發展智慧型手機應用於地震即時警報系統

Abstract

地震即時警報[EEW] 近年來已成為地震學及訊號處理領域裡的研究先驅之一。此研究會如此受歡迎關鍵原因是因為現今社會對應用程式的大量使用，以及地震仍然造相當大比例的人員傷亡及財產損害。當今所擁有的知識還無法做到地震的預測，而 EEW 是目前最接近的選擇，它可以拯救生命和減少損失。 對於台灣、日本及美國等常發生地震的區域，地震即時警報是現代非常重要的工具。在不同類型及種類的EEW 發展研究上，各方都投入了相當多的資源。現行的制度可能是由私人機構及政府部門共同運作；政府系統較傳統，主要是根據不同地理位置的地震觀測站，當事件發生時，觀測站裡的感測器會發送訊息給遠端的感測器及主觀測站並警告即將有地震波的傳入。私人機構則是發展研究較多的新方法，研究人員將手機當成地震感測站，並安裝應用程式，當檢測到地震事件發生時該程式可加速處理數據並反饋到中控式網路。 後者的方式是本研究文獻的重點。這是台灣在智慧型手機地震檢測網路上使用MATLAB多階段開發的第一步。最初的步驟是證明智慧型手機可用於測量地震強度，並透過MATLAB平台向每個用戶發出警報。本研究所使用的手機為Samsung Galaxy S6。使用的其他工具包括在智慧型手機上安裝MATLAB Mobile應用程式、一臺安裝有MATLAB軟體的電腦及路由器。測試在國立交通大學結構工程大樓和國家地震工程研究中心進行。本研究的其中一個目標是，研究出除了最受歡迎的STA/LTA 法之外其他可觸動地震警報的替代方法。但此研究的主要目標是能夠寫一個可以在發生地震時向每個用戶發出警報MATLAB腳本。藉由運行MATLAB代碼的同時，將智能手機放在搖晃的桌上來模擬地震信號。其結果允許在遠端監測地震運動，並接收、發出目前正在發生的地震警報。最終結果顯示，測量的PGA（峰值地面加速度）值在輸入信號峰值加速度幅度的85％內，從事件發生到發出報告的反應時間估計平均約為10秒。在此基礎上，未來可以開發以MATLAB為平台作為區域應用的機械，在當地建置智慧型手機地震網路。

Earthquake Early Warning [EEW] has become one of the forefront researches in seismology and signal processing in recent years. The key reason for this popularity is related to the great deal of application this research has in present day society since earthquakes are still responsible for a large percentage of property damages and lives lost. At present it is still beyond our understanding to predict an earthquake before it occurs, however EEW is the closest option we have to help save lives and reduce losses. Earthquake early warning hence is an important tool for modern day earthquake prone societies like Taiwan, Japan and the US. Lots of resources are being spent on the development of different types of EEW system networks of varying types. Current systems may be operated by both government of private sectors. Most if not all government systems are mainly based on traditional seismic stations positions at different geographical locations, these sensors alert distant sensors and main observation station when an event is triggered, giving warning of the incoming propagation of an earthquake wave. More advanced methods being develop utilized by private companies and researchers use smartphones as sensors with installed applications that feeds back acceleration data of the smartphone to a centralized network that triggers when an earthquake event is detected. The latter of these methods are the focus of this research document. This is the first step in a multi-phase development a smartphone based seismic detection network using MATLAB in Taiwan. This initial step is to show that a smartphone can be used to measure earthquake intensity and issue an alert to a single user using the MATLAB platform. The smart phone used in this research is a Samsung Galaxy S6 device. Other tools used includes installation of the MATLAB Mobile app on the smartphone, a computer with MATLAB software and a router. Tests were performed at the National Chiao Tung University Structural Engineering Building and at the National Center for Research on Earthquake Engineering in Taiwan. One of the main goals in this research was to investigate alternative methods to trigger an earthquake alarm apart from using the more popular STA/LTA algorithm however the main objective was to be able to create a MATLAB script that can alert a single user when an earthquake is occurring. To do this an earthquake event was simulated by placing the smartphone on a shaking table while running the written MATLAB code. The result of which allowed the researcher to remotely detect an earthquake motion and receive and alert that an earthquake event was being propagated. Final results showed PGA (Peak Ground Acceleration) values measured were within eighty-five (85%) of input signal’s peak acceleration amplitudes. Reaction time from the start of the event to reporting of an event is estimated to be around ten (10) seconds on average. On this basis one can develop future mechanisms to create a smartphone seismic network locally which can be regionally applied.