A 2-D Seismic Signal Detector for Stand Alone 3-Component stations

Abstract

An integral part of modem earthquake monitoring is that of real time signal detection. When digital seismometry was introduced in the early 1970-ties with the deployment and subsequent operations of the LASA and NORSAR large aperture arrays automatic and optimal seismic signal detection become a research issue. Much ingenuity was invested in the signal detector design and some of these efforts were indeed elaborated. However, hardly any of them outperformed the simple I D STAXTA-detector - the ratio between Short Term and Long Term Averages of signal RMS-power on exclusively vertical sensors. When digital stand-alone 3-component stations become operational in the 1980-ties the array signal detector was adapted to these stations as well and hence excluding signal presence on the horizontal components. In this article we present a novel 2D signal detector incorporating all seismometer components and also demonstrate that the 2D detector not unexpected outperforms the I-D detector at local and regional distance ranges.