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Yona Istifarna Pasi - One of the best experts on this subject based on the ideXlab platform.
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PENENTUAN DISTRIBUSI KETEBALAN LAPISAN SEDIMEN MENGGUNAKAN MIKROTREMOR DENGAN METODE QUASI TRANSFER SPECTRAL (QTS) DI KAWASAN MEUREUDU KABUPATEN PIDIE JAYA
'Fakultas Teknik Elektronika dan Komputer Universitas Kristen Satya Wacana', 2019Co-Authors: Yona Istifarna PasiAbstract:ABSTRAKAceh merupakan salah satu daerah yang dilalui oleh dua lempeng aktif yaitu Lempeng Indo-Australia dan Lempeng Eurasia. Kondisi itu menjadi penyebab sering terjadi bencana alam khususnya gempa bumi di Aceh. Pada tanggal 7 Desember 2016, terjadi gempa bumi di Kabupaten Pidie Jaya dengan kekuatan 6,5 Mw dan pada kedalaman 15 km. Kerusakan struktur bangunan akibat gempa bumi dipengaruhi oleh kondisi geologi dan kondisi tanah daerah tersebut. Daerah dengan lapisan sedimen yang tebal dapat memperkuat guncangan pada saat gempa bumi terjadi. Penelitian ini bertujuan untuk mengetahui distribusi ketebalan lapisan kawasan Kecamatan Meureudu Kabupaten Pidie Jaya berdasarkan nilai frekuensi dominan (f?) dan nilai amplifikasi (A) menggunakan mikrotremor dengan metode Quasi Transfer Spectral (QTS). Hasil penelitian menunjukkan bahwa kawasan Kecamatan Meureudu memiliki nilai frekuensi dominan 0,5-14 Hz dan nilai amplifikasi 0,6-5 kali. Nilai frekuensi dominan 0,5 sampai 4,5 Hz berada di daerah yang dekat dengan pantai dan nilai frekuensi dominan 10 sampai 14 Hz berada di daerah yang jauh dari pantai. Sedangkan nilai amplifikasi 0,6 sampai 1,8 berada di daerah yang jauh dari pantai dan nilai amplifikasi 3 sampai 4 berada di daerah yang dekat dengan pantai. Sehingga dapat dikatakan bahwa daerah yang dekat dengan pantai memiliki potensi kerusakan struktur bangunan yang lebih parah dibanding daerah yang jauh dari pantai apabila gempa bumi yang besar terjadi. Kata Kunci : Gempa bumi, mikrotremor, Quasi Transfer Spectral (QTS), frekuensi dominan, amplifikasiABSTRACTAceh is located between two active plates namely the Indo-Australian Plate and the Eurasian Plate. This is the reason why earthquake frequently happen in Aceh. An earthquake occurred in Pidie Jaya Regency with strength of 6.5 Mw and at depth of 15 km on December 7, 2016. Damage to building structures is influenced by geological conditions and soil conditions. Areas with thick sedimentary layers can strengthen shocks during earthquake. This study aims to determine the distribution thickness of the Meureudu district of Pidie Jaya district based on the value of the dominant frequency (f?) and the amplification value (A) using a Microtremor with the Quasi Transfer Spectral (QTS) method. The results showed the fact that the Meureudu District area has a dominant frequency value of 0.5-14 Hz and an amplification value of 0.6-5 times. A dominant frequency value of 0.5 to 4.5 Hz is in an area close to the coast and a dominant frequency value of 10 to 14 Hz is in an area far from the coast. While the amplification value of 0.6 to 1.8 is in an area far from the coast and the amplification value of 3 to 4 is in an area close to the coast. In conclusion, the area close the coast has the potential for damage to building structures which is more severe than areas far from the coast if an a large earthquake occured.Keywords: Earthquake, Microtremor, Quasi Transfer Spectral (QTS), dominant frequency, amplificationBanda Ace
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PENENTUAN DISTRIBUSI KETEBALAN LPISAN SEDIMEN MENGGUNAKAN MIKROTREMOR MENGGUNAKAN MIKROTREMOR DENGAN METODE QUASI TRANSFER SPECTRAL (QTS) DI KAWASAN MEUREUDU KABUPATEN PIDIE JAYA
'Fakultas Teknik Elektronika dan Komputer Universitas Kristen Satya Wacana', 2019Co-Authors: Yona Istifarna PasiAbstract:ABSTRAKAceh merupakan salah satu daerah yang dilalui oleh dua lempeng aktif yaitu Lempeng Indo-Australia dan Lempeng Eurasia. Kondisi itu menjadi penyebab sering terjadi bencana alam khususnya gempa bumi di Aceh. Pada tanggal 7 Desember 2016, terjadi gempa bumi di Kabupaten Pidie Jaya dengan kekuatan 6,5 Mw dan pada kedalaman 15 km. Kerusakan struktur bangunan akibat gempa bumi dipengaruhi oleh kondisi geologi dan kondisi tanah daerah tersebut. Daerah dengan lapisan sedimen yang tebal dapat memperkuat guncangan pada saat gempa bumi terjadi. Penelitian ini bertujuan untuk mengetahui distribusi ketebalan lapisan kawasan Kecamatan Meureudu Kabupaten Pidie Jaya berdasarkan nilai frekuensi dominan (f?) dan nilai amplifikasi (A) menggunakan mikrotremor dengan metode Quasi Transfer Spectral (QTS). Hasil penelitian menunjukkan bahwa kawasan Kecamatan Meureudu memiliki nilai frekuensi dominan 0,5-14 Hz dan nilai amplifikasi 0,6-5 kali. Nilai frekuensi dominan 0,5 sampai 4,5 Hz berada di daerah yang dekat dengan pantai dan nilai frekuensi dominan 10 sampai 14 Hz berada di daerah yang jauh dari pantai. Sedangkan nilai amplifikasi 0,6 sampai 1,8 berada di daerah yang jauh dari pantai dan nilai amplifikasi 3 sampai 4 berada di daerah yang dekat dengan pantai. Sehingga dapat dikatakan bahwa daerah yang dekat dengan pantai memiliki potensi kerusakan struktur bangunan yang lebih parah dibanding daerah yang jauh dari pantai apabila gempa bumi yang besar terjadi. Kata Kunci : Gempa bumi, mikrotremor, Quasi Transfer Spectral (QTS), frekuensi dominan, amplifikasiABSTRACTAceh is located between two active plates namely the Indo-Australian Plate and the Eurasian Plate. This is the reason why earthquake frequently happen in Aceh. An earthquake occurred in Pidie Jaya Regency with strength of 6.5 Mw and at depth of 15 km on December 7, 2016. Damage to building structures is influenced by geological conditions and soil conditions. Areas with thick sedimentary layers can strengthen shocks during earthquake. This study aims to determine the distribution thickness of the Meureudu district of Pidie Jaya district based on the value of the dominant frequency (f?) and the amplification value (A) using a Microtremor with the Quasi Transfer Spectral (QTS) method. The results showed the fact that the Meureudu District area has a dominant frequency value of 0.5-14 Hz and an amplification value of 0.6-5 times. A dominant frequency value of 0.5 to 4.5 Hz is in an area close to the coast and a dominant frequency value of 10 to 14 Hz is in an area far from the coast. While the amplification value of 0.6 to 1.8 is in an area far from the coast and the amplification value of 3 to 4 is in an area close to the coast. In conclusion, the area close the coast has the potential for damage to building structures which is more severe than areas far from the coast if an a large earthquake occured.Keywords: Earthquake, Microtremor, Quasi Transfer Spectral (QTS), dominant frequency, amplificationBanda Ace
Hiroaki Yamanaka - One of the best experts on this subject based on the ideXlab platform.
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Microtremor exploration at strong motion stations in Aydin and Denizli provinces, western Turkey
Exploration Geophysics, 2021Co-Authors: Özgür Tuna Özmen, Hiroaki Yamanaka, Erkan Ateş, Kudret Tekin, Ulubey Çeken, Erkan Koparmal, Ali Etiz, Nalan ElmasAbstract:This paper reports the results of a case study of the application of the Microtremor exploration method in western Turkey. We have conducted Microtremor surveys at strong motion stations in Aydin a...
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Exploration of S-wave velocity profiles at strong motion stations in Eskisehir, Turkey, using Microtremor phase velocity and S-wave amplification
Journal of Seismology, 2018Co-Authors: Hiroaki Yamanaka, Ögur Tuna Özmen, Kosuke Chimoto, Mehmet Akif Alkan, Emrah Pekkan, Oguz Özel, Derya Polat, Murat NurluAbstract:We have explored 1D S-wave velocity profiles of shallow and deep soil layers over a basement at strong motion stations in Eskisehir Province, Turkey. Microtremor array explorations were conducted at eight strong motion stations in the area to know shallow 1D S-wave velocity models. Rayleigh wave phase velocity at a frequency range from 3 to 30 Hz was estimated with the spatial autocorrelation analysis of array records of vertical Microtremors at each station. Individual phase velocity was inverted to a shallow S-wave velocity profile. Low-velocity layers were identified at the stations in the basin. Site amplification factors from S-wave parts of earthquake records that had been estimated at the strong motion stations by Yamanaka et al. ( 2017 ) were inverted to the S-wave velocities and Q-values of the sedimentary layers. The depths to the basement with an S-wave velocity of 2.2 km/s are about 1 km in the central part of the basin, while the basement becomes shallow as 0.3 km in the marginal part of the basin. We finally discussed the effects of the shallow and deep sedimentary layers on the 1D S-wave amplification characteristics using the revealed profiles. It is found that the shallow soil layers have no significant effects in the amplification at a frequency range lower than 3 Hz in the area.
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estimation of shallow s wave velocity structure using Microtremor array exploration at temporary strong motion observation stations for aftershocks of the 2016 kumamoto earthquake
Earth Planets and Space, 2016Co-Authors: Kosuke Chimoto, Hiroaki Yamanaka, Seiji Tsuno, Hiroe Miyake, Nobuyuki YamadaAbstract:Shallow S-wave velocity V S profiles were estimated for 26 temporary strong motion observation sites surrounding the epicenters of a sequence of the 2016 Kumamoto earthquake. The Microtremor array method was used to gather the dispersion characteristics of Rayleigh waves. V S profiles were obtained by inverting the dispersion curves for each site and those of three permanent strong motion stations that recorded the sequence of seismic events. The shallow V S profiles near two of the permanent strong motion stations in the town of Mashiki were almost identical. However, the V S profiles at other stations varied. The V S profiles were found to have the common feature of the uppermost low-velocity layer being widely distributed from Mashiki to the village of Minami-Aso, and it was especially thick in the areas that suffered heavy damage. This low-velocity layer was a major contributor to the site amplification. The horizontal-to-vertical spectral ratios of the Microtremors indicate that both the shallow soil and deep sedimentary layers may control the site response characteristics over a broad frequency range.
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estimation of shallow s wave velocity structure and site response characteristics by Microtremor array measurements in tekirdag region nw turkey
Earth Planets and Space, 2015Co-Authors: Hiroaki Yamanaka, Kosuke Chimoto, Oguz Özel, Ozlem Karagoz, Seckin Citak, Ken HatayamaAbstract:In this study, we aimed to explore the S-wave velocity structure of shallow soils using Microtremors in order to estimate site responses in Tekirdag and surrounding areas (NW Turkey). We collected Microtremor array data at 44 sites in Tekirdag, Marmara Ereglisi, Corlu, and Muratli. The phase velocities of Rayleigh waves were estimated from the Microtremor data using a Spatial Autocorrelation method. Then, we applied a hybrid genetic simulated annealing algorithm to obtain a 1D S-wave velocity structure at each site. Comparison between the horizontal-to-vertical ratio of Microtremors and computed ellipticities of the fundamental mode Rayleigh waves showed good agreement with validation models. The depth of the engineering bedrock changed from 20 to 50 m in the Tekirdag city center and along the coastline with a velocity range of 700–930 m/s, and it ranged between 10 and 65 m in Marmara Ereglisi. The average S-wave velocity of the engineering bedrock was 780 m/s in the region. We obtained average S-wave velocities in the upper 30 m to compare site amplifications. Empirical relationships between the AVs30, the site amplifications, and also average topographic slopes were established for use in future site effects microzonation studies in the region.
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estimation of shallow s wave velocity structure in damascus city syria using Microtremor exploration
Soil Dynamics and Earthquake Engineering, 2012Co-Authors: Hussam Eldein Zaineh, Hiroaki Yamanaka, Rawaa Dakkak, Ahlam Khalil, Mohamad DaoudAbstract:Abstract Array measurements of Microtremors were carried out at thirty sites in Damascus city, Syria to estimate S-wave velocity structures of shallow soil formations for site effect analysis. The Microtremor data were recorded by 6 vertical-component seismometers distributed along the circumferences of two circles as well as a 3-component seismometer deployed in the center. The phase velocities were estimated at each site from the vertical components of recorded Microtremor data by using the Spatial Autocorrelation method. Then, Genetic Simulated Annealing Algorithm technique was applied for inversion of the phase velocities to estimate 1-D S-wave velocity structures beneath the sites. The inverted Vs profiles are not uniform in Damascus city and the results show that a shallow soft layer (∼200 m/s) appears in the eastern part of the city as well as the central part along Barada River. This layer controls the amplification distribution in the city with a high amplification mainly observed at the locations having this layer. The inversion results also show that the depth to the engineering bedrock (∼750 m/s) is very shallow along the foothills of Mt. Qasyoun in the north-west. Then the depth increases towards the east and the south. The maximum depth to the engineering bedrock (∼80 m) was observed in the southern part of Damascus. To validate the results of the inversions, the spectral ratios between the horizontal and vertical components (H/V) of the recorded Microtremor data at the central seismometer were compared with the computed ellipticities of the fundamental-mode Rayleigh-waves based on the respective Vs structure. The results show a good agreement in a period range of 0.05 s to 0.5 s. In this period range, the dominant peaks of the H/V ratios are due to the overall effect of the velocity contrasts between the shallow layers representing the subsurface S-wave velocity structure. Moreover, the average S-wave velocity for the top 10 m of soils (V S10 ) shows a better correlation with the averaged site amplification in a period range of 0.05 s to 0.5 s than V S30 which indicates that V S10 can be a better proxy for high-frequency site amplification in the case of Damascus city.
Hiroshi Kawase - One of the best experts on this subject based on the ideXlab platform.
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Difference of horizontal-to-vertical spectral ratios of observed earthquakes and Microtremors and its application to S-wave velocity inversion based on the diffuse field concept
Earth Planets and Space, 2018Co-Authors: Hiroshi Kawase, Yuta Mori, Fumiaki NagashimaAbstract:We have been discussing the validity of using the horizontal-to-vertical spectral ratios (HVRs) as a substitute for S-wave amplifications after Nakamura first proposed the idea in 1989. So far a formula for HVRs had not been derived that fully utilized their physical characteristics until a recent proposal based on the diffuse field concept. There is another source of confusion that comes from the mixed use of HVRs from earthquake and Microtremors, although their wave fields are hardly the same. In this study, we compared HVRs from observed Microtremors (MHVR) and those from observed earthquake motions (EHVR) at one hundred K-NET and KiK-net stations. We found that MHVR and EHVR share similarities, especially until their first peak frequency, but have significant differences in the higher frequency range. This is because Microtremors mainly consist of surface waves so that peaks associated with higher modes would not be prominent, while seismic motions mainly consist of upwardly propagating plain body waves so that higher mode resonances can be seen in high frequency. We defined here the spectral amplitude ratio between them as EMR and calculated their average. We categorize all the sites into five bins by their fundamental peak frequencies in MHVR. Once we obtained EMRs for five categories, we back-calculated EHVRs from MHVRs, which we call pseudo-EHVRs (pEHVR). We found that pEHVR is much closer to EHVR than MHVR. Then we use our inversion code to invert the one-dimensional S-wave velocity structures from EHVRs based on the diffuse field concept. We also applied the same code to pEHVRs and MHVRs for comparison. We found that pEHVRs yield velocity structures much closer to those by EHVRs than those by MHVRs. This is natural since what we have done up to here is circular except for the average operation in EMRs. Finally, we showed independent examples of data not used in the EMR calculation, where better ground structures were successfully identified from pEHVRs again. Thus we proposed here a simple empirical method to estimate S-wave velocity structures using single-station Microtremor records, which is the most cost-effective method to characterize the site effects. Open image in new window
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Difference of horizontal-to-vertical spectral ratios of observed earthquakes and Microtremors and its application to S-wave velocity inversion based on the diffuse field concept
Earth Planets and Space, 2018Co-Authors: Hiroshi Kawase, Yuta Mori, Fumiaki NagashimaAbstract:We have been discussing the validity of using the horizontal-to-vertical spectral ratios (HVRs) as a substitute for S-wave amplifications after Nakamura first proposed the idea in 1989. So far a formula for HVRs had not been derived that fully utilized their physical characteristics until a recent proposal based on the diffuse field concept. There is another source of confusion that comes from the mixed use of HVRs from earthquake and Microtremors, although their wave fields are hardly the same. In this study, we compared HVRs from observed Microtremors (MHVR) and those from observed earthquake motions (EHVR) at one hundred K-NET and KiK-net stations. We found that MHVR and EHVR share similarities, especially until their first peak frequency, but have significant differences in the higher frequency range. This is because Microtremors mainly consist of surface waves so that peaks associated with higher modes would not be prominent, while seismic motions mainly consist of upwardly propagating plain body waves so that higher mode resonances can be seen in high frequency. We defined here the spectral amplitude ratio between them as EMR and calculated their average. We categorize all the sites into five bins by their fundamental peak frequencies in MHVR. Once we obtained EMRs for five categories, we back-calculated EHVRs from MHVRs, which we call pseudo-EHVRs (pEHVR). We found that pEHVR is much closer to EHVR than MHVR. Then we use our inversion code to invert the one-dimensional S-wave velocity structures from EHVRs based on the diffuse field concept. We also applied the same code to pEHVRs and MHVRs for comparison. We found that pEHVRs yield velocity structures much closer to those by EHVRs than those by MHVRs. This is natural since what we have done up to here is circular except for the average operation in EMRs. Finally, we showed independent examples of data not used in the EMR calculation, where better ground structures were successfully identified from pEHVRs again. Thus we proposed here a simple empirical method to estimate S-wave velocity structures using single-station Microtremor records, which is the most cost-effective method to characterize the site effects.
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Applicability of Theoretical Horizontal-to-Vertical Ratio of Microtremors Based on the Diffuse Field Concept to Previously Observed Data
Bulletin of the Seismological Society of America, 2015Co-Authors: Hiroshi Kawase, Shinichi Matsushima, Toshimi Satoh, Francisco J. Sánchez-sesmaAbstract:Abstract Horizontal-to-vertical spectral ratios of Microtremors (MHVRs) have been interpreted as representing either the Rayleigh-wave ellipticity or the amplitude ratio of the sum of Rayleigh and Love waves in a horizontally layered structure. However, based on the recently established diffuse field concept, the theoretical form of MHVR has been proposed to be the square root of the ratio between the imaginary part of the horizontal Green’s function on the surface and that of the vertical one. The theory assumes that the energy of a wavefield inside the earth will be equipartitioned among the various states in 3D space. In the case of Microtremors, this may occur for randomly applied point-force loadings on the surface after sufficient lapse time to allow multiple scattering. Recent works on diffuse fields suggest that equipartition may arise in several ways, but understanding the emergence of equipartition in realistic settings requires further scrutiny. In the meantime, the resulting formula is quite simple, and its meaning has theoretical support from deterministic exact solutions. As references, we use observed Microtremor data from several sites that were reported previously and validate the diffuse field method (DFM) as an alternative method to explain observed MHVR. We use only sites with reliable velocity structures to compare different methods quantitatively. As a result, we found that the DFM solutions with the corresponding 1D layered structures well explain the observed MHVRs for most of the sites. Thus, we believe that MHVR can be used to invert a 1D velocity structure by using DFM as a theoretical tool.
Francisco J. Sánchez-sesma - One of the best experts on this subject based on the ideXlab platform.
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Applicability of Theoretical Horizontal-to-Vertical Ratio of Microtremors Based on the Diffuse Field Concept to Previously Observed Data
Bulletin of the Seismological Society of America, 2015Co-Authors: Hiroshi Kawase, Shinichi Matsushima, Toshimi Satoh, Francisco J. Sánchez-sesmaAbstract:Abstract Horizontal-to-vertical spectral ratios of Microtremors (MHVRs) have been interpreted as representing either the Rayleigh-wave ellipticity or the amplitude ratio of the sum of Rayleigh and Love waves in a horizontally layered structure. However, based on the recently established diffuse field concept, the theoretical form of MHVR has been proposed to be the square root of the ratio between the imaginary part of the horizontal Green’s function on the surface and that of the vertical one. The theory assumes that the energy of a wavefield inside the earth will be equipartitioned among the various states in 3D space. In the case of Microtremors, this may occur for randomly applied point-force loadings on the surface after sufficient lapse time to allow multiple scattering. Recent works on diffuse fields suggest that equipartition may arise in several ways, but understanding the emergence of equipartition in realistic settings requires further scrutiny. In the meantime, the resulting formula is quite simple, and its meaning has theoretical support from deterministic exact solutions. As references, we use observed Microtremor data from several sites that were reported previously and validate the diffuse field method (DFM) as an alternative method to explain observed MHVR. We use only sites with reliable velocity structures to compare different methods quantitatively. As a result, we found that the DFM solutions with the corresponding 1D layered structures well explain the observed MHVRs for most of the sites. Thus, we believe that MHVR can be used to invert a 1D velocity structure by using DFM as a theoretical tool.
Asskar Janalizadeh Choobbasti - One of the best experts on this subject based on the ideXlab platform.
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Application of the Microtremor measurements to a site effect study
Earthquake Science, 2017Co-Authors: Sadegh Rezaei, Asskar Janalizadeh ChoobbastiAbstract:Earthquake has left much life and property damages. The occurrence of such events necessitates the execution of plans for combating the earthquakes. One of the most important methods for combating earthquakes includes assessing dynamic characteristics of soil and site effect. One of the methods by which one can state dynamic characteristics of the soil of an area is the measurement of Microtremors. Microtremors are small-scale vibrations that occur in the ground and have an amplitude range of about 0.1–1 microns. Microtremor measurement is fast, applicable, cost-effective. Microtremor measurements were taken at 15 stations in the Babol, north of Iran. Regarding H / V spectral ratio method, peak frequency and amplification factor were calculated for all Microtremor stations. According to the analysis, the peak frequency varies from 0.67 to 8.10 Hz within the study area. Also, the authors investigated the validity of the results by comparing them with SESAME guidelines and geotechnical conditions of study area. The Microtremor analysis results are consistent with SESAME guidelines and geotechnical condition of study area. The results show that the Microtremor observations are acceptable methods for assessing dynamic characteristics of soil and site effect in the Babol City.
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site effect assessment using Microtremor measurement equivalent linear method and artificial neural network case study babol iran
Arabian Journal of Geosciences, 2015Co-Authors: Sadegh Rezaei, Asskar Janalizadeh Choobbasti, Saman Soleimani KutanaeiAbstract:Site effect assessment is an important procedure for a reliable site-specific hazard assessment. Fundamental frequency is a very important factor that must be considered in a construction site for examining the potential damage resulting from earthquake. In the two last decades, the Microtremor H/V spectral ratio method has been widely used for site effect studies. Microtremor measurement is fast, applicable, and cost-effective. Microtremor measurement was undertaken at 60 stations in the Babol, north of Iran, during 2011 and 2012. Regarding Nakamura’s method, H/V spectral ratios, fundamental frequency, and amplification factor were calculated for all Microtremor stations. The obtained results were controlled with SESAME guidelines. In order to assess the accuracy of the Microtremor measurements and its application in site effect evaluation, a preliminary site response modeling was carried out using the equivalent linear methods at some stations. More than 18 boreholes in the study area were modeled as multilayer column, overlaid on bedrock. Also, the artificial neural networks (ANN) with different inputs including thickness, type of soil, unit weight, shear wave velocity, and max shear modulus of soil layer were trained. Then, the trained ANN predicts the fundamental frequency, and the output results were compared with Microtremor measurement. The results showed that Microtremor measurement approach provides an acceptable means of site effect evaluation in the study area.
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Liquefaction assessment using Microtremor measurement, conventional method and artificial neural network (Case study: Babol, Iran)
Frontiers of Structural and Civil Engineering, 2014Co-Authors: Sadegh Rezaei, Asskar Janalizadeh ChoobbastiAbstract:Recent researchers have discovered Microtremor applications for evaluating the liquefaction potential. Microtremor measurement is a fast, applicable and cost-effective method with extensive applications. In the present research the liquefaction potential has been reviewed by utilization of Microtremor measurement results in Babol city. For this purpose Microtremor measurements were performed at 60 measurement stations and the data were analyzed by suing Nakmaura’s method. By using the fundamental frequency and amplification factor, the value of vulnerability index ( K _ g ) was calculated and the liquefaction potential has been evaluated. To control the accuracy of this method, its output has been compared with the results of Seed and Idriss [1] method in 30 excavated boreholes within the study area. Also, the results obtained by the artificial neural network (ANN) were compared with Microtremor measurement. Regarding the results of these three methods, it was concluded that the threshold value of liquefaction potential is K _ g = 5. On the basis of the analysis performed in this research it is concluded that Microtremors have the capability of assessing the liquefaction potential with desirable accuracy.
