摘要
通过在福建沿海边缘陆域地区活动断裂带附近进行水压致裂原地应力测量,得到了地表浅部构造应力的大小、方向和分布特征.根据实测的地应力资料,用库仑摩擦滑动准则分析研究了断裂带的性质和活动性.结果表明:①沿海岸线边缘自北向南,其最大水平主压应力方向为北西向,与测区北西向断裂带走向近于平行,与地质构造、跨断层形变测量等方法反映的主压应力方向大体一致,与震源机制解反映的主压应力方向夹角20°左右;②水平主应力值随深度增加而增大,与垂直应力值的关系为SH＞SV＞Sh和SH≈SV＞Sh,应力状态有利于走滑断层和正断层活动;③利用库仑摩擦滑动准则,摩擦强度取0.6～1.0分析,断层附近的现今地应力状态达到或超过产生正断层摩擦滑动的临界值,表明测区现今构造活动以正断层为主;④反映出本区现今构造应力场的力源主要来自太平洋板块向西和菲律宾板块向北西对欧亚板块的水平挤压作用.
The in-situ hydraulic fracturing stress measurements have been carried out around the coastal marginal land in Fujian Province. And the characteristics of magnitude, direction and distribution of tectonic stress have been obtained. Based on the observed stress data, the character and activity of fault zone are analyzed and studied in the paper according to the Coulomb friction criteria. ① The maximum horizontal principal compressive stress is in the NW-WNW direction from the north to the south along the coastline verge, which is parallel to the strike of the NW-trending fault zone, consistent with the direction of principal compressive stress obtained from geological structure and across-fault deformation data, and different from that reflected by focal mechanism solution by about 20°. ② The horizontal principal stress increases with depth, the relation among three stresses is SH〉Sv〉Sh or SH≈Sv〉Sh, and the stress state is liable to normal fault and strike-slip fault activities. ③ According to Coulomb friction criteria and taking the friction strength μ as 0.6～1.0 for analysis, the stress state reaching or exceeding the threshold for normal-fault frictional sliding near the fault implies that the current tectonic activity in the measuring area is mainly normal faulting. ④ The force source of current tectonic stress field comes mainly from the westward and northwestward horizontal extrusions from the Pacific and Philippine Plates respectively to the Eurasian Plate.
出处
《地震学报》
CSCD
北大核心
2005年第5期508-514,共7页
Acta Seismologica Sinica
基金
国家发展与改革委员会发改投资[2004]1138资助.
关键词
福建沿海
活动断裂带
水压致裂地应力测量
库仑摩擦滑动准则
Fujian coast
active fault zone
hydraulic fracturing stress measurement
Coulomb friction criteria
