Masters Thesis Abstract: Bina Singh
A GIS Application for Seismic Risk Assessment in Christchurch City, New Zealand.
The Alpine Fault, located at about 130 km west of Christchurch, is the largest active fault in New Zealand and extends over 650 km. Several seismic hazard assessment studies in Christchurch and the Canterbury region suggest that the Alpine Fault is one of the most likely sources of seismic threat to Christchurch City. It has ruptured four times in the past 900 years, each time producing an earthquake of about magnitude 8. Furthermore, paleoseismic studies along the fault provide evidence for the occurrence of great earthquakes with recurrence intervals of a few hundred years indicating that the fault has a high probability of rupturing in the next 40 years.
It is thought that a magnitude 8 earthquake on the Alpine fault will produce widespread felt intensities of around MM6 in Christchurch, with the possibility of MM7 on the softer soils. In such an event the city will be subject to extreme ground shaking, soil liquefaction, landsliding and fires. These seismic hazards will have a major impact on the lives of many people.
This research aims to develop an integrated GIS based methodology for assessing seismic risk in Christchurch City based on a “scenario earthquake”, in this case a magnitude 8 earthquake generated on the Alpine Fault.
The methodology entails combining several data sets such as surface geology, ground shaking (a function of earthquake strength, distance from the epicentre, and ground/soil composition), liquefaction potential, terrain slope, inventories of co-seismic landslide occurrences to derive seismic hazard susceptibility maps which in turn will be combined with building construction (e.g. brick versus timber, number of storeys), building valuation, and census data within a GIS using vulnerability relationships. Risk will be assessed in terms of direct physical damage - damage to residential and commercial buildings; economic loss-repair and reconstruction costs; and social impacts–deaths and injuries.
This study is being carried out in collaboration with the Institute of Geological and Nuclear Sciences, Environment Canterbury and the Christchurch City Council.