Abstract

The objective of this project is to obtain a preliminary  processed image of subsets of the Shatsky Rise field Data by applying post-stack migration. We have applied pre-processing to remove noise from the data, followed by velocity analysis, Normal Moveout (NMO) correction,  stacking and Kirchhoff migration. One of the data sets, tape 20, presented challenging issues such as conflicting dipping reflectors and conflicting moveouts due to the presence of  backscattering from the surrounding rock. The first strategy was to re-pick higher velocities to improve the under-migration due to the conflicting dipping reflectors. This attempt was not successful. We then reprocessed by applying Dipmoveout (DMO) correction which improved the image on the high dipping reflectors but overall the data was over-migrated. We also re-picked velocities to improve the flattening of reflectors coming directly below of the seismic line. This step improved the image around the high dipping area. Further proposed processing steps are DMO pre-stack migration. Finally we interpreted the preliminary image delineating the top of  the igneous basement below a sedimentary layer. The sedimentary layer thins and the igneous rock breaks through the sedimentary layer forming the high dipping structures.

Introduction

The Shatsky Rise  is part of the oceanic plateau  of the north-western pacific Ocean and it is comprised of massive basaltic volcanoes. According to \citet{Sager2013}, seismic data was acquired to improve the understanding  of the structure of Shatsky Rise.  Fig. \ref{565742} shows the seismic lines deployed over the Shatsky Rise. In particular, we are showing in Fig. \ref{864959}  the processed image of line AB. This line  shows a cross section of the Tamu Massif. According to \citet{Sager2013}, this is a single, immense volcano originated from lava flows emanated from the volcano center. We want to call attention to the steep peak around shot 6000 since we expect  that a similar structure might be present in our data.  This steep feature may cause difficulties in velocity picking due to the high dip and backscattering from the surrounding rock.