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Optimized Design of a Stacked Diaphragm MEMS Pressure Sensor for Tsunami Warning System Suja K J, Santo Mathew, Rama Komaragiri Department of Electronics and Communication engineering National Institute of Technology Calicut, Kerala. rama@nitc.ac.in  Abstract—Tsunami is a large scale, short duration vertical dis-placement of water column. Tsunami results in a pressure change in the sea bed. The Tsunami warning system (TWS) con-sist of a series of sensors which detect the change in pressure at the sea bed when tsunami waves are generated. Micro electro mechanical system based silicon pressure sensors have under-gone a significant growth in the last few years. The sensitivity, maximum measurable pressure and linear range over the deflec-tion of pressure sensor highly depend upon the diaphragm struc-ture. In this work, a stacked diaphragm pressure sensor is de-signed and simulated which can be used for under water pres-sure measurements. A novel method for sensitivity enhancement by optimizing the thickness of various layers for stacked dia-phragms is presented. Also a study of the bulk micro machined silicon piezoresistive pressure sensor and a surface micro ma-chined stacked diaphragm pressure sensor is presented, simulat-ed and compared with respect of sensitivity and deflection. Keywords— Tsunami Monitoring, MEMS, Piezoresistive Pres-sure Sensor, Surface micromachining, Bulk micro machining. INTRODUCTION Tsunamis generally consist of a series of waves with periods ranging from minutes to hours, arriving in a so-called wave train. Wave heights of tens of metres can be gen-erated by large events. Although the impact of tsunamis is limited to coastal areas, their destructive power can be enor-mous has huge impact on economy, lives and environment and even can result in catastrophes. The principal generation mechanism of a tsunami is the displacement of a substantial volume of water or perturbation of the sea. This displacement of water is usually attributed