The Array Analyzing of The High Quality Glacial Seismic Events Active in Greenland Using Long-Period Surface Rayleigh Wave Detection by the German Regional Seismic Network

Abstract

This study reports on four high quality glacial events in Greenland, M 4.9, 2007-07- 04; M 4.8, 2007-07-09; M 4.7, 2007-07-09; M 4.7, 2007-07-20 detected using the long-period surface waves Rayleigh wave recorded at the stations of the German Regional Seismic Network GRSN array German-GR and Geofon-GE programs . The waveform patterns of the detected slow events for Greenland updated through 2008 were monitored to analyze this new class of low-frequency earthquakes in the context of the array processing technique and array parameters using the software Seismic Handler Motif SHM . The array geometry of GRSN was defined by seven stations and processed to associate seismic phase arrivals to define glacial events. Two stations of GRSN were assigned the role of reference sites. The long-period surface wave characteristics of the event signals with magnitudes M 4.9, M 4.8, M 4.7, and M 4.7 were detected using filtering, beamforming, and location-relocation steps; then, the results were updated using SHM. The event data were filtered with a Butterworth band pass filter of 35s-70s with a common amplification. Using the array-beamforming technique, the beam traces were computed to calculate the beam-slowness the apparent velocity and the beam-azimuth of incoming wavefronts for particular time intervals to further analyze the observed glacial events. Then, the detected event signals were relocated and used to estimate array parameters; beam-slowness and beam-azimuth. Finally, in this study, the array processing technique was used with array parameters computed from the SHM to detect and analyze the slow glacial events using the array installation data from GRSN.

Keywords

• greenland
• glacial events
• surface waves
• waveform patterns
• beamforming