2016年8月24日意大利中部Mw6．2地震强地面运动特征分析

Characteristics of Strong Ground Motion Recorded During the August 24,2016,Italy M_W6.2 Earthquake

对意大利国家强震台网在2016年8月24日获得的其中部拉齐奥大区阿库莫利市发生的M W6.2地震强震动三分向记录进行处理和分析。完成原始数据基线校正、滤波等基本数据处理,回归此次地震动幅值衰减规律,发现其整体与ITA08及BA08的衰减趋势一致,但远场实际值低于预测值,不同场地条件下的衰减特性与ITA10一致,近震源幅值较大,且方向性明显;计算并回归分析几种持时,与全球经验预测方程均基本吻合;比较4个幅值较大的近震源台站的反应谱,发现其明显高于欧洲抗震设计规范中的设计反应谱。结合此次震害特点,该地区在实际建设中仍需提高抗震设防能力,以确保安全性等级。

This paper analyzes characteristics of strong ground motion recorded during the August 24, 2016, Italy Mw6.2 earthquake. Regression analysis is used to obtain the amplitude attenua tion of ground motion occurring during this earthquake. A comparison is then conducted with other models and attenuation characteristics are found to be in basic agreement with those of oth er prediction equations; however, the far field actual observed values are lower than those of pre dicted values. The response spectra during different periods and with differing site conditions are subsequently calculated using a damping ratio of 5%. Results show that large amplitude response spectra at four near source stations are higher than the design response spectrum of the Europe seismic design code of 2008, and that peak values of response spectra are focused on a range be tween 0 and 0.5 s. The earthquake caused relatively serious damage to Rieti, Italy, particularly to short period structures; this is mainly because： （1） the earthquake was a shallow destructive e vent and local buildings were built with un reinforced bricks and cement; and （2） the seismic for tification level was not high enough. In relation to these earthquake damage characteristics, it is evident that the central Italian region needs to improve seismic fortification during practical con struction to ensure the security level of structures.