Behavioral Characteristics of the Yangsan Fault based on Geometric Analysis of Fault Slip

단층슬립의 기하분석에 의한 양산단층의 거동 특성

  • Published : 2009.09.30

Abstract

In order to assess the fault behavior by the geometric analysis of fault slip, the study area between Yangsan city and Shinkwang-myon, Pohang city along the strike of the Yangsan fault is divided into 5 domains($A{\sim}E$ domains) based on the strike change of main fault, the type of fault termination, the cyclic variation of fault zone width, deformation pattern of fault rocks and angular deviation of secondary shears. And, we would apply the relationship between the mode of fault sliding and the resultant deformation texture obtained from previous several experimental studies of simulated fault gouge to the study of the Yangsan fault. To understand sliding behavior of the fault we measured the data of fault attitude and fault slip, and analyzed relationships between the main fault and secondary Riedel shear along the Yangsan fault. The sliding behavioral patterns in each section were analyzed as followings; the straight sections of A, D and E domains were analyzed as the creeping section of stably sliding. In contrast, the curved section of B domain was analyzed as the locked section of stick-slip movement.

단층슬립의 기하분석에 의한 단층의 거동특성을 평가하고자 주단층의 주향변화, 단층 선단부의 발달 상태, 단층대의 폭의 주기적 변화, 단층암의 변형양상, 2차 소단층의 각관계를 근거로 양산단층의 주향을 따라 남쪽 양산에서 북쪽으로 포항시 신광면에 이르는 구간을 5개의 구역($A{\sim}E$)으로 구분하였다. 또한 가상의 단층비지를 대상으로 시행한 이전 여러 실험연구 결과들로부터 얻어진 단층작용의 운동 양상과 변형 조직과의 관계를 양산단층에 적용하고자 하였다. 단층의 미끄럼 거동을 이해하기 위하여 양산단층을 따라 단층의 자세와 단층슬립을 측정하였고, 주단층과 2차 소단층의 Riedel shear 각 관계를 분석하였다. 양산단층 각 구역에서 주단층과 2차 단열의 방향성 및 단층슬립을 이용하여 각 구역별 단층의 거동특성을 해석한 결과 A, D 및 E와 같은 직선구역들은 안정된 전단운동을 한 creeping 운동의 구역으로 평가되었고, 반대로 B와 같은 곡선구역은 stick-slip 운동을 한 locked 구역으로 평가되었다.

Keywords

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