FEASIBILITY STUDY FOR DEVELOPMENT OF LOW COST SENSOR ACCELEROGRAPH AND ITS TRIGGERING ALGORITHMS

Abstract

This thesis outlines the feasibility study for development of a low cost seismic station using MEMS sensors to record strong ground motions and study its suitable triggering algorithm. Initially, literature on the various ground motion measuring instruments has been presented. The working principles of various ground motion recording instruments and their types are discussed. Later, the latest developments in the area of Micro-Electromechanical systems (MEMS) based sensors and their suitability to record ground motions are presented. Suitable methodology to use MEMS sensors to record strong ground motions is outlined. Then the feasibility study for development of low cost sensor accelerograph has been discussed. Under this suitable MEMS sensor has been selected according to the minimum required specification for recording strong ground motions. The efficiency of MEMS accelerograph in recording seismic events depends mainly upon the efficiency of triggering algorithm. There are different types of classical triggering algorithms developed by past researchers to detect the seismic events, varying from amplitude threshold type to sophisticated pattern recognition type. Algorithms based on STA/ LTA are reported to be computationally economical for real time monitoring. All these different types of triggering algorithm have been studied and setting of different parameters has been discussed for triggering of channels on the past recorded triggered earthquake. Various STA/LTA triggering algorithms are tested for their efficiency and suitability for MEMS accelerograph. Finally, optimum case parameter sets for each of the triggering algorithms has been identified.