《工程地质》第二章——活断层地震.ppt

* * 工 程 地 质 学 活断层 地震 水库诱发地震 活断层的工程地质意义 活断层：一般理解为目前还在持续活动的断层，或在历史时期 或近期地质时期（11000a～35000a间）活动过、极有可能在不远的将来（一般理解为重要建筑物如大坝、核电站的使用年限之内，约100a ～ 200a）重新活动的断层。 ⒉ 活动特点 蠕滑（稳滑）—— 持续不断缓慢蠕动 粘滑 —— 间断性、周期性突然错断，常伴有地震 The Landers fault (red lines at left) and the Hector Mine fault and its aftershocks (red lines and circles at right). The Hector Mine earthquake was a magnitude 7.1, and it produced thousands of aftershocks. (Image courtesy of Egill Hauksson, Caltech) ⒊ 活动强度 以错动速率判定 速率变化特点 相当缓慢，1mm/a已属强活动断层 圣安德列斯断层（最有名的）仅5cm/a San Andreas Fault Through Carrizo Plain The San Andreas fault cuts spectacularly across the Carrizo Plain of California in this view looking to the northwest toward Soda Lake (white salt flat visible on the horizon). Streams draining off the Temblor Range to the east (lower right of picture) are offset to the north by right-lateral strike-slip fault motion along the San Andreas. The San Andreas marks the boundary between the Pacific Plate to the west and the North American Plate to the east, and is among the most active fault systems in the world. Geologists believe that the total accumulated displacement from earthquakes and creep is at least 550 kilometers along the San Andreas fault since it came into being about 15-20 million years ago. The entire San Andreas fault system is more than 1300 kilometers long and extends to depths of at least 16 kilometers within the Earth. In detail, the fault is a complex zone of crushed and broken rock from a few hundred meters to several kilometers wide. Many smaller faults branch from and join the San Andreas fault zone. ⒋ 活动性断层判定标志 ⑴ 必威体育精装版沉积层被错断（Q3以来的地层 直接测量数据） 美国南加州莫哈维沙漠中的圣安德烈亚斯断层的活动，将第四系中的沟壑错开 图中充当标尺的小伙是UC Davis地质系大地构造专业研究生Peter Gold，何鹏摄于2009年4月26日 断层错动方向 ⑵ 地形地貌标志（古建筑被错断 山地、平原地貌突变等） ⑶ 断层物质绝对年龄测试结果 ⒌ 研究 意义 ·它的活动会直接损害跨断层修建或与断层邻近的建筑物 The town of Hollister has the dubious distinction of having been built directly on top of an active creeping fault. The Calavera