Shallow/upper crustal shear wave structure of the Tehran region (Central Alborz, Iran) from the inversion of Rayleigh wave dispersion measurements

Autor(es)

Shirzad, Taghi ^{[1, 2]} ; Naghavi, Mojtaba ^[2] ; Fard, Farzam Yamini ^[3]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Astron Geophys & Atmospher Sci, Sao Paulo - Brazil

^[2] Univ Tehran, Inst Geophys, Tehran 141556466 - Iran

^[3] Int Inst Earthquake Engn & Seismol, Tehran 1953714453 - Iran

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF SEISMOLOGY; v. 22, n. 6, p. 1409-1421, NOV 2018.
• Citações Web of Science: 1

Resumo

Surface wave dispersion curves from microearthquakes are used to obtain group velocity dispersion maps. The calculation of the local dispersion curves for each grid point from these maps then produces the input data to retrieve the 3D shear wave velocity model of the Tehran region. The group velocity maps indicate that the tomographic results agree well with the three main tectonic features and the geological units in the study area. The tomographic maps generally possess high-velocity structures across most of the mountain belts (Central Alborz and east-southeast mountains), whereas the Tehran Basin correlates to a low-velocity structure. Increasing the period in the study area highlights four independent low-velocity zones that reflect faults and fault junction systems. The shear wave velocity profiles indicate that the depth to bedrock exhibits southward variation ranging from similar to 300 m to similar to 1500 m. We also focus our analysis on the existence of faults within the shear wave profiles and discuss the low shear wave velocity anomalies deeper than 2 km result from the main fault structures (e.g., North Tehran, North-South Rey and Parchin). Furthermore, we argue that the dip angle of the North Tehran fault varies along fault strike, whereas the North-South Rey fault possesses a constant dip angle. Moreover, initial model uncertainties and checkerboard resolution tests are used to identify reliable and robust anomaly features in the 3D shear wave velocity model and 2D tomographic maps, respectively. Microearthquake analysis provides an effective approach for studying the upper crustal structure heterogeneity, especially the fault structure, of the Tehran region. (AU)

• Processo FAPESP: 16/20952-4 - Tomografia de ruído ambiental nas bacias do Pantanal e Paraná
• Beneficiário: Taghi Shirzad Iraj
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado