Objective Hydrous minerals are important carriers that transport water from the shallow to the deep of the Earth, so their physical and chemical properties are crucial to understanding the water cycle in the Earth's interior. This paper aims to explore the elastic properties of various hydrous minerals and their influencing factors, so as to constrain the estimation of water content in subduction zones.

Methods The methods of measurement of wave velocity under high temperature and high pressure in laboratory are introduced, as well as the elastic properties and the effect of some factors on the elastic properties of typical hydrous minerals, and compares several mineral models used to estimate material composition and water content in subduction zones.

Results It is found that the P and S wave velocities of low−pressure hydrous minerals are generally lower than those of mantle minerals, while the values of V_P/V_S are higher than those of mantle minerals. These properties are consistent with geophysical observations in subduction zones. However, the wave velocities of some high−pressure hydrous minerals are close to those of mantle minerals. The change of wave velocity of hydrous minerals before and after dehydration can be used to reveal the cause of abnormal wave velocity in deep Earth. By modeling hydrous minerals in the earth's deep environment and comparing with geophysical observation data, the water content and wave velocity anomalies in the subduction zone can be effectively constrained.

Conclusions Based on velocity−minerals composition models constructed from experimental petrology data (e.g., olivine−serpentine system), combined with Monte Carlo simulation, the serpentization degree (approximately 10%~40%) and water content (about 1%~5%) of mantle wedge in subduction zones are quantitatively estimated. Seismic velocity structures at depths of 200~400 km in cold subduction zones such as Northeast Japan and Tonga suggest water content in these regions are at least 5%.