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Mas de Barberans seismic station (CMAS)

Code: CA.CMAS Name: Mas de Barberans 

Latitude: 40.7256 N Longitude: 0.3138 E Height: 530 m

Local depth: - m

Owner: Institut Cartogràfic i Geològic de Catalunya

Subsoil features

Lithology

Period

Vs30 (m/s)

Classe EC8

F0 (Hz)

Black dolostone

Jurassic

890

A

-

Instrumentation by channels and periods

Channels

Start date

Sensor type

Digitizer type

Instrumental response

HHZ, HHN, HHE

01/04/2006

Broadband velocimeter

24 bits

[StationXML]

Geophysical characterisation

H/V Spectral ratio from seismic noise

H/V Spectral ratio from seismic noise records of Mas de Barberans seismic station. A peak around 4.5 Hz is observed with H/V amplitude lower than 2. According to the criteria of SESAME project (ftp://ftp.geo.uib.no/pub/seismo/SOFTWARE/SESAME/USER-GUIDELINES/SESAME-HV-User-Guidelines.pdf) this peak cannot be interpreted as the soil fundamental frequency, since amplitude higher than 2 is required. But, the amplitude of this peak could be related to the presence of a velocity inversion or with a low impedance contrast within the near-surface layers.

H/V Spectral ratio curve using seismic noise records from Mas de Barberans seismic station.

H/V Spectral ratio curve using seismic noise records from Mas de Barberans seismic station.

P-waves velocity  model

The P-waves velocity model, obtained by seismic tomography provides information of the subsoil up to 10 meters depth. A first layer of variable thickness is observed, between 2 and 6 meters, with a velocity lower than 2500 m/s. These velocity values correspond to rippable materials and can be related to a fractured or weathered rock. Velocity is lower than 1500 m/s in some sectors, which is associated with low compacted material, and at some point these sectors reach 4 meters depth. Below 8-9 meters depth, the P-wave velocity exceeds 3000m/s, values that are related to non-rippable bedrock.

P-waves velocity model of Mas de Barberans seismic station, obtained by seismic tomography technique.

P-waves velocity model of Mas de Barberans seismic station, obtained by seismic tomography technique.

S-waves velocity model

From the surface waves analysis (MASW) a vertical shear waves velocity profile is retrieved (Vs). Four layers are identified: (1) the shallowest layer has a thickness of 2 meters and a velocity about 400 m/s. (2) Below, a high velocity layer is identified, with values higher than 1300 m/s and about 5 meters thick. (3) Underlying this second layer, a velocity inversion is identified and the Vs decreases up to 750 m/s. This layer reaches near 20 meters depth. (4) Finally the velocity increases again in the last layer up to 1200 m/s.

S-Waves velocity model of Mas de Barberans seismic station, obtained from the analisi of surface waves (MASW).

S-Waves velocity model of Mas de Barberans seismic station, obtained from the analisi of surface waves (MASW).

Images

3 multimedia

General view: instrumental house, lightning rod, geodetic pillar, VSAT antenna, solar pannels and fence.