Fluids in seismicity

Anti-repeaters – earthquakes that happen in the same location but with opposite focal mechanisms – are widespread but under-recognised and likely result from fluid migration processes, suggests a synthesis of observations of these phenomena from a range of tectonic environments.

Factors such as fault mineralogy, roughness, temperature, geological settings, and fluid injection strategies influence seismicity-permeability coupling behavior of faults, with fault gouge controlling interactions in mature faults and rough surfaces governing them in incipient faults, according to a synthesis of theoretical, experimental, and numerical studies.

The Kuju volcanic area’s shallow magma margin features a low-amplitude reflection zone that allows pressurized fluids to migrate upward, causing diverse earthquake clusters with complex mechanisms, according to analysis of magma-related and hydrothermal structures in the Kuju volcanic area in Japan.

The spatiotemporal evolution of fluid-induced microearthquakes can be accurately forecasted using a transformer-based deep learning approach trained on hydraulic stimulation and microseismic history from the EGS Collab field experiment.

What makes slow earthquakes “slower” than ordinary earthquakes has long been enigmatic. This study presents the experimental reproduction of multiple slow earthquake statistics by shearing soft hydrogel particles in a viscous fluid.

Deep subducted sediments along the Lesser Antilles subduction zone act as a strong asperity on the plate interface and release fluids that drive hydrofracturing and interplate seismicity, according to analysis of a reprocessed multichannel seismic profile.

Post-injection aseismic slip in the Weiyuan shale gas field perturbed stress fields sufficiently to trigger the 2019 ML 5.6 induced mainshock, according to numerical modeling informed by an earthquake catalog for the preceding 11 months.

Seismic velocity changes near the subduction thrust of the Hikurangi subduction zone in New Zealand result from fluid pressure dynamics associated with deep slow-slip earthquakes, as revealed from receiver function analysis.

Migrating earthquake sequences from a wide range of tectonic contexts exhibit two distinct behaviors. One is linked to slow slip and characterized by elevated migration velocities and moments, and the other is related to fluid-induced processes, with lower velocities and moments.

Through fluid-injection fault-reactivation experiments and analysis, the authors here define and report the relationship between the maximum seismic magnitude and injection volume for fluid-injection triggered earthquakes.

Water expelled from subducting slabs has a strong control over seismic events, with changes in hot spring water chemistry recording the surge of slab derived water, according to geochemical studies of water samples from the Arima hot springs, Japan.

While foreshocks in nature are rare, dynamic slip in the laboratory is generally preceded by bursts of foreshocks. This study shows that laboratory foreshocks become increasingly rare at conditions that are more similar to pressure and stress conditions at average seismogenic depth.

This study provides evidence for the migration of deep energy sources along tectonic discontinuities in subduction zones and suggests causal relationships with brittle failure of hard rocks that may trigger seismic activity.

Geological structure and pore fluid pressure in the subduction zone forearc govern the size and recurrence of megathrust earthquakes in Chile, according to quasi-dynamic simulations of the seismic cycle.

Long-term saltwater disposal in western Canada triggers resurgent earthquakes by reactivating a complex fault system, according to a joint analysis of InSAR and seismic data which highlights the risk of long-term saltwater disposal.

Fluids at the plate interface are sourced from the dehydrating slab mantle beneath the Shumagin Gap in Alaska, and contribute to regional seismic risk by influencing rupture propagation, according to magnetotelluric observations and electrical resistivity modelling.