arXiv subjects

Qinghua Lei

Publications and source records attributed to Qinghua Lei.

15 recordsLinked to original sources

arXiv2026

Axial Seamount Eruption Forecasting Experiment

We introduce the Axial Seamount Eruption Forecasting Experiment (EFE), a real-time initiative designed to test the predictability of volcanic eruptions through a transparent, physics-based framework. The experiment is inspired by the Financial Bubble Experiment, adapting its principles of digital authentication, timestamped archiving, and delayed disclosure to the field of volcanology. The EFE implements a reproducible protocol in which each forecast is securely timestamped and cryptographically hashed (SHA-256) before being made public. The corresponding forecast documents, containing detailed diagnostics and probabilistic analyses, will be released after the next eruption or, if the forecasts are proven incorrect, at a later date. This procedure ensures full transparency while preventing premature interpretation or controversy surrounding public predictions. Forecasts will be issued monthly, or more frequently if required, using real-time monitoring data from the Ocean Observatories Initiative's Regional Cabled Array at Axial Seamount. By committing to publish all forecasts, successful or not, the EFE establishes a scientifically rigorous, falsifiable protocol to evaluate the limits of eruption forecasting. The ultimate goal is to transform eruption prediction into a cumulative and testable science founded on open verification, reproducibility, and physical understanding.

physics.geo-ph↗

arXiv2026

Two-branch retention behavior in unsaturated fractured rock driven by fracture-matrix flow partitioning

Upscaling unsaturated flow in fractured rock remains challenging because fractures and matrix often exhibit sharply contrasting hydraulic behaviors across saturation states. Here, we demonstrate that unsaturated flow undergoes a transition between matrix- and fracture-dominated regimes. Three-dimensional direct numerical simulations reveal that both relative permeability and capillary pressure curves display a robust two-branch structure. We analytically derive a generalized retention formulation that identifies a critical saturation marking the transition between the two distinct retention regimes and reproduces the two-branch behavior captured in the numerical simulations. An analytical expression for the critical pressure head is further derived to represent the limiting case of fully connected fracture networks, providing a physical explanation for the retention regime shift and showing good agreement with the numerical results for systems above the percolation threshold. Our results provide a mechanistic framework for understanding and upscaling unsaturated flow in fractured rock, with broad implications for hydrology and geophysics.

physics.geo-ph↗

arXiv2026

Primary creep encodes time to failure across laboratory and natural systems

Geomaterials often exhibit progressive creep characterized by an initial decelerating phase, frequently followed by an extended period of approximately constant deformation rate, and ultimately an accelerating regime leading to catastrophic failure. Despite extensive research, the timing of rupture and its relationship to the different creep phases, particularly in natural systems, remain poorly constrained. Here, we compile creep data from laboratory experiments on rocks, composites, papers, and glasses, together with observations from field systems including landslides, rockfalls, and glaciers. We find that the duration of the early-stage creep, marked by the transition to the minimum (or quasi-stationary) deformation rate, correlates nearly linearly with the time to rupture over five orders of magnitude. This unified scaling highlights that the early-time dynamics reflect the full evolution toward failure, providing a simple and robust framework for forecasting rupture across laboratory and natural systems.

physics.geo-ph↗

arXiv2026

Universal scaling between precursory duration and event size across mechanically driven geohazards

Many catastrophic events, including landslides, rockbursts, glacier breakoffs, and volcanic eruptions, are preceded by an observable acceleration phase that offers a critical window for early warning and hazard mitigation; however, the duration of this precursory phase remains poorly constrained across sites, scales, and hazard types. This limitation arises because the onset of acceleration is often identified using heuristic thresholds or empirical criteria. Here, we introduce a physics-based framework that objectively constrains the precursory duration from accelerating dynamics, without prescribing the onset a priori or being tied to any specific observable. We analyze a global dataset of 109 geohazard events across seven continents over the past century, quantifying their precursory durations in a consistent manner. For mechanically driven instabilities, we identify a robust scaling between precursory duration and failure volume spanning more than ten orders of magnitude. When expressed in terms of a characteristic system size, this relationship is close to linear, consistent with finite-size scaling near a dynamical critical point. This behavior indicates that precursory duration reflects the progressive growth of correlated deformation up to system-spanning scales, rather than local rupture kinetics. The resulting universality points to common organizing mechanisms governing the approach to catastrophic failure across mechanically driven geohazards.

physics.geo-ph↗

arXiv2026

On the coupled geometrical-mechanical origin of the earthquake b-value in fault networks

The Gutenberg-Richter law is a fundamental empirical law in seismology describing earthquake frequency-magnitude distributions, with one of its key parameters, the so-called b-value, quantifying the relative frequency of small versus large events. While the b-value is commonly interpreted as reflecting crustal heterogeneity and regional stress conditions, its underlying physical origin remains poorly understood, particularly the relative roles of geometrical versus mechanical controls. Here, we develop analytical and numerical models to elucidate the origin of the b-value in three-dimensional fault networks subject to mainshock-aftershock sequences. We demonstrate that the b-value emerges from the power-law scaling of fault rupture area together with the scaling of slip magnitude. Our results reveal a two-branch frequency-magnitude distribution, with the regime transition governed by fault criticality and fracture energy dissipation, while the transition magnitude reflects the finite population of faults triggered during the sequence. Our findings provide a physically grounded interpretation of earthquake b-values, establishing a link between fault mechanics and earthquake statistics.

physics.geo-ph↗

arXiv2025

An analytical framework to assess static versus dynamic triggering of fault-slip rockbursts

Fault-slip rockbursts, triggered by seismic rupture of nearby or remote faults, constitute a significant geohazard during deep underground excavations. Although these events occur frequently in underground projects, their underlying mechanisms are not yet fully understood. Most studies tacitly assume dynamic stress waves as the main triggering factor, often disregarding the role of coseismic static stress changes associated with fault slip. This paper introduces a novel analytical framework to diagnose both static and dynamic coseismic stress perturbations and quantify their contributions to fault-slip rockburst around a circular tunnel. Building on linear elastic fracture mechanics, seismic source theory, and the Kirsch solution, the model assesses whether coseismically elevated maximum tangential stress on the tunnel boundary under static and dynamic triggering effects is sufficient to induce failure around the tunnel. We extensively test our framework using synthetic case studies that represent typical fault-slip rockburst scenarios. Our results yield a rockburst hazard map that delineates regions of elevated triggering potential in the near-field and far-field of the seismogenic fault, and classify the triggering types as static, dynamic, or dual. We perform a comprehensive parametric sensitivity analysis to investigate how key factors, including seismic source characteristics, rock mass properties, and in-situ stress conditions, influence the spatial distribution of rockburst susceptibility. The model is further applied to a historical fault-slip rockburst event at the Gotthard Base Tunnel, effectively capturing the triggering mechanism of the observed failure. Our research provides a physically grounded and computationally efficient analytical framework with the results carrying significant implications for rockburst hazard assessments during deep underground excavations.

physics.geo-ph↗

arXiv2025

Emergence of Finite-Time Singularities from Accelerated Event Recurrence: Insights into the Mechanism of Catastrophic Failure

We develop a discrete-event modeling framework that captures the progression of geophysical systems toward catastrophic failure through sequences of distinct damage events. By representing system evolution as a succession of temporally accelerating and amplitude-varying events, the framework reveals how finite-time singularities, both logarithmic and power law types, naturally emerge from the interplay between shrinking interevent intervals and growing event magnitudes. This event-based perspective provides an intuitive physical understanding of rupture processes, highlighting how precursory signals such as accelerating strain rate, event frequency, and energy release can be traced back to simple underlying mechanisms. A mean-field formulation further links the observed power law exponents to the evolving stiffness of the system under constant or time-varying stress. Incorporating stochastic fluctuations, the model captures the inherent randomness of natural systems leading to the emergence of stochastic finite-time singular behavior. Altogether, this unified approach offers a simple conceptual and quantitative tool for interpreting the lead-up to failure in a wide range of geophysical settings.

physics.geo-ph↗

arXiv2025

Endo-exo classification of episodic rock creep in deep mines: Implications for forecasting catastrophic failure

Rock masses in deep underground environments under high in-situ stress often exhibit episodic creep behavior, driven by complex interactions between external perturbation and internal reorganization. The causes of these creep episodes and their link to potential catastrophic failure remain poorly understood. Here, we present a novel 'endo-exo' framework for analyzing episodic rock creep in deep underground mines, capturing the interplay between exogenous triggers (e.g., blasting and excavation) and endogenous processes (e.g., damage and healing within rock masses). The underlying physical mechanism involves cascades of locally triggered rock block movements due to fracturing and sliding. We identify four fundamental types of episodic dynamics, classified by the origin of disturbance (endogenous or exogenous) and the level of criticality (subcritical or critical). All four types exhibit power law relaxations with distinct exponents: 1+θ(exogenous subcritical), 1-θ(exogenous critical), 1-2θ(endogenous critical) and 0 (endogenous subcritical), all governed by a single parameter 0 < θ< 1. Our theoretical predictions are examined using the comprehensive dataset of a platinum mine in South Africa, where stopes display episodic closure behavior during successive mining operations. All creep episodes recorded can be accounted for in our classification with θ\approx 0.35\pm0.1, providing strong validation of our theory. This θvalue is interpreted in terms of a first-passage process driven by anomalous stress diffusion, represented by fractional Brownian motion or Lévy-type processes. Finally, we offer new insights into endo-exo interactions and the system's transition from episodic creep to catastrophic failure, with important implications for forecasting large-scale panel collapses.

physics.geo-ph↗

arXiv2025

Endo-exo framework for a unifying classification of episodic landslide movements

Landslides exhibit intermittent gravity-driven downslope movements developing over days to years before a possible major collapse, commonly boosted by external events like precipitations and earthquakes. The reasons behind these episodic movements and how they relate to the final instability remain poorly understood. Here, we develop a novel "endo-exo" theory to quantitatively diagnose landslide dynamics, capturing the interplay between exogenous stressors such as rainfall and endogenous damage/healing processes. We predict four distinct types of episodic landslide dynamics (endogenous/exogenous-subcritical/critical), characterized by power law relaxations with different exponents, all related to a single parameter \vartheta. These predictions are tested on the dataset of the Preonzo landslide, which exhibited multi-year episodic movements prior to a catastrophic collapse. All its sporadic activities can be accounted for within this classification with \vartheta \approx 0.45\pm0.1, providing strong support for our parsimonious theory. We find that the final collapse of this landslide is clearly preceded over 1-2 months by an increased frequency of medium/large velocities, signaling the transition into a catastrophic regime with amplifying positive feedbacks. Our research suggests that landslides may not permanently operate at a critical state, which has major implications for forecasting catastrophic failure events.

physics.geo-ph↗

arXiv2025

Modelling lined rock caverns subject to hydrogen embrittlement and cyclic pressurisation in fractured rock masses

The technology of lined rock cavern (LRC) with great geographical flexibility is a promising, cost-effective solution to underground hydrogen storage. However, the air-tight steel tanks used in this technology are susceptible to material degradation due to hydrogen embrittlement (HE), potentially leading to leakage and structural failure, especial for LRCs constructed in complex geological conditions. In this paper, we develop a 2D multiscale numerical model based on the finite element method to assess the impact of HE on the LRC performance in fractured rock masses under cyclic gas pressurisation. Within this framework, a large-scale model is used to simulate the deformation and damage evolution of both fractured rock and an LRC under in-situ stresses and internal gas pressurisation, while a small-scale model captures HE in the steel lining of the LRC. Our simulations reveal that damage in the rock, concrete, and steel degradation is strongly affected by pre-existing fractures and in-situ stresses. Our results also reveal the presence of a strong positive feedback between hydrogen concentration and stress redistribution in the steel lining. Moreover, a comparison between models with and without considering HE illuminates that hydrogen concentration significantly contributes to steel degradation, particularly during the long-term LRC operation, highlighting the critical role of HE in the safety and performance of the LRC. The findings and insights obtained from our work have important implications for the design optimisation and performance assessment of LRCs for sustainable underground hydrogen storage.

physics.comp-ph↗

arXiv2025

Log-Periodic Precursors to Volcanic Eruptions: Evidence from 34 Events

Forecasting volcanic eruptions remains a formidable challenge due to the inherent complexity and variability of volcanic processes. A key source of uncertainty arises from the sporadic nature of volcanic unrest, which is often characterised by intermittent phases of quiescent deceleration and sudden acceleration, rather than a consistent, predictable progression towards eruption. This seemingly erratic pattern complicates volcano forecasting as it challenges conventional time-to-failure models that often assume a simple smooth power law acceleration. We propose a log-periodic power law singularity model, which effectively captures the intermittent and non-monotonic rupture dynamics characteristic of reawakening volcanoes at the site scale. Mathematically, generalising the power law exponent by extending it from real to complex numbers, this model captures the partial break of continuous scale invariance to discrete scale invariance that is inherent to the intermittent dynamics of damage and rupture processes in heterogeneous crustal systems. By performing parametric and nonparametric tests on a large dataset of 34 historical eruptions worldwide, we present empirical evidence and theoretical arguments demonstrating the statistical significance of log-periodic oscillations decorating power law finite-time singularities during pre-eruptive volcanic unrest. Log-periodicity in volcanoes may originate from various mechanisms, including diffusion-dominated magma flow, magma-driven propagation of subparallel dykes, interaction between stress drop and stress corrosion, and/or interplay of inertia, damage, and healing within volcanic systems. Our results have important implications for volcano forecasting, because understanding and characterising log-periodicity could turn the intermittency of volcanic activity from a challenge into a valuable asset for improving predictions.

physics.geo-ph↗

arXiv2025

Oscillatory finite-time singularities in rockbursts

Forecasting violent rockbursts remains a formidable challenge due to significant uncertainties involved. One major uncertainty arises from the intermittency of rock failure processes, typically characterised by a series of progressively shorter quiescent phases punctuated by sudden accelerations, rather than a smooth continuous progression towards the final breakdown. This non-monotonic evolution of rock mass deformation complicates rockburst prediction, challenging conventional time-to-failure models that often assume a smooth power law accelerating behaviour. Here, we introduce a generalised time-to-failure model called log-periodic power law singularity (LPPLS) model to effectively capture the intermittent dynamics of damage and rupture processes in rock leading up to violent rockbursts. We perform parametric and nonparametric tests on 11 historical rockburst events at three underground mines, documenting empirical evidence and providing theoretical arguments to demonstrate the significance of log-periodic oscillatory power law finite-time singularities. Log-periodicity in these rockburst events is likely driven by the interaction of subparallel propagating cracks, the diffusion of stress-triggering processes, or the interplay between stress drop and stress corrosion. Our results and insights obtained have significant implications for not only understanding but also forecasting rockbursts, as recognising and characterising log-periodicity can help transform intermittency from traditionally perceived noise into valuable predictive information.

physics.geo-ph↗

arXiv2025

Log-Periodic Power Law Singularities in Landslide Dynamics: Statistical Evidence from 52 Crises

Landslide movements typically show a series of progressively shorter quiescent phases, punctuated by sudden bursts during an acceleration crisis. We propose that such intermittent rupture phenomena can be described by a log-periodic power law singularity model. Amounting mathematically to a generalization of the power law exponent from real to complex numbers, this model captures the partial break of continuous scale invariance to discrete scale invariance that is inherent to the intermittent dynamics of damage and rupture processes in heterogeneous geomaterials. By performing parametric and nonparametric tests on a large dataset of 52 landslides, we present empirical evidence and theoretical arguments demonstrating the statistical significance of log-periodic oscillations decorating power law finite-time singularities during landslide crises. Log-periodic landslide motions may stem from the interaction between frictional stress drop along geological structures and stress corrosion damage in rock bridges, as well as the interplay of inertia, damage, and healing.

physics.geo-ph↗

arXiv2024

Generalized failure law for landslides, rockbursts, glacier breakoffs, and volcanic eruptions

Catastrophic failures have momentous impact in many scientific and technological fields but remain challenging to understand and predict. One key difficulty lies in the burstiness of rupture phenomena, which typically involve a series of progressively shorter quiescent phases punctuated by sudden bursts, rather than a smooth continuous progression. This seemingly erratic pattern challenges the conventional power law assumption of continuous scale invariance. Here, we propose a generalized material failure law based on the log-periodic power law, which better captures the discrete scale invariance inherent in intermittent rupture dynamics. Our method's superiority is demonstrated through testing on 109 historical geohazard events, including landslides, rockbursts, glacier breakoffs, and volcanic eruptions. The results indicate that our method is general and robust, offering significant potential to forecast catastrophic failures.

physics.geo-ph↗

arXiv2021

Anderson localization and reentrant delocalization of tensorial elastic waves in two-dimensional fractured media

We study two-dimensional tensorial elastic wave transport in densely fractured media and document transitions from propagation to diffusion and to localization/delocalization. For large fracture stiffness, waves are propagative at the scale of the system. For small stiffness, multiple scattering prevails, such that waves are diffusive in disconnected fracture networks, and localized in connected ones with a strong multifractality of the intensity field. A reentrant delocalization is found in well-connected networks due to energy leakage via evanescent waves and cascades of mode conversion.

physics.geo-ph↗