Seismic microzonation of Marsa Alam, Egypt using inversion HVSR of microtremor observations

El-Hady, Sherif M.; Fergany, Elsayed; Othman, Adel; Mohamed, Gad-Elkareem A.

doi:10.1007/s10950-011-9249-4

Cited by 30 publications

(11 citation statements)

References 18 publications

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“…The ambient noise and its applicability have been widely observed by several researchers, such as Lachet et al [9], El Hady et al [10], and Mase et al [11]. In the implementation, microtremor is applicable to observe the geophysical characteristic.…”

Section: Theory and Methods Ambient Noise Measurement By Microtremor Amentioning

confidence: 99%

Seismic Vulnerability Maps of Ratu Agung District, Bengkulu City, Indonesia

Mase

2019

ced

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During the 8.6 Mw Bengkulu-Mentawai Earthquake Ratu Agung District was identified as an impacted area. This paper aims to deliver the seismic vulnerability based on geophysical observation. This study was initiated by performing the ambient noise measurement to obtain the geophysical characteristic, such as amplification and predominant frequency. Furthermore, the vulnerability index analysis was performed from the geophysical information collected from the investigation. To observe the tendency of ground damage during the earthquake, ground damages analysis is also performed. All results are depicted into the microzonation maps. The results showed that the amplification and predominant frequency on site are generally ranging from 3 to 5 and 5 to 8 Hz, respectively. The seismic vulnerability index in study area is up to 10-3. The results showed that during the Bengkulu-Mentawai Earthquake, the investigated sites could be possible to undergo crack settlement which can trigger massive sand boiling in the study area.

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Section: Theory and Methods Ambient Noise Measurement By Microtremor Amentioning

confidence: 99%

Seismic Vulnerability Maps of Ratu Agung District, Bengkulu City, Indonesia

Mase

2019

ced

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“…HVSR has been widely used to estimate the natural frequency and soil amplification (Nakamura, 1997(Nakamura, , 2000(Nakamura, , 2008Bard, 1999;Gosar, 2007;Fergany and Bonnefoy-Claudet, 2009). The main advantages of HVSR method are easy to use in anytime and anywhere, lowcost measurement, and estimate the frequency of sediment directly without having to know the geology and shear wave velocity structure beneath the surface using inversion tool (Herak, 2008;Triwulan et al, 2010;El-Hady et al, 2011). Further, the use of microtremor was later expanded to identify the vulnerability index for ground (Nakamura, 1996(Nakamura, , 1997(Nakamura, , 2000(Nakamura, , 2009Daryono et al, 2009).…”

Section: Assessment Of Liquefaction Potentialmentioning

confidence: 99%

Liquefaction potential of Nile delta, Egypt

Fergany

Omar²

2017

NRIAG Journal of Astronomy and Geophysics

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Understanding how sedimentary basins respond to seismic-wave energy generated by earthquake events is a significant concern for seismic-hazard estimation and risk analysis. The main goal of this study is assessing the vulnerability index, K g , as an indicator for liquefaction potential sites in the Nile delta basin based on the microtremor measurements. Horizontal to Vertical spectral ratio analyses (HVSR) of ambient noise data, which was conducted in 2006 at 120 sites covering the Nile delta from south to north were reprocessed using Geopsy software. HVSR factors of amplification, A, and fundamental frequency, F, were calculated and K g was estimated for each measurement. The K g value varies widely from south toward north delta and the potential liquefaction places were estimated. The higher vulnerability indices are associated with sites located in southern part of the Nile delta and close to the branches of Nile River. The HVSR factors were correlated with geologic setting of the Nile delta and show good correlations with the sediment thickness and subsurface stratigraphic boundaries. However, we note that sites located in areas that have greatest percentage of sand also yielded relatively high K g values with respect to sites in areas where clay is abundant. We concluded that any earthquake with ground acceleration more than 50 gal at hard rock can cause a perceived deformation of sandy sediments and liquefaction can take place in the weak zones of K g ! 20. The worst potential liquefaction zones (K g > 30) are frequently joined to the Damietta and Rosetta Nile River branches and south Delta where relatively coarser sand exists. The HVSR technique is a very sensitive tool for lithological stratigraphy variations in two dimensions and varying liquefaction susceptibility.

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“…Application of the passive seismic techniques is used frequently in Egypt to obtain fundamental site frequency and amplification factors for seismic hazard assessment at several areas (Abd el-aal, 2008(Abd el-aal, , 2010a(Abd el-aal, , 2010b(Abd el-aal, , 2010c(Abd el-aal, , 2013Abdel-Rahman et al, 2012;El-Hady et al, 2012;Toni, 2007Toni, , 2012Abd el-aal and Soliman, 2013;El-Eraki et al, 2013;Abd el-aal et al, 2015). The rapid increasing in urbanization, tourist beach resorts and land use planning in the Red Sea coastal areas are the motivation of the current study.…”

Section: Introductionmentioning

confidence: 98%

Ambient noise for determination of site dynamic properties at Hurghada and Safaga cities, Red Sea, Egypt

Toni¹

2016

Acta Geodynamica Et Geomaterialia

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Recording ambient noise at the surface is increasingly used for the assessment of site response and has become a fundamental task for seismic risk reduction in urbanized areas. Methods based on the measurement of seismic noise, which typically are fast, non invasive, and low cost, have become a very attractive option in microzonation studies. In the current work, we use the ambient noise recordings collected by single seismic stations and two-dimensional arrays to determine the response of the near-surface soil at the two touristic cities of Hurghada and Safaga which are located at the Red Sea coast in Egypt. Based on the horizontal-to-vertical (H/V) spectral ratio Nakamura's technique, recordings of the single stations are analyzed to estimate the fundamental site frequency (f 0 ). Using the raw noise signals recorded by two arrays, we present a joint inversion scheme for surface wave dispersion curves. In particular, the Rayleigh wave dispersion curves and the H/V curves are combined in a joint inversion procedure. We present inversion procedure based on the computation of high-frequency correlation functions between arrays' stations. The calculation of Rayleigh wave phase velocities is based on the frequency-domain SPatial AutoCorrelation (SPAC) and frequency-wavenumber (f-k) methods. Constitutively, a tomographic inversion of the travel-times estimated for each frequency is performed, allowing the vertically varying 1-D shear wave velocity structure below the array to be retrieved. Following the relationship between resonance frequency (f 0 ) and thickness of sediments, the thickness of unconsolidated sediments at the investigated sites are determined. ARTICLE INFO

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Seismic microzonation of Marsa Alam, Egypt using inversion HVSR of microtremor observations

Cited by 30 publications

References 18 publications

Seismic Vulnerability Maps of Ratu Agung District, Bengkulu City, Indonesia

Seismic Vulnerability Maps of Ratu Agung District, Bengkulu City, Indonesia

Liquefaction potential of Nile delta, Egypt

Ambient noise for determination of site dynamic properties at Hurghada and Safaga cities, Red Sea, Egypt

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