Yazarlar
Yayınlar
- 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.
AtıfScopus27WoS20OpenAlex22
İncele - MakaleYalnız künye2018Scopus SJRQ2Earthquake hazard potential in the Eastern Anatolian Region of Turkey: seismotectonic b and Dc-values and precursory quiescence Z-value
Öztürk, S.
The Eastern Anatolian Region of Turkey is one of the most seismically and tectonically active regions due to the frequent occurrence of earthquakes. Thus, the main goal of this study is to analyze the regional and temporal characteristics of seismicity in the Eastern Anatolia in terms of the seismotectonic b-value, fractal dimension Dc-value, precursory seismic quiescence Z-value, and their interrelationships. This study also seeks to obtain a reliable empirical relation between b and Dc-values and to evaluate the temporal changes of these parameters as they relate to the earthquake potential of the region. A more up-to-date relation of Dc = 2:55–0:39*b is found with a very strong negative correlation coefficient (r =–0.95) by using the orthogonal regression method. The b-values less than 1.0 and the Dc-values greater than 2.2 are observed in the Northeast Anatolian Fault Zone, Aşkale, Erzurum, Iğdır and Çaldıran Faults, Doğubeyazıt Fault Zone, around the Genç Fault, the western part of the Bitlis-Zagros Thrust Zone, Pülümür and Karakoçan Faults, and the Sancak- Uzunpınar Fault Zone. In addition, the regions having small b-values and large Z-values are calculated around the Genç, Pülümür and Karakoçan Faults as well as the Sancak-Uzunpınar Fault Zone. Remarkably, the combinations of these seismotectonic parameters could reveal the earthquake hazard potential in the Eastern Anatolian Region of Turkey, thus creating an increased interest in these anomaly regions.
AtıfScopus51WoS36OpenAlex53İncele - MakaleAçık Erişim2017Scopus SJRQ2Spatial and temporal analysis of recent seismicity in different parts of the vlora-lushnja-elbasani-dibra transversal fault zone, Albania
Ormeni, Rrapo; öZtürk, Serkan; Fundo, Akli; çElik, Kemal
Spatial and temporal evaluation of current seismic activity throughout the Vlora- Lushnja-Elbasani-Dibra (VLED) transversal fault zone were carried out at the beginning of year 2016. The seismotectonic b-value, fractal dimension Dc-value and precursory seismic quiescence Z-value are considered for a detailed statistical analysis. Completeness magnitude Mc-value varies from 2.5 to 2.7 for different parts of the VLED fault zone. The b-value is calculated as 1.10±0.04 for the south western part and 1.13±0.05 for the middle part, whereas it is estimated as 0.94±0.07 for the north eastern part of the study region. These results reveal that b-values for all regions are well represented by a b-value typically close to 1.0. There are clear decreasing trends in temporal changes of b-values before the occurrences of some strong main shocks. On the contrary, no earthquakes are observed in some periods after decrease of b-value. Dc-values are computed as 2.66±0.04 for the south western part, 2.64±0.03 for the middle part and 2.15±0.02 for the north eastern part of the VLED fault zone. These rather large values show that earthquake activity is more clustered at larger scales or in smaller areas in the study area. Considering the phenomenon of seismic quiescence as a precursor of the main earthquakes gives successful outcomes in defining the potential anomalies and possible locations of future earthquakes. Quiescence analysis of current seismicity at the beginning of 2016 in the VLED fault zone is performed with the test of standard normal deviate Z-value. Distributions of resulting Z-values show six anomalous regions along the different parts of the VLED fault zone. These quiescence areas are detected at (i) 40.81°N- 19.86°E (including Kuc-Bubullim, southeast of Lushnja town), (ii) 41.00°N-20.01°E (in the Cerriku, south of Elbasani town), (iii) 41.31°N-20.13°E (around Bene-Qafe, northeast of Elbasani town), (iv) 41.43°N-20.21°E (Krasta-Batra, south of Bulqiza town), (v) 41.28°N-20.49°E (including Carrishta-Stebleve, northeast of Librazhdi town), (vi) 41.51°N-20.51°E (including Qerrenec-Gjorica, west of Dibra town). As an important result, analyses of spatial and temporal characteristics of the earthquake activity may supply significant clues for revealing the future seismic hazard along the VLED fault zone, and these anomaly regions may be interpreted as the locations of next possible earthquakes.
AtıfScopus11WoS6OpenAlex11İncele - MakaleYayıncıda açık erişim2015Scopus SJRQ2A study on the correlations between seismotectonic b-value and Dc-value, and seismic quiescence Z-value in the western anatolian region of Turkey
Öztürk, Serkan
The Western Anatolian region is one of the most seismically active sectors of Turkey where small-magnitude events with considerable clustering occur frequently. The spatial and temporal behaviors of seismic activity as quantified by the fractal dimension Dc-value, seismotectonic b-value and seismic quiescence Z-value are investigated for the Western Anatolian region. For this purpose, a statistical relationship is developed between b and Dc-values, and regional and temporal changes of these parameters are analyzed in order to reveal the potential of future earthquakes in the study region. By using standard deviate Z-value, current seismicity rate changes are estimated in the beginning of 2014. The Western Anatolian region is divided into 18 different seismogenic subregions. Orthogonal regression fit is preferred in order to estimate more up-to-date and reliable statistical correlation between two seismotectonic parameters. The relationship of Dc=2.74-0.29*b is computed with a significant negative correlation (r = -0.73) between b and Dc-values for the Western Anatolian earthquake distributions. There are clear fluctuations in the temporal changes of these two parameters and the same results are relatively obtained in previous studies in literature. Lower b-values smaller than 1.0 and also higher Dc-value are observed in the Burdur fault zone and Kütahya graben. In addition, the regions in which the lower b-values and the higher Z-values are estimated cover the Burdur fault zone, Aliağa-Dumlupınar faults and Bakırçay grabens. Consequently, the relationships between seismic bvalue, fractal dimension Dc-value and seismic quiescence Z-value may provide important evidences to put forth the next earthquake potential in Western Anatolia. In addition, monitoring of microseismic activity and behaviors of some other geophysical parameters should be analyzed in space and time and evaluated carefully.
AtıfScopus34WoS22OpenAlex28İncele - MakaleYalnız künye2012Scopus SJRQ4Statistical correlation between b-value and fractal dimension regarding Turkish epicentre distribution
Öztürk, Serkan
This study was aimed at analysing the relationship between seismic b-value and fractal dimension Dc-value for Turkish epicentres. The earthquake catalogue consisting of 99,737 instrumentally-registered Turkish events was analysed for the period between 1970 and 2011; Turkey was divided into 55 tectonic zones for making a detailed comparison. The b-values were calculated by the maximum likelihood method and the Dc-values were obtained with 95% confidence limits by linear regression. The results showed that higher Dc-values were associated with lower b-values and this could have been an indication of relatively high stress intensity and stronger epicentre clustering in these regions. Orthogonal regression was used to estimate a suitable statistical correlation between two seismotectonic parameters; the Dc = 2.44 - 0.30*b relationship was obtained with a strong negative correlation (r = -0.82) between b-value and Dc-value for Turkish earthquake distribution. This seemed to agree with other regional results obtained for different parts of Turkey and the rest of the world.
AtıfScopus25WoS17İncele