{"title":"Directivity analysis and source parameter estimation: insights from the 2014 Arzew earthquake, Mw3.9, northwestern Algeria","authors":"Oualid Boulahia, Fethi Semmane","doi":"10.1007/s10950-024-10226-3","DOIUrl":null,"url":null,"abstract":"<div><p>The March 20, 2014, magnitude M<sub>w</sub>3.9 earthquake near Arzew, Algeria, instigated a study to deepen comprehension of seismic activity and hazard in the region. Analyzing data from Algerian and Spanish seismic networks, we explored earthquake characteristics and rupture mechanisms. The earthquake's epicenter was located at 35.825° latitude and -0.366° longitude, with a depth of 7 km, exhibiting intensity IV-V in the Arzew-Oran area. Preceding this event, a magnitude M<sub>D</sub>3.1 foreshock occurred on February 1, 2014, at the same location. The waveforms of the foreshock and mainshock exhibited striking similarities, validating the effectiveness of the Empirical Green's Function method employed for deconvolution. Through waveform inversion and P-wave polarities, we estimated the focal mechanism, revealing a near-pure strike-slip mechanism with nodal planes oriented ~E-W and ~N-S. The rupture process, characterized by multiple episodes, propagated predominantly from the south towards the N5°-15°E direction at a velocity around 2.7 km/s along an 870 m fault length in 0.32 seconds. The mainshock's fault plane was identified as the N-S plane, indicating the direction of rupture propagation. Source parameter estimation utilizing the EGF method revealed larger corner frequencies and stress drops compared to individual spectra estimation, attributed to the method’s improved correction for attenuation and site effects, without the need for simplified a priori models. Despite its low magnitude, the 2014 Arzew earthquake provided valuable insights into the region’s seismic behavior, contributing significantly to ground motion predictions. In particular, the study highlights the necessity of accounting for rupture directivity in seismic hazard assessments and mitigation strategies.</p></div>","PeriodicalId":16994,"journal":{"name":"Journal of Seismology","volume":"28 4","pages":"951 - 972"},"PeriodicalIF":1.6000,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Seismology","FirstCategoryId":"89","ListUrlMain":"https://link.springer.com/article/10.1007/s10950-024-10226-3","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
The March 20, 2014, magnitude Mw3.9 earthquake near Arzew, Algeria, instigated a study to deepen comprehension of seismic activity and hazard in the region. Analyzing data from Algerian and Spanish seismic networks, we explored earthquake characteristics and rupture mechanisms. The earthquake's epicenter was located at 35.825° latitude and -0.366° longitude, with a depth of 7 km, exhibiting intensity IV-V in the Arzew-Oran area. Preceding this event, a magnitude MD3.1 foreshock occurred on February 1, 2014, at the same location. The waveforms of the foreshock and mainshock exhibited striking similarities, validating the effectiveness of the Empirical Green's Function method employed for deconvolution. Through waveform inversion and P-wave polarities, we estimated the focal mechanism, revealing a near-pure strike-slip mechanism with nodal planes oriented ~E-W and ~N-S. The rupture process, characterized by multiple episodes, propagated predominantly from the south towards the N5°-15°E direction at a velocity around 2.7 km/s along an 870 m fault length in 0.32 seconds. The mainshock's fault plane was identified as the N-S plane, indicating the direction of rupture propagation. Source parameter estimation utilizing the EGF method revealed larger corner frequencies and stress drops compared to individual spectra estimation, attributed to the method’s improved correction for attenuation and site effects, without the need for simplified a priori models. Despite its low magnitude, the 2014 Arzew earthquake provided valuable insights into the region’s seismic behavior, contributing significantly to ground motion predictions. In particular, the study highlights the necessity of accounting for rupture directivity in seismic hazard assessments and mitigation strategies.
期刊介绍:
Journal of Seismology is an international journal specialising in all observational and theoretical aspects related to earthquake occurrence.
Research topics may cover: seismotectonics, seismicity, historical seismicity, seismic source physics, strong ground motion studies, seismic hazard or risk, engineering seismology, physics of fault systems, triggered and induced seismicity, mining seismology, volcano seismology, earthquake prediction, structural investigations ranging from local to regional and global studies with a particular focus on passive experiments.