基于FK方法和GP14.3震源模型的2023年土耳其M_(w)7.8级地震宽频地震动合成

Synthesis of broadband ground motion for the 2023 Turkey M_(w)7.8 earthquake based on FK method and GP14.3 source model

本文合成了2023年2月6日土耳其M_(w)7.8地震的地震动时空场。首先,依据USGS网站提供的V s30数据和全球地壳模型Crust1.0数据,构建了土耳其南部地区的地下一维速度结构模型;其次,依据美国地质调查局(USGS)发布的断层滑动量及破裂前端分布结果,构建了此次地震的GP14.3运动学混合震源模型;然后,采用作者提出的FK方法对本次地震进行了0~10 Hz的宽频三分量地震动合成。通过合成结果与距离震中50 km范围内地震动较强的8个台站强震记录及相应反应谱的比较,检验了方法的可靠性和模型的适用性;最后,重点分析了土耳其东南部的加济安泰普市及附近地区地震动时空场特征。结果表明:1)本文计算的加济安泰普市区范围内的NS向PGA接近180 cm/s^(2)、PGV接近100 cm/s,伊斯拉希耶镇地区的EW向PGA高达560 cm/s^(2)、PGV高达150 cm/s,地震动强度比较大。2)基于本文强地面运动合成结果得到的加济安泰普市区范围内的地震烈度为VII度,伊斯拉希耶镇地区的地震烈度高达IX度,与USGS给出的结果一致。3)此次土耳其M_(w)7.8地震呈现明显的近断层地震动集中性效应、地面永久位移以及破裂方向性效应。

This paper synthesizes the spatial-temporal field of ground motion of M_(w)7.8 earthquake in Turkey on February 6,2023.Firstly,based on the V s30 data provided on the USGS website and global crustal model Crust 1.0,the subsurface 1D velocity structure model of southern Turkey is constructed.Then,according to the distribution of the slip and rupture-front released by USGS,the GP14.3 hybrid source model of this earthquake is constructed.Furthermore,the frequency-wavenumber(FK)method proposed by the author is used to synthesize the broadband ground motion of 0~10Hz for this earthquake.Comparison with the strong-earthquake records and the response spectrums of eight stations with stronger shaking within 50 km from the epicenter verifies the reliability of the method and the applicability of the model.Finally,the characteristics of the spatial-temporal field of ground motion in Gaziantep and its vicinity in southern Turkey are analyzed.The results show that:①the PGA and the PGV in NS direction of Gaziantep′s urban area calculated in this paper are close to 180 cm/s^(2)and 100 cm/s.The PGA and the PGV in EW direction of Islahiye town calculated in this paper are as high as 560 cm/s^(2)and 150 cm/s,indicating that the ground motion intensity is relatively high;②based on the results of strong ground motion synthesis in this paper,the urban area of Gaziantep has a seismic intensity of VII and the region of Islahiye has a seismic intensity of IX,which are consistent with the results given by the USGS;③the M_(w)7.8 Turkey earthquake presents obvious concentration effects,permanent ground displacement and rupture directional effects.