Abstract. Theoretical approaches to earthquake instabilities propose shear-dominated instabilities as a source mechanism. Here we take a fresh look at the role of possible volumetric instabilities preceding a shear instability. We investigate the phenomena that may prepare earthquake instabilities using the coupling of Thermo-Hydro-Mechano-Chemical reaction-diffusion equations in a THMC diffusion matrix. We show that the off-diagonal cross-diffusivities can give rise to a new class of waves known as cross-diffusion waves. Their unique property is that for critical conditions cross-diffusion waves can funnel wave energy into a quasi-stationary wave focus from large to small-scale. The equivalent extreme event in ocean waves and optical fibres leads to the appearance of rogue waves and high energy pulses of light in lasers. In the context of hydromechanical coupling, a rogue wave would appear as a sudden fluid pressure spike on the future fault plane. This is here interpreted as a trigger for the ultimate (shear) seismic moment release.

中文翻译：

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交叉扩散波引发多尺度，多物理场不稳定性：在地震中的应用

摘要。地震失稳的理论方法提出以剪切力为主的失稳为震源机制。在这里，我们重新审视了剪切不稳定性之前可能存在的体积不稳定性的作用。我们使用THMC扩散矩阵中的热-水力-化学-化学反应扩散方程来研究可能造成地震不稳定的现象。我们证明了非对角交叉扩散会引起一类称为交叉扩散波的新波。它们的独特特性是，在临界条件下，交叉扩散波可以将波能集中到从大到小的准平稳波焦点。海浪和光纤中的等效极端事件导致流氓波的出现和激光中的高能量脉冲。在流体力学耦合的情况下，流浪将作为未来故障平面上的突然的流体压力峰值出现。在这里，这被解释为最终（剪切）地震力矩释放的触发。