DSpace

Digital.CSIC > Recursos Naturales > Instituto de Astronomía y Geodesia (IAG) > (IAG) Artículos >

Share

EndNote

Impact

Open Access item Source parameters of the 2008 Bukavu-Cyangugu earthquake estimated from InSAR and teleseismic data

Authors:D'Oreye, N.
González Méndez, Pablo José
Shuler, Ashley
Oth, Adrien
Bagalwa, Louis
Ekström, Göran
Kavotha, Déogratias
Kervyn, F.
Lucas, Celia
Lukay, François
Osodundu, Etoy
Wauthier, C.
Fernández Torres, José
Keywords:Radar interferometry, Earthquake source observations, Seismicity and tectonics, Body waves, Continental tectonics, extensional, Africa, InSAR
Issue Date:Feb-2011
Publisher:Royal Astronomical Society
Citation:d’Oreye, N., González, P. J., Shuler, A., Oth, A., Bagalwa, L., Ekström, G., Kavotha, D., Kervyn, F., Lucas, C., Lukaya, F., Osodundu, E., Wauthier, C. and Fernández, J. (2011), Source parameters of the 2008 Bukavu-Cyangugu earthquake estimated from InSAR and teleseismic data. Geophysical Journal International, 184: 934–948. doi: 10.1111/j.1365-246X.2010.04899.x
Abstract:Earthquake source parameter determination is of great importance for hazard assessment, as well as for a variety of scientific studies concerning regional stress and strain release and volcano-tectonic interaction. This is especially true for poorly instrumented, densely populated regions such as encountered in Africa, where even the distribution of seismicity remains poorly documented. In this paper, we combine data from satellite radar interferometry (InSAR) and teleseismic waveforms to determine the source parameters of the Mw 5.9 earthquake that occurred on 2008 February 3 near the cities of Bukavu (DR Congo) and Cyangugu (Rwanda). This was the second largest earthquake ever to be recorded in the Kivu basin, a section of the western branch of the East African Rift (EAR). This earthquake is of particular interest due to its shallow depth and proximity to active volcanoes and Lake Kivu, which contains high concentrations of dissolved carbon dioxide and methane. The shallow depth and possible similarity with dyking events recognized in other parts of EAR suggested the potential association of the earthquake with a magmatic intrusion, emphasizing the necessity of accurate source parameter determination. In general, we find that estimates of fault plane geometry, depth and scalar moment are highly consistent between teleseismic and InSAR studies. Centroid-moment-tensor (CMT) solutions locate the earthquake near the southern part of Lake Kivu, while InSAR studies place it under the lake itself. CMT solutions characterize the event as a nearly pure double-couple, normal faulting earthquake occurring on a fault plane striking 350° and dipping 52° east, with a rake of –101°. This is consistent with locally mapped faults, as well as InSAR data, which place the earthquake on a fault striking 355° and dipping 55° east, with a rake of –98°. The depth of the earthquake was constrained by a joint analysis of teleseismic P and SH waves and the CMT data set, showing that the earthquake occurred in the shallow crust, at approximately 8 km depth. Inversions of ENVISAT (Environment Satellite) and ALOS (Advanced Land Observation Satellite) data place the earthquake at 9 km. A comparison of the scalar moment (9.43 ± 0.06 × 1017 Nm from seismology and 8.99 ± 0.010 × 1017 Nm from the joint InSAR solution) shows good agreement between the two data sets. Such an agreement is in contrast to the large discrepancies observed (up to an order of magnitude) in other places along the EAR where similar earthquake sequences are associated with magmatic intrusion. From this, we infer that the rupture was brittle and occurred with little aseismic deformation as might be expected from magma injection. Our results provide insights into the style of rifting occurring in the South Kivu Volcanic Province and hence will aid future studies on seismic risk in the context of Lake Kivu and underline the importance of systematic monitoring of the EAR area.
Publisher version (URL):http://dx.doi.org/10.1111/j.1365-246X.2010.04899.x
URI:http://hdl.handle.net/10261/61346
???metadata.dc.identifier.doi???:10.1111/j.1365-246X.2010.04899.x
Appears in Collections:(IAG) Artículos

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.