Search results for "Focal mechanism"

The Palermo (Sicily) seismic cluster of September 2002, in the seismotectonic framework of the Tyrrhenian Sea-Sicily border area

2009

The northern coast of Sicily and its offshore area represent a hinge zone between a sector of the Tyrrhenian
 Basin, characterized by the strongest crustal thinning, and the sector of the Sicilian belt which has emerged. This
 hinge zone is part of a wider W-E trending right-lateral shear zone, which has been affecting the Maghrebian
 Chain units since the Pliocene. Seismological and structural data have been used to evaluate the seismotectonic
 behavior of the area investigated here. Seismological analysis was performed on a data set of about 2100 seismic
 events which occurred between January 1988 and October 2002 in the Southern Tyrrhenian Sea. This paper
 focuses…

New seismological, structural and marine geology constraints for a seismotectonic model of the hinge zone between northern Sicily and southern Tyrrhe…

2013

A New Dissimilarity Measure for Clustering Seismic Signals

2011

Hypocenter and focal mechanism of an earthquake can be determined by the analysis of signals, named waveforms, related to the wave field produced and recorded by a seismic network. Assuming that waveform similarity implies the similarity of focal parameters, the analysis of those signals characterized by very similar shapes can be used to give important details about the physical phenomena which have generated an earthquake. Recent works have shown the effectiveness of cross-correlation and/or cross-spectral dissimilarities to identify clusters of seismic events. In this work we propose a new dissimilarity measure between seismic signals whose reliability has been tested on real seismic dat…

Source Mechanisms of Laboratory Earthquakes During Fault Nucleation and Formation

2021

Identifying deformation and pre-failure mechanisms preceding faulting is key for fault mechanics and for interpreting precursors to fault rupture. This study presents the results of a new and robust derivation of first motion polarity focal mechanism solutions (FMS) applied to acoustic emission (AE). FMS are solved using a least squares minimization of the fit between projected polarity measurements and the deviatoric stress field induced by dilatational (T-type), shearing (S-type), and compressional (C-type) sources. 4 × 10 cm cylindrical samples of Alzo Granite (AG, porosity <1%) and Darley Dale Sandstone (DDS, porosity ≈14%) underwent conventional triaxial tests in order to investigat…

Simultaneous seismic wave clustering and registration

2012

In this paper we introduce a simple procedure to identify clusters of multivariate waveforms based on a simultaneous assignation and alignment procedure. This approach is aimed at the identification of clusters of earthquakes, assuming that similarities between seismic events with respect to hypocentral parameters and focal mechanism correspond to similarities between waveforms of events. Therefore we define a distance measure between seismic curves in R^d d>=1, in order to interpret and better understand the main features of the generating seismic process.

A contribution to a seismotectonic model of the hinge zone between northern Sicily and southern Tyrrhenian by some seismological and structural const…

2013

An integrated research on the hinge zone between northern Sicily and its Tyrrhenian off-shore has been carried out, by means of structural, seismological and statistical analyses. The main structural features of the area are represented by both NWSE to W–E striking right-lateral and N–S to NE-SW striking leftlateral fault systems, responsible of uplifting (restraining) and subsiding (releasing) zones. Within this hinge zone the seismicity is mainly located between 10 and 20 km of depth and clustered according to the orientation of the outcropping fault systems. The brittle strain partitioning related to a right-lateral simple shear zone has been reconstructed in the onshore sector, while in…