EGU2020-18084
https://doi.org/10.5194/egusphere-egu2020-18084
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Four years of soil strain monitoring on Etna Volcano Mount by means of a Three-axial Fiber Bragg Grating Sensor

Umberto Giacomelli1,2, Enrico Maccioni1, Giorgio Carelli1,3, Daniele Carbone4, Salvatore Gambino4, Massimo Orazi5, Rosario Peluso5, and Fiodor Sorrentino3,6
Umberto Giacomelli et al.
  • 1Università di Pisa, Dipartimento di Fisica, Pisa Italy
  • 2INFN - Sezione Pisa, Pisa, Italy
  • 3Marwan Technology srl, Pisa, Italy
  • 4Osservatorio Etneo, INGV - Sezione di Catania, Catania, Italy
  • 5Osservatorio Vesuviano, INGV - Sezione di Napoli, Napoli, Italy
  • 6INFN - Sezione di Genova, Genova, Italy

Rock strains detection is one of the principal ways to monitor geohazards. Classic strainmeters are cumbersome, hard to install and very expensive. Opto-electronics devices based on fiber Bragg grating technology allow to realize strainmeters with high sensitivity, low-cost, small volume and high performance.
We present the long term result of continuous soil strain monitoring on the Etna mount by a three-axial fiber Bragg grating sensor. The sensor has been developed in the framework of European Project MED-SUV (MEDiterranean SUpersite Volcanos). The installation site is a 8.5 meters deep borehole at a distance of about 7 km South-West from the summit craters of the Etna mount, at an elevation of about 1740 meters. This kind of sensor has a resolution better than 100 nanostrains on a daily timescale. Despite it is only a prototype, the sensor has worked for four years with a duty-cycle higher than 90% detecting both fast event, as earthquakes, and slow event, as epochal rocks strain behavior.

How to cite: Giacomelli, U., Maccioni, E., Carelli, G., Carbone, D., Gambino, S., Orazi, M., Peluso, R., and Sorrentino, F.: Four years of soil strain monitoring on Etna Volcano Mount by means of a Three-axial Fiber Bragg Grating Sensor, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18084, https://doi.org/10.5194/egusphere-egu2020-18084, 2020

Comments on the presentation

AC: Author Comment | CC: Community Comment | Report abuse

Presentation version 1 – uploaded on 24 Apr 2020
  • CC1: Comment on EGU2020-18084, Mark Woods, 06 May 2020

    Curious about the sensor emplacement. How are the sensors coupled to the Earth?

    • AC1: Reply to CC1, Umberto Giacomelli, 06 May 2020

      We have selected a specific concrete produced by MAPEI that has similar characteristics of the basalt rock. The 3 sensors are walled-up in a concrete cylinder and then walled up on the bottom of the borehole.

      • CC2: Reply to AC1, Mark Woods, 06 May 2020

        Thank you. How close are the concrete characteristics to the surrounding basalt? Do you expect "impedance" contrasts? Can you minimize the effects with suitably sized cavity for the sensors?

        This is a very interesting topic. Also, can you compare the in-situ strain measurements with surface GPS measurements, or are they not measuring comparable deformations?

        • AC2: Reply to CC2, Umberto Giacomelli, 06 May 2020

          This concrete has the same poisson-ratio of the basalt rocks so the transmission of the strain is optimal. The sensors are made by optical fiber so it is necessary a shield around it is hard to connect it directly on the rocks without breaking it. We have performed several calibration and comparison also using local GPS stations, you can find a more detailed explanation in our paper: https://doi.org/10.1063/1.5086516
          If you need a copy please send me an email (you can find my address clicking my name in the presentation) I'll be happy to send you a copy

          • CC3: Reply to AC2, Mark Woods, 06 May 2020

            Yes, I think that I should like a copy. Thank you very much.