An Improvement of Low Cost Sensor Network for Earthquake Early Warning in Taiwan: Using Arrival-time Order Location Method and Small Arrays

Since there is no practical method for earthquakes prediction today, the main disaster prevention method is based on the seismic design of buildings. Earthquake early warning (EEW) is another effective way to reduce damage in real-time (Kanamori et al., 1997). Because EEW needs to provide reliable message in a short time, it is important to shorten the reporting time window by the improving of data process. In order to provide location and magnitude after an earthquake just happened, a low cost and high density EEW system has been developed and established by using the Palert seismometers in Taiwan (Wu et al., 2013). Due to the distribution of the stations, which detected the signals at first, is poor. It needs more than eight stations to get reliable information. Thus, it shortens the lead time before strong ground shaking. This study use the arrival-time order location (AOL) method, which introduced by Anderson in 1981, to improve the efficiency of Palert EEW system for earthquake location. At the same time, because of Palert has a relatively low signal-to-noise ratio (S/N) in τc (Kanamori, 2005, Wu and Kanamori, 2005a) determinations. So τc approach does not use in the Palet EEW system (Wu et al., 2013). This study try to use the signals stacking small arrays to enhance S/N ratio and try to use τc for magnitude estimation.
Results shows that, AOL method can provide a reliable earthquake location by only using four to five stations. It can improve the EEW efficiency. By stacking the signals from small array can also get more accurate magnitude estimation usingτc. So that more information can be provided in on-site EEW warning purpose.