Kostić Srđan, Franović Igor, Perc Matjaž, Vasović Nebojša, Todorović Kristina
Department of Geology, University of Belgrade, Faculty of Mining and Geology, Serbia.
Scientific Computing Lab., Institute of Physics, University of Belgrade, PO Box 68, 11080 Beograd-Zemun, Serbia.
Sci Rep. 2014 Jun 23;4:5401. doi: 10.1038/srep05401.
The study is focused on the effect of transient external force induced by a passing seismic wave on fault motion in different creep regimes. Displacement along the fault is represented by the movement of a spring-block model, whereby the uniform and oscillatory motion correspond to the fault dynamics in post-seismic and inter-seismic creep regime, respectively. The effect of the external force is introduced as a change of block acceleration in the form of a sine wave scaled by an exponential pulse. Model dynamics is examined for variable parameters of the induced acceleration changes in reference to periodic oscillations of the unperturbed system above the supercritical Hopf bifurcation curve. The analysis indicates the occurrence of weak irregular oscillations if external force acts in the post-seismic creep regime. When fault motion is exposed to external force in the inter-seismic creep regime, one finds the transition to quasiperiodic- or chaos-like motion, which we attribute to the precursory creep regime and seismic motion, respectively. If the triggered acceleration changes are of longer duration, a reverse transition from inter-seismic to post-seismic creep regime is detected on a larger time scale.
该研究聚焦于地震波通过时产生的瞬态外力对不同蠕变状态下断层运动的影响。沿断层的位移由弹簧 - 滑块模型的运动表示，其中匀速运动和振荡运动分别对应于震后和震间蠕变状态下的断层动力学。外力的影响以由指数脉冲缩放的正弦波形式的滑块加速度变化引入。针对超临界霍普夫分岔曲线之上未受扰动系统的周期性振荡，研究了模型动力学随诱导加速度变化的可变参数的情况。分析表明，如果外力作用于震后蠕变状态，会出现微弱的不规则振荡。当断层运动在震间蠕变状态下受到外力作用时，会发现向准周期或混沌状运动的转变，我们分别将其归因于前兆蠕变状态和地震运动。如果触发的加速度变化持续时间更长，则在更大的时间尺度上会检测到从震间蠕变状态到震后蠕变状态的反向转变。
