甘肃礼县至罗家堡断裂带沿线地质灾害分布规律及断层效应研究

Research on the distribution law of geological disasters and fault effect along the Lixian-Luojiabu fault zone in Gansu

甘肃礼县至罗家堡断裂带是西秦岭活动块体内部的一条相对活动断裂,区内地震活动性强,地质灾害较发育。通过资料搜集、遥感解译和野外调查,总结了该断裂带沿线的地质灾害分布规律,并基于GIS技术开展了地震地质灾害断层效应研究。结果表明,礼县至罗家堡断裂带沿线的地质灾害在历史时间上绝大部分发生在1654年罗家堡地震同期及之后至今的时间范围内,在水平空间上具有区域分布的不均衡性、沿沟谷的成带性和流域的集中性等特点,在垂直空间上斜坡各部位发育的地质灾害数量相差不大,但大部分地震滑坡的剪出口位于斜坡中部及上部。区内断层效应作用较明显,距断裂带越近,地震地质灾害发育数量和密度越大;活动断裂的上盘比下盘地震地质灾害分布密度更大;地震地质灾害的优势主滑方向近似垂直于法阵断裂走向;越靠近极震区,地震地质灾害点密度尽管有所增加,但增加速率明显减小;随着离极震区越来越近,地震烈度越来越大,尽管单位面积发育的地震地质灾害点数有增长缓慢的趋势,但地震地质灾害面积增长速率却是直线上升的。

Lixian-Luojiabu fault zone in Gansu is a relatively active fault within the active block of the West Qinling Mountains.The seismic activity in the area is strong and the geological disasters are relatively developed.Through data collection,remote sensing interpretation and field investigation,the distribution law of geological disasters along the fault zone is summarized,and the fault effect of earthquake geological disasters is carried out based on GIS technology.The results show that most of the geological disasters along the Lixian-Luojiabu fault zone occurred in the time range of the 1654 Luojiabu earthquake in the same period and since then,and there is an uneven regional distribution in the horizontal space.The characteristics of the zoning along the valley and the concentration of the drainage basin,the number of geological disasters developed in each part of the slope in the vertical space is not much different,but most of the shear outlets of seismic landslides are located in the middle and upper parts of the slope.The fault effect in the area is obvious.The closer to the buffer zone,the greater the number and density of earthquake geological disasters.The hanging wall of active faults is more densely distributed than the foot wall of earthquake geological disasters.The dominant sliding direction of earthquake geological disasters is approximately perpendicular to the direction of the normal fault.The closer to the extreme earthquake zone,although the density of earthquake geological disasters increases,the increase rate decreases significantly.It is getting closer to the extreme earthquake zone,and the earthquake intensity is getting bigger and bigger.Although the number of earthquake geological disasters per unit area has a slow growth trend,the growth rate of the area of earthquake geological disasters has risen linearly.