ABSTRACT:

This paper presents the application of a Geographic Information System (GIS) to the assessment of karst collapse risk in Tangshart, China. It gives the main factors that influence the risk of karst collapse and the method for assessing it. Using the automated GIS-based risk assessment method developed, three zones with different risk levels are delineated in downtown Tangshan. Based on the risk assessment resuits, recommendations are given on the risk assessment method and development of downtown Tangshah.

INTRODUCTION

Tangshan is an important industrial city in China. In 1978 a catastrophic earthquake, with a magnitude of 7.8, rocked this city and took the lives of a quaaer of a million people. This earthquake also brought many unforeseen problems subsequently to Tangshah. Karst collapses are one of the unforeseen problems. From 1979 to 1994, 18 confirmed or possible karst collapses occurred with a total affected area of nearly 20 km 2.

A karst collapse usually originates from the loss of stability of a hidden karst cave in a fragmented rock mass. Since karst caves are usually covered by Quaternary sediments, they are difficult to locate and their stability difficult to assess. An analysis of the factors influencing karst collapse leads to a regional risk assessment and a hazard zoning scheme for the re-construction of Tangsban, especially the new downtown.

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