A recording of an mL 1.2 quarry blast located 43 km SW is presented. The record shows a clear P-wave arrival, with particle motion confirming the location (backazimuth of 252°). The spectrogram reveals that the surface waves are dominant in low frequencies and extend more weakly into higher frequencies.
Automated algorithm pick on the vertical component, precisely identifying the first seismic arrival with high temporal resolution. The zoomed view shows the exact onset of the P-wave, which is critical for accurate event location and characterization.
Zoomed-in view of a 3-component waveform showing the P-wave from an mL 1.2 quarry blast. The P-wave arrival (marked by the red dashed line) displays positive polarity on all three components
The combined analysis of P-wave polarity and linear particle motion polarization determines the backazimuth from the seismic station to the quarry blast. Particle motion of the initial P-wave across three components yields a backazimuth of 252°, confirming the southwestern direction to the event source.
Select a pair of components to view the particle motion analysis:
Spectrograms reveal the P-wave onset as a brief, broad-frequency energy packet and show surface wave energy predominantly concentrated below 3 Hz. The three-component spectrograms provide a comprehensive view of frequency content evolution over time.
Select a component to view its spectrogram:
