Publication Date:
2021-03-15
Description:
In a recent work we computed the relative frequencies with which strong shocks (4.0≤Mw〈5.0),
widely felt by the population were followed in the same area by potentially destructive main shocks
(Mw≥5.0) in Italy. Assuming the stationarity of the seismic release properties, such frequencies can
be tentatively used to estimate the probabilities of potentially destructive shocks after the occurrence
of future strong shocks. This allows us to set up an alarm-based forecasting hypothesis related to
strong foreshocks occurrence. Such hypothesis is tested retrospectively on the data of a homogenized
seismic catalogue of the Italian area against a purely random hypothesis that simply forecasts the
target main shocks proportionally to the space-time fraction occupied by the alarms. We compute the
latter fraction in two ways a) as the ratio between the average time covered by the alarms in each area
and the total duration of the forecasting experiment (60 years) and b) as the same ratio but weighted
by the past frequency of occurrence of earthquakes in each area. In both cases the overall retrospective
performance of our forecasting algorithm is definitely better than the random case. Considering an
alarm duration of three months, the algorithm retrospectively forecasts more than 70% of all shocks
with Mw5.5 occurred in Italy from 1960 to 2019 with a total space-time fraction covered by the
alarms of the order of 2%. Considering the same space-time coverage, the algorithm is also able to
retrospectively forecasts more than 40% of the first main shocks with Mw5.5 of the seismic
sequences occurred in the same time interval. Given the good reliability of our results, the forecasting
algorithm is set and ready to be tested also prospectively, in parallel to other ongoing procedures
operating on the Italian territory.
Description:
This paper benefitted from funding provided by the European Union within the ambit of the H2020 project
RISE (No. 821115), which in particular fully financed the PhD grant of one of the authors (E.B.).
Description:
Published
Description:
1192–1206
Description:
6T. Studi di pericolosità sismica e da maremoto
Description:
JCR Journal
Keywords:
Earthquake interaction
;
Statistical seismology
;
forecasting,
;
prediction
;
04.06. Seismology
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Permalink
