Yazarlar
Yayınlar
- MakaleYalnız künye2025Scopus SJRQ2A Comprehensive Assessment for the Aftershock Sequence of August 11, 2012 Varzaghan-Ahar Doublet Mainshocks, NW Iran
Öztürk, Serkan; Yaghmaei-Sabegh, Saman
In this study, an evaluation of regional, temporal and magnitude properties of the August 11, 2012 Varzaghan-Ahar aftershock sequence was performed based on the different variables such as the Gutenberg-Richter b-value, the Modified Omori p-value, fractal dimension Dc-value and the maximum aftershock magnitude Mamax value which commonly used to describe aftershock behaviors. b-value was computed as 0.73 ± 0.03 for the study area where catalog has a completeness magnitude Mc = 2.0. This b-value is relatively small from typical b≈1 and it can be due to the abundance of aftershocks larger than Mw = 4 in the region. Structural heterogeneity of the seismic source along with the compressive stress situation of the aftershock area could be another reason for this finding as well. p-value was estimated as 1.00 ± 0.03 where c-value took 0.342 ± 0.106 according to the analysis which shows that the number of aftershocks of the Varzaghan-Ahar mainshock shows a relatively fast decrease. Dc-value was computed as 1.84 ± 0.07. This large value indicates homogeneously distributed aftershocks and more clustering in smaller areas or larger scales. As a result, the smallest b-values (< 0.7) and Mamax values larger than 5.0 were obtained around the mainshock. In addition, the biggest p-values (> 1.2) were found in and around the mainshock including Varzaghan. The areas having the biggest p-value and the lowest b-value have great coseismic deformation and stress, respectively. Hence, we can say that coseismic deformation and stress distributions are very effective on the b- and p-value changes. Thus, particular attention on assessing the aftershock hazard may be directed on the understanding of these spatio-temporal aftershock variables.
AtıfScopus2OpenAlex2
İncele - MakaleAçık Erişim2023Scopus SJRQ4An evaluation of the characteristic aftershock parameters following the 24 January 2020 MW = 6.8 Elazığ-Sivrice (Türkiye) earthquake
Öztürk, Serkan
A comprehensive evaluation of region-time-magnitude behaviours of aftershocks following the 24 January 2020 (Mw = 6.8) Elazığ-Sivrice (Türkiye) earthquake was achieved by using the characteristic parameters such as b-value, p-value, Dc-value and Mamax value of aftershock occurrences. The b-value was calculated as 0.82 ± 0.02 by considering the magnitude of the completeness value as Mcomp = 1.9, and it is relatively small compared to typical b ≈ 1 for the magnitude-frequency relationship of aftershocks. This low b-value may also be caused by the abundance of aftershocks with ML ≥ 4.0. The p-value was computed as 0.80 ± 0.02 with c-value = 0.279 ± 0.098 and is smaller than the global value of p ≈ 1. This low p-value may be due to a relatively slow decay rate of aftershock activity, and the modified Omori model seems appropriate for the estimation of decay parameters. The Dc-value was estimated as 1.87 ± 0.07. This large value shows that aftershocks are homogeneously distributed and more clustered at larger scales/in smaller areas. The temporal variation of b-value indicates that decreases in b-value may result from the gradual increase in the effective stress following the larger aftershocks. The lowest b-values and Mamax values greater than 5.0 were observed in the north, south and southwest parts of the mainshock including Pütürge and Erkenek segments. These results show that there is an apparent relation between the smallest b-values and the largest Mamax values. The largest p-values were estimated in and around the main shock including Pütürge segment. The regions with the smallest b-value and the largest p-value have high stress and coseismic deformation, respectively. Stress variations and coseismic deformation are extremely effective on the changes of b-and p-values. As a remarkable result, aftershock hazard following the mainshock may be considered extremely related to aftershock parameters, and detailed analyses of the region-time-magnitude characteristics of aftershocks are recommended for a preliminary evaluation following the mainshock.
AtıfScopus3WoS2OpenAlex2
İncele - MakaleYalnız künye2019Scopus SJRQ1A statistical space-time-magnitude analysis on the aftershocks occurrence of the July 21th, 2017 M W = 6.5 Bodrum-Kos, Turkey, earthquake
Öztürk, Serkan; Şahin, Şakir
In this study, a detailed space-time-magnitude assessment on the aftershock sequence of July 21th, 2017, M W 6.5, Bodrum-Kos earthquake (Turkey) is carried out by focusing on the analyses of aftershock parameters: b-value, p-value, Dc-value and Mamax. b-value is estimated as 0.90 ± 0.05 with a completeness magnitude Mc = 1.6 and this relatively small b-value may be resulted from the abundance of aftershocks with magnitude M L ≥ 4.0. However, it is well represented by the Gutenberg-Richter law with a typically b ≈ 1.0. p-value is estimated as 1.04 ± 0.02 with a c-value = 0.224 ± 0.039 and is well characterized nearly close to the global p ≈ 1.0. This relatively high p-value may be a result of the relative fast decay rate of the aftershock activity. Dc-value is calculated as 1.74 ± 0.09 and it means that aftershocks are homogeneously distributed. Temporal distribution of b-value shows that small b-values may be due to a stepwise increase in effective stress before the occurrence of larger aftershocks. Regional changes range from 0.5 to 1.2 in b-value, from 0.4 to 1.3 in p-value and from 3.0 to 5.2 in Mamax. The smallest b-values are found in and around mainshock, including Karaada, Bodrum, Akyarlar and Turgutreis, and these regions have high stress as well as coseismic deformation. The largest p-values are found in and around the mainshock epicenter including Karaada, and it is interpreted that this situation may be caused by coseismic deformation. Mamax values larger than 4.4 are observed in and around mainshock epicenter, including Bodrum and Akyarlar, and there is a clear correlation between spatial variations of b-values and Mamax. These results show that stress changes and coseismic deformation seem highly effective on b and p-value variations. Therefore, a special interest needs to be given to these anomaly regions since aftershock hazard is highly associated with these parameters and may be developed considering their space-time-magnitude distribution.
AtıfScopus27WoS20OpenAlex22İncele