Scaling properties of seismicity and faulting

Telesca

2022

Sci Rep

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Faults become more and more responsive to stress perturbations as instability mounts. We utilize this property in order to identify the different phases of the seismic cycle. Our analysis provides new insights about the features of impending mainshocks, which are proposed to emerge from a large-scale crustal-weakening preparation process whose duration depends on their seismic moments, according to the power-law T $$\propto$$ ∝ M$$_{0}^{1/3}$$ 0 1 / 3 for M$$_{0}$$ 0 $$\le$$ ≤ 10$$^{19}$$ 19 N m. Moreover, further studies are performed about the impact of tidal stress perturbation on seismicity; in particular, the relationship between frequency-magnitude scaling and perturbations is discussed, showing that the sensitivity of earthquakes to solid Earth tides decreases as their magnitudes increase.

Section: Discussionmentioning

confidence: 99%

Correlation between seismic activity and tidal stress perturbations highlights growing instability within the brittle crust

Telesca

2022

Sci Rep

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“…The roughness of the dislocation surface is proven to affect stress accumulation, strain accommodation and release 24 . In this regard, geometrical complexities, and heterogeneity, i.e., state of fracturing and fault topology, represent the hidden factor shaping the seismic dynamics from coseismic to spatial and temporal scale of tectonics [25][26][27] . Fault topology is in fact suggested to control the statistical properties of seismicity, producing a wide range of behaviors with different varying recurrence times, periodicity, and consistency over time in seismic time series, its magnitude and radiation pattern 28 .…”

mentioning

confidence: 99%

The impact of faulting complexity and type on earthquake rupture dynamics

2022

Commun Earth Environ

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The statistical properties of seismicity are known to be affected by several factors such as the rheological parameters of rocks. We analysed the earthquake double-couple as a function of the faulting type. Here we show that it impacts the moment tensors of earthquakes: thrust-faulting events are characterized by higher double-couple components with respect to strike-slip- and normal-faulting earthquakes. Our results are coherent with the stress dependence of the scaling exponent of the Gutenberg-Richter law, which is anticorrelated to the double-couple. We suggest that the structural and tectonic control of seismicity may have its origin in the complexity of the seismogenic source marked by the width of the cataclastic damage zone and by the slip of different fault planes during the same seismic event; the sharper and concentrated the slip as along faults, the higher the double-couple. This phenomenon may introduce bias in magnitude estimation, with possible impact on seismic forecasting.

“…In [336] is instead showed that, using bifurcation theory, the Omori scaling exponent can be written in the form p = 1+θ , where θ is a small parameter which can also be negative. A recent research, [31], based on updated results suggests a slightly different empirical relation…”

Section: The Effect Of Terrestrial Gradients On the Features Of Earth...mentioning

confidence: 99%

“…What is certain is that earthquake dynamics evolves such that crustal volumes can be displaced, in order to improve the state of mechanical stability of fault interfaces, by optimizing the total energy gain produced via fault segment breaking constrained by dynamic conditions. Hence, given the seismic moment acting as a dislocation constraint, M, which depends on the deformation rates of local geodynamics, seismicity optimizes the triggering power of crack propagation, so that both seismic sequences and single earthquakes are ultimately driven by fault disorder (spatial distribution of barriers and asperities) [31]. In this view, the maturity level of fault damage zones may play an important role in featuring seismicity.…”

Section: The Effect Of Relative Plate Motionsmentioning

confidence: 99%

“…Classical seismology explains what happens during a few seconds of fault slip following rock breakdown, with the consequent radiation of seismic waves, while statistical seismology describes how seismicity occurs in space and time. On the other hand, seismic sequences follow the rules of statistical seismology, mainly grounded on two fundamental mathematical power-law frequency-size distributions, the so-called Gutenberg-Richter and Omori-Utsu laws, respectively describing the frequency of seismic events as a function of their magnitudes and the temporal attenuation of seismic activity with time after a mainshock [28][29][30][31]. In our article, we review some significant results in geodynamics and earthquake geology following the thread of gradients shaping our planet; a wide discussion is realized to compare models and observations, describing successes, but also underlying inconsistencies, paying great attention to open questions and lively scientific debates.…”

Section: Introductionmentioning

confidence: 99%

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Earth’s gradients as the engine of plate tectonics and earthquakes

2022

Riv. Nuovo Cim.

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The processes occurring on the Earth are controlled by several gradients. The surface of the Planet is featured by complex geological patterns produced by both endogenous and exogenous phenomena. The lack of direct investigations still makes Earth interior poorly understood and prevents complete clarification of the mechanisms ruling geodynamics and tectonics. Nowadays, slab-pull is considered the force with the greatest impact on plate motions, but also ridge-push, trench suction and physico-chemical heterogeneities are thought to play an important role. However, several counterarguments suggest that these mechanisms are insufficient to explain plate tectonics. While large part of the scientific community agreed that either bottom-up or top-down driven mantle convection is the cause of lithospheric displacements, geodetic observations and geodynamic models also support an astronomical contribution to plate motions. Moreover, several evidences indicate that tectonic plates follow a mainstream and how the lithosphere has a roughly westerly drift with respect to the asthenospheric mantle. An even more wide-open debate rises for the occurrence of earthquakes, which should be framed within the different tectonic setting, which affects the spatial and temporal properties of seismicity. In extensional regions, the dominant source of energy is given by gravitational potential, whereas in strike-slip faults and thrusts, earthquakes mainly dissipate elastic potential energy indeed. In the present article, a review is given of the most significant results of the last years in the field of geodynamics and earthquake geology following the common thread of gradients, which ultimately shape our planet.