Magma Pathways and Their Interactions Inferred from InSAR and Stress Modeling at Nyamulagira Volcano, D.R. Congo

Remote Sensing

Christelle Wauthier³  Valérie Cayol⁴  Benoît Smets⁵  Nicolas d’Oreye¹  François Kervyn⁶  Zhong Lu²  Salvatore Stramondo² 

[1] European Center for Geodynamics and Seismology, Walferdange 7256, Luxembourg; E-Mail:;id="af1-remotesensing-07-15179">1Department of Geosciences, The Pennsylvania State University, State College, PA 16801, U;Department of Geosciences, The Pennsylvania State University, State College, PA 16801, USA;DSPT3, LMV-LTL, The Lyon University, Université Jean Monnet-CNRS-IRD, Saint-Etienne 42023, France; E-Mail:;Department of Geography, Vrije Universiteit Brussel, Brussels 1050, Belgium; E-Mail:;Department of Earth Sciences, Royal Museum for Central Africa, Tervuren 3080, Belgium; E-Mail:

关键词: radar interferometry;    numerical modeling;    non-linear inversion;    dike;    normal-stress;    Virunga;    East African Rift;   

DOI  :  10.3390/rs71115179

来源: mdpi

【 摘 要 】

A summit and upper flank eruption occurred at Nyamulagira volcano, Democratic Republic of Congo, from 2–27 January 2010. Eruptions at Nyamulagira during 1996–2010 occurred from eruptive fissures on the upper flanks or within the summit caldera and were distributed along the ~N155E rift zone, whereas the 2011–2012 eruption occurred ~12 km ENE of the summit. 3D numerical modeling of Interferometric Synthetic Aperture Radar (InSAR) geodetic measurements of the co-eruptive deformation in 2010 reveals that magma stored in a shallow (~3.5 km below the summit) reservoir intruded as two subvertical dikes beneath the summit and southeastern flank of the volcano. The northern dike is connected to an ~N45E-trending intra-caldera eruptive fissure, extending to an ~2.5 km maximum depth. The southern dike is connected to an ~N175E-trending flank fissure extending to the depth of the inferred reservoir at ~3.5 km. The inferred reservoir location is coincident with the reservoir that was active during previous eruptions in 1938–1940 and 2006. The volumetric ratio of total emitted magma (intruded in dikes + erupted) to the contraction of the reservoir (r_v) is 9.3, consistent with pressure recovery by gas exsolution in the small, shallow modeled magma reservoir. We derive a modified analytical expression for r_v, accounting for changes in reservoir volume induced by gas exsolution, as well as eruptive volume. By using the precise magma composition, we estimate a magma compressibility of 1.9–3.2 × 10⁹ Pa⁻¹ and r_v of 6.5–10.1. From a normal-stress change analysis, we infer that intrusions in 2010 could have encouraged the ascent of magma from a deeper reservoir along an ~N45E orientation, corresponding to the strike of the rift transfer zone structures and possibly resulting in the 2011–2012 intrusion. The intrusion of magma to greater distances from the summit may be enhanced along the N45E orientation, as it is more favorable to the regional rift extension (compared to the local volcanic rift zone, trending N155E). Repeated dike intrusions beneath Nyamulagira’s SSE flank may encourage intrusions beneath the nearby Nyiragongo volcano.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.