Classification of Volcanic Earthquakes Observed at Nyamulagira and Nyiragongo Volcanoes Reference on Frequency Analyses and its Implication in Volcano Monitoring
Keywords:
Frequency band, Types of earthquakes, Nyamulagira Volcano, Nyiragongo Volcano.Abstract
Identification of the types of seismic signals is the basic of the seismo-volcano analysis, because it allows to have information on the magmatic activity prevailing in the crater. Modern analysis for this work identifies the frequency observed in the evaluation of the signals that can lead to a proper classification following groups arranged in specific spectral bands. This frequency analysis was applied to seismic data that preceded the eruption of Nyamulagira Volcano of 6 November 2011 and the persisted lava lake within Nyiragongo Volcano. The data analyzed covered a period of two years, from January 2010 until November 2011. The work consisted to analyze the frequency content of the signals and to deduce the type of the signals reference to the general classification made by Lahr et al. [1], Miller et al. [2] and White et al. [3]. The work resulted on a classification ranging signals into 5 groups including: (1) Earthquakes whose frequency band row from 10 Hz and over, which were identified as volcano-tectonic earthquakes or A-Types, (2) Earthquakes whose frequency band row between 3 and 10 Hz identified as Hybrid earthquakes or B-Type earthquakes, (3) Earthquakes whose frequency band row between 1 and 3 Hz identified as Long Periods earthquakes or C-type earthquakes, (4) ) Earthquakes whose frequency band row between 0.25 and 1Hz identified as Very Long Period, VLP earthquakes and (5) Continuous signals marking the same values as the Long Period earthquakes identified as volcanic tremors.
It was eventually found that swarms of Long period and hybrid earthquakes are those related to magmatic intrusions, and thus can lead to volcanic eruptions. At other hand, there are only VLP and A-type earthquakes which are observed in the period of persisted Lava Lake. This classification can be used in the monitoring of the volcanoes.
References
[2] Smets, B., Wauthier, C. and d'Oreye, N., “A new map of the lava flow field of Nyamulagira from satellite imagery”, Journal of African Earth Sciences, Vol. 58, pp. 778–786, 2010
[3] Minakami, T. “Fundamantal research of predicting volcanic eruptions (I) – Earthquakes and crustal deformations originating from volcanic activities”, Bulletin of Earth ressources, Tokyo Univ., Vol. 38, P. 497-544, 1960
[4] Marcia McNutt and Alain Bonneville, “ A shallow chemical origin for the Marquesas swell” Geochemistry, Geophysics, Geosystem, AGU, Vol. 1, Issue 6, 1014, doi:10.1029/1999GC000028, 2000
[5] Hiroyuki Hamaguchi, Ndontoni Zana, Kazuo Tanaka, Minoru Kasahara, Masaaki Mishina, Sadato Ueki, Katsongo Sawa-Sawa and Kenji Tachirana, “Observations of Volcanic Earthquakes and Tremors at Volcanoes Nyiragongo and Nyamuragira in the Western Rift Valley of Africa.”, Tohoku Geophysical Journal (Sci. Rep. Tohoku Univ., Ser. 5), Vol. 29, No. 1, pp. 41-56, 1982.
[6] Lukaya, N., Ciraba, M., Mavonga, T. and Wafula, M., “Main pattern of waveforms observed in the Virunga volcanic zone, Western Rift Valley of Africa”, Tectonophysics Vol. 209, pp. 261–265, 1992
[7] Mavonga, T., Kavotha, K.S., Lukaya, N., Etoy, O., Mifundu, W., Bizimungu, R.K., and Durieux, J., “Some aspects of seismicity prior to the 27 November 2006 eruption of Nyamuragira volcano and its implication for volcano monitoring and risk mitigation in the Virunga area, Western Rift Valley of Africa”, Journal of African Earth Sciences, Vol. 58, pp. 829–832, 2010
[8] Platz T., Foley S.F. and André L.;” Low-pressure fractionation of the Nyiragongo volcanic rocks, Virunga Province, D.R. Congo”, Journal of Volcanology and Geothermal Research, Vol. 136, pp. 269-295, 2004
[9] N.M. Pagliuca, L. Badiali, M. Cattaneo, H. Ciraba, A. Delladio, M. Demartin, A. Garcia, A. Lisi, F. Lukaya, A. Marchetti, G. Monachesi, G. Mavonga, T. Sgroi and D. Tedesco, “Preliminary results from seismic monitoring at Nyiragongo Volcano (Democratic Republic of Congo) through telemetered seismic network, Goma Volcanological Observatory” Bollettino di Geofisica Teorica ed Applicata, Vol. 50, n° 2, pp. 117-127, 2009
[10] Vila, J., Correig, A.M., Marti, J., “Attenuation and source parameters et Deception Island (South Shetland Islands, antarctica)”. Pure and applied Geophysics 144, 229-250, 1995
[11] Ibanez, J.M., Del Pezzo, E., Almendros, J., Carmona, E., , M., Alguacil, G., Saccorotti, G., Abril, M., Ortiz, R., 2000, “ The 1998-1999 seismic series at Deception Island Volcano, Antarctica”, Journal of Volcanology and Geothermal Research, Vol. 128, P. 65-88, 2003
[12] Chouet B. “At an active volcano, long-period seismicity (with typical periods in the range 0.2–2 s) reflects pressure fluctuations resulting from unsteady mass transport in the sub-surface plumbing system, and hence provides a glimpse of the internal dynamics of the volcanic edifice. When this activity occurs at shallow depths, it may signal the pressure-induced disruption of the steam-dominated region of the volcano, and can accordingly be a useful indicator of impending eruption”, Nature Vol. 380, P. 309 - 316; doi:10.1038/380309a0, 1996
[13] Julian, B., “Volcanic tremor: Nonlinear excitation by fluid flow” Journal of geophys. Research, solid earth, Vol., 99, P. 11859-11877, 1994
[14] Chouet, B., “A seismic model for the source of long-period events and harmonic tremor”. In: P. Gasparini, R. Scarpa and K. Aki (Editors), Volcanic Seismology. Springer, Berlin, pp. 133-156, 1992.
[15] Almendros, J., and Chouet B., “Performance of the Radial Semblance Method for the Location of Very Long Period Volcanic Signals” Bulletin of the Seismological Society of America, Vol. 93, No. 5, pp. 1890–1903, October 2003
[16] Lee, W. H. K. and J. C. Lahr, “HYP071 (Revised): A computer program for determining hypocenter, magnitude, and first motion pattern of local earthquakes”, U. S. Geological Survey Open File Report 75-311, 113 pp, 1975
[17] Chouet, B.; Matoza, Robin S. « A multi-decadal view of seismic methods for detecting precursors of magma movement and eruption” Journal of Volcanology and Geothermal Research, Volume 252, p. 108-175, 2013
[18] Ohminato, T., Chouet, B.A., Dawson, P. and Kedar, S.” Waveform inversion of very long period impulsive signals associated with magmatic injection beneath Kilauea Volcano, Hawaii”. Journal of Geophysical Research 103: doi: 10.1029/98JB01122. issn: 0148-0227, 1998
[19] Chouet, B., P. Dawson, M. R. James, and S. J. Lane, “Seismic source mechanism of degassing bursts at Kilauea volcano, Hawaii: Results from waveform inversion in the 10–50 s band”, Journal of Geophysical. Research.,Vol. 115, B09311,doi:10.1029/2009JB006661, 2010
[20] Chouet, B., and Dawson, P., “ Very long period conduit oscillations induced by rockfalls at Kilauea Volcano, Hawaii” Journal of Geophysical Research, Solid earth, Vol., 118, P. 5352-5371, 2013
[21] Dawson, P., and Chouet, B., “Characterization of very-long-period seismicity accompanying summit activity at K?lauea Volcano, Hawai'i: 2007–2013”: Journal of Volcanology and Geothermal Research, v. 278–279, p. 59–85, 2014
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