Application of Geospatial Technology in Earthquake Risk Assessment in Papua New Guinea

Abstract

The multifaceted discipline GIS has a definite role to play in monitoring tectonism-induced calamities. Before installing high-valued infrastructure, one can utilize the GIS technology to find out the usefulness of the investment, by carrying out proper site analysis. Abetted by affable subsoil, severe ground shaking might lead to liquefaction causing infrastructure collapse and conflagration, which is the common earthquake hazards experienced worldwide. Tremor-induced damage to built-up infrastructures like roads, bridges, buildings and other properties is accompanied by human and other livestock casualties. The appropriate planning process should be in place with a view to safeguarding people’s welfare, infrastructures and other properties at a site based on proper evaluation and assessments of the potential level of earthquake hazard. One can use the information so derived in minimizing risk from earthquakes and also can foster appropriate construction design and formulation of building codes at a particular site. Different disciplines adopt different approaches in assessing and monitoring earthquake hazard throughout the world. In the current study, the potentials of space technology and spatial science were used to appraise potentials of earthquake hazards in the study area. Subsurface geology and geomorphology were the common features or factors that were assessed and integrated in GIS platform complemented with seismic data record like peak ground acceleration (PGA), historical earthquake magnitude and earthquake depth to evaluate and prepare liquefaction potential zones (LPZ) culminating in earthquake hazard zonation of our study sites. The precept has been that during any earthquake event, the seismic wave is generated and propagates from earthquake focus to the surface. As it propagates, it passes through certain geological, geomorphological and specific soil features, where these features according to their strength/stiffness/moisture content aggravate or attenuate the strength of wave propagation to the surface. Depending upon the media of the propagation of seismic waves, the resulting intensity of shaking might culminate in the collapse of built-up infrastructures. For the case of earthquake hazard zonation, the overall assessment was carried out through integrating seismicity data layers with LPZ. Multi-criteria evaluation (MCE) with Saaty’s Analytical Hierarchy Process (AHP) was adopted for this study. In the current study, GIS technology was used to integrate several thematic layers having potential contributions to liquefaction triggered by earthquake hazard. The factors were appropriately weighted and ranked in tune with their contribution to earthquake-induced liquefaction. The weightage and ranking assigned to each factor were normalized with AHP technique. ArcGIS 10 software was mainly utilized such as ‘raster calculator’, ‘reclassify’ and ‘overlay analysis’ as spatial analysis tools in the study. The earthquake hazard zones along with LPZ were reclassified as final output. Hazard zones were segmented as ‘Very high’, ‘High’, ‘Moderate’, ‘Low’ and ‘Very Low’ to indicate the levels of vulnerability in the study region.