Seismic and volcanic activities and aseismic movements as plate motion components in the Aegean area

Abstract

Slip rates varying between 0.22 and 2.18 cm yr −1 are determined from seismicity in several segments of the Aegean fore-arc and back-arc regions. The rate along the main zone of plate interaction is about 0.5 cm yr −1 while aseismic slip rate, equal to 2.5 or 0.5 cm yr −1 depending on the plate motion rate assumed, indicates that at least 50% of the plate motion is accommodated by creep. These values, with respect to the rate of volcanic eruption (= 0.13 eruptions per year/1000 km of arc length) reinforce the suggestion that active volcanism in subduction zones is related to aseismic subduction. The eruption rate is, however, anomalously low with respect to the degree of plate decoupling (= 0.83 or 0.5) implying that volcanism is not necessarily related to the degree of decoupling and suggesting that the high aseismic slip component of the plate motion is taken up by subcrustal seismicity. A tentative hypothesis is made that the Hellenic subduction zone is of intermediate type between the Marianas and Chile subduction types.