Active interrogation of underground piezoelectric fabrics using high energy muon beams propagating across seismogenic faults

TL;DR

This paper advances the ERMES concept for actively interrogating tectonic stress in seismogenic faults by transmitting high-energy muon beams through quartz-rich rock and detecting piezoelectric-induced perturbations in the outgoing beam. Using Monte Carlo simulations with Fluka and Geant4, it shows that muons with energies up to $10\, ext{TeV}$ can traverse up to roughly $3\ \text{km}$ of rock with a substantial survival probability and a detectable residual energy, while the observed beam spot evolution encodes the piezoelectric response of embedded quartz. The study cross-validates simulation frameworks and introduces a muonic lens to refocus the large-emittance surviving beam, enabling practical downstream detection and signaling. Together these results suggest a pathway toward real-time monitoring of tectonic stress evolution as a potential earthquake precursor, with the caveat that detector optimization and geological realism remain key future steps.

Abstract

In this paper we extend a previous analysis of a newly conceived technique based on active interrogation of tectonic stress evolution in regions hosting active seismogenic faults. The aim is to monitor and detect stable and reliable precursor signals on an adequate time scale, well before an earthquake event, that can play a crucial role in activating alarms for civil protection systems. The precursor signal relies on continuous measurements of the time evolution of tectonic stress, obtained by interrogating underground, with a high energy collimated muon beam, the piezoelectric fabrics present in quartz rich granite like rocks surrounding a known seismogenic fault in the Earth crust. Beam propagation through the rock across the active fault conveys to a detector at the exit of the traversal information on the amplitude of the piezoelectric field, which scales with the tectonic stress applied to quartz crystals embedded in the rock. The system, named ERMES (Earthquake Reconnaissance using Muon beam Evolution in Silicon dioxide), differs from other techniques under study detecting electromagnetic signals generated by piezoelectricity outside the Earth crust, as it probes piezoelectric effects directly inside the source region of the associated electromagnetic field, namely the near field within quartz crystals rather than the far field in open space. We present a focused analysis of muon beam manipulation after rock traversal and before detection using a newly conceived muonic lens, and we explore the maximum rock penetration capability of a high energy muon beam, reaching about 3 km of rock thickness for a 10 TeV beam. Owing to the peculiarity of muon propagation through such kilometer scale targets, we cross checked previous FLUKA Monte Carlo simulations with Geant4 to clarify the secondary muons role generated by primary muon interactions in solid matter over long propagation lengths.

Figures (13)

• Figure 1: Muon energy loss and range in silicon dioxide (fused quartz, SiO$_2$) as a function of the muon kinetic energy $T$ (in GeV, logarithmic scale). Top panel: differential energy loss $dE/dz$, expressed in GeV per meter of propagation. Bottom panel: CSDA (Continuous Slowing Down Approximation) range in meters, representing the mean path length traveled by a muon before stopping in the material. Both quantities are obtained from data reported in ParticleDataGroup:2024cfk.
• Figure 2: Muon fluence for an initial 10 TeV muon beam, shown on a logarithmic color scale, as a function of propagation distance through a composite medium. The muons propagate first through 3 km of silicon dioxide (SiO$_2$) and subsequently through 500 m of air.
• Figure 3: Particle density distribution on the transverse plane at beam entrance (left panel) and after 3 km of propagation (right panel) in SiO$_2$. The density is shown on a logarithmic color scale.
• Figure 4: Energy distribution of the muon beam at different propagation depths in SiO$_2$. The spectra are shown after 1 km, 2 km, and 3 km of propagation, illustrating the progressive energy loss and spectral deformation of the beam as a function of depth in the material.
• Figure 5: Energy distribution of primary muons at various depths inside SiO$_2$. It is worth noting that the error bars are present, but they are barely visible, since the since the uncertainties on simulated data are very small.