黄河三角洲海底滑坡诱发条件——以埕岛海区为例

TRIGGERING FACTORS OF SUBMARINE LANDSLIDE IN THE YELLOW RIVER DELTA: TAKE THE CHENGDAO AREA AS AN EXAMPLE

2003年11月,黄河水下三角洲2条海底电缆断裂,推测与该区域冲蚀沟较为发育有关。通过多波束测深、浅地层剖面探测、侧扫声呐调查等物探调查方法对埕岛海区开展地质调查,以揭示黄河三角洲地区海底滑坡诱发条件。研究发现:埕岛海区海底存在多条冲蚀沟,软弱土层较为发育,冲蚀沟地层扰动较为明显;通过波浪海流对海底土体的影响分析,判断不同水深和不同土体在浪潮流作用下海底冲蚀沟的发育程度,得出海底滑坡的诱发条件,结合人类活动和海底自然坡度等因素的影响,分析研究区仍然具有发生海底滑坡的可能性。

Two submarine cables at the Yellow River underwater delta broke in November 2003, presumably owing to the relatively developed erosion ditches and landslide in the area. Geological survey was undertaken later in the Chengdao area in order to find out the reasons and conditions of the event. Various geophysical methods, such as multi-beam sounding, shallow profile exploration and side scan sonar survey, are applied. It is found that there do occur many erosional gullies on the sea bottom in the Chengdao area. Soft soil layers are common. Sediment disturbance are obvious in erosional trenches by the actions of wave and current. Based on the analysis of wave and current influences on seabed soil, the development degree of the erosional ditches and their relationship with water depth and soil properties are revealed. Upon the basis, triggering conditions of the seabed landslide are worked out. Increasing human activity is also the factor to be considered for the submarine landslide happened in the study area.