The mechanisms of intermediatedepth earthquakes were always attracting extensive researches of interest. Among various hypotheses about the mechanisms, the close relationship between the dehydration embrittlement and earthquakes is generally accepted. The intermediate-depth earthquakes in subducting slabs occur mainly in two distinct layers, corresponding with the dehydration respectively in the hydrous meta-basalts and the serpentinite layers. In the past decades, theory researches, interpretations of seismic data and laboratory experiments have been widely adopted as the major approaches to attest the hypothesis of dehydration embrittlement. However, in the latest ten years, pseudotachylytes and some brittle structures have been discovered in paleo-subduction zones like Alps, shedding a light for a new way to study intermediate-depth earthquakes.