We study whether the shallow volcanic seismic tremors related to the bradyseism observed at the Phlegraean Fields (Campi Flegrei, Pozzuoli, and Naples) from 2008 to 2020 by the Osservatorio Vesuviano could be partially triggered by local rainfall events. We use the daily rainfall record measured at the nearby Meteorological Observatory of San Marcellino in Naples and develop two empirical models to simulate the local seismicity starting from the hypothesized rainfall-water effect under different scenarios. We found statistically significant correlations between the volcanic tremors at the Phlegraean Fields and our rainfall model during years of low bradyseism. More specifically, we observe that large amounts and continuous periods of rainfall could trigger, from a few days to 1 or 2 weeks, seismic swarms with magnitudes up to M = 3. The results indicate that, on long timescales, the seismicity at the Phlegraean Fields is very sensitive to the endogenous pressure from the deep magmatic system causing the bradyseism, but meteoric water infiltration could play an important triggering effect on short timescales of days or weeks. Rainfall water likely penetrates deeply into the highly fractured and hot shallow-water-saturated subsurface that characterizes the region, reduces the strength and stiffness of the soil and, finally, boils when it mixes with the hot hydrothermal magmatic fluids migrating upward. The structural collapse of the saturated fractured soil and the mixing of the meteoric fluid with the hot deep fluids triggers the local seismic activity.

中文翻译：

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降雨触发玄武岩田间火山震

我们研究了维苏威火山（Osservatorio Vesuviano）在2008年至2020年间在Phlegraean油田（Campi Flegrei，Pozzuoli和那不勒斯）观测到的与布雷迪斯地震有关的浅层火山地震，是否可能部分由局部降雨事件触发。我们使用在那不勒斯附近的圣马塞利诺气象台附近测得的每日降雨记录，并开发了两个经验模型，从假设的降雨-水效应在不同情况下开始，模拟了当地的地震活动。在低缓震年代，我们发现了Phlegraean油田的火山震与我们的降雨模型之间的统计显着相关性。更具体地说，我们观察到，连续几天的大量降雨可能会触发从几天到一到两周不等的地震群M =3。结果表明，在很长的时间尺度上，Phlegraean油田的地震活动对深层岩浆系统引起的缓震的内生压力非常敏感，但是，快速的水渗透可能会在短短的几天内发挥重要的触发作用。或几周。降雨水可能会深深地渗透到该区域的特征，即高度裂缝化的浅水饱和地下，降低土壤的强度和刚度，最后与向上迁移的热液热岩浆流体混合时会沸腾。饱和裂缝性土壤的结构坍塌以及流星流体与热深层流体的混合触发了局部地震活动。