Prospects for Volcano Monitoring by Ambient Body-Wave Correlation Using Planar Arrays of Geophones

Earthquake swarms observed before the 2006 and 2011 Nyamuragira eruptions were analysed. The activitiesand hypocenter distributions of these earthquake swarms were mainly examined.The former swarm was characterised by a higher seismic activity than the later. Although the two swarmsaccompanied eruptions, most of the swarms observed in 2006 and 2011 were not followed by any eruptions. Theseswarms probably represent an intrusion of magma at a shallow depth. Hypocenters of these earthquake swarms showthat most of the events are located in and around the crater of Nyamuragira summit at a shallow depth less than 5km.Some of events were located at a deep depth around 20-25km. Numerical examinations of the hypocenter determinationindicate that some small errors in arrival times make the hypocenters not re-located or relocated at a depth of 0km. Thissuggests that to obtain more reliable hypocenter distribution, it is necessary to deploy seismic stations on and aroundVolcano Nyamuragira. Such a dense seismic network will enable us to discuss more in detail the swarm activitypreceding eruptions and differences between the swarms preceding eruptions and those caused only by magma intrusionat a shallow depth.The analysis of the RSAM showed that, two months before the eruption, the energy increases linearly, from7.46 * 106 A.U to 1.8 * 107 A.U and from 1.80 x 105 to 1.76 *106 A.U respectively for the 2006 and 2011Nyamulagira eruptions.