Publication Date:
2019-02-19
Description:
The central Italy seismic sequence, started with the Mw = 6.0 Amatrice earthquake on August 24th 2016, is
the first significant one after the Italian Seismic Bulletin (BSI) changed its analysis strategies in 2015.
These new strategies consist on the release of the BSI every four months, the review of the events with ML ≥
1.5 and the priority on the review of events with ML ≥ 3.5. Furthermore, in the last year we improved the
bulletin tools and made possible the analysis of all the stations whose data are stored in the European Integrated
Data Archive (EIDA). The new procedures and software utilities allowed, during the first month of
2016 emergency, to integrate, in the Bulletin, the temporary stations installed by the emergency group
SISMIKO, both in real–time transmission and in stand-alone recording.
In the early days of the sequence many of the BSI analysts were engaged in the monitoring room shifts,
nevertheless at the end of August all events occurred in those days with ML ≥ 4 were analyzed; the largest
event recovered and localized is a ML = 4.5 event immediately following the main shock.
In September 2016, 83 events with ML ≥ 3.5 were analyzed and re-checked, the number of pickings greatly
improved. The focal mechanism of the main shock was evaluated using first motion polarities, and compared
with the available Time Domain Moment Tensors and Regional Centroid Moment Tensor.
The first eight hours of the day on August 24th, the most critical for the INGV surveillance room, were
carefully analyzed: the number of located events increased from 133 to 408. The magnitude of completeness,
after the analysis of the BSI, has dropped significantly from about 3.5 to 2.7. The mainshock focal
mechanism and the relative locations of the first 8 hours’ aftershocks give clues on the initial fault activation.
The seismic sequence in November 2016 is still ongoing; it included a mainshock of Mw = 6.5 on October
30th and 3 events of magnitude greater than 5.0 one on August 24th and two on October 26th.
Description:
Published
Description:
4IT. Banche dati
Description:
JCR Journal
Keywords:
Central Italy seismic sequence
;
Amatrice earthquake August 24th 2016
;
Italian Seismic Bulletin BSI
;
04.06. Seismology
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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