Results from the temporary installation of a small aperture seismic
array in the Central Appennines and its merits for local event detection
and location capabilities
In order to evaluate the detection and localisation improvement of
a small aperture array in the Northern Apennines, we installed an
irregularly spaced test configuration in the vicinity of Città
di Castello (CDC) for a period of two weeks. The experimental array
consisted of nine 3-component stations with inter-station distances
between 150 m and 2200 m. Seismic data were digitised at 125 Hz and
telemetered to a mobile acquisition, processing and storage centre.
The data could only be recorded in trigger mode. The peculiarity
of the test array installation was the exclusive use of 3-component
sensors at all array sites, which also allowed beamforming for S-phases
on the horizontal components. Since the altitudes of the single array
sites differed considerably among each other, for f-k analysis and
beamforming an elevation correction was included. During the two
weeks of operation about 20 local earthquakes with magnitudes ML<2.6,
1 regional, and several teleseismic events were recorded. In addition
to these events, the array occasionally triggered on coherent noise-signals
generated by local industrial activity. The data analysis was performed
by means of f-k analysis and beamforming, providing wavenumber characteristics
of the incident plane wave. Typical apparent velocities were determined
to be 4.8 km/s and 6 km/s for Pg-phases and \~10 km/s for Pn-phases.
We observed local seismic events, which occurred just beneath the
array. In these cases wavefronts with unusual high apparent velocities,
similar to those found for the Pn-phase, were observed. Since no
continuously recorded array data were available, we extrapolated
the lower detection magnitude threshold as a result of the SNR improvement
due to array beamforming. Compared to the actual detection threshold
of MT \~1.6 reached by the national seismic network in this area,
a nine element array would improve this value up to MT \~0.8.
%0 Journal Article
%1 braun_etal:2004
%A Braun, Thomas
%A Schweitzer, Johannes
%A Azzara, Riccardo M.
%A Piccinini, Davide
%A Cocco, Massimo
%A Boschi, Enzo
%D 2004
%J Annals of Geophysics
%K geophysics seismology
%N 5
%P 1557--1568
%R 10.4401/ag-3359
%T Results from the temporary installation of a small aperture seismic
array in the Central Appennines and its merits for local event detection
and location capabilities
%U http://www.annalsofgeophysics.eu/index.php/annals/article/view/3359
%V 47
%X In order to evaluate the detection and localisation improvement of
a small aperture array in the Northern Apennines, we installed an
irregularly spaced test configuration in the vicinity of Città
di Castello (CDC) for a period of two weeks. The experimental array
consisted of nine 3-component stations with inter-station distances
between 150 m and 2200 m. Seismic data were digitised at 125 Hz and
telemetered to a mobile acquisition, processing and storage centre.
The data could only be recorded in trigger mode. The peculiarity
of the test array installation was the exclusive use of 3-component
sensors at all array sites, which also allowed beamforming for S-phases
on the horizontal components. Since the altitudes of the single array
sites differed considerably among each other, for f-k analysis and
beamforming an elevation correction was included. During the two
weeks of operation about 20 local earthquakes with magnitudes ML<2.6,
1 regional, and several teleseismic events were recorded. In addition
to these events, the array occasionally triggered on coherent noise-signals
generated by local industrial activity. The data analysis was performed
by means of f-k analysis and beamforming, providing wavenumber characteristics
of the incident plane wave. Typical apparent velocities were determined
to be 4.8 km/s and 6 km/s for Pg-phases and \~10 km/s for Pn-phases.
We observed local seismic events, which occurred just beneath the
array. In these cases wavefronts with unusual high apparent velocities,
similar to those found for the Pn-phase, were observed. Since no
continuously recorded array data were available, we extrapolated
the lower detection magnitude threshold as a result of the SNR improvement
due to array beamforming. Compared to the actual detection threshold
of MT \~1.6 reached by the national seismic network in this area,
a nine element array would improve this value up to MT \~0.8.
@article{braun_etal:2004,
abstract = {In order to evaluate the detection and localisation improvement of
a small aperture array in the Northern Apennines, we installed an
irregularly spaced test configuration in the vicinity of Citt\`{a}
di Castello (CDC) for a period of two weeks. The experimental array
consisted of nine 3-component stations with inter-station distances
between 150 m and 2200 m. Seismic data were digitised at 125 Hz and
telemetered to a mobile acquisition, processing and storage centre.
The data could only be recorded in trigger mode. The peculiarity
of the test array installation was the exclusive use of 3-component
sensors at all array sites, which also allowed beamforming for S-phases
on the horizontal components. Since the altitudes of the single array
sites differed considerably among each other, for f-k analysis and
beamforming an elevation correction was included. During the two
weeks of operation about 20 local earthquakes with magnitudes ML<2.6,
1 regional, and several teleseismic events were recorded. In addition
to these events, the array occasionally triggered on coherent noise-signals
generated by local industrial activity. The data analysis was performed
by means of f-k analysis and beamforming, providing wavenumber characteristics
of the incident plane wave. Typical apparent velocities were determined
to be 4.8 km/s and 6 km/s for Pg-phases and \~{}10 km/s for Pn-phases.
We observed local seismic events, which occurred just beneath the
array. In these cases wavefronts with unusual high apparent velocities,
similar to those found for the Pn-phase, were observed. Since no
continuously recorded array data were available, we extrapolated
the lower detection magnitude threshold as a result of the SNR improvement
due to array beamforming. Compared to the actual detection threshold
of MT \~{}1.6 reached by the national seismic network in this area,
a nine element array would improve this value up to MT \~{}0.8.},
added-at = {2012-09-01T13:08:21.000+0200},
author = {Braun, Thomas and Schweitzer, Johannes and Azzara, Riccardo M. and Piccinini, Davide and Cocco, Massimo and Boschi, Enzo},
biburl = {https://www.bibsonomy.org/bibtex/28bf78c779fd062e9713ffa1be6a5fca5/nilsma},
doi = {10.4401/ag-3359},
interhash = {f14d5a5c173303e317d1dd4fd2a7ea3c},
intrahash = {8bf78c779fd062e9713ffa1be6a5fca5},
journal = {Annals of Geophysics},
keywords = {geophysics seismology},
number = 5,
pages = {1557--1568},
timestamp = {2021-02-09T13:23:09.000+0100},
title = {Results from the temporary installation of a small aperture seismic
array in the Central Appennines and its merits for local event detection
and location capabilities},
url = {http://www.annalsofgeophysics.eu/index.php/annals/article/view/3359},
volume = 47,
year = 2004
}