Impact of chlorite dehydration on intermediate-depth earthquakes in subducting slabs

Abstract

AbstractIntermediate-depth earthquakes are common in the double seismic structures of many subduction zones under high pressures (~1–4 GPa). Serpentine dehydration exhibits well-established links with double seismic zone earthquakes. Additionally, dehydration of several hydrous minerals including lawsonite and chlorite underlying the upper and lower layers, respectively, may be responsible for intermediate-depth earthquakes. Here, we present experimental evidence suggesting that chlorite dehydration can trigger intermediate-depth earthquakes at the lower plane (~700 °C). We conducted deformation experiments on chlorite peridotite under high-pressure (0.5–2.5 GPa) and high-temperature (500–750 °C) using a modified Griggs apparatus. Experiments revealed the presence of faults in samples that had undergone partial chlorite dehydration with the presence of the dehydration product Ca-amphibole along these faults. Our findings confirm, together with correlation studies between seismicity and mineral stability, that a part of intermediate-depth seismicity in the lower plane of double seismic zones can be attributed to chlorite dehydration.