Horizontal-to-Vertical Spectral Ratio (HVSR) IRIS Station Toolbox

2020 ◽  
Vol 91 (6) ◽  
pp. 3539-3549
Author(s):  
Manochehr Bahavar ◽  
Zack J. Spica ◽  
Francisco J. Sánchez-Sesma ◽  
Chad Trabant ◽  
Arash Zandieh ◽  
...  
Keyword(s):  
Ambient Noise ◽  
Spectral Ratio ◽  
Site Effect ◽  
Predominant Frequency ◽  
Density Estimates ◽  
Effect Analysis ◽  
Seismic Stations ◽  
Arctic Regions ◽  
Power Spectral ◽  
The Many

Abstract The horizontal-to-vertical spectral ratio (HVSR) for seismic ambient noise is a popular method that can be used to estimate the predominant frequency at a given site. In this article, we introduce the Incorporated Research Institutions for Seismology (IRIS) Data Management Center’s (DMC’s) openly available HVSR station toolbox. These tools offer a variety of ways to compute the spectral ratio by providing different averaging routines. The options range from the simple average of spectral ratios to the ratio of spectral averages. Computations take advantage of the available power spectral density estimates of ambient noise for the seismic stations, and they can be used to estimate the predominant frequency of the many three-component seismic stations available from the IRIS DMC. Furthermore, to facilitate the identification of the peaks in HVSR profiles for the assessment of the predominant frequency of station sites, the toolbox can also process the results of HVSR analysis to detect and rank HVSR peaks. To highlight the toolbox capabilities, three different examples of possible use of this toolbox for routine site-effect analysis are discussed: (1) site effects related to thawing in Arctic regions, (2) ground-motion amplification in urban area, and (3) estimation of station VS30.

scholarly journals Antarctic ice sheet thickness estimation using the horizontal-to-vertical spectral ratio method with single-station seismic ambient noise

2018 ◽  
Vol 12 (2) ◽  
pp. 795-810 ◽  
Author(s):  
Peng Yan ◽  
Zhiwei Li ◽  
Fei Li ◽  
Yuande Yang ◽  
Weifeng Hao ◽  
...  
Keyword(s):  
Ambient Noise ◽  
Ice Sheet ◽  
Sheet Thickness ◽  
Spectral Ratio ◽  
Ice Thickness ◽  
Antarctic Ice Sheet ◽  
Seismic Stations ◽  
Thickness Estimation ◽  
Seismic Ambient Noise ◽  
The Antarctic

Abstract. We report on a successful application of the horizontal-to-vertical spectral ratio (H / V) method, generally used to investigate the subsurface velocity structures of the shallow crust, to estimate the Antarctic ice sheet thickness for the first time. Using three-component, five-day long, seismic ambient noise records gathered from more than 60 temporary seismic stations located on the Antarctic ice sheet, the ice thickness measured at each station has comparable accuracy to the Bedmap2 database. Preliminary analysis revealed that 60 out of 65 seismic stations on the ice sheet obtained clear peak frequencies (f0) related to the ice sheet thickness in the H / V spectrum. Thus, assuming that the isotropic ice layer lies atop a high velocity half-space bedrock, the ice sheet thickness can be calculated by a simple approximation formula. About half of the calculated ice sheet thicknesses were consistent with the Bedmap2 ice thickness values. To further improve the reliability of ice thickness measurements, two-type models were built to fit the observed H / V spectrum through non-linear inversion. The two-type models represent the isotropic structures of single- and two-layer ice sheets, and the latter depicts the non-uniform, layered characteristics of the ice sheet widely distributed in Antarctica. The inversion results suggest that the ice thicknesses derived from the two-layer ice models were in good concurrence with the Bedmap2 ice thickness database, and that ice thickness differences between the two were within 300 m at almost all stations. Our results support previous finding that the Antarctic ice sheet is stratified. Extensive data processing indicates that the time length of seismic ambient noise records can be shortened to two hours for reliable ice sheet thickness estimation using the H / V method. This study extends the application fields of the H / V method and provides an effective and independent way to measure ice sheet thickness in Antarctica.

scholarly journals A STUDY OF MICROTREMOR HVSR IN THE RIO-ANTIRIO AREA, (GREECE)

2017 ◽  
Vol 50 (3) ◽  
pp. 1194
Author(s):  
M.E. Norda ◽  
A. Prapiga ◽  
P. Paraskevopoulos ◽  
G.A Tselentis
Keyword(s):  
Fundamental Frequency ◽  
Main Part ◽  
Ambient Noise ◽  
Spectral Ratio ◽  
Recording Time ◽  
Seismic Stations ◽  
Central Greece ◽  
Hvsr Method

Horizontal to Vertical Spectral Ratio (HVSR) method has been applied on ambient noise records at the Rio- Antirio area (central Greece). The dataset used was recorded during 7 days by 12 temporary seismic stations deployed in the area. The stations were laid out along a profile and their interval was approximately 500m. The main part of the processing was done using Geopsy software. The aim of this study was to estimate the fundamental frequency at the station sites and its variation with time and azimuth. The processing results showed that for most stations along the profile, the peaks of the HVSR curve are not strong enough and often there are, more than one, peaks, which seem to be persistent during the whole recording time. When taking the azimuth into account, some of the stations show dominant and persistent directions were the HVSR ratio is stronger, while it has been observed that this direction could vary for different frequency peaks of the same stations. Finally, the top sediment layer’s geometry and thickness were estimated using Vs velocity results from nearby crosshole measurements.

The Site Effect Analysis of Semi-Cylindrical Canyons and Soft Alluvial Basins by H/V Spectral Ratio

2012 ◽  
Vol 204-208 ◽  
pp. 2465-2468
Author(s):  
Cheng Chih Chen ◽  
Wen Shinn Shyu ◽  
Chau Shioung Yeh ◽  
Cheh Shyh Ting
Keyword(s):  
Frequency Domain ◽  
Earthquake Engineering ◽  
Scattering Problem ◽  
Expansion Method ◽  
Spectral Ratio ◽  
Site Effect ◽  
Scattering Problems ◽  
Effect Analysis ◽  
Wave Amplification ◽  
Seismic Wave Amplification

The source, path and site effects are the main causes for ground motions. Soft alluvial basins especially result in seismic wave amplification as the site effect. Irregular alluvial basins and canyons in this study are semi-cylindrical for simplifying analysis. To deal with the scattering problems in frequency domain, Yeh et al. have gained positive outcomes by using a hybrid method which combined finite elements and the series expansion method to effectively solve the scattering problem in the irregular basins. These displacements derived from the frequency domain are computed with the H/V ratio to estimate the site effect. As the site effect is crucial in earthquake engineering, this study may serve as a quantitative contribution towards the amplified effect in alluvial basins and canyons. It can also simulate the effects of different incident angles on the H/V ratio.

scholarly journals Antarctic ice sheet thickness estimation using the H/V spectral ratio method with single-station seismic ambient noise

2017 ◽  
Author(s):  
Peng Yan ◽  
Zhiwei Li ◽  
Fei Li ◽  
Yuande Yang ◽  
Weifeng Hao ◽  
...  
Keyword(s):  
Ambient Noise ◽  
Ice Sheet ◽  
Sheet Thickness ◽  
Spectral Ratio ◽  
Ice Thickness ◽  
Antarctic Ice Sheet ◽  
Seismic Stations ◽  
Thickness Estimation ◽  
Seismic Ambient Noise ◽  
The Antarctic

Abstract. The horizontal-to-vertical spectral ratio (H/V) method implemented at single stations using seismic ambient noise waveforms is a fast, noninvasive, efficient method to investigate the subsurface velocity structures of the shallow crust. In this study, we report on a successful application of the H/V method to estimate the Antarctic ice sheet thickness for the first time. Using three-component, five-day long, seismic ambient noise records gathered from more than 60 temporary seismic stations located on the Antarctic ice sheet, the ice thickness at each station was reliably measured. Preliminary analysis revealed that 60 out of 65 seismic stations on the ice sheet obtained clear peak frequencies (f0) related to the ice sheet thickness in the H/V spectrum. Thus, assuming that the isotropic ice layer lies atop a high velocity half-space bedrock, the ice sheet thickness can be calculated by a simple approximation formula. About half of the calculated ice sheet thickness were consistent with the Bedmap2 ice thickness values. To further improve the reliability of ice thickness measurements, two-type models were built to fit the observed H/V spectrum through non-linear inversion. The two-type models represent the isotropic structures of single and two-layer ice sheet, and the latter depicts the non-uniform, layered characteristics of the ice sheet widely distributed in Antarctica. The inversion results suggest that the ice thicknesses derived from the two-layer ice models were highly consistent with the Bedmap2 ice thickness database, and their ice thickness differences were within 300 m at almost all stations. Our results support previous finding that the Antarctic ice sheet is stratified. Extensive data processing indicates that the time length of seismic ambient noise records can be shortened to 1–2 hours for reliable ice sheet thickness estimation using the H/V method. This study extends the application fields of the H/V method and provides a complementary and independent way to measure ice sheet thickness in Antarctica.

scholarly journals Reference stations for Christchurch

2012 ◽  
Vol 45 (4) ◽  
pp. 184-195 ◽  
Author(s):  
C. Van Houtte ◽  
O.-J. Ktenidou ◽  
T. Larkin ◽  
A. Kaiser
Keyword(s):  
Reference Site ◽  
Spectral Ratio ◽  
Site Effect ◽  
Reference Station ◽  
Topographic Effects ◽  
S Wave ◽  
Rock Outcrop ◽  
Soft Soils ◽  
Seismic Stations ◽  
Hvsr Method

During the Canterbury earthquake sequence, the observed level of ground motion on the soft soils of Christchurch was very strong and highly variable. Many studies are now emerging that analyse the amplification effect of these soft soils, usually by estimating a frequency-dependent amplification function relative to a rock outcrop station, or ‘reference site’. If the rock outcrop has its own amplification due to weathering or topographic effects, then the calculated amplification for the soil sites can be compromised. This study examines ten seismic stations in Canterbury to determine the best reference site for Christchurch, using the horizontal-to-vertical spectral ratio (HVSR) method for S-wave shaking. More broadly, this study uses HVSR to expand existing knowledge of the dynamic characteristics of seismic stations in the Canterbury area. Most rock stations show their own local amplification effects that reduce their individual ability to be used as reference stations. The recently installed Huntsbury station (HUNS) appears to be the best reference site for Christchurch, but this will need to be verified when more records become available. In the meantime, the D13C temporary station is currently the best reference station for site effect studies in both Christchurch and Lyttelton.

scholarly journals A new noise detected in the ocean

2007 ◽  
Vol 87 (5) ◽  
pp. 1255-1256 ◽  
Author(s):  
Angel Guerra ◽  
Xavier Martinell ◽  
Angel F. González ◽  
Michael Vecchione ◽  
Joaquin Gracia ◽  
...  
Keyword(s):  
Ambient Noise ◽  
Sound Production ◽  
Biological Activities ◽  
Physical Processes ◽  
Defensive Strategy ◽  
Reflection And Refraction ◽  
Turbulent Pressure ◽  
In The Wild ◽  
The Many ◽  
Many Sources

Many observers have noted that the sea is full of loud sounds, both ongoing and episodic. Among the many sources of natural ambient noise are wave action, physical processes such as undersea earthquakes, and biological activities of shrimps, fish, dolphins and whales. Despite interest by acoustics experts, sound production by cephalopods has been reported only twice, both involving squid. The ‘faint poppings’ produced were thought to result from fluttering of the thin external lips of the squid's funnel while water is being expelled through it. Otherwise, no information is available on cephalopod sounds. Here we present a noise produced by a stressed common octopus. The event was filmed and recorded in the wild. The hypothesis we offer to explain how this sound was produced is cavitation, which has been documented in several biological systems. In our case, the water expelled through the funnel may have created a jet with a velocity so high that the turbulent pressure dropped locally below the vapour pressure of the water. Seawater contains gas microbubbles, which will grow in size when they are entrained in the region of low pressure. Subsequently, the bubbles collapse violently when pressure rises again. The sound produced by the octopus is like a gunshot, and distinct lights observed at the same time contradict the existence of a simple pressure wave and point to the possible presence of gas-bubbles, which would change the light intensity by reflection and refraction of the sunlight. This behaviour seems to be a defensive strategy to escape from vibration-sensitive predators.

scholarly journals Multiple Geophysical Techniques for Investigation and Monitoring of Sobradinho Landslide, Brazil

2019 ◽  
Vol 11 (23) ◽  
pp. 6672 ◽  
Author(s):  
Yawar Hussain ◽  
Martin Cardenas-Soto ◽  
Salvatore Martino ◽  
Cesar Moreira ◽  
Welitom Borges ◽  
...  
Keyword(s):  
Ambient Noise ◽  
Geophysical Methods ◽  
Spectral Ratio ◽  
Dynamic Monitoring ◽  
Physical Parameters ◽  
Sliding Surface ◽  
Time Duration ◽  
Geophysical Techniques ◽  
Short Time

Geophysical methods have a varying degree of potential for detailed characterization of landslides and their dynamics. In this study, the application of four well-established seismic-based geophysical techniques, namely Ambient Noise Interferometry (ANI), Horizontal to Vertical Spectral Ratio (HVSR), Multi-Channel Analysis of Surface Waves (MASW) and Nanoseismic Monitoring (NM), were considered to examine their suitability for landslide characterization and monitoring the effect of seasonal variation on slope mass. Furthermore, other methods such as Ground Penetrating Radar (GPR) and DC Resistivity through Electrical Resistivity Tomography (ERT) were also used for comparison purpose. The advantages and limitations of these multiple techniques were exemplified by a case study conducted on Sobradinho landslide in Brazil. The study revealed that the geophysical characterization of the landslide using traditional techniques (i.e., GPR, ERT and MASW) were successful in (i) the differentiation between landslide debris and other Quaternary deposits, and (ii) the delineation of the landslide sliding surface. However, the innovative seismic based techniques, particularly ambient noise based (HVSR and ANI) and emitted seismic based (NM), were not very effective for the dynamic monitoring of landslide, which might be attributed to the short-time duration of the data acquisition campaigns. The HVSR was also unsuccessful in landslide site characterization i.e., identification of geometry and sliding surface. In particular, there was no clear evidence of the light seasonal variations, which could have been potentially detected from the physical parameters during the (short-time) ambient noise and microseismic acquisition campaigns. Nevertheless, the experienced integration of these geophysical techniques may provide a promising tool for future applications.

Estimation of Site Dynamic Characteristics from Ambient Noise Measurements Using HVSR Method in Microzonation Study: Senggarang, Batu Pahat, Malaysia

2014 ◽  
Vol 931-932 ◽  
pp. 803-807 ◽  
Author(s):  
Ahmad Fahmy Kamarudin ◽  
Mohd Effendi Daud ◽  
Zainah Ibrahim ◽  
Ibrahim Azmi ◽  
Mohamad Khairani Yub ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Ambient Noise ◽  
Hazard Analysis ◽  
Resonance Effect ◽  
Spectral Ratio ◽  
Boundary Area ◽  
Contour Maps ◽  
The North ◽  
Hvsr Method ◽  
Noise Measurements

Site dynamic characteristics evaluation of fundamental ground frequency, Fo and amplification factor, Ao in Senggarang region were presented in 2D and 3D contour maps (microzonation maps) based on the ambient noise measurements carried out using Lennartz 1 Hz tri-axial seismometer sensors. Reliability of Fo and Ao determined from the ambient noise technique has become the main key components in seismic hazard analysis, resonance effect assessment, predictions of sedimentary layer and shear wave velocity, through cheaper, non-destructive and quick methodology. 73 points of ambient noise records were analyzed using Horizontal-to-Vertical Spectral Ratio (HVSR) method in the boundary area of 800 m x 800 m with the grid spacing of 100 m x 100 m. Significant peaks of mean HVSR curves were checked against the criterions proposed by the SESAME guideline. Slight difference of the Fo contours pattern between the North-South (NS) and the East-West (EW) directions was observed, but vice versa to the Ao contours between both directions. Significant peaks of Fo values were distributed from 1.61 to 6.35 Hz, whereas the Ao values were found from 3.18 to 9.39. Wide gap between the ranges of Fo and Ao in respective direction have shown to the variation of sediment thicknesses. Meanwhile, dominance shape of significant peak from the HVSR curves may indicate to a large velocity contrast presence underneath the ground surfaces.

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