We describe and apply a new inversion method for 3-D modeling of\u00a0magnetic anomalies designed for general application but which is\u00a0particularly useful for the interpretation of near-seafloor magnetic\u00a0anomalies. The crust subsurface is modeled by a set of prismatic\u00a0cells, each with uniform magnetization, that together reproduce the\u00a0observed magnetic field. This problem is linear with respect to the\u00a0magnetization, and the number of cells is normally greater than the\u00a0amount of available data. Thus, the solution is obtained by solving\u00a0an under-determined linear problem. A focused solution, exhibiting\u00a0sharp boundaries between different magnetization domains, is obtained\u00a0by allowing the amplitudes of magnetization to vary between a pre-determined\u00a0range and by minimizing the region of the 3-D space where the source\u00a0shows large variations, i.e., large gradients. A regularization functional\u00a0based on a depth-weighting function is also introduced in order to\u00a0counter-act the natural decay of the magnetic field intensity with\u00a0depth. The inversion method has been used to explore the characteristics\u00a0of the submarine hydrothermal system of Brothers volcano in the Kermadec\u00a0arc, by inverting near-bottom magnetic data acquired by Autonomous\u00a0Underwater Vehicles (AUVs). Different surface expressions of the\u00a0hydrothermal vent fields show specific vertical structures in their\u00a0underlying demagnetization regions that we interpret to represent\u00a0hydrothermal upflow zones. For example, at focused vent sites the\u00a0demagnetized conduits are vertical, pipe-like structures extending\u00a0to depths of similar to 1000 m below the seafloor, whereas at diffuse\u00a0vent sites the demagnetization regions are characterized by thin\u00a0and inclined conduits.<\/p>\n","protected":false},"excerpt":{"rendered":"
3-D focused inversion of magnetic data with application to the submarine Brothers volcano hydrothermal system (Southern Pacific Ocean, New Zealand) F.C. Tontini, C.E.J. de Ronde, M.I. Leybourne, D.R. Yoerger, J.C. Kinsey, and M.A. Tivey. Journal of Geophysical Research. Vol. 117, B10102, doi:10.1029\/2012JB009349, 2012. We describe and apply a new inversion method for 3-D modeling of\u00a0magnetic…<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":659,"menu_order":5,"comment_status":"closed","ping_status":"closed","template":"","meta":[],"_links":{"self":[{"href":"https:\/\/www2.whoi.edu\/site\/jameskinsey\/wp-json\/wp\/v2\/pages\/718"}],"collection":[{"href":"https:\/\/www2.whoi.edu\/site\/jameskinsey\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www2.whoi.edu\/site\/jameskinsey\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www2.whoi.edu\/site\/jameskinsey\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www2.whoi.edu\/site\/jameskinsey\/wp-json\/wp\/v2\/comments?post=718"}],"version-history":[{"count":2,"href":"https:\/\/www2.whoi.edu\/site\/jameskinsey\/wp-json\/wp\/v2\/pages\/718\/revisions"}],"predecessor-version":[{"id":720,"href":"https:\/\/www2.whoi.edu\/site\/jameskinsey\/wp-json\/wp\/v2\/pages\/718\/revisions\/720"}],"up":[{"embeddable":true,"href":"https:\/\/www2.whoi.edu\/site\/jameskinsey\/wp-json\/wp\/v2\/pages\/659"}],"wp:attachment":[{"href":"https:\/\/www2.whoi.edu\/site\/jameskinsey\/wp-json\/wp\/v2\/media?parent=718"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}