Insight in Laboratory and Monitoring Station: Mutual Visits of PTB and BGR

Within the European-funded project Infra-AUV the Bundesanstalt für Geowissenschaften und Rohstoffe (BGR, Federal Institute for Geosciences and Natural Resources) and PTB cooperate in the field of calibration of seismometers. These vibration measuring instruments are used by the BGR to monitor compliance with the nuclear test ban treaty within an international network.

In PTB's Department 1.7, new extended calibration procedures for such sensors are being developed, which should ultimately enable metrological traceability of seismic measuring stations. During summer of this year, it was possible for the members from the participating groups to visit each other for the first time in order to gain insights into the work of the other party, to exchange knowledge and technical information and to discuss problems and further ideas on site.

In July, the colleagues from BGR visited the laboratories of PTB's AG 1.71 to gain a deeper understanding of the procedures of the primary calibration of the vertical and 3-component seismometers. These seismometers had previously been provided by BGR for the development of appropriate methods.

Fig. 1: Seismometer during calibration at PTB. a) Vertical 1-component seismometer on the multi-component shaker. b) 3-component seismometer being calibrated at the horizontal shaker.

At the end of August, staff members of PTB's AG 1.71 visited the seismic station PS19 operated by BGR in the Bavarian Forest. There, the formerly primary calibrated seismometers were put back into their original position, to act as reference sensors. The aim is to calibrate further seismometers of the station installed in the vicinity by comparison with the reference sensors on site ("on-site calibration"). In contrast to the laboratory environment, where electrodynamic shakers ensure a well-defined movement of the sensors during calibration, here in the Bavarian Forest, various naturally or anthropogenically generated ground vibrations, for example from earthquakes or quarry blast, have to be facilitated as source of calibration input.

Fig. 2: PTB visit to the seismic station PS19 of BGR in the Bavarian Forest. a) Colleagues from PTB and BGR at a seismic vault. b) The view into a vault. c) One reinstalled vertical reference next to a DUT. d) 3-component reference in the neighbouring vault.

Through the visit and the joint installation work, the PTB colleagues were able to gain an insight into the practical operation of the station and the measuring conditions of the seismometers, which will be incorporated into further refinements of the calibration methods.

The transfer of calibration capability from the laboratory to the field is a significant milestone in this project. It reflects a cornerstone in the EMPIR program and demonstrates that innovations in metrology are ready for real-world applications.

Links:

EMPIR-project Infra-AUV Link

Contacts:

Thomas Bruns, FB 1.7, E-Mail: thomas.bruns(at)ptb.de

Leonard Klaus, FB 1.7, E-Mail: leonard.klaus(at)ptb.de