The low-frequency flat levels and corner frequencies of the aftershocks of the Kobe earthquake, together with the site effects of the recording stations, are inverted by using genetic algorithms. All records were corrected by the quality factor, Q, of propagation-path, and for each aftershock, a different omega-squared model was assumed such that the low-frequency flat levels and corner frequencies would minimize the standard deviation of the site effects at all stations. It was observed that site effects for rock sites showed significant amplification at high frequencies. This amplification was found to correlate with spectral ratios of records located at 70-m depth and at the surface for one of the stations. After estimating the seismic moment and the stress drop, it was observed that the relation of the seismic moment, M 0 , versus the corner frequency, fo, followed the scaling law M 0 ␣ fo ‫3מ‬ . Large values of stress drop were found around asperities on the fault zone and at depth.

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Understanding the relationship cause/effect between tectonic earthquakes and volcanic eruptions is a striking topic in Earth Sciences. Volcanoes erupt with variable reaction times as a consequence of the impact of seismic waves (i.e. dynamic stress) and changes in the stress field (i.e. static stress). In 2012, three large (Mw ≥ 7.3) subduction earthquakes struck Central America within a period of 10 weeks; subsequently, some volcanoes in the region erupted a few days after, while others took months or even years to erupt. Here, we show that these three earthquakes contributed to the increase in the number of volcanic eruptions during the 7 years that followed these seismic events. We found that only those volcanoes that were already in a critical state of unrest eventually erupted, which indicates that the earthquakes only prompted the eruptions. Therefore, we recommend the permanent monitoring of active volcanoes to reveal which are more susceptible to culminate into eruption in the aftermath of the next large-magnitude earthquake hits a region.

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