2-WAY COUPLING BETWEEN VESUVIUS ERUPTIONS AND SOUTHERN APENNINE EARTHQUAKES, ITALY, BY ELASTIC STRESS TRANSFER

During the past 1000 years, eruptions of Vesuvius have often been acco mpanied by large earthquakes in the Apennines 50-60 km to the northeas t. Statistical investigations had shown that earthquakes often precede d eruptions, typically by less than a decade, but did not provide a ph ysical explanation for the correlation, Here, we explore elastic stres s interaction between earthquakes and eruptions under the hypothesis t hat small stress changes can promote events when the Apennine normal f aults and the Vesuvius magma body are close to failure. We show that e arthquakes can promote eruptions by compressing the magma body at dept h and opening suitably oriented near-surface conduits. Voiding the mag ma body in turns brings these same normal faults closer to Coulomb fai lure, promoting earthquakes. Such a coupling is strongest if the magma reservoir is a dike oriented normal to the regional extension axis, p arallel to the Apennines, and the near-surface conduits and fissures a re oriented normal to the Apennines, This preferred orientation sugges ts that the eruptions issuing from such fissures should be most closel y linked in time to Apennine earthquakes. Large Apennine earthquakes s ince 1400 are calculated to have transferred more stress to Vesuvius t han all but the largest eruptions have transferred to Apennine faults, which may explain why earthquakes more commonly lead than follow erup tions. A two-way coupling may thus link earthquakes and Vesuvius erupt ions along a 100-km-long set of faults, We test the statistical signif icance of the earthquake-eruption correlation in the two-way coupling zone, and find a correlation significant at the 95% confidence level.