Absorbent Porous Paper Reveals How Earthquakes Could be Mitigated

Abstract

Earthquakes nucleate when large amounts of elastic energy, stored in the earth's crust, are suddenly released due to abrupt sliding over a fault. Fluid injections can reactivate existing seismogenic faults and induce/trigger earthquakes by increasing fluid pressure. Here we develop an analogous experimental system of simultaneously loaded and wetted absorbent porous paper to quantify theoretically the process of wetting‐induced earthquakes. This strategy allows us to gradually release the stored energy by provoking low intensity tremors. We identify the key parameters that control the outcome of the applied injection strategy, which include the initial stress state, fault segmentation, and segment‐activation rate. Subsequent injections, initiated at high stress levels, can drive the system faster toward its instability point, nucleating a large earthquake. Starting at low stress levels, however, they can reduce the magnitude of the natural event by at least one unit.

Earthquake Control: An Emerging Application for Robust Control. Theory and Experimental Tests

“…In a real-scale scenario, fluid injections in the earth's crust change the fluid pore pressure over seismic faults [8]. As shown in [29] among others, this can destabilize the fault system and induce/trigger larger earthquakes. In order to illustrate this phenomenon, in Fig.…”

“…The dynamics of earthquakes can be represented, in average/energetical sense, with the spring-slider analogue system (see [1], [9], [10], [28], [29]) depicted in Fig. 1.…”

Preventing Instabilities and Inducing Controlled, Slow‐Slip in Frictionally Unstable Systems

“…Notice that if one wanted to stabilize the system by simply satisfying the stability condition emerging from the expression of the nucleation length (assuming that the frictional parameters are somehow known), then the average fluid pressure should be immediately increased to approximately 68 MPa in order to achieve a resulting effective normal stress equal to approximately 6 MPa. But even if this was possible, the slip‐rate would be still unmanageable (in the best case scenario, it would be equal to the far‐field tectonic velocity) and, most importantly, the rapid increase of the fluid pressure could trigger a rupture event (see also Tzortzopoulos et al., 2021 ).…”

“…But even if c) is taken at the maximum developed average velocity during the earthquake event (point A in Figure 9a), while the closed-loop one (d) at the maximum developed average velocity during the applied control strategy (point B in Figure 9c). this was possible, the slip-rate would be still unmanageable (in the best case scenario, it would be equal to the far-field tectonic velocity) and, most importantly, the rapid increase of the fluid pressure could trigger a rupture event (see also Tzortzopoulos et al, 2021).…”

“…However, the recent human activity, related to energy production, revived the need for fault stabilization and seismic risk reduction. Numerous laboratory and field experiments focused on determining factors influencing the transition from seismic to a‐seismic slip during fluid injections (see Cappa et al., 2019 ; Guglielmi et al., 2015 ; Scuderi & Collettini, 2018 ; Tinti et al., 2016 ; Tzortzopoulos et al., 2021 , among others). Seismic traffic‐light systems have been also proposed for minimizing seismicity and risks to acceptable levels (see Baisch et al., 2019 ; Bommer et al., 2006 ; Bommer et al., 2015 ; Bosman et al., 2016 ; Broccardo et al., 2020 ; Häring et al., 2008 ; Kwiatek et al., 2019 ; Verdon & Bommer, 2021 ; Walters et al., 2015 ).…”