LOCAL SEISMIC HAZARD ASSESSMENT OF THE MATARAM CITY, INDONESIA BASED ON SINGLE STATION MICROTREMOR MEASUREMENT

Mapping Intimacies ◽

10.31227/osf.io/ghxed ◽

2018 ◽

Author(s):

Syamsuddin

Keyword(s):

Seismic Hazard ◽

Resonant Frequency ◽

Resonance Frequency ◽

Seismic Hazard Assessment ◽

Spectral Ratio ◽

Frequency Variation ◽

Single Station ◽

Noise Measurements ◽

Dominant Period ◽

Microtremor Measurement

Horizontal to vertical spectral ratio technique is used to assess the local seismic hazard through estimation of fundamental resonant frequency in Mataram city, Indonesia. In this study ambient noise measurements are carried out at 332 sites with the minimum duration of noise recording is about ten menit. Results of measurement indicate that the fundamental resonance frequency for Mataram range from 0.311 to 12,534 Hz. The resonance frequency variation showed a heterogeneous lithological conditions of the area. The resonant frequency is low or high are the dominant period in the western city of Mataram, while the resonant frequency high or low dominant periods are in the eastern. This means that the western region is very prone to earthquakes. In addition, there is a good correlation was found between Geology of Mataram city and HVSR results obtained in this research.

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Contribution for seismic hazard assessment with local scale focus on Durrës (Albania) and damage observation after the ML 5.4, 21st September 2019 earthquake

10.5194/egusphere-egu2020-19528 ◽

2020 ◽

Author(s):

Marco Mancini ◽

Iolanda Gaudiosi ◽

Redi Muci ◽

Maurizio Simionato ◽

Klodian Skrame

Keyword(s):

Seismic Hazard ◽

Cultural Heritage ◽

Ground Motion ◽

Seismic Risk ◽

Preliminary Results ◽

Joint Research Project ◽

Single Station ◽

Noise Measurements ◽

The City ◽

2D Array

The city of Durr&#235;s was recentely struck by a Mw 6.2 mainshock event (http://cnt.rm.ingv.it/event/23487611) that caused considerable damage and 51 victims. The city is located on an actively seismotectonic belt where seismic catalogues report few past events with magnitude higher than 6.Surface geology is generally considered to influence the ground motion recorded on site. The analysis of the influence of local effects on seismic response at ground surface appears relevant also considering that Durr&#235;s is a densely populated city prone to high seismic risk and is characterized by several important archeological and cultural heritage sites.Preliminary results obtained from recent geophysical in-situ measurements and geological surveys, carried out in Durr&#235;s after the ML 5.4, 21st September 2019 event, are presented with the aim of providing new elements for the assessment of local seismic hazard and following a comprehensive approach to the modifications induced by the site.Twenty-nine single-station noise measurements, processed through the HVSR technique, two MASW surveys and two 2D array measurements were performed. Results from noise measurements define a zone eastward of the historical centre, where the characteristics of surficial soil layers are responsible for modification to the seismic demand. In particular, HVSR curves in this area show amplification higher than 4 at a period higher than 1s. Moreover, on this location a surface waves-velocity profile obtained from a joint inversion of Rayleigh curves from MASW and 2D array with ellipticity individuates a class D soil, EC8 sensu, corresponding to marshy soil of very poor geotechnical quality. These data may be considered as key elements in the site-specific response analyses, i.e. realized according to the international codes (EC8, NEHRP), which allow to quantify the expected ground motion. These results are potentially useful for &#160;correlating&#160; construction typologies and period vibration of the buildings with the site amplification.In addition, a damage survey was carried out in one of the most damaged zones after the 21st September 2019 earthquake. Because of the following stronger event of the 26th November 2019, we think that these preliminary results may provide useful information for the post-earthquake reconstruction and enhancement of the urban resilience.&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; The activities are carried out wihin the framework of the CNR/MOES Joint research project &#8220;Seismic risk assessment in cultural heritage cities of Albania&#8221; in the biennium 2018-2019 (https://www.cnr.it/en/bilateral-agreements/agreement/60/moes-ministry-of-education-and-sport-of-the-republic-of-albania).

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Seismic Hazard and Microzonation Study of Tanjung Region, North Lombok (Indonesia) using Microtremor Measurement

Jurnal Pendidikan Fisika Indonesia ◽

10.15294/jpfi.v14i2.9919 ◽

2018 ◽

Vol 14 (2) ◽

pp. 105-110 ◽

Cited By ~ 2

Author(s):

S. Syamsuddin ◽

I. Ashari ◽

M. A. Adhi

Keyword(s):

Seismic Hazard ◽

Resonant Frequency ◽

Amplification Factor ◽

Vulnerability Index ◽

Frequency Characteristics ◽

Severe Damage ◽

The North ◽

Microtremor Measurement ◽

Physical Quantities

Tanjung Region is one of the severely damaged areas by the Lombok earthquake on June 22, 2013. Therefore, to anticipate the similar events, it is necessary to perform microzonation in this region. Objective of this study is to map the distribution of the physical quantities related to the vulnerability of area included the frequency characteristics, amplification factor, and soil vulnerability index. The results showed that the value of the resonant frequency in this region ranged from 0.401 to 16.92 Hz. In general, the lower frequency was 0.40 to 5.91 Hz contained 87 data (71%) were located in the north of the region, which meant that that area has a high vulnerability. While based on the H/V amplitude and vulnerability index, the zone that suffered severe damage on the earthquake of June 22, 2013, showed a different uncertainty of amplification and vulnerability index value.Wilayah Tanjung adalah salah satu daerah yang mengalami rusak parah akibat gempa Lombok pada tanggal 22 Juni 2013. Oleh karena itu, untuk mengantisipasi kejadian serupa, maka perlu untuk melakukan mikrozonasi di daerah tersebut. Tujuan dari penelitian ini adalah untuk memetakan distribusi besaran fisis yang terkait dengan kerentanan suatu daerah terhadap gempa bumi yang meliputi frekuensi respon, amplitudo getaran tanah dan indeks kerentanan tanah. Hasil penelitian menunjukkan bahwa nilai frekuensi resonansi di wilayah ini berkisar antara 0,401-16,92 Hz. Secara umum, frekuensi respon di daerah ini rendah yaitu 0,40-5,91 Hz dengan jumlah 87 data (71%) yang terletak di utara dari wilayah tersebut, yang berarti bahwa bagian utara wilayah memiliki kerentanan yang tinggi. Meskipun berdasarkan nilai amplitudo H/V dan indeks kerentanan, daerah yang mengalami kerusakan parah saat gempa 22 Juni 2013 menunjukkan pola amplifikasi dan indeks kerentanan yang sangat tidak biasa.

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Study on the applicability of microtremor HVSR method to support seismic microzonation in the town of Idrija (W Slovenia)

10.5194/nhess-2016-405 ◽

2017 ◽

Author(s):

Andrej Gosar

Keyword(s):

Seismic Hazard ◽

Resonance Frequency ◽

Complex Geometry ◽

Free Field ◽

Seismic Refraction ◽

Spectral Ratio ◽

Seismic Microzonation ◽

Clear Correlation ◽

Resonance Frequencies ◽

Hvsr Method

Abstract. The Idrija town is located in area with increased seismic hazard in W Slovenia and is partly built on alluvial sediments or artificial mining and smelting deposits which can amplify seismic ground motion. There is a need to prepare a comprehensive seismic microzonation in the near future to support seismic hazard and risk assessment. To study the applicability of microtremor Horizontal-to-Vertical Spectral Ratio (HVSR) method for this purpose, 70 free-field microtremor measurements were performed in 0.8 km2 large town area with 50–200 m spacing between points. HVSR analysis has shown that it is possible to derive sediments resonance frequency at 48 point, whereas at remaining one third of measurements nearly flat HVSR curves were obtained indicating small or no impedance contrast with the seismological bedrock. Iso-frequency (range 2.5–19.5 Hz) and HVSR peak amplitude (range 3–6, with few larger values) maps were prepared by using natural neighbour interpolation algorithm and compared with the geological map and map of artificial deposits. Surprisingly no clear correlation was found between distribution of resonance frequencies or peak amplitudes and the known extent of supposed soft sediments or deposits. This can be explained by relatively well compacted and rather stiff deposits and complex geometry of sedimentary bodies. However, at several individual locations it was possible to correlate the shape and amplitude of the HVSR curve with the known geological structure and prominent site effects were established in different places. On the other hand, in given conditions (very limited free space and high level of noise) it would be difficult to perform active seismic refraction or MASW measurements to investigate the S-waves velocity profiles and thickness of sediments in details, which would be representative enough for microzonation purposes. The importance of microtremor method is therefore even greater, because it enables direct estimation of the resonance frequency without knowing the internal structure and physical properties of the shallow subsurface. The results of this study can be used directly in analyses of possible occurrence of soil-structure resonance of individual buildings, including important cultural heritage mining and other structures protected by UNESCO. Second application of the derived free-field iso-frequency map is to support soil classification according to the recent trends in building codes.

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Integrated Seismic Hazard Analysis Of Southwest Penang Island Through Horizontal-To-Vertical Spectral Ratio And Probabilistic Seismic Hazard Assessment

Bulletin of the Geological Society of Malaysia ◽

10.7186/bgsm71202107 ◽

2021 ◽

Vol 71 ◽

pp. 79-87

Author(s):

Siti Noor Shafiqah Badrolhisham ◽

◽

Abdul Halim Abdul Latiff

Keyword(s):

Seismic Hazard ◽

Hazard Assessment ◽

Ground Motions ◽

Seismic Hazard Assessment ◽

Spectral Ratio ◽

Seismic Survey ◽

Survey Method ◽

Probabilistic Seismic Hazard Assessment ◽

Probabilistic Seismic Hazard ◽

Loose Deposits

Peninsular Malaysia is susceptible to large magnitude earthquakes induced by the regional sources as it is surrounded by countries that are known for their active seismicity. Tremors were felt in Penang Island of Pulau Pinang due to earthquake events in Sumatra, Indonesia in 2005 and 2009. Presence of cracks on buildings in the island was reported caused by the earthquake on 2nd November 2002. The tsunami that hit the island on 26 December 2004 was the aftermath of the Great Sumatra-Andaman earthquake with magnitude 9.1. The investigation of earthquake risks ensures that the effect of earthquake disasters in the inclined region can be reduced effectively. This paper aims to provide a comprehensive seismic hazard assessment in Penang Island by analysing the predominant natural frequency distribution in Balik Pulau through a passive seismic survey method known as horizontal-to-vertical spectral ratio (HVSR) and evaluating the ground motion throughout the island using probabilistic seismic hazard assessment (PSHA) approach. The natural frequencies of Balik Pulau mostly falls in the range of 3 to 4 Hz which is associated with loose deposits and stiff soil layer. The amplification factor extracted from the HVSR curves ranges approximately 4 to 5. The minimum ground motions estimated for a fixed intensity in 50 years for Penang Island is 0.006 g1 and can reach up to 0.025 g. While the minimum ground motions for a fixed return period of 98 years in 50 years is 0.016 g with maximum of 0.035 g.

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Soft soil mapping using Horizontal to Vertical Spectral Ratio (HVSR) for seismic hazard assessment of Chandigarh city in Himalayan foothills, north India

Journal of the Geological Society of India ◽

10.1007/s12594-009-0166-x ◽

2009 ◽

Vol 74 (5) ◽

pp. 551-558 ◽

Cited By ~ 4

Author(s):

A. K. Mundepi ◽

Conrad Lindholm ◽

Kamal

Keyword(s):

Seismic Hazard ◽

Hazard Assessment ◽

Soft Soil ◽

Seismic Hazard Assessment ◽

Spectral Ratio ◽

Soil Mapping ◽

North India ◽

Himalayan Foothills

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Study on the Main Factors of Frequency Variation of LC Resonant Prestress Detection Method

Advances in Materials Science and Engineering ◽

10.1155/2020/9526843 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Benniu Zhang ◽

Yuanyuan Zhao ◽

Xingxing Li ◽

Yanpeng Su ◽

Qiang Yin ◽

...

Keyword(s):

Resonant Frequency ◽

Resonance Frequency ◽

Relative Permeability ◽

Stress Measurement ◽

Length Change ◽

Resonant Circuit ◽

Frequency Variation ◽

Stress Detection ◽

Electric Circuits ◽

Stress Changes

Stress loss of prestressed steel strands of existing bridges influences their bearing capacity, so it is of great significance to realize the stress detection. A steel strand that has an inductive property is designed into the resonant circuit, which can realize the stress measurement of the steel strands by testing the resonant frequency. This method is a promising approach for the stress detection of the steel strands. Previous research found that structural stress made the permeability of steel strands change due to the influence of magnetoelastic effect. In the process, the length of steel strands is also changed. Therefore, further research needs to be done to verify the main influence parameter affecting the resonant frequency of the circuit. Furthermore, it is very important to know how the stress affects the resonant frequency to realize the detection of the prestressed force of the steel strands. Therefore, in this paper, the relationship between stress and relative permeability and length is analyzed theoretically, and the theory of stress frequency of steel strands is modified and verified by experiments. The stress-frequency experiments of steel strands and aluminum strands with great difference in relative permeability are carried out. Experiments on stress frequencies of 7-Ф15.20 mm steel strands with different lengths are carried out. The influence of length and permeability parameters on resonance frequency is analyzed. The experimental results show that under the same conditions, the resonant frequencies of steel strands and aluminum strands are almost the same on LC electric circuits, and the resonant frequency decreases linearly with the increase of the natural length of the component and increases linearly with the increase of stress. Consequently, compared with the influence of length change on LC electromagnetic resonance frequency, the relative permeability of the stress change component can be ignored. The stress changes the resonant frequency mainly by changing the length of the strands.

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