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Cassa de la Selva seismic station (CCAS)

Code: CA.CCAS Name: Cassà de la Selva 

Latitude: 41.8828 N Longitude: 2.9041 E Height: 197 m

Local depth: -30 m

Owner: Institut Cartogràfic i Geològic de Catalunya

Subsoil features

Lithology

Period

Vs30 (m/s)

Classe EC8

F0 (Hz)

Sandstones and lutites

Ordovician

672 (0 m)

1184 (-30 m)

B (0 m)

A (-30 m)

5 (0 m)

- (-30 m)

Instrumentation by channels and periods

Channels

Start date

Sensor type

Digitizer type

Instrumental response

HHZ, HH1, HH2

16/12/2005

Broadband velocimeter

24 bits

[StationXML]

Geophysical characterisation

H/V Spectral ratio from seismic noise

H/V Spectral ratio from seismic noise records of Cassà de la Selva seismic station. It is observed an almost flat curve, without any significant peak which might be associated to  the fundamental frequency of the soil. This behaviour is typical of rock sites.

H/V Spectral ratio of seismic noise records of Cassà de la Selva seismic station.

P-waves velocity  model

In the P-waves velocity model, obtained by seismic refraction tomography a package of low velocity materials (VP <2000 m/s) has been detected that extends up to 30 meters deep (ripable materials). Up to approximately 5 meters deep, the velocity is less than 1000-1500 m/s, these values ​​are usually associated with unconsolidated sedimentary materials. Around 40 meters deep, velocities above 2500 m/s are reached, velocity values ​​associated with healthy non-ripable rock (bedrock). There is a strong speed gradient on the southeast side of the profile, where it exceeds 4000-5000 m/s at a depth of 50 meters.

P-waves velocity model of Cassà de la Selva seismic station.

S-waves velocity model

In the shear wave propagation velocity model (VS) obtained by analyzing the dispersion curves (array + MASW) a surface layer with a velocity of about 200 m/s of about 2 meters thick is observed. Below the velocity grows progressively as the depth increases. Up to 24 meters there is 770 m/s and then the velocity increases up to 950 m/s. At a depth of about 40 meters, velocity values ​​close to 1300 m/s are detected that can be interpreted as the bedrock. Finally, at a depth of 60 meters, values ​​close to 3000 m/s are observed.

S-waves velocity model of Cassà de la Selva seismic station.

Images

6 multimedia

General view of the diferent elements: instrumental house, lightning rod (PDC), geodetic pillar with GPS antenna, VSAT antenna, solar pannels and security fence.