SE Solid Earth SE Solid Earth 1869-9529 Copernicus Publications Göttingen, Germany 10.5194/se-5-873-2014 Evidence of magma activation beneath the Harrat Lunayyir basaltic field (Saudi Arabia) from attenuation tomography Koulakov I. https://orcid.org/0000-0002-0327-4416 1 2 El Khrepy S. 3 4 Al-Arifi N. 3 Sychev I. 1 Kuznetsov P. 1 Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Prospekt Koptyuga, 3, 630090, Novosibirsk, Russia Novosibirsk State University, Pirogova 2, 630090, Novosibirsk, Russia King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia National Research Institute of Astronomy and Geophysics, NRIAG, 11421, Helwan, Egypt 27 08 2014 5 2 873 882 Copyright: © 2014 I. Koulakov et al. 2014 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://se.copernicus.org/articles/5/873/2014/se-5-873-2014.html The full text article is available as a PDF file from https://se.copernicus.org/articles/5/873/2014/se-5-873-2014.pdf

We present a seismic attenuation model for the crust beneath the Cenozoic basaltic field of Harrat Lunayyir (western Saudi Arabia), where a strong seismic swarm occurred in 2009. The tomography inversion uses the envelope shape of the S wave seismograms from over 300 strong events (<i>M</i> < 3.5). The resulting attenuation structures appear to be consistent with the distribution of seismic velocities. The obtained 3-D attenuation model distinguishes the low-attenuation zones down to 5 km depth corresponding to the rigid basaltic cover. At greater depths, we detect a high-attenuation anomaly coinciding with the main seismicity cluster. We propose that this zone corresponds to the upper part of the conduit area ascending from deeper magma sources. According to the distributions of local events, fluids and melts from this conduit appear to reach a depth of &sim;2 km, but were not able to reach the surface and cause the eruption in 2009.

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