advanced seismic sensor capable of measuring rotational seismic motions
(FMP CUP patented technology)

For the latest prototype documentation and current measurement, please see

Scientific cooperation between the Charles University in Prague, Faculty of Mathematics and Physics, Department of Geophysics, and the Czech Academy of Sciences, Institute of Rock Structure and mechanics, Department of Seismotectonics, has led to development of new advanced seismic sensors called Rotaphones. These sensitive portable sensors suitable for field measurements operate at higher frequency range (above 2 Hz) and provide collocated records of translational and rotational components of seismic ground motion.

The device consists of paired geophones mounted to a rigid frame anchored to the ground. The first prototype (see Fig. 1) was deployed in the station Nový Kostel in West Bohemia belonging to the WEBNET seismic network in autumn 2008. The device measured motion in a horizontal plane, i.e. two perpendicular translational velocity components and rotation rate about vertical axis. Examples of rotational records from this instrument are shown in Fig. 2. More details and more examples can be found in the papers by Brokesova and Malek (2010) or Brokesova et al. (2012).

A prototype of Rotaphone

Fig. 1: A prototype of the seismic rotational sensor system Rotaphone (older prototype)

The latest 6DOF Rotaphone prototype

Fig. 3: The latest 6DOF Rotaphone prototype

Vertical rotation rate due to three micro-earthquakes near Bad Brambach

Fig. 2: Vertical rotation rate due to three micro-earthquakes near Bad Brambach, May 2010, ML=0.3−0.9, dist=11 km, depth cca 10 km.

In 2012 a new six-degree-of-freedom (6DOF) Rotaphone (Brokesova end Malek, 2013, SRL, in press) was developed by Czech specialists from Department of Geophysics (FMP CUP) and Department of Seismotectonics (IRSM, CAS). This new instrument (Fig. 3) was tested at the USGS Albuquerque Seismological Laboratory, New Mexico, USA (Brokesova et al., 2012). The device measures three translational velocity components and three rotation rate components. It was deployed in various seismotectonic regions (Western Bohemia swarm region, stations Lazy, Luby and Nový Kostel; East Bohemia Hronov/Poříčí fault zone, station Ostaš; Provadia region in Bulgaria characterized by induced seismicity due to salt-production, station Provadia; an active rift region in the Gulf of Corinth, station Sergoula and Loutraki, Greece, etc.). An example of its record from Greece is shown in Fig. 4.

6DOF record

Fig. 4: 6DOF record from the tectonic event of ML=4.3 from April 25, 2012, 10:34:12 UTC. Left column: vertical, radial and transverse ground velocity components, right column: Z-, R- and T-axis rotation rate components. Time scale origin is at 10:34:17 UTC.