Seismic Investigation in Upper Mantle Beneath the Asia Using PP precursor Analyses
The region between Moho and Transition zone plays a very significant role in plate tectonics and mantle convection in the earth’s interior which makes it an extremely crucial study area. The PP precursors have significant global coverage in both continental and oceanic regions which can be used to study the occurrence of the mantle discontinuities and their characteristics. This study aims to focus on using PP precursor to image the subsurface to delineate the complex features and understand dynamic plate movement in upper mantle beneath the Asia. There have been a lot of seismic high-resolution local investigations in southeast and eastern Asia showing complex tectonic evolution influenced by a long history of subduction, conversion, and continental collision. However, getting a more regional high-resolution seismic image remains challenging and overall, clear indication of tectonic behavior and slab subduction is not seen in seismic tomography models. Therefore, this research tries to extend study across Asia to areas that comparatively have been subject to few studies. In this research, PP precursors are used to provide a higher resolution image of the Upper mantle beneath Asia utilizing data from IRIS (Incorporated Research Institutions for Seismology). For this study, earthquakes data for PP and SS, greater than 5.6 magnitude were downloaded between January 1990 to December 2021 for every broadband seismic station. The study area extends from 5° South to 75° North, 55° to 160° East. We processed the data through different parameters including frequency, bin size stacking and spacing between stacking midpoints to explore the dependency on image resolution and how this relates to the image enhancement by stacking larger amounts of data from larger bins, to obtain the best possible results from the available data.