Mike Sandiford edited Results.md  over 9 years ago

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#Early results from borehole array.  A Since their dployment a  number of earthquakes have been detected with the new borehole instruments. instruments, including low magnitude events following the M3.2 Moe earthquake of ... date.  As our processing and analysis methods develop, we envisage that much smaller events will emerge from the data. ##2014-10-10UTC10:20, near Korumburra, Estimated magnitude: 1.5  This One such  event near Korumburra (hypocentre ...) was recorded on both borehole and surface instruments, providing ..., 2014-10-10UTC10:20) provides  an opportunity to compare waveforms. waveformson surface and subsurface instruments.  Whilst P-wave arrivals can be easily detected on borehole stations, they are difficult to detect on surface stations. S-waves arrivals from borehole stations will substantially improve event location. Figure 1 shows this event at the nearest borehole station, and Figure 2 shows the corresponding STA/LTA filter response, which is commonly used for automatic event detection. Figure 3 shows the P and S-wave picks from the borehole station furthest from the event.   Figure 4 shows the event at the nearest telemetered surface staion. Whilst the event is clearly present on the surface record, the signal to noise level is much smaller. Also, no clear S-wave arrival can be determined. The corresponding STA/LTA filter shows multiple spikes of similar amplitude, meaning that any  automatic detection would be difficult for this event. routine using a STA/LTA filter is ambiguous.