[ QUELQUES ASCPECTS SÉISMIQUES PRECEDANT L'ERUPTION DU NYAMULAGIRA 6 NOVEMBRE 2011, REPUBLIQUE DEMOCRATIQUE DU CONGO ]
Volume 10, Issue 2, February 2015, Pages 752–766
Silvanos Fiama Bondo1, Clarisse Balegamire Njovu2, Jean Robert Nshokano3, and Justin Lonji Lubula4
1 Département de Géophysique, Centre de Recherche en Sciences Naturelles (CRSN/Lwiro), Sud Kivu/DS Bukavu, RD Congo
2 Département de Géophysique, Centre de Recherche en Sciences Naturelles (CRSN/Lwiro), Sud Kivu/DS Bukavu, RD Congo
3 Centre de Recherche Géologique et Minière, Station du Sud – Kivu/Lwiro, RD Congo
4 Département de Géophysique, Centre de Recherche en Sciences Naturelles (CRSN/Lwiro), Sud Kivu/DS Bukavu, RD Congo
Original language: French
Copyright © 2015 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The Nyamulagira volcano enters in eruption approximately each 2 years and the last eruption of November 06, 2011 was started 22 months after that of January 02, 2010. The aim of this work is the characterization of some aspects of seismicity prior the Nyamulagira eruption on 2011by temporal analysis of the hypocenters (epicenters and depths), earthquake number and spectral frequency. A temporal evolution showed that the seismicity rate, the hypocenters, the corner frequency and energies release vary and give a comprehension of the behavior of the volcanic activity. 10 months before the eruption, earthquakes were deep (10 - 30 km) and scattered with weak corner frequencies (< 2.6 Hz) in the field of Nyamulagira. That confirms a partial melt or deep magmatic intrusion with weak displacement. The magmatic migration starts between April and October 2011 with shallow earthquakes (0 - 5 km) and high corner frequency and high energy. This period prepares a pathway of magma to the surface. The frequency and energy were then higher in the last swarms of 04 and 05 November 2011, 2 days prior the eruption. This last seismicity denote at the same time a magmatic intrusion, a fracturing of the weakness zones and an extrusion of the lava at the surface. A deep investigation of these parameters on several eruptive cycles would facilitate the knowledge of the magmatic dynamics of Nyamulagira volcano and also the predictive approach of its eruptions.
Author Keywords: Hypocenters, corner frequency, swarms, energy release, earthquake number.
Volume 10, Issue 2, February 2015, Pages 752–766
Silvanos Fiama Bondo1, Clarisse Balegamire Njovu2, Jean Robert Nshokano3, and Justin Lonji Lubula4
1 Département de Géophysique, Centre de Recherche en Sciences Naturelles (CRSN/Lwiro), Sud Kivu/DS Bukavu, RD Congo
2 Département de Géophysique, Centre de Recherche en Sciences Naturelles (CRSN/Lwiro), Sud Kivu/DS Bukavu, RD Congo
3 Centre de Recherche Géologique et Minière, Station du Sud – Kivu/Lwiro, RD Congo
4 Département de Géophysique, Centre de Recherche en Sciences Naturelles (CRSN/Lwiro), Sud Kivu/DS Bukavu, RD Congo
Original language: French
Copyright © 2015 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
The Nyamulagira volcano enters in eruption approximately each 2 years and the last eruption of November 06, 2011 was started 22 months after that of January 02, 2010. The aim of this work is the characterization of some aspects of seismicity prior the Nyamulagira eruption on 2011by temporal analysis of the hypocenters (epicenters and depths), earthquake number and spectral frequency. A temporal evolution showed that the seismicity rate, the hypocenters, the corner frequency and energies release vary and give a comprehension of the behavior of the volcanic activity. 10 months before the eruption, earthquakes were deep (10 - 30 km) and scattered with weak corner frequencies (< 2.6 Hz) in the field of Nyamulagira. That confirms a partial melt or deep magmatic intrusion with weak displacement. The magmatic migration starts between April and October 2011 with shallow earthquakes (0 - 5 km) and high corner frequency and high energy. This period prepares a pathway of magma to the surface. The frequency and energy were then higher in the last swarms of 04 and 05 November 2011, 2 days prior the eruption. This last seismicity denote at the same time a magmatic intrusion, a fracturing of the weakness zones and an extrusion of the lava at the surface. A deep investigation of these parameters on several eruptive cycles would facilitate the knowledge of the magmatic dynamics of Nyamulagira volcano and also the predictive approach of its eruptions.
Author Keywords: Hypocenters, corner frequency, swarms, energy release, earthquake number.
Abstract: (french)
Le volcan Nyamulagira entre en éruption environ chaque 2 ans et la dernière éruption du 06 Novembre 2011 s'est produit 22 mois après celle du 02 janvier 2010. L'objet de ce travail est la caractérisation de certains aspects séismiques précédant l'éruption du Nyamulagira en 2011 par analyse temporelle des hypocentres (épicentres et profondeur), nombre des séismes et la fréquence spectrale. Une évolution temporelle a démontré que le nombre de séismicité, les hypocentres, la fréquence coin et les énergies varient et donnent une compréhension du comportement de l'activité volcanique. 10 mois avant l'éruption, les séismes ont été profonds (10 – 30 Km) et dispersés avec des fréquences coin faibles (< 2.6 Hz) dans le champ du Nyamulagira. Cela confirme une fusion partielle ou une intrusion magmatique en profondeur avec faible déplacement. La migration magmatique commence entre Avril et Octobre 2011 avec des séismes superficiels (0 – 5 Km) et à haute fréquence coin et énergie élevée. Cette période prépare une voie de passage au magma pour la surface. La fréquence et l'énergie étaient alors plus élevées dans les derniers essaims du 04 et 05 Novembre 2011, soit deux jours avant l'éruption. Cette dernière séismicité dénote à la fois une intrusion magmatique, une fracturation des zones de faiblesse et une extrusion de la lave à la surface. Un approfondissement de ces paramètres sur plusieurs cycles éruptifs faciliterait la connaissance de la dynamique magmatique du volcan Nyamulagira et aussi l'approche prédictives de ses éruptions.
Author Keywords: Hypocentres, fréquence coin, essaims, énergie libérées, nombre des séismes.
How to Cite this Article
Silvanos Fiama Bondo, Clarisse Balegamire Njovu, Jean Robert Nshokano, and Justin Lonji Lubula, “SOME SISMIC ASPECTS PRIOR THE NOVEMBER 06, 2011 NYAMULAGIRA ERUPTION, DEMOCRATIC REPUBLIC OF CONGO,” International Journal of Innovation and Applied Studies, vol. 10, no. 2, pp. 752–766, February 2015.
