An application of the time- and magnitude-predictable model to long-term earthquake prediction in eastern Anatolia

• Published in: Journal of seismology Vol. 9; no. 3; pp. 367 - 379
• Main Author: SAYIL, Nilgün
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01.07.2005; Springer Nature B.V
• Subjects: Correlation coefficient; Earth sciences; Earth, ocean, space; Earthquake prediction; Earthquakes; Earthquakes, seismology; Engineering and environment geology. Geothermics; Exact sciences and technology; Internal geophysics; Natural hazards: prediction, damages, etc; Seismic activity; Seismology; Standard deviation; Middle East; Turkey; Anatolia; earthquake prediction; models; Anatolia; time- and magnitude-predictable model; probability; recurrence time; coordinates; mainshocks; earthquakes; surface waves; Asia; prediction; magnitude; seismic moment; correlation coefficient; standard deviation; seismicity
• DOI: 10.1007/s10950-005-0037-x
• ISSN: 1383-4649

In order to estimate the recurrence intervals for large earthquakes occurring in eastern Anatolia, this region enclosed within the coordinates of 36^sup ^-42^sup ^N, 35^sup ^-45^sup ^E has been separated into nine seismogenic sources on the basis of certain seismological and geomorphological criteria, and a regional time- and magnitude-predictable model has been applied for these sources. This model implies that the magnitude of the preceding main shock which is the largest earthquake during a seismic excitation in a seismogenic source governs the time of occurrence and the magnitude of the expected main shock in this source. The data belonging to both the instrumental period (M^sub S^≥ 5.5) until 2003 and the historical period (I^sub 0^≥ 9.0 corresponding to M^sub S^≥ 7.0) before 1900 have been used in the analysis. The interevent time between successive main shocks with magnitude equal to or larger than a certain minimum magnitude threshold were considered in each of the nine source regions within the study area. These interevent times as well as the magnitudes of the main shocks have been used to determine the following relations: log T^sub t^ = 0.11M^sub min^ - 0.12M^sub p^ - 0.11 log M^sub 0^ + 2.51 M^sub f^ = 0.89M^sub min^ - 0.24M^sub p^ + 0.31 log M^sub 0^ - 4.99 where T^sub t^ is the interevent time measured in years, M^sub min^ is the surface wave magnitude of the smallest main shock considered, M^sub p^ is the magnitude of the preceding main shock, M^sub f^ is magnitude of the following main shock, and M^sub 0^ is the released seismic moment per year in each source. Multiple correlation coefficient and standard deviation have been computed as 0.50 and 0.28, respectively for the first relation. The corresponding values for the second relation are 0.64 and 0.32, respectively. It was found that the magnitude of the following main shock M^sub f^ does not depend on the preceding interevent time T^sub t^. This case is an interesting property for earthquake prediction since it provides the ability to predict the time of occurrence of the next strong earthquake. On the other hand, a strong negative dependence of M^sub f^ on M^sub p^ was found. This result indicates that a large main shock is followed by a smaller magnitude one and vice versa. On the basis of the first one of the relations above and taking into account the occurrence time and magnitude of the last main shock, the probabilities of occurrence P(Δ t) of main shocks in each seismogenic source of the east Anatolia during the next 10, 20, 30, 40 and 50 years for earthquakes with magnitudes equal 6.0 and 7.0 were determined. The second of these relations has been used to estimate the magnitude of the expected main shock. According to the time- and magnitude-predictable model, it is expected that a strong and a large earthquake can occur in seismogenic Source 2 (Erzincan) with the highest probabilities of P^sub 10^ = 66% (M^sub f^ = 6.9 and T^sub t^ = 12 years) and P^sub 10^ = 44% (M^sub f^ = 7.3 and T^sub t^ = 24 years) during the future decade, respectively.[PUBLICATION ABSTRACT]