between 1976 and 1988. During the last 3 yr of this period (1985-1988), both the b-value and D C rose significantly, suggesting that stress release occurs through increased levels of low-magnitude and increasingly scattered seismicity. This dispersed pattern of seismicity, in combination with higher slip rates in the central NAFZ, may be one that did not adequately relieve stress along the main fault zone. This change in behavior and the tendency during the last century for the seismicity to migrate westward along the NAFZ may point to an increased risk of larger magnitude events such as the İzmit earthquake.

Earthquake frequency-magnitude distribution and fractal dimension in mainland Southeast Asia

“…Both the b value of the FMD and the D C value are significantly related to, and therefore directly controlled by, the seismicity and tectonic stress levels in that region (Scholz 1968;Öncel et al 1996). During the past few decades, the relationship between the b and D C values has been successfully calibrated (Hirata 1989;Öncel and Wilson 2002;Wyss et al 2004), and the D C /b ratio has been used as an indicator of earthquake hazards (Bayrak and Bayrak 2012).…”

Spatial and temporal analysis of recent seismicity in different parts of the Vlora-Lushnja-Elbasani-Dibra Transversal Fault Zone, Albania

“…It is well known that the higher Dc-values are related to active faults and these fault systems have an increasing complexity (Öncel and Wilson, 2002). Also, the faults in which earthquakes are caused by failure of isolated, small asperities and occurred in clusters have lower Dc-values (Barton et al, 1999).…”

“…In recent years, many authors have used the combination of several statistical parameters such as Gutenberg-Richter b-value, correlation dimension Dc-value and precursory seismic quiescence Z-value in order to reveal the possible locations of future earthquakes in a given region (e.g., Wiemer and Wyss, 1994;Wyss and Martirosyan, 1998;Katsumata and Kasahara, 1999;Öncel and Wilson, 2002;Chouliaras and Stavrakakis, (2000); Huang et al, (2002); Wyss et al, 2004;Polat et al, 2008;Roy et al, 2011;Öztürk and Bayrak, 2012;Öztürk, 2011;2013;Ali, 2016). The basic idea of these types of studies is that the regions with the lower b-value, the larger Dc-value and the higher Z-value are probable areas for next earthquake hazard.…”

“…Smaller b-value which is related to larger Dc-value is the dominant characteristic in the field of increased complexity for an active fault regime. As an important result, this may arise from the clusters of earthquakes, and the variations in Dc-value may provide some evidences for evaluations of stress relaxation on the fault regions (Öncel and Wilson, 2002;Polat et al, 2008).…”

Türkiye’nin Batı Anadolu Bölgesi için Deprem İstatistiği ve Olası Güçlü Depremlerin Orta Vadede Bölgesel Olarak Tahmini Üzerine Bir Çalışma

“…r uzaklığına (1°111 km alarak) karşı C(r) değerleri çift logaritmik koordinatlarda çizilirse fraktal boyut Dc, pratik olarak grafiğin eğiminden hesaplanabilir. (Öncel ve Wilson, 2002). Ayrıca, daha yüksek Dc ve daha düşük b-değerleri, çalışma alanındaki baskın yapısal özellikledir ve kümelenmelerden kaynaklanabilir.…”