Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/1197
AuthorsCocco, M.* 
Ardizzoni, F.* 
Azzara, R. M.* 
Dall'Olio, L.* 
Delladio, A.* 
Di Bona, M.* 
Malagnini, L.* 
Margheriti, L.* 
Nardi, A.* 
TitleBroadband waveforms and site effects at a borehole seismometer in the Po alluvial basin (Italy)
Issue DateFeb-2001
Series/Report no.44/1
URIhttp://hdl.handle.net/2122/1197
Keywordsbroadband data
borehole seismometer
site effect
alluvial basin
Subject Classification04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring 
AbstractBroadband seismograms recorded at a borehole three-component (high dynamic range) seismic station in the Po Valley (Northern Italy) were analyzed to study the velocity structure of the shallow sedimentary layers as well as the local site effects in soft sediments. The broadband borehole seismometer was installed at a depth of 135 m just below the quaternary basement, while a second digital broadband seismometer was installed in the same site at the Earth surface. The velocity structure in the shallower layers was determined both by means of cross-hole and up-hole measurements and by inverting seismic data recorded during a seismic exploration experiment.Velocity discontinuities are quite well related to the stratigraphy of the site. We are interested to record local earthquakes as well as regional and teleseismic events. The analyzed data set includes local, regional and teleseismic events, most of which were recorded during the seismic sequence that started on October 15, 1996, near Reggio Emilia 80 km away from the borehole site. The orientation of the borehole sensor is determined using the recordings of a teleseismic event and of some local earthquakes. The noise reduction for the borehole sensor is 2 decades in power spectral density at frequencies larger than 1.0 Hz. We studied the site amplification of the shallow alluvial layers by applying the spectral ratio method. We analyzed the spectral ratios of noise recorded by the surface and borehole seismometers as well as those from local earthquakes. We compared these observations with a theoretical model for the site response computed by the Haskell-Thomson method.
Appears in Collections:Manuscripts
Annals of Geophysics
Papers Published / Papers in press

Files in This Item:
File Description SizeFormat 
10.pdf5.97 MBAdobe PDFView/Open
Show full item record

Page view(s)

154
checked on May 26, 2017

Download(s)

432
checked on May 26, 2017

Google ScholarTM

Check