A group of distinct seismic phases that could be used to detect metastable olivine
一组可用于探测亚稳态橄榄石存在情况的震相

We employ a 2-D pseudo-spectral code to study the seismic wave propagation in subduction zones, in which the deep earthquakes that generate the seismic waves are located at different places in subduction slabs. A group of easy to detect P-S converted phases with planar wave front emerges between P and S phases when a high wave speed slab has a 6% low velocity rectangular zone in it. The propagation directions of these phases are only related with the wave velocities of the materials located in two sides of the contact interface. It keeps the same when the hypocenter location deviates from the center of the slab. These phases are still very clear when the boundaries of the low velocity zone are uneven, e.g., with ±2 km undulation, when the low velocity zone changes to wedge shaped, when the surrounding mantle has PREM structure. For a 100~200 km long low velocity wedge, these phases are still detectable. So, we suggest people to employ these phases to detect metastable olivine in subduction zones.