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- MakaleAçık Erişim2020Scopus SJRQ3A comparison of alternative curve fitting techniques for different earthquake fault parameters of Iranian earthquakes; [Comparación de técnicas de ajuste de curvas para diferentes parámetros de fallas en terremotos en Irán]
Öztürk, Serkan; Ghassemi, Mohammad R.; Sarı, Mahmut
In this study, we tried to estimate the optimum linear equations among the parameters associated with different earthquake fault mechanisms for Iranian earthquakes. For this purpose, we tested different curve fitting methods in order to present the most proper empirical relationships between several seismic parameters for different fault systems. In the present paper, 46 large and destructive Iranian earthquakes whose magnitudes change between 5.8 and 7.8 from 1900 to 2014 were used for the analyses. A comparison was made by using four types of curve fitting techniques. The estimation procedures are considered as (1) L2 or Least Squares Regression, (2) L1 or Least Sum of Absolute Deviations Regression, (3) Robust Regression and, (4) Orthogonal Regression. Confidence intervals were selected as 95% for all types of regression relationships. In the selection of the best probability distribution, we considered the correlation coefficients of the linear regressions as a powerful and conceptually simple method. Correlation coefficients of all relationships change between 0.299 and 0.986 with Orthogonal regression, between 0.168 and 0.792 with L1 regression, between 0.059 and 0.829 with Robust regression. For Iranian earthquakes, the most suitable and reliable empirical relationships between moment magnitude (Mw) and surface wave magnitude (Ms), Mw and surface rupture length (SRL), Mw and maximum displacement (MD), and SRL and MD were obtained by Orthogonal regression since it supplies stronger correlation coefficients than those of the other regression techniques in most estimates. The results show that estimated empirical relationships among the different fault parameters by using the Orthogonal regression method can be accepted as more up-to-date and more appropriate in comparison with the other regression norms. Consequently, these equations were suggested as more reliable in the estimation of the maximum surface displacement, maximum surface rupture length and associated with the maximum credible earthquakes for different areas of Iran. Furthermore, obtained relationships can be statistically significant for the assessment of seismic, tectonic and geologic activities, and they can be used to evaluate the rupture hazard of the Iranian Plateau.
AtıfScopus2WoS2OpenAlex2İncele - MakaleYalnız künye2018Scopus SJRQ3EMPIRICAL RELATIONS AMONG THE PARAMETERS ASSOCIATED WITH EARTHQUAKE RUPTURE MECHANISMS FOR IRANIAN EARTHQUAKES
Öztürk, Serkan; Ghassemi, Mohammad Reza; Sari, Mahmut
In this study, we aimed to derive the new and more reliable empirical relationships among different seismic parameters associated with the earthquake rupture mechanisms for Iranian earthquakes. For this purpose, we firstly converted the surface wave magnitudes into moment magnitudes in order to prepare a uniform earthquake dataset. Thereafter, we estimated the empirical relationships between moment magnitude and surface rupture length, moment magnitude and maximum displacement, and surface rupture length and maximum displacement. These linear empirical equations were obtained by orthogonal regression and the goodness of fits were discussed in terms of the correlation coefficients. The results obtained by the orthogonal regression in this paper are compared with the results obtained by the least square method in the literature. The present study confirms that representations of statistical correlations among different earthquake faulting parameters can be given more clear and straightforward by the orthogonal regression as compared to the least square method. In addition, such kind of relationships may provide some significant insights for the calculation of the maximum surface rupture length, maximum surface displacement, and associated maximum credible earthquakes for different seismotectonic regions of Iran as well as the estimation of earthquake magnitudes in paleoseismological studies.
AtıfWoS2İncele - MakaleYalnız künye2018Scopus SJRQ2Determining the degree of saturation of rocks as a function of time: A case study from mountainous area of Turkey
Dağ, Serhat
The aim of this study is to scrutinize whether, in terms of saturation, the 48 hour duration suggested by ISRM (International Society for Rock Mechanics) methods and ASTM (American Society for Testing and Materials) standard in rocks is sufficient or not, and to examine how the degree of saturation of rocks may be determined as a function of time. For this purpose, samples from five different rock groups including igneous (andesite, granite, andesitic tuff) and sedimentary (limestone, sandstone) exposed in Gümüşhane city which is from mountainous area of north-eastern Turkey, have been compiled. Measurements were taken on the samples left for saturation under laboratory conditions as a result of which the degree of saturation values at the end of these time periods were determined. Similarly, at the end of 48 hours, the samples were left to dry under atmospheric conditions in the laboratory environment and their time dependent degree of saturation were also calculated at different times. The changes as a function of time in the degree of saturation were then examined mathematically using non-linear, exponential and logarithmic functions. Graphs and equations related with the acquired time-degree of saturation values and the correlation coefficient (r) values for these equalities have indicated a high accordance between time and degree of saturation for the studied rock groups. The applied methodology will be beneficial for determining the degree of saturation based on time for engineering studies that will be carried out in similar lithologies.
AtıfScopus4WoS1OpenAlex5İncele - MakaleYayıncıda açık erişim2014Scopus SJRQ3A New Empirical Relation between Surface Wave Magnitude and Rupture Length for Turkey Earthquakes
Öztürk, Serkan
Many practical problems encountered in quantitative oriented disciplines entail finding the best approximate solution to an over determined system of linear equations. In this study, it is investigated the usage of different regression methods as a theoretical, practical and correct estimation tool in order to obtain the best empirical relationship between surface wave magnitude and rupture length for Turkey earthquakes. For this purpose, a detailed comparison is made among four different regression norms: (1) Least Squares, (2) Least Sum of Absolute Deviations, (3) Total Least Squares or Orthogonal and, (4) Robust Regressions. In order to assess the quality of the fit in a linear regression and to select the best empirical relationship for data sets, the correlation coefficient as a quite simple and very practicable tool is used. A list of all earthquakes where the surface wave magnitude (Ms) and surface rupture length (L) are available is compiled. In order to estimate the empirical relationships between these parameters for Turkey earthquakes, loglinear fit is used and following equations are derived from different norms: Ms = 1.02* LogL + 5.18, for L-2 Norm regression (R-2=0.71), Ms = 1.15* LogL + 4.98, for L-1 Norm regression (R-2=0.92), Ms = 1.04* LogL + 5.15, for Robust regression (R-2=0.75), Ms = 1.25* LogL + 4.86, for Orthogonal regression (R-2=0.68), Consequently, the empirical equation given by the Least Sum of Absolute Deviations regression as Ms = 1.15* LogL + 4.98 with a strong correlation coefficient (R-2=0.92) can be thought as more suitable and more reliable for Turkey earthquakes. Also, local differences in rupture length for a given magnitude can be interpreted in terms of local variation in geologic and seismic efficiencies. Furthermore, this result suggests that seismic efficiency in a region is dependent on rupture length or magnitude.
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