The guided wave in the subduction zone
Speaker: Mu-Ching Liu
Abstract
Wave multiple reflection can be caused easily in any continuous layered structure that is slow compared to bounding media, and this reflected wave could produce prominent interference. In the seismograph, we could find the dispersion in the phase which is caused by this effect, and we named the reflected wave guided wave because the wave is guided in this structure. This phenomenon is observed in many structures, especially in fault zone, but in many subduction lithosphere, for instance, Ryukyu slab in Japan, we can also observe this effect. In this study, we focus on the guided wave in the subduction zone, and we find that the body wave is also influenced by this effect, both P and S wave Though this effect is apparent in shear wave, we focus on the P onset in this study because the shear wave is probably contaminated by the P coda waves. Both in Alaska and chile subduction zone, we observe this effect. We use different methods to discuss the guided wave in the Alaska and Chile subduction zone respectively, and explore how the structures cause this phenomenon. Finally, we refer that there is a significant structure in the range of 2-6 scale in the Alaska subduction zone and a structure which thickness is smaller than 4.5 km in the Chile and Peru subduction zone.
Reference
Geoffrey A. Abers and Golam Sarker. Dispersion of regional body waves at 100-150 km depth beneath Alaska: In situ constraints on metamorphism of subducted crust. Gepphysical Research Letters, Vol. 23, No. 10, Pages 1171-1174, MAY 15, 1996.
S. Martin and A. Rietbrock. Guided waves propagating in subducted oceanic crust, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. B11, 2536, doi:10.1029/2003JB002450, 2003.