Simultaneous seismic and magnetic measurements in the Low-Noise Underground Laboratory (LSBB) of Rustrel, France, during the 2001 January 26 Indian earthquake

Abstract

S U M M A R YSince the decommission of the underground launching control room of the ground-based component of the French nuclear missile system, the whole installation has been turned into a cross-disciplinary underground laboratory. The LSBB is a unique low-noise underground laboratory because of its initial military conception and its location in the regional park of Luberon far from large cities, industry and heavy traffic. The deepest point is 500 m below the surface. At this depth a huge and non-conventional shielded cylindrical capsule is installed with no µ-metal, 1268 m 3 in volume, with a residual electromagnetic noise lower than 2 fT Hz −1/2 above 10 Hz. As a result, fluctuations of the Earth's magnetic field under 10 Hz can be recorded at a very low-noise level with a low-T c SQUID 3-D magnetometer. Taking advantage of the main gallery topology, a broad-band underground seismic array has been deployed since 2001. An analysis of data recorded simultaneously by the seismic underground array and by the magnetometer sensors during the Indian earthquake of 2001 January 26 is presented. Evidence of a magnetic field perturbation induced by the seismic waves at teleseismic distance (6250 km) is supported by a polarization analysis of seismic and magnetic signals. Spectral analysis shows specific frequency bands of perturbation related to physical processes such as ground water flow acceleration within the mountain structure.

Detection and localization of hydromechanical disturbances in a sandbox using the self‐potential method

“…Distinct electromagnetic (EM) signals are generated during rock fracturing, steam injection in Hot Dry Rock (HDR) reservoirs, detonation of explosive charges in boreholes, and generally speaking any kind of hydro‐mechanical disturbances affecting the porous and conductive ground [e.g., Surkov and Pilipenko , 1997; Ushijima et al , 1999; Yoshida , 2001; Gaffet et al , 2003; Yoshida and Ogawa , 2004; Soloviev and Sweeney , 2005; Moore and Glaser , 2006, 2007; Park et al , 2007]. In addition, possible EM signals in various frequency ranges have been reported preceding earthquakes [e.g., Tate and Daily , 1989; Fraser‐Smith et al , 1990; Dea et al , 1991; Park et al , 1993, Fenoglio et al , 1995, and references therein].…”

Soil anomaly mapping using a caesium magnetometer: Limits in the low magnetic amplitude case

“…Series of recent contributions (Pride, 1994;Pride and Haartsen, 1996;Haartsen and Pride, 1997) ( Garambois and Dietrich, 2001); they were mainly investigated to develop potential geophysical exploration tools (Thompson and Gist, 1993). On the other hand, a magnetic signal was recently reported during an earthquake, far from the seismogenic region (Gaffet et al, 2003). It was recorded in the Low Noise Underground Laboratory (LSBB) of Rustrel, France.…”

Earth–ionosphere couplings, magnetic storms, seismic precursors and TLEs: Results and prospects of the [SQUID]2 system in the low-noise underground laboratory of Rustrel-Pays dʼApt

“…Simultaneously at the P wave arrival from an M w = 7.6 earthquake (Bhuj, India) the SQUID has recorded a magnetic signal in the tens of picoteslas range: the magnetic-hydro-seismic response of the karstic system of the Plateau de Vaucluse into which the LSBB is embedded [3].…”