Repeat survey in Tournemire

From June 20 to 30, the 3D-US Lab team together with other GFZ staff from the section "Geophysical Imaging " performed seismic measurements at the underground laboratory Tournemire of IRSN (institut de radioprotection et de sureté nucléaire). Seismic impact hammers and magnetostrictive vibration source developed by the Lab were used along a section profile of about 100 m for structural imaging of a fault zone in the claystone. Two new horizontal wells parallel to the fault were used for high-resolution cross-hole measurements (see figure). For the first time, the prototype of a newly developed borehole vibrator source was used and eight levels of a horizontal geophone chain of the 3D-US Lab.