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| Titel |
Appraising the Early-est earthquake monitoring system for tsunami alerting at the Italian Candidate Tsunami Service Provider |
| VerfasserIn |
F. Bernardi, A. Lomax, A. Michelini, V. Lauciani, A. Piatanesi, S. Lorito |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Sciences ; 15, no. 9 ; Nr. 15, no. 9 (2015-09-11), S.2019-2036 |
| Datensatznummer |
250119680
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| Publikation (Nr.) |
 copernicus.org/nhess-15-2019-2015.pdf |
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| Zusammenfassung |
| In this paper we present and discuss the performance of the procedure for
earthquake location and characterization implemented in the Italian Candidate
Tsunami Service Provider at the Istituto Nazionale di Geofisica e Vulcanologia (INGV) in Rome.
Following the ICG/NEAMTWS guidelines, the first tsunami warning messages are based only on seismic
information, i.e., epicenter location, hypocenter depth, and magnitude, which
are automatically computed by the software Early-est. Early-est is a package
for rapid location and seismic/tsunamigenic characterization of earthquakes.
The Early-est software package operates using offline-event or
continuous-real-time seismic waveform data to perform trace processing and
picking, and, at a regular report interval, phase association, event
detection, hypocenter location, and event characterization. Early-est also
provides mb, Mwp, and Mwpd magnitude estimations. mb
magnitudes are preferred for events with Mwp ≲ 5.8, while
Mwpd estimations are valid for events with Mwp ≳ 7.2. In this
paper we present the earthquake parameters computed by Early-est between the
beginning of March 2012 and the end of December 2014 on a global scale for
events with magnitude M ≥ 5.5, and we also present the detection timeline. We compare
the earthquake parameters automatically computed by Early-est with the same
parameters listed in reference catalogs. Such reference catalogs are
manually revised/verified by scientists. The goal of this work is to test the
accuracy and reliability of the fully automatic locations provided by
Early-est. In our analysis, the epicenter location, hypocenter depth and
magnitude parameters do not differ significantly from the values in the
reference catalogs. Both mb and Mwp magnitudes show differences
to the reference catalogs. We thus derived correction functions
in order to minimize the differences and correct biases between our values
and the ones from the reference catalogs. Correction of the Mwp distance
dependency is particularly relevant, since this magnitude refers to
the larger and probably tsunamigenic earthquakes. Mwp values at
stations with epicentral distance Δ ≲ 30° are
significantly overestimated with respect to the CMT-global solutions, whereas
Mwp values at stations with epicentral distance Δ ≳
90° are slightly underestimated. After applying such distance
correction the Mwp provided by Early-est differs from CMT-global
catalog values of about δ Mwp ≈ 0.0 ∓ 0.2. Early-est
continuously acquires time-series data and updates the earthquake source
parameters. Our analysis shows that the epicenter coordinates and the
magnitude values converge within less than 10 min (5 min in the
Mediterranean region) toward the stable values. Our analysis shows that we can
compute Mwp magnitudes that do not display short epicentral
distance dependency overestimation, and we can provide robust and reliable
earthquake source parameters to compile tsunami warning messages within less
than 15 min after the event origin time. |
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