Publication Date:
2017-04-04
Description:
Macroseismic intensities are the only available data for most historical earthquakes and often
represent the unique source of information for crucial events in the definition of seismic
hazard. In this paper, we attempt at getting insight into source characteristics by reproducing
the observed intensity field. As a test case, we study the source of 1908 Messina Straits
earthquake (
M
W
=
7.1), by testing three distinct fault models deduced from the analysis of
geodeticdata.Startingfromthestaticslipdistribution,wedevelop kinematicsourcemodelsfor
the investigated fault and compute full waveform synthetic seismograms in a 1-D structural
model, also accounting for anelastic attenuation. Then, we convert both computed peak-
ground acceleration (PGA) and peak-ground velocity (PGV) to macroseismic intensity at 100
selected sites, by means of specific empirical relations for the Italian region. By comparing
the original data separately with PGA- and PGV-based intensity fields, we discriminate among
the tested faults and determine the best values for the investigated kinematic parameters of the
source. We also perform a misfit analysis for the best source model, in order to investigate the
dependence of the results on the selected parametrization. The results of the analysis indicate
that among the tested models, the one characterized by an east-dipping fault, with strike-
oriented NS slightly rotated clockwise, better explains the observed macroseismic field of the
1908 Messina Straits earthquake. Besides, the fracture nucleated at the southern end of the
fault and ruptured northward, producing considerable directivity effects. This is in agreement
with the published results obtained from the investigation of the historical seismograms. We
alsodeterminerealisticvalues fortherupturevelocityand therise-time.Ourstudyconfirms the
greatpotentialofthemacroseismicdata,demonstratingthattheycontainenoughinformationto
constrain important characteristics of the fault, which can be retrieved by using complex source
models and computing complete wavefield. Moreover, we also show that the simultaneous
comparison of both PGA- and PGV-based synthetic macroseismic fields with the original
intensities provides tighter constraints for discriminating among different source models, with
respect to what attainable from each of them
Description:
Published
Description:
164-173
Description:
4T. Fisica dei terremoti e scenari cosismici
Description:
JCR Journal
Description:
restricted
Keywords:
Earthquake ground motions; Earthquake source observations.
;
04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
