Wave separation for the great Sumatra-Andaman earthquake with regional seismic array
Tóm tắt
We analyzed the seismic waveforms from the December 26, 2004 Sumatra-Andaman earthquake recorded at broadband seismic stations in western Europe. Previous studies involving of the beam-forming technique and high frequency analysis suggest that the earthquake ruptured with a duration of around 500 s. This very long duration makes P wave overlap with later arrivals such as PP wave, which follows P in about 200 s. Since P waves are crucial for modeling earthquake processes, we propose an iterative method to separate P and PP waveforms. The separated P waveform confirms a second large energy release around 300 s after the initial rupture. The iterative signal separation technique is particularly useful for mixed signals that are not independent and the number of recording stations far exceeds number of mixed signal sources.
Tài liệu tham khảo
Amindavar H and Reza A M (2005). A new simultaneous estimation of directions of arrival and channel parameters in a multipath environment. IEEE Trans Signal Processing53(2): 471–483.
Ammon C J, Ji C, Thio H K, Robinson D, Ni S D, Hjorleifsdottir V, Kanamori H, Lay T, Das S, Helmberger D, Ichinose G, Polet J and Wald D (2005). Rupture process of the 2004 Sumatra-Andaman earthquake. Science308(5725): 1 133–1 139.
Banerjee P, Pollitz F, Nagarajan B and Bürgmann R (2007). Coseismic slip distributions of the 26 December 2004 Sumatra-Andaman and 28 March 2005 Nias earthquakes from GPS static offsets. Bull Seismol Soc Am97(1A): S86–S102.
Catherine J K, Gahalaut V K and Sahu V K (2005). Constraints on rupture of the December 26, 2004, Sumatra earthquake from far-field GPS observations. Earth Planet Sci Lett237: 673–679.
Guilbert J, Vergoz J, Schissele E, Roueff A and Cansi Y (2005). Use of hydroacoustic and seismic arrays to observe rupture propagation and source extent of the MW9.0 Sumatra earthquake. Geophys Res Lett32: L15310, doi:10.1029/2005GL022966.
Ishii M, Shearer M, Houston H and Vidale J (2005). Extent, duration and speed of the 2004-Sumatra-Andaman earthquake imaged by the Hi-net array. Nature435: 933–936.
Kikuchi M and Kanamori H (1982). Inversion of complex body waves. Bull Seismol Soc Am72: 491–506.
Kruger F and Ohrnberger M (2005). Tracking the rupture of the MW=9.3 Sumatra earthquake over 1 150 km at teleseismic distance. Nature435: 937–939.
Ng W, Reilly J P, Kirubarajan T and Larocque J (2005). Wideband array signal processing using MCMC methods. IEEE Trans Signal Processing53(2): 471–483.
Ni S D, Helmberger and Kanamori H (2005). Energy radiation from the Sumatra earthquake. Nature434: 582.
Ozcetin A (2003). Music, CBF and differential algebraic constant modulus algorithms for direction of arrival estimation in passive coherent locators. Turk J Elec Engin11(2): 95–115.
Vorobyov S A, Gershman A B and Wong K M (2005). Maximum likelihood direction-of-arrival estimation in unknown noise fields using sparse sensor arrays. IEEE Trans Signal Processing53(1): 471–483.
Weinstein E, Feder M and Oppenheim A V (1993). Multichannel signal separation by decorrrelation. IEEE Trans Signal Processing1(4): 405–413.