Publication Date:
2021-03-04
Description:
The ground-motion median and standard deviation of empirical groundmotion
prediction equations (GMPEs) are usually poorly constrained in the nearsource
region due to the general lack of strong-motion records. Here we explore the
use of a deterministic–stochastic simulation technique, specifically tailored to reproduce
directivity effects, to evaluate the expected ground motion and its variability at a
near-source site, and seek a strategy to overcome the known GMPEs limitations.
To this end, we simulated a large number of equally likely scenario events for three
earthquake magnitudes (Mw 7.0, 6.0, and 5.0) and various source-to-site distances. The
variability of the explored synthetic ground motion is heteroscedastic, with smaller
values for larger earthquakes. The standard deviation is comparable with empirical
estimates for smaller events and reduces by 30%–40% for stronger earthquakes.
We then illustrate how to incorporate directivity effects into probabilistic seismichazard
analysis (PSHA). This goal is pursued by calibrating a set of synthetic GMPEs
and reducing their aleatory variability (∼50%) by including a predictive directivity
term that depends on the apparent stress parameter obtained through the simulation
method. Our results show that, for specific source-to-site configurations, the nonergodic
PSHA is very sensitive to the additional epistemic uncertainty that may augment
the exceedance probabilities when directivity effects are maximized.
The proposed approach may represent a suitable way to compute more accurate
hazard estimates.
Description:
This work was supported by the project MASSIMO—Cultural Heritage
Monitoring in Seismic Area, PON01/02710—coordinated by Istituto
Nazionale di Geofisica e Vulcanologia (INGV) and funded by the Italian
Ministry of Education, University and Research and by the Seismic Hazard
Center of Istituto Nazionale di Geofisica e Vulcanologia (Centro per la Pericolosità
Sismica [CPS]).
Description:
Published
Description:
966-983
Description:
5T. Modelli di pericolosità sismica e da maremoto
Description:
JCR Journal
Keywords:
seismogenic sources
;
finite fault simulations
;
near source
;
directivity effects
;
ground motion variability
;
seismic hazard
;
Southern Italy
;
04.06. Seismology
;
05.06. Methods
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
