| Abstract: | We propose a method to investigate the dimensions and oscillation characteristics of the source of volcano-seismic signals based on waveform inversion for an extended source. An extended source is realized by a set of point sources distributed on a grid surrounding the centroid of the source in accordance with the source geometry and orientation. The source-time functions for all point sources are estimated simultaneously by waveform inversion carried out in the frequency domain. We apply a smoothing constraint to suppress short-scale noisy fluctuations of source-time functions between adjacent sources. The strength of the smoothing constraint we select is that which minimizes the Akaike Bayesian Information Criterion (ABIC). We perform a series of numerical tests to investigate the capability of our method to recover the dimensions of the source and reconstruct its oscillation characteristics. First, we use synthesized waveforms radiated by a kinematic source model that mimics the radiation from an oscillating crack. Our results demonstrate almost complete recovery of the input source dimensions and source-time function of each point source, but also point to a weaker resolution of the higher modes of crack oscillation. Second, we use synthetic waveforms generated by the acoustic resonance of a fluid-filled crack, and consider two sets of waveforms dominated by the modes with wavelengths 2L/3 and 2W/3, or L and 2L/5, where W and L are the crack width and length, respectively. Results from these tests indicate that the oscillating signature of the 2L/3 and 2W/3 modes are successfully reconstructed. The oscillating signature of the L mode is also well recovered, in contrast to results obtained for a point source for which the moment tensor description is inadequate. However, the oscillating signature of the 2L/5 mode is poorly recovered owing to weaker resolution of short-scale crack wall motions. The triggering excitations of the oscillating cracks are successfully reconstructed. Copyright 2007 by the American Geophysical Union. |
| Genre: | Article |
| ProdID: | 70032728 |
| Citation Author: | Nakano, M.; Kumagai, H.; Chouet, B.; Dawson, P. |
| Citation Contributing Office: | |
| Citation Datum: | |
| Citation Day: | |
| Citation Edition: | |
| Citation Editor: | |
| Citation End Page: | |
| Citation Issue: | 2 |
| Citation Keywords: | |
| Citation Language: | English |
| Citation Larger Work Title: | Journal of Geophysical Research B: Solid Earth |
| Citation LatN: | |
| Citation LatS: | |
| Citation LonE: | |
| Citation LonW: | |
| Citation Month: | |
| Citation No Pagination: | |
| Citation Number Of Pages: | |
| Citation Online Only Flag: | |
| Citation Phsyical Description: | |
| Citation Projection: | |
| Citation Public Comments: | |
| Citation Publisher: | |
| Citation Series: | |
| Citation Series Code: | |
| Citation Series Number: | |
| Citation Search Results Text: | Waveform inversion of volcano-seismic signals for an extended source; 2007; Article; Journal; Journal of Geophysical Research B: Solid Earth; Nakano, M.; Kumagai, H.; Chouet, B.; Dawson, P. |
| Citation Start Page: | |
| Citation Volume: | 112 |
| Citation Year: | 2007 |
| Type: | citation/reference |
| Text: | Waveform inversion of volcano-seismic signals for an extended source; 2007; Article; Journal; Journal of Geophysical Research B: Solid Earth; Nakano, M.; Kumagai, H.; Chouet, B.; Dawson, P. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1029/2006JB004490 |
| Date Other: | Mon, 1 Jan 2007 00:00 -0600 |
| Publisher: | |
