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
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
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 thelong-period surface waves (Rayleigh wave) recorded at the stations of the German RegionalSeismic Network (GRSN) array (German-GR and Geofon-GE programs). The waveformpatterns of the detected slow events for Greenland updated through 2008 were monitoredto analyze this new class of low-frequency earthquakes in the context of the array processingtechnique and array parameters using the software Seismic Handler Motif (SHM).The array geometry of GRSN was defined by seven stations and processed to associateseismic phase arrivals to define glacial events. Two stations of GRSN were assigned the roleof reference sites. The long-period surface wave characteristics of the event signals withmagnitudes 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 datawere 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 thebeam-slowness (the apparent velocity) and the beam-azimuth of incoming wavefronts forparticular time intervals to further analyze the observed glacial events. Then, the detectedevent signals were relocated and used to estimate array parameters; beam-slowness andbeam-azimuth. Finally, in this study, the array processing technique was used with arrayparameters computed from the SHM to detect and analyze the slow glacial events using thearray installation data from GRSN.
___
- Nettles M, Ekström G. Glacial earthquakes in Greenland and
Antarctica. Annual Review of Earth and Planetary Sciences 38
(2010) 467-491. doi:10.1146/annurev-earth-040809-152414.
- Ekström G, Nettles M, Abers GA. Glacial earthquakes. Science 302
(2003) 622–624.
- Ekström G, Nettles M, Tsai, VC. Seasonality and increasing
frequency of Greenland glacial earthquakes. Science 311 (2006)
1756–1758.
- Tsai VC, Ekström G. Analysis of glacial earthquakes. Journal of
Geophysical Research 112 (2007) F03S22.
- Ekström G. Global detection and location of seismic sources
by using surface waves. Bulletin of the Seismological Society of
America 96 (2006) 1201–1212.
- Kawakatsu H. Centroid single force inversion of seismic waves
generated by landslides. Journal of Geophysical Research 94 (1989)
12363–12374.
- Stammler K. SeismicHandler - Programmable multichannel data
handler for interactive and automatic processing of seismological
analysis. Computers & Geosciences 19 (1992) 135–140.
- Korn M. (Ed.). Ten years of German Regional Seismic Network
(GRSN): Report 25 of the Senate Commission for Geosciences.
Deutsche Forschungsgemeinschaft, Wiley-VCH Verlag, Weinheim,
2002.
- Trnkoczy A, Havskov J, Ottemöller L. Seismic networks, in:
Bormann P. (Ed.). New Manual of Seismological Observatory
Practice (NMSOP). Deutsches GeoForschungsZentrum, Potsdam,
pp. 1-60, 2009.
- Schweitzer J, Fyen J, Mykkeltveit S, Kvaerna T. Seismic arrays,
in: Bormann P. (Ed.). New Manual of Seismological Observatory
Practice (NMSOP). Deutsches GeoForschungsZentrum, Potsdam,
pp. 1-52, 2009. doi:10.2312/GFZ.NMSOP_r1_ch9.
- Tur, H, Hoskan, N., Aktaş, G., 2015. Tectonic evolution of the
northeastern shelf of the Marmara Sea (Turkey): interpretation of
seismic and bathymetric data. Mar. Geophys. Res. v. 36: 1-34. Doi:
10.1007/s11001-014-9230-z.
- Gökaşan, E., Tur, H., Ecevitoğlu, B., Görüm, T., Türker,
A., Tok, B., Çağlak, F., Birkan, H., Şimşek, M., 2005. Evidence
and implications of massive erosion along the Strait of İstanbul
(Bosphorus). Geo-Mar Lett. v. 25: 324-342. Doi: 10.1007/s00367-
005-0216-3.
- Gökaşan, E., Algan, O., Tur, H., Meriç, E., Türker, A., Şimşek, M.,
2005. Delta formation at the southern entrance of Istanbul Strait
(Marmara Sea, Turkey): a new interpretation based on highresolution
seismic stratigraphy. Geo-Mar Lett. v. 25: 370-377. Doi:
10.1007/s00367-005-0215-4.