arXiv subjects

J. B. Rundle

Publications and source records attributed to J. B. Rundle.

9 recordsLinked to original sources

arXiv2025

Seismic quiescence and activation prior to the 2025 M8.8 Kamchatka, Russia earthquake

The 2025 M8.8 Kamchatka earthquake in the Kamchatka-Kuril subduction system provides a unique opportunity to investigate the preparatory processes of a great subduction event. Despite Kamchatka's high seismic activity, the long-term evolution of seismicity preceding major ruptures has been poorly documented. Identifying temporal patterns-such as multiyear quiescence and short-term activation-is essential for understanding megathrust failure processes. We applied the Epidemic-Type Aftershock Sequence model and change-point analysis to earthquakes with M5+ within a 100-km radius of the 2025 mainshock epicenter, using the Advanced National Seismic System catalog spanning 1975-2025. This approach quantified temporal variations in the seismicity rate and detected statistically significant change points. We found a pronounced approximately 20-year quiescent interval beginning around mid-2003, followed by an abrupt activation that commenced with the M7.4 foreshock on 20 July 2025. Similar quiescence-to-activation sequences near the eventual hypocenter have been reported in previous studies for the 1997 M7.8 Kronotsky and 2006 M8.3 Simushirskoe earthquakes, which ruptured segments immediately north and south of the 2025 rupture, respectively. Together with these earlier studies, our findings suggest that such quiescence-to-activation transitions may represent a recurring preparatory process for megathrust earthquakes in the Kamchatka-Kuril subduction system, although this inference is based on a small number of events. Decadal-scale quiescence has also been reported off Hokkaido, Japan, overlapping the area assessed as having an elevated likelihood of a 17th-century-type M9-class earthquake. Given that Hokkaido is in the Kamchatka-Kuril subduction system, tracking a possible transition from quiescence to activation is important for situational awareness and time-dependent hazard assessment.

physics.geo-ph↗

arXiv2010

A damage-mechanics model for fracture nucleation and propagation

In this paper a composite model for earthquake rupture initiation and propagation is proposed. The model includes aspects of damage mechanics, fiber-bundle models, and slider-block models. An array of elements is introduced in analogy to the fibers of a fiber bundle. Time to failure for each element is specified from a Poisson distribution. The hazard rate is assumed to have a power-law dependence on stress. When an element fails it is removed, the stress on a failed element is redistributed uniformly to a specified number of neighboring elements in a given range of interaction. Damage is defined to be the fraction of elements that have failed. Time to failure and modes of rupture propagation are determined as a function of the hazard-rate exponent and the range of interaction.

physics.geo-ph↗

arXiv2009

A Cellular Automaton Model of Damage

We investigate the role of equilibrium methods and stress transfer range in describing the process of damage. We find that equilibrium approaches are not applicable to the description of damage and the catastrophic failure mechanism if the stress transfer is short ranged. In the long range limit, equilibrium methods apply only if the healing mechanism associated with ruptured elements is instantaneous. Furthermore we find that the nature of the catastrophic failure depends strongly on the stress transfer range. Long range transfer systems have a failure mechanism that resembles nucleation. In short range stress transfer systems, the catastrophic failure is a continuous process that, in some respects, resembles a critical point.

cond-mat.stat-mech↗

arXiv2007

The structure of fluctuations near mean-field critical points and spinodals and its implication for physical processes

We analyze the structure of fluctuations near critical points and spinodals in mean-field and near-mean-field systems. Unlike systems that are non-mean-field, for which a fluctuation can be represented by a single cluster in a properly chosen percolation model, a fluctuation in mean-field and near-mean-field systems consists of a large number of clusters, which we term fundamental clusters. The structure of the latter and the way that they form fluctuations has important physical consequences for phenomena as diverse as nucleation in supercooled liquids, spinodal decomposition and continuous ordering, and the statistical distribution of earthquakes. The effects due to the fundamental clusters implies that they are physical objects and not only mathematical constructs.

cond-mat.stat-mech↗

arXiv2006

Ergodicity in Natural Earthquake Fault Networks

Numerical simulations have shown that certain driven nonlinear systems can be characterized by mean-field statistical properties often associated with ergodic dynamics [C.D. Ferguson, W. Klein, and J.B. Rundle, Phys. Rev. E 60, 1359 (1999); D. Egolf, Science 287, 101 (2000)]. These driven mean-field threshold systems feature long-range interactions and can be treated as equilibrium-like systems with dynamics that are statistically stationary over long time intervals. Recently the equilibrium property of ergodicity was identified in an earthquake fault system, a natural driven threshold system, by means of the Thirumalai-Mountain (TM) fluctuation metric developed in the study of diffusive systems [K.F. Tiampo, J.B. Rundle, W. Klein, J.S. Sa Martins, and C. D. Ferguson, Phys. Rev. Lett. 91, 238501 (2003)]. In this work we analyze the seismicity of three naturally-occurring earthquake faults networks from a variety of tectonic settings in an attempt to investigate the range of applicability of effective ergodicity, using the TM metric and other, related statistics. Results suggest that, once variations in the catalog data resulting from technical and network issues are accounted for, all of these natural earthquake systems display stationary periods of metastable equilibrium and effective ergodicity that are disrupted by large events. We conclude that a constant rate of events is an important prerequisite for these periods of punctuated ergodicity, and that while the level of temporal variability in the spatial statistics is the controlling factor in the ergodic behavior of seismic networks, no single statistic is sufficient to ensure quantification of ergodicity. Specifically, we demonstrate that stationarity, while a necessary condition, is not sufficient to ensure ergodicity in fault systems.

physics.geo-ph↗

arXiv2006

Simulation of the Burridge-Knopoff Model of Earthquakes with Variable Range Stress Transfer

Simple models of earthquake faults are important for understanding the mechanisms for their observed behavior, such as Gutenberg-Richter scaling and the relation between large and small events, which is the basis for various forecasting methods. Although cellular automaton models have been studied extensively in the long-range stress transfer limit, this limit has not been studied for the Burridge-Knopoff model, which includes more realistic friction forces and inertia. We find that the latter model with long-range stress transfer exhibits qualitatively different behavior than both the long-range cellular automaton models and the usual Burridge-Knopoff model with nearest neighbor springs, depending on the nature of the velocity-weakening friction force. This result has important implications for our understanding of earthquakes and other driven dissipative systems.

cond-mat.stat-mech↗

arXiv2005

Pattern Informatics and Its Application for Optimal Forecasting of Large Earthquakes in Japan

Pattern informatics (PI) technique can be used to detect precursory seismic activation or quiescence and make earthquake forecast. Here we apply the PI method for optimal forecasting of large earthquakes in Japan, using the data catalogue maintained by the Japan Meteorological Agency. The PI method is tested to forecast large (magnitude m >= 5) earthquakes for the time period 1995-2004 in the Kobe region. Visual inspection and statistical testing show that the optimized PI method has forecasting skill, relative to the seismic intensity data often used as a standard null hypothesis. Moreover, we find a retrospective forecast that the 1995 Kobe earthquake (m = 7.2) falls in a seismically anomalous area. Another approach to test the forecasting algorithm is to create a future potential map for large (m >= 5) earthquake events. This is illustrated using the Kobe and Tokyo regions for the forecast period 2000-2009. Based on the resulting Kobe map we point out several forecasted areas: the epicentral area of the 1995 Kobe earthquake, the Wakayama area, the Mie area, and the Aichi area. The Tokyo forecasted map was created prior to the occurrence of the Oct. 23, 2004 Niigata earthquake (m = 6.8) and the principal aftershocks with m >= 5.0. We find that these events occurred in a forecasted area in the Tokyo map. The PI technique for regional seismicity observation substantiates an example showing considerable promise as an intermediate-term earthquake forecasting in Japan.

physics.geo-ph↗

arXiv2002

Precursory dynamics in threshold systems

A precursory dynamics, motivated by the analysis of recent experiments on solid-on-solid friction, is introduced in a continuous cellular automaton that mimics the essential physical contents of earthquake source processes. The resulting system of equations for the inter-event cycle can be decoupled and yields an analytical solution in the mean-field limit, exhibiting a smoothing effect of the dynamics on the stress field. Simulation results show the resulting departure from scaling at the large-event end of the frequency distribution, and support claims that the field leakage may parametrize the superposition of scaling and characteristic regimes observed in real earthquake faults.

cond-mat.stat-mech↗

arXiv2000

Scaling in a cellular automaton model of earthquake faults

We present theoretical arguments and simulation data indicating that the scaling of earthquake events in models of faults with long-range stress transfer is composed of at least three distinct regions. These regions correspond to three classes of earthquakes with different underlying physical mechanisms. In addition to the events that exhibit scaling, there are larger ``breakout'' events that are not on the scaling plot. We discuss the interpretation of these events as fluctuations in the vicinity of a spinodal critical point.

cond-mat.stat-mech↗