This paper proposes a new model—the Markov-modulated Hawkes process with stepwise decay (MMHPSD)—to investigate the variation in seismicity rate during a series of earthquake sequences including multiple main shocks. The MMHPSD is a self-exciting process which switches among different states, in each of which the process has distinguishable background seismicity and decay rates. Parameter estim...

In 2012 August 11 (12:23 UTC) a moderate earthquake with MW=6.4 (USGS) occurred between Ahar and Varzaghan towns in Azarbayjan Province at northwest of Iran. After eleven minutes another earthquake shook the area with MW=6.2 (USGS). These consecutive earthquakes followed by intensive sequences of aftershocks whereas the strongest one had MW=5.3 (USGS). In data processing including depth modific...

Compound aftershock sequences are of special interest because the decay of secondary aftershocks contains information about the mechanisms that generate all earthquakes. If earthquakes nucleate as a result of accelerating slip, growing cracks, or any similar failure process, then the rate of decay of aftershock sequences is a direct result of that failure process, as influenced by local materia...

The occurrence of aftershocks is a signature of physical systems exhibiting relaxation phenomena. They are observed in various natural or experimental systems and usually obey several non-trivial empirical laws. Here we consider a cellular automaton realization of a nonlinear viscoelastic slider-block model in order to infer the physical mechanisms of triggering responsible for the occurrence o...

1) quantile points at the selected times, S, corresponding to the expected probability and ± 1 SD (Table 1). The standard error in P rapidly decreases with increasing time after the mainshock due to the inclusion of current data. For example, at S = 1 day after the mainshock, the ± 1 SD range about the generic 1-day interval probability (0.052) is 0.034 to 0.075 (Table 1). Rydelek suggests esti...

We perform analytical and numerical studies of aftershock sequences following abrupt steps of strain in a rheologically layered model of the lithosphere. The model consists of a weak sedimentary layer, over a seismogenic zone governed by a viscoelastic damage rheology, underlain by a viscoelastic upper mantle. The damage rheology accounts for fundamental irreversible aspects of brittle rock def...

This study investigates the effects of earthquake types, magnitudes, and hysteretic behavior on the peak and residual ductility demands of inelastic single-degree-of-freedom systems and evaluates the effects of major aftershocks on the non-linear structural responses. An extensive dataset of real mainshock–aftershock sequences for Japanese earthquakes is developed. The constructed dataset is la...