Journal ArticleDOI
High-Frequency Directivity Effect for an Mw 4.1 Earthquake, Widely Felt by the Population in Southeastern France
Françoise Courboulex,Alain Dujardin,Martin Vallée,Bertrand Delouis,Christophe Sira,Anne Deschamps,Laetitia Honoré,François Thouvenot +7 more
TLDR
In this article, a moderate earthquake in the French Alps (26 February 2012 M w ǫ 4.1) that has been much more distinctly felt south of the event than north of it was documented.Abstract:
We document a moderate earthquake in the French Alps (26 February 2012 M w 4.1) that has been much more distinctly felt south of the event than north of it. This discrepancy was especially clear in the two large cities of Nice and Grenoble, both situated at 100 km from the epicenter. This observation was confirmed by ground‐motion measurements that were eight times larger in one city than in the other one, for the same site conditions. Using a time‐domain deconvolution between the broadband recordings of the mainshock and an aftershock used as empirical Green’s functions, we show that the rupture process of this event had a strong directivity effect toward a direction of N155°±5 on an ∼2 km long fault, detectable only at frequencies higher than 1 Hz. The fault size and direction are in good accordance with the location of the aftershocks. Despite the various possible contributions leading to high‐frequency amplification, we show here that this simple directivity effect controlled the intensity felt by the population and the acceleration measured in the cities.read more
Citations
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Aftershocks triggered by fluid intrusion: Evidence for the aftershock sequence occurred 2014 in West Bohemia/Vogtland
TL;DR: In this article, the authors analyzed the details of the major ML4.4 sequence based on focal mechanisms and relocated earthquake data and concluded that the mainshock opened fluid pathways from a finite fluid source into the fault plane explaining the unusual high rate of aftershocks, the migration patterns, and the exponential decrease of the aseismic signal.
Journal ArticleDOI
Diminishing high-frequency directivity due to a source effect: Empirical evidence from small earthquakes in the Abruzzo region, Italy
TL;DR: In this article, the authors investigate the directivity effects of 250 aftershocks of the Mw 6.1 2009 L'Aquila earthquake (central Italy) and evaluate the residuals between the apparent source spectra and the event mean source spectrum at selected frequencies.
Journal ArticleDOI
Stress-drop variability of shallow earthquakes extracted from a global database of source time functions
TL;DR: In this article, the authors use the new global database of source time functions (STFs) and focal mechanisms proposed by Vallee (2013) using the automatic SCARDEC method (Vallee et al., 2011) to constrain earthquake rupture duration and variability.
Journal ArticleDOI
Experimental and Numerical Evidence of the Clustering Effect of Structures on Their Response during an Earthquake: A Case Study of Three Identical Towers in the City of Grenoble, France
Philippe Guéguen,Andrea Colombi +1 more
TL;DR: In this paper, the interpretation of an equivalent to a macroseismic intensity survey, performed in three identical stand-alone buildings located in Grenoble, France, after an M L 4.1 earthquake, reveals a clustering effect, resulting in different levels of perception of seismic loading by inhabitants.
References
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Journal ArticleDOI
A Double-Difference Earthquake Location Algorithm: Method and Application to the Northern Hayward Fault, California
TL;DR: In this paper, a least square solver is found by iteratively adjusting the vector difference between hypocentral pairs to minimize residuals between observed and theoretical travel-time differences.
Journal ArticleDOI
Modification of Empirical Strong Ground Motion Attenuation Relations to Include the Amplitude and Duration Effects of Rupture Directivity
TL;DR: In this article, the authors developed modifications to empirical strong ground motion attenuation relations to account for the effects of rupture directivity on strong motion amplitudes and durations, based on an empirical analysis of near-fault data.
OtherDOI
HYPO71 (revised; a computer program for determining hypocenter, magnitude, and first motion pattern of local earthquakes
Journal ArticleDOI
Earthquake aftershocks as Green's functions
TL;DR: In this paper, the authors used the aftershocks associated with a large earthquake as Green's functions to model the earthquake strong ground motion, and used the effects of the true earth structure are included in the modeling process.
Journal ArticleDOI
Empirical Equations for the Prediction of PGA, PGV, and Spectral Accelerations in Europe, the Mediterranean Region, and the Middle East
Sinan Akkar,Julian J. Bommer +1 more
TL;DR: In this article, the authors present an update that corrects the shortcomings identified in those equations, which are primarily, but not exclusively, related to the model for the ground-motion variability.