Interoccurrence times and seismic hazard for upper-crustal volcanic chain earthquakes in El Salvador: are they Poissonian distributed?

Cross-validated Probabilistic Seismic Hazard 

“…Poisson model setting a fixed lifetime would mislead the resulting spectral accelerations for design. Although the hazard assessment gives spectral motions for the subduction interface zone, we corroborated the lifetime location-dependency due to the volcanic chain zone's influence at three sites under analysis based on Salazar (2021). We confirm that for the nearby sites to the volcanoes centers -San Salvador city and Port of Acajutla -a lifetime of 50 and 60 years matches time-independent and dependent models; a lifetime of 75 years is suitable for the Town of Arcatao 55 km away from the volcanic zone axis (Fig.…”

“…The reverse-slip focal mechanism obeys Hauksson (1990), yielding rakes angles of 45⁰ to 135⁰ and within ±20⁰ of the strike of the trench. The northern limit of the interface subduction zone matches the southern limit of the volcanic chain seismogenic source in Central America (Salazar, 2021).…”

“…A key consideration when using time-dependent models for calculating the probability of exceedance in Eq. 5 is to set a lifetime L of one year to consider that a level of motion might be exceeded in the next year after the selected elapse time for a specific earthquake size (Salazar, 2021). f) For the free-zone methods: Table 3 shows the magnitude and epicentral uncertainties adopted.…”

“…However, there is a lack of a validation procedure in the results of a memoryless seismic hazard assessment; although, in some cases, this method overestimates peak ground accelerations compared with historical data in California and other parts of the world (Salditch et al, 2020;Stein et al, 2017). Salazar (2021) studied earthquake interoccurrence times using Weibull and Poisson magnitude probabilities distributions connected with hazard models for the volcanic chain in El Salvador and neighboring Central American countries. Within this article, we augment the work of Salazar (2021) for the interface subduction zone in the region and propose a methodology to cross-validate the classical time-independent seismic hazard schemes via a comparison of time-dependent calculations in a rigid and free-zone fashion.…”

“…Salazar (2021) studied earthquake interoccurrence times using Weibull and Poisson magnitude probabilities distributions connected with hazard models for the volcanic chain in El Salvador and neighboring Central American countries. Within this article, we augment the work of Salazar (2021) for the interface subduction zone in the region and propose a methodology to cross-validate the classical time-independent seismic hazard schemes via a comparison of time-dependent calculations in a rigid and free-zone fashion.…”