Publication Date:
2017-04-04
Description:
With the aim to find a more objective way to detect seismic families,
we applied a series of successive steps to constrain the results of a waveform similarity
analysis. The evaluation of similarity was carried out on the waveforms recorded
in the period 1999–2003 by the stations operating in the Garfagnana area,
located in northern Tuscany (Italy). The algorithm is based on the cross-correlation
technique applied in a process that overcomes the limit of one order of magnitude
between events to be compared through a bridging technique. In practice, if two
couples of events (A, B) and (B, C), each exceeding the correlation threshold, share
a common quake (B), then all three events are attributed to the same family even if
the match between A and C is below a value chosen as a reference for similarity.
To avoid any subjective choice of threshold for cross-correlation values, the results
from the computation algorithm are submitted to a routine that gives increasing
reliability to them if they are confirmed by the three components of the seismogram
and if the number of families detected by each station is confirmed by more recordings.
This latter constraint is made possible by the geometry of the recording network,
with interdistances between stations of the order of 40–50 km. The process finally
leads to the recognition of 27 families detected and confirmed by, on average, 3
stations that represent 40% of the recording capabilities. Since the performances of
the recording network have been very odd in the past, especially in the early years
of operation, the reliability of the detection is much higher, as in most cases the
stations that detected the families were the only ones to be effectively recording.
The methodology proved to be more efficient than other methods applied in the
past; moreover, the results could be probably improved even more if, instead of doing
a one-run process, it would be borne as a trial-and-error approach.
Description:
Published
Description:
1903-1915
Description:
JCR Journal
Description:
reserved
Keywords:
Seismicity
;
multiplets
;
seismic families
;
seismic sequences
;
04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
;
04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
;
04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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