摘要
计算发现,主应力方向和大小不同时,断层活动的方式不同,与主应力方向交角(θ_0)为65.2°至61.3°(β_0为24.8°至28.7°)时,断层克服摩擦阻力而滑动所需差应力△σ_0最小。△σ值越大,可滑动的断层范围(△θ=θ_1-θ_2)也越大。θ_1与θ_2以θ_0为对称,其极限为40.4°和90(β的极限为49.6°和0°)。接近或大于此极限值的断层是地震破裂断层。北京附近的这类断层是八宝山断层和南口——孙河断层,它们是重点监视目标。
The result of calculation reveals that the way of fault reactivation is dependent on the principal stress direction and magnitude: when the angle between directions of principal stress and fault plane θ_0 is about 65.2° to 61.3°( β_0 is 24.8° to 28.7°), the differential stress △σ=σ_(xx)-σ_(yy) between the maximum principal stress σ_(xx) and the minimum principal stress σ_(yy), needed for overcoming the friction drag and moving the fault, is smallest. The bigger the △σ, the larger the range △θ=θ_1-θ_2 of sliding fault. θ_1 and θ_2 are symmetrical to the θ_0. The extreme values of θ are 40.4° and 90° ( forβ, 49.6° and 0° ) The faults closing to or exceeding the extremum of θ are able to be earthquake rupture faults. This kind of faults around Beijing might be Babaoshan fault and Nankou—Sunhe fault. They are active faults and might be the major monitoring objectives.
出处
《地壳形变与地震》
CSCD
1989年第3期44-52,共9页
Crustal Deformation and Earthquake
