Antigorite’s anisotropy impacts seismicity of intermediate-depth earthquakes
In some subduction zones, intermediate-depth earthquakes (~70–300 km depth) occur along two separate planes, known as double seismic zones. The subduction system in eastern Taiwan has a similar feature with shallower double seismic zone. Mechanisms forming such intriguing seismicity, however, remain inconclusive. The research, led by Dr. Wen-Pin Hsieh, Research Fellow at the Institute of Earth Sciences, Academia Sinica, has precisely measured the thermal conductivity of antigorite, an important serpentine mineral in subducting slabs, at high pressure-temperature conditions along slab subduction. The study demonstrated that antigorite has a strong thermal conductivity anisotropy. Combined with numerical modeling on slab’s thermal evolution, the team further showed that such strong thermal conductivity anisotropy combined with shear-induced crystal-preferred-orientation creates a thermal blanket effect that suppresses heat flow, significantly affecting slab’s thermal evolution and promoting dehydration embrittlement. Meanwhile, such effect also facilitates thermal runaway, a positive feedback accumulating heat, to trigger intermediate-depth earthquakes. These exciting findings highlight the important role that hydrous minerals play on the thermal state of a slab and the fundamental mechanisms triggering deep earthquakes. This research has been published on June 18, 2024 in Nature Communications. The first author of this research, Yu-Hsiang Chien, is a PhD candidate of TIGP-ESS at Academia Sinica, and coauthors include Yi-Chi Tsao of IES, and Dr. Enrico Marzotto of GeoForschungsZentrum (GFZ), Germany.
Chien, YH., Marzotto, E., Tsao, YC. et al. Anisotropic thermal conductivity of antigorite along slab subduction impacts seismicity of intermediate-depth earthquakes. Nat Commun 15, 5198 (2024).
Article link: https://www.nature.com/articles/s41467-024-49418-3
Post by Academia Sinica: https://www.sinica.edu.tw/en/News_Content/36/2645
