Publication Date:
2024-05-22
Description:
We investigate the variability of Brune stress drop (Δσ), apparent stress (τa), and Savage–
Wood radiation efficiency (ηsw
τa= Δσ), in the 2013–2014 Mw 5.0 earthquake sequence
that struck the Matese area in the southern Apennines range of Italy. The sequence is
clustered in a relatively small crustal volume in the 13–22 km depth range, which is
greater than that of background seismicity and normal-faulting sequences that occurred
under the range axis, usually located in the first 15 km of the crust.We find high Savage–
Wood radiation efficiency values for most of the analyzed earthquakes located in a narrow
crustal volume, with values ranging from well above the self-similarity value to very
high values as high as 0.55. In addition, a large variability in radiation efficiency (up to
90%) is observed for two similar magnitude events at different depths. Previous studies
reported seismic evidence of fluid involvement in the nucleation process of the Matese
earthquakes. By integrating our results with crustal geophysical data published recently,
we propose that most of the earthquakes characterized by high values of ηsw are
nucleated within high pore pressure zones located in the crystalline midcrust of Adria.
We reckon that high pore pressure fluids of deep origin played a role in the rupture process
and were responsible for themixed shear-tensile sources inferred from the analysis of
the S-wave/P-wave spectral amplitude ratio for most of 2013–2014 earthquakes.
Description:
Published
Description:
299–319
Description:
JCR Journal
Keywords:
stress drop
;
apparent stress
;
radiation efficiency
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
