Seismic wave recordings in the Alps

Seismic wave recording in the Alps by RAP accelerometer stations: https://rap.resif.fr/

The displacement of the Alps generated by this earthquake is about 1 cm. This displacement is not permanent and corresponds to displacements that occur over several seconds (long wavelength). This displacement is of the same order of magnitude as that observed in the Alps during the Sumatra earthquake (2004).

Figure 1 - Accelerations recorded by some resorts at the rock in the Alps. - horizontal component of the signal between 0.01 and 0.1 Hz. Stations Argentière-La-Bessée (05), Annecy (74), Meyronnes/St-Ours (04), Chambéry (73) and Grenoble (38).

Figure 2 - Speeds recorded by some resorts at the rock in the Alps. - horizontal component of the signal between 0.01 and 0.1 Hz. Same stations.

Figure 3 - Travelling recorded by some resorts to the rock in the Alps. - horizontal component of the signal between 0.01 and 0.1 Hz. The Alps moved uniformly, without internal deformation. Same stations.

Figure 4 - Accelerations recorded by the station at the OGMU rock and in the middle of the OGDH basin - vertical component of the signal between 0.01 and 0.5 Hz.

Figure 5 - Accelerations recorded by the station at the OGMU rock and in the middle of the OGDH basin - horizontal component of the signal between 0.01 and 0.5 Hz. We observe the effect of the Grenoble sedimentary basin which vibrates from 0.3-0.4 Hz.

Figure 6 - Accelerations recorded by the station at the top OGH4 and at the base OGH1 of the Hôtel de Ville de Grenoble - horizontal component of the signal between 0.01 and 0.5 Hz. At these frequencies the tower moves without deformation, in the same way as the sedimentary basin.

Figure 7 - Accelerations recorded by the station at the top OGH4 and at the base OGH1 of the Hôtel de Ville de Grenoble - horizontal component of the signal between 0.5 and 2 Hz. At these frequencies, the top of the tower, which has a resonance frequency around 1Hz, moves more than the sedimentary basin.

Figure 8 - Speeds recorded by the three stations at the top of Grenoble City Hall - horizontal component of the signal between 0.5 and 2 Hz. At these frequencies, the top of the tower moves regularly: few internal deformations are suspected.