318国道沿线芦山地震的震害特征与烈度区划探讨

Characteristics of Damage along National Highway 318 Induced by the Lushan Ms7.0 Earthquake and the Intensity Zonation

针对318国道雅安市政府路段向西一直到二郎山隧道东端沿线两侧的芦山地震震害特征进行总结,并按照《中国地震烈度表》进行地震烈度区划,确定不同地震烈度圈的分界线。同时,将调查结果和中国地震局发布的四川省芦山"4·20"7.0级强烈地震烈度图进行比较。研究表明:318国道沿线地震烈度全部低于Ⅸ度,Ⅷ度区的边界以天全县始阳镇为界即往东约偏移3 km,Ⅶ度区的边界以天全县紫石乡为界即往东偏移约2 km,Ⅵ度区的边界以二郎山隧道东端为界即往东偏移约8 km。同时,根据不同地震烈度圈的分界线,结合微观震中的位置,采用椭圆拟合芦山地震各烈度的等值线,探讨不同地震烈度圈的长半轴、短半轴和面积等。

Damage characteristics of both sides along national highway 318 from Ya＇an City Government House to the east side of Erlangshan tunnel during Lushan Ms7. 0 earthquake are summarized. According to the code of Chinese Seismic Intensity Scale,seismic intensities are zoned and dividing lines of different intensity ovals are determined. Meanwhile,results of field investigation and seismic intensity zonation issued by China Earthquake Administration are compared. Researches indicate that the seismic intensity along the whole national highway 318 is less than Ⅸ; the boundary of Ⅷ is the Shiyang country in Tianquan city,moving towards east about 3 km; the boundary of Ⅶ is the Zishi country in Tianquan city,moving towards east about 2 km; the boundary of Ⅵ is the east side of Erlangshan tunnel,moving towards east about 8 km. Meanwhile,according to the boundary of different seismic intensity ellipses,combined with microscopic epicenter location,contour-line of the ovals are fit with ellipses. The major semiaxis,minor semiaxis and area of different seismic intensity ellipses are discussed.