Developing a Seismic Damage Evaluation Model for Tehran’s Buildings in a GIS Environment
A. Bazgard, B. Omidvar
1,3 : Faculty of environment Eng., University of Tehran, Tehran, Iran.
a.bazgard@gmail.com, bomidvar@ut.ac.ir
A. Mansourian
2: Faculty of Geodesy & Geomatics Eng., K.N.Toosi University of Technology, Tehran, Iran.
mansourian@kntu.ac.ir
Abstract
In an earthquake disaster, having proper estimation about destructed buildings and the degree of destruction, can considerably facilitate decision-making and planning for disaster managers. By use of this information, the managers can estimate disaster area and number of victims to determine required resources and how to allocate them.
Scientific studies and historical data show that the faults around Tehran, the capital of Iran, are capable to create strong earthquakes which would bring the largest damages in the world history to Tehran. So it is necessary to be prepared for a rapid and knowledge-based response to such an earthquake. One of the aspects of such preparedness relates to developing a proper model to estimate destruction of buildings. Since, no practical model has been proposed for Tehran yet, so devising such a model seems to be absolutely essential.
In the context of a research project, development of a model to estimate destruction of buildings is ongoing. The model is going to be developed by using the data obtained from the buildings and the fragility curves in Tehran as well as probabilistic seismic hazard analysis. Since mainly spatial data is used in this project, the model is developing in a GIS environment. This paper outlines the results of the project till now.
Introduction
Due to time-sensitive nature of disasters, rapid and reliable decision-making has a significant impact on managing disasters. Such decision-making highly requires proper information on current emergency situation. Meanwhile, estimation on disaster area and number of victims is initial and essential information that a manager may need for a proper decision-making. As a result, a map of destructions and their severity is indeed of a high value to managers.
Tehran, the capital of Iran with a population of more than ten millions, is built on a network of faults with high risk to earthquake. Historically, Tehran has an earthquake return period of 150 years and no earthquake has occurred since 175 years ago. Having mentioned that, Tehran is threatened by a strong earthquake which will bring large damages and casualties to the city. So, disaster management community should prepare itself for responding to such huge disaster. One of the aspects of the mentioned preparedness relates to having proper tools and models to estimate disaster area and number of victims for preparing initial plans.
Attenuation relationships and fragility curves are two basic concepts/models that are used for estimating damage level of buildings in the case of earthquake. In these models, different data such as the earthquake center and magnitude, distance of building from the center, soil type and geological characteristics of the ground between the center and building, structural characteristics of the building and the age of the building are used. As most of these data have spatial component and location, GIS is a proper tool for their integration and analysis to get the result.