A new conceptual methodology for interpretation of mass transport processes from seismic data

Abstract

Abstract Identification and seismic mapping of mass-transport deposits (MTDs) are vital targets for marine geological studies both for a better understanding of mass wasting processes and geohazards and for economic prospects in sedimentary basins. In recent decades, refinements in the interpretation of these geobodies have benefited from increasingly good quality 3D seismic data. However, approaches to define the characteristics, rheology and mechanics of such slope failure deposits still rely mainly on inferences from case-dependent interpretations of these stratigraphic elements; what is more, features and seismic characteristics of MTDs may vary significantly from one case to another, implying the existence of many different environments and related physics. This makes the study of submarine mass movement a challenging task for a seismic interpreter. In this paper, we present a new conceptual analytical method based on an objective approach for interpreting the wide range of diverse objects related to mass wasting, in order to minimize seismic interpretation subjectivity. We propose an ontology-like methodology, based on a conceptual organization of a diversity of interpretation elements arranged in a knowledge base. MTDs are considered as objects with representative properties, each one characterized by several descriptors, which are themselves impacted by multiple physical processes in a graph-based conception. We thus propose a method to infer the most probable interpretations for one mass movement from its deposit characteristics. We applied our graph-based methodology to two MTDs delineated in 3D seismic data in the Offshore Amazon Basin, Brazil. Based on the analysis of all MTD properties and their possible causes, several candidate interpretations were provided. The interpretations yielded by the graph are in line with the known geology and instability processes of the region, thereby validating the feasibility of the approach. The next development stage is a numerical definition of the knowledge base for further sharing and operability.