The big ears of Barcelona

Seismometers are simply ears listening the ground noise. As in a room full of people, the "ears" set up at the Observatory Fabra (built in 1904) listen what's going on in the city of Barcelona. Any phenomena suitable to radiate elastic waves that propagates in the ground can provide its signature in the record of the seismograph of the observatory.

View of the Observatory Fabra at the Tibidabo mountain in Barcelona


Yesterday, May 17, 2006, in a place more than 1000 km away from Barcelona, there were 22 guys playing a football match (the 2006 UEFA Champions League final), half of them represented the most popular team of the City. The match ended exactly at 22h 42' (20h 42' UTC). The explosion of happiness of the whole city of Barcelona (jumps, fireworks, etc.) provided a significant increase on the background seismic noise.



The geophones set up at the Observatory Fabra undoubtedly detected these new signals as shown in the near-real time ISEV systems managed by the team of Physics of the Earth of the Departament d’Astronomia i Meteorologia (UB) and the Laboratori d'Estudis Geofísics "Eduard Fontserè" (IEC).

Seismic record (long period band) of the Observatory Fabra corresponding to May 17, 2006.
There is a clear perturbation at 20h 42' (UTC) that coincides with the end of the match.
Two earthquakes (03h 25' and 22h 21') of magnitude 6.0 and 5.9 that occurred in Tonga Islands can also be appreciated.



The high-pass filtered waveform trace (short-period band) emphasizes the increase of high frequency noise that started in the previous minutes before the end, raising the maximum amplitude at 22h 42'.


Short-period record of station FBR (Observatory Fabra). Time axis units are minutes starting at 22h 00' of May 17,2006



Photograph of the seismic sensors set up at the Observatory Fabra. These are the "ears" of Barcelona.






The above example is not the first time that the ISEV seismic systems record football-related seismic signals. In September 3rd, 2003, the match F.C.Barcelona vs. Sevilla F.C. was scheduled in a very unusual time: 5 minutes past midnight. The first goal of Ronaldinho in an official match was scored at 01h 26' AM (local time). The very low level of cultural noise made easy to detect the "scream" of the 80237 surprised people that were on the stadium. The impact of the sound wave in the Tibidabo mountain created a seismic wave.

To see the "Clam del camp" go to ronaldinho



Page created by Josep Vila (jvilaam.ub.es) on May 18, 2006.