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| Author: | Pavel Martysevich |
| Institution: | * Commissariat pour l’Energie Atomique, Department Analyse Surveillance Environment (CEA, DASE), France; ** International Monitoring System (IMS) Division, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), Vienna Austria |
| Email: | pavel.martysevich@ctbto.org |
| Authors: | B. Alcoverro*, C. Le Corre-Guimard*, P. Dupont*, Th. Heritier*, P. Martysevich**, J-C. Queval*, Y. Starovoit** |
Abstract Title:
"Mechanical sensitivity of microbarometers MB2000 (France) and Chaparral M5 (USA) to vertical and horizontal ground motion." |
Abstract:
Mechanical sensitivity of two pressure sensors MB2000 and Chaparral5, widely used in the International Monitoring System (IMS) infrasound network, has been examined using shake table at Saclay, Commissariat pour l’Energie Atomique (CEA) facility in France.
Both sensors appeared to be sensitive to mechanical vibration with different level and shape of mechanical response. MB2000 mechanical response has been found to be similar to strong motion Guralp accelerometer CMG5T (flat in acceleration from DC - 50Hz) with sensitivity 0.81 V/m/s2. Chaparral5 microbarometer has about 40 times less sensitivity to mechanical vibrations than MB2000.
Mechanical sensitivity of both sensors to ground motion allows to estimate the level of acceleration amplitudes generated by different size earthquakes or explosions, which can potentially induce the output signal from microbarometer above the acoustic background. Exceeding of the noise threshold for recording of seismic signals by MB2000 could be expected even for events with Mw=3.5 for epicentral distances about 1o. However, this detection could only happen in very quiet atmospheric condition, assuming very low acoustic background at the station. Seismic signal detection for Chaparral5 could happen yet for Mw=5.5 event with epicenter distance about 1o. In case of noisier conditions the exceeding of the acoustic background level should be expected for earthquakes with higher level of magnitudes. As summary the work results contain the graph of expected microbarometer signal-to-noise ratios for different earthquake magnitudes and epicentral distances.
Further investigation of the coupling mechanism between ground motion and pressure sensors output will be beneficial for correct interpretation of signals recorded by infrasound stations of the IMS network.
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| Keywords: | Microbarometer, mechanical response |
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