tsunami warning sys

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TSUNAMI WARNING SYSTEM Name : PRADEEP KR SHARMA Roll No. : 0902831061 ECE 3 rd year

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TSUNAMI WARNING SYSTEM

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INTRODUCTION WHAT IS TSUNAMI DESTRUCTION CAUSED BY TSUNAMI ABOUT TSUNAMI WARNING SYSTEM TYPES OF TSUNAMI WARNING SYSTEM TSUNAMIMETER TSUNAMI DETECTION ALGORITHM THEROTICAL PRESSURE SERIES CONCLUSION

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Tsunami warning system (TWS) is a system to detect tsunamis and issue warnings to prevent loss of life and property. It consists of two equally important components: a network of sensors to detect tsunamis and a communications infrastructure to issue timely alarms to permit evacuation of coastal area INTRODUCTION

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Tsunami is the Japanese name given to large waves that sometimes devastated the shores and ports of Japan. Tsunamis have very long wavelengths. Crest to crest they measure between 10 and 500 km and they travel through the ocean at more than 700 km/h. Sometimes there appears to be just one wave but often there are multiple waves travelling a few minutes apart WHAT IS TSUNAMI

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DESTRUCTION CAUSED BY TSUNAMI

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Tsunamis strike without warning .The resulting damage can be maintained and lives can saved if the people living near the coastal areas are already prepared to survive the strike. This requires a warning system . The type discussed here is Deep ocean Assessment and Reporting of Tsunamis {DART}. Each DART station consists of a seafloor Bottom Pressure Recording {BPR} package that detects pressure changes caused by tsunamis and a surface Buoy which receives transmitted information from BPR via an acoustic link. TSUNAMI WARNING SYSTEM ABOUT

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There are two distinct types of tsunami warning systems: INTERNATIONAL and REGIONAL. Both depend on the fact that, while tsunamis travel at between 500 and 1,000 km/h (around 0.14 and 0.28 km/s) in open water, earthquakes can be detected almost at once as seismic waves travel with a typical speed of 4 km/s (around 14,400 km/h). TYPES OF TSUNAMI WARNING SYSTEM

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Each Deep ocean Assessment and Reporting of Tsunamis (DART) gauge is designed to detect and report tsunamis on its own, without instruction from land. The tsunami detection algorithm in the gauge’s software works by first estimating the amplitudes of the pressure fluctuations within the tsunami frequency band and then testing these amplitudes against a threshold value. The amplitudes are computed by subtracting predicted pressures from the observations, in which the predictions closely match the tides and lower frequency fluctuations TSUNAMI DETECTION ALGORITHM

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Background oceanic noise determines the minimum detection threshold. Based on passed observations, a reasonable threshold for the north pacific is 3cm. if the amplitudes exceed the threshold; the gauge goes into a rapid reporting mode to provide detailed information about the tsunami.

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The graph shows the application of the algorithm to a theoretical pressure series. The series consist of an M2 tide with amplitude of 1mm and a short pulse that has amplitude of 5cm and duration of 15 minutes. The pulse affects the difference both directly and through its indirect effect on the prediction This is due to the mismatch between the time series and the constant values placed initially in the H*array This phenomenon will also occur during field deployments of DART gauges as they fall through the water column towards the bottom. THEROTICAL PRESSURE SERIES

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However, the difference will stabilize at sub-threshold values 4-5 hours after the gauges reach the bottom. Then, the H* array contains only on-bottom pressure values, and the gauges are in thermal equilibrium with the bottom waters. A software flag is set to -1 each time the difference exceeds the threshold. In turn, this excedance flag controls a reporting flag that puts the DART gauge into its rapid reporting mode. The reporting flag is set to -1 as soon as the threshold is exceeded and remains equal to -1 until 4 hours has passed since the last time the threshold was exceeded.

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GRAPH

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From the graph, the pressure difference has a response near unity over the tsunami band, which spans the periods from 2-90 minutes. At lower frequencies, the attenuation Increases rapidly with decreasing frequency. Hence, tsunami and higher frequency signals dominate the pressure difference. THE FREQUENCY RESPONSE

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FREQUENCY RESPONSE

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Small amplitude tsunamis observed by internally recording gauges in the north pacific. Relative to the high-passed data, the background noise in the difference series is either equal in amplitude or slightly enhanced. Neither tsunami high enough in amplitude to set a DART gauge into rapid reporting mode. OBSERVED TSUNAMI

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Time taken to warn people by conventional method is too high. So we have devised a method using GSM technique. This GSM based alert system monitors the sea waves using the Tsunamimeter and broadcasts an alert message to towns and villages through the cell phone network existing throughout the state. Here the mobile phones are used both as transmitters and receiver. The handset, in turn, will transfer it to Base Transceiver Stations (BTS) if it is within 10-17 km of BTS. Otherwise it may require a repeater for transferring data to cell phone network. COMMUNICATING THE DANGER

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When SMS is sent from the mobile handset, it first goes to the SMS of the mobile network, then to the destination receiver handset This is possible if the SMS server of the mobile network is programmed for such a facility. In fact, this type of facility already exists in the GSM network in the form of ‘cell broadcast’. But it is not advisable to disturb the main server for this. Another application server may be included for this purpose. The SMS server sends 40 messages per second to all destinations through the GSM network. DECISION SYSTEM

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The Tsunami warning center senses tsunami, transits these discrete magnitude values to central place via GSM cell phone network, and uses computer-based decision making to deliver alert signals to the identified receivers placed at different towns and cities for both public and government consumption. The system is simple and could be configured with available resources .here only concepts are discussed .detailed simulation, feasibility study and experimentation are required to optimize the system and reduce the possibilities of false alarm. CONCLUSION

References:: 

References: 1. Suk, Sarah, Did disaster forum achieve anything?, crisscross.com, 23 January 2005 2.^ Indian Ocean Tsunami Warning System up and running, UNESCOPRESS, 28 June 2006 3.^ Asia tsunami warning system ready, BBC News, 28 June 2006 4.^ UN plans interim tsunami warning system that could be running almost at once, UN News, 13 January 2005

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