BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Memento EPFL// BEGIN:VEVENT SUMMARY:4D seismics in the laboratory: imaging using acoustic emission tom ography DTSTART:20171103T121500 DTEND:20171103T131500 DTSTAMP:20260510T013026Z UID:d7ae3cdf854f4f4efc38b28a70b454b1ebddf5c6edec8c91fcfe51cb CATEGORIES:Conferences - Seminars DESCRIPTION:Dr Nicolas Brantut\, NERC Research Fellow\, Rock and Ice Physi cs Laboratory\, Seismological Laboratory\, Department of Earth Sciences\, University College London\, (UCL) UK\nAbstract: Over the past three decade s\, there has been tremendous technological developments of laboratory equ ipment and studies using acoustic emission and ultrasonic monitoring of ro ck samples during deformation. Using relatively standard seismological tec hniques\, acoustic emissions can be detected\, located in space and time\, and source mechanisms can be obtained. In parallel\, ultrasonic velocitie s can be measured routinely using standard pulse-receiver techniques.\n \ nDespite these major developments\, current acoustic emission and ultrason ic monitoring systems are typically used separately\, and the poor spatial coverage of acoustic transducers precludes performing active 3D tomograph y in typical laboratory settings.\n \nHere\, I present an algorithm and s oftware package that uses both passive acoustic emission data and active u ltrasonic measurements to determine acoustic emission locations together w ith the 3D\, anistropic P-wave structure of rock samples during deformatio n. The technique is analogous to local earthquake tomography\, but tailore d to the specificities of small scale laboratory tests. The fast marching method is employed to compute the forward problem. The acoustic emission l ocations and the anisotropic P-wave field are jointly inverted using the Q uasi-Newton method. I will present benchmark tests\, as well as a real-lif e example showing the propagation of a compaction front in a porous sandst one.\n \nBio: Nicolas Brantut has been working as a NERC Research Fellow at University College London (where he also holds a proleptic lectureship appointment) since October 2013. He obtained his PhD in 2010 from the Éco le Normale Supérieure and the Institut de Physique du Globe\, Paris\, wor king under the supervision of Pr. Yves Guéguen and Dr. Alexandre Schubnel on thermo-hydro-mechanical and chemical coupling process during earthquak es. He served as a post-doctoral research associate in the Rock and Ice Ph ysics Laboratory at UCL\, under the supervision of Pr. Philip Meredith\, b etween 2010 and 2013. His research interests are in fault and earthquake m echanics\, rock physics\, and seismology. He uses both experimental approa ches with high pressure rock deformation experiments and theoretical appro aches with a strong emphasis on micro-mechanical modelling. LOCATION:GC C3 30 https://plan.epfl.ch/?room=GCC330 STATUS:CONFIRMED END:VEVENT END:VCALENDAR