吉林地区波速比分布特征及构造意义

REGIONAL CHARACTERISTICS OF WAVE VELOCITY RATIO IN JILIN AREA AND THEIR TECTONIC IMPLICATIONS

利用吉林地区2001年1月至2013年6月模拟和数字化资料(共254次地震事件的P波和S波到时资料),采用单震多台和达法计算每个事件的平均波速比,重点分析吉林地区波速比的空间变化特征。为了保证计算结果的可信度,对收集到的震相数据和计算结果进行严格筛选和限定。结果表明,吉林地区波速比横向不均匀性显著,南北部差异较大。伊通-舒兰断裂带北侧波速比横向不均匀性突出,高低值异常区方向与NE向扶余-肇东断裂带一致;伊通-舒兰断裂带南侧波速比高值区域主要集中在火山区,其中长白山火山区北侧波速比低而西南侧较高,可能表明长白山下方低速异常体位于火山口的西南侧。通过分析波速比分布特征与地震活动的关系,认为在波速比高值区和高、低值过渡区为地震易发地带。

Using the analog and digital P and S wave data of 254 events from January 2001 to June 2013,we obtained the wave velocity ratio with the multi-station method and got the mean value for every earthquake. This study analyzes the spatial variation of the wave velocity ratios of Jilin area. To ensure the accuracy and stability of the calculated results,we carefully winnow the collected data and the calculated results. Our results show that there are strong lateral heterogeneity and difference between the south and north of Jilin area. The wave velocity ratio in the north part of Yitong-Shulan Fault shows strong lateral heterogeneity,the orientation of anomaly area for high and low wave velocity is in accordance with the NE-trending Fuyu-Zhaodong Fault; The high wave velocity ratio areas in the south part of Yitong-Shulan Fault mainly concentrate in the volcanic region,the wave velocity ratio in the southwest is little higher than that in the north part of Changbai Mountains volcanoes,suggesting that the low velocity abnormal body maybe locates in the southwest under Changbai Mountains,The study suggests that the high value zone and the transitional zone of high to low value are earthquakeprone zone by analyzing the distribution characteristic of wave velocity ratio and the earthquake activity.