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

2017 ◽  
Vol 17 (6) ◽  
pp. 925-937 ◽  
Author(s):  
Andrej Gosar
Keyword(s):  
Seismic Hazard ◽  
Resonance Frequency ◽  
Complex Geometry ◽  
Free Field ◽  
Seismic Microzonation ◽  
Clear Correlation ◽  
S Wave ◽  
Resonance Frequencies ◽  
Hvsr Method ◽  
The Town

Abstract. The town of Idrija is located in an area with an 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 the microtremor horizontal-to-vertical spectral ratio (HVSR) method for this purpose, 70 free-field microtremor measurements were performed in a town area of 0.8 km2 with 50–200 m spacing between the points. The HVSR analysis has shown that it is possible to derive the sediments' resonance frequency at 48 points. With the remaining one third of the measurements, nearly flat HVSR curves were obtained, indicating a small or negligible impedance contrast with the seismological bedrock. The isofrequency (a range of 2.5–19.5 Hz) and the HVSR peak amplitude (a range of 3–6, with a few larger values) maps were prepared using the natural neighbor interpolation algorithm and compared with the geological map and the map of artificial deposits. Surprisingly no clear correlation was found between the distribution of resonance frequencies or peak amplitudes and the known extent of the supposed soft sediments or deposits. This can be explained by relatively well-compacted and rather stiff deposits and the 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. In given conditions (very limited free space and a high level of noise) it would be difficult to perform an active seismic refraction or MASW measurements to investigate the S-wave velocity profiles and the thickness of sediments in detail, which would be representative enough for microzonation purposes. The importance of the microtremor method is therefore even greater, because it enables a 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 directly used in analyses of the possible occurrence of soil–structure resonance of individual buildings, including important cultural heritage mining and other structures protected by UNESCO. Another application of the derived free-field isofrequency map is to support soil classification according to the recent trends in building codes and to calibrate Vs profiles obtained from the microtremor array or geophysical measurements.

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

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.

scholarly journals Seasonal variations in amplitudes and resonance frequencies of the HVSR amplification peaks linked to groundwater

2021 ◽  
Vol 226 (1) ◽  
pp. 1-13
Author(s):  
Alexis Rigo ◽  
Efthimios Sokos ◽  
Valentine Lefils ◽  
Pierre Briole
Keyword(s):  
Soil Moisture ◽  
Wave Velocity ◽  
Maximum Amplitude ◽  
Spectral Ratio ◽  
Vertical Surface ◽  
Sediment Layer ◽  
S Wave ◽  
Surface Displacements ◽  
Resonance Frequencies ◽  
Hvsr Method

SUMMARY Following the installation of a temporary seismological network in western Greece north of the Gulf of Patras, we determined the quality of the sites of each of the 10 stations in the network. For this, we used the horizontal-to-vertical spectral ratio (HVSR) method and calculated an average curve over randomly selected days between 0 and 10 Hz. The daily HVSR curve is determined by the HVSR 12-hr calculation (1 hr every two) without distinction between seismic ambient noise and earthquake signal. The HVSR curves obtained can be classified in three categories: flat curves without amplification, curves with a amplification peaks covering a large frequency range, and curves with one or more narrow peaks. In this third category C3, one station has one peak, two have two and one has three. On the contrary of what it is commonly assumed, the amplitudes and the resonance frequencies of these narrow peaks are not stable over time in C3. We determined the maximum of the amplitude of each peak with the corresponding central frequency for each day during 2.5 yr. Except for the station with three peaks, which finally appears stable within the uncertainties, the principal peak exhibits a seasonal variation, with a maximum in winter and a minimum in summer, the observations being more dispersed during winter. The second peak, when it exists, varies in the same way except at one station where it varies oppositely. These variations are clearly correlated with the loading and unloading cycle of the underlying aquifers as shown by the comparison with water level and yield measurements from wells located close to the stations. Moreover, they are also correlated with the vertical surface displacements observed at continuously recording GPS stations. The dispersion of the observed maximum amplitude in winter is probably related to the rainfall and the soil moisture modifying the S-wave velocity as revealed by other studies. From this study, we would like to emphasize that the use the HVSR method to constrain the S-wave velocity and the thickness of the sediment layer over the bedrock in the basin, has to be done with caution. Upon further confirmation of its robustness, the HVSR methodology presented here could be a good and easy-to-use tool for a qualitative survey of the aquifer backdrop and its seasonal behaviour, and of the soil moisture conditions.

Determination of Resonance Frequency of Two-Dimensional Alluvial Valley by Background Phase Subtraction Method

1998 ◽  
Vol 14 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Tsung-Jen Teng ◽  
Juin-Fu Chai ◽  
Chau-Shioung Yeh
Keyword(s):  
Phase Shift ◽  
Resonance Frequency ◽  
Partial Wave ◽  
Free Field ◽  
Geometrical Shape ◽  
Two Dimensional ◽  
Subtraction Method ◽  
Alluvial Valley ◽  
Resonance Frequencies ◽  
Background Phase

ABSTRACTThis paper is to develop the background phase subtraction method to determine the resonance frequency of a two-dimensional alluvial valley subjected to an incident plane SH-wave. The scattered wave due to the alluvium can be expressed in a series of basis functions, and the associated coefficients are related to the coefficients of free field by the so-called T-matrix method. By applying the resonance scattering theory, the effects among all normal modes can be decoupled and hence one can obtain the phase shift of each eigen partial wave. Similarly, the phase shift of each eigen partial wave due to a canyon with the same geometrical shape of the alluvium can be determined, and is recognized as the background effect. Furthermore, based on the phase represented scattering matrix, the resonance frequencies of each normal mode and its overtones can be determined by the subtraction of the associated phase dependent function due to the canyon from that due to the alluvium.

The 2002 Molise, Italy, Earthquake: Geological and Geomorphological Data on the San Giuliano di Puglia Area

2004 ◽  
Vol 20 (1_suppl) ◽  
pp. 53-64 ◽  
Author(s):  
Emilio Casciello ◽  
Massimo Cesarano ◽  
Giuseppe Naso ◽  
Gerardo Pappone ◽  
Carmen Rosskopf
Keyword(s):  
Seismic Hazard ◽  
Drill Hole ◽  
Seismic Microzonation ◽  
Earthquake Sequence ◽  
Large Set ◽  
Civil Protection ◽  
Severe Damage ◽  
Geomorphological Mapping ◽  
Molise Earthquake ◽  
The Town

The small village of San Giuliano di Puglia sustained the most severe damage from the Molise earthquake sequence of 2002. This study involved detailed geological and geomorphological mapping and is supported by a large set of geotechnical, geophysical and drill-hole data available from existing studies. These data were used to compile a seismic microzonation map of the San Giuliano di Puglia area as part of a study officially commissioned by the Department of Civil Protection. The map provides seismic hazard information that will be useful in the repair and reconstruction of the town.

scholarly journals Determination of the resonance frequency – thickness relation based on the ambient seismic noise records from Upper Silesia Coal Basin

2014 ◽  
Vol 3 (1) ◽  
pp. 41-51 ◽  
Author(s):  
Maciej Jan Mendecki ◽  
Barbara Bieta ◽  
Mateusz Mycka
Keyword(s):  
Resonance Frequency ◽  
Seismic Data ◽  
Seismic Noise ◽  
Spectral Ratio ◽  
Seismic Survey ◽  
Coal Basin ◽  
Upper Silesia ◽  
Resonance Frequencies ◽  
Hvsr Method

Abstract In this paper the Horizontal-to-Vertical Spectral Ratio (HVSR) method and seismic data were applied to evaluate the resonance frequency - thickness relation. The HVSR method was used to estimate the parameters of site effects: amplification and resonance frequency from seismic noise records. The seismic noise was generated by artificial source occurring in Upper Silesia Coal Basin (UBSC), Poland, such as: traffic, industry, coal plants etc. The survey points were located near the Faculty of Earth Sciences in Sosnowiec, Bytom and Chorzow. Based on Albarello’s statistical test the observed H/V maxima was confirmed or rejected. Resonance frequencies were compared with available thicknesses of soft layer obtained by seismic survey (Mendecki 2012). Finally, the estimated resonance frequency - thickness relation for UBSC area showed quite similar power function coefficients as those obtained by other authors

scholarly journals Simulation Analysis on Cymbal Transducer

2011 ◽  
Vol 2-3 ◽  
pp. 140-143
Author(s):  
Qing Feng Yang ◽  
Peng Wang ◽  
Yu Hong Wang ◽  
Kai Zhang
Keyword(s):  
Finite Element ◽  
Resonance Frequency ◽  
Piezoelectric Ceramic ◽  
Electromechanical Coupling ◽  
Free Field ◽  
Voltage Sensitivity ◽  
Element Analysis ◽  
Cavity Bottom ◽  
Finite Element Software ◽  
Cymbal Transducer

The resonance frequency of the cymbal transducer ranges from 2kHz to 40kHz and its effective electromechanical coupling factor is around 20%. Finite element analysis has been performed to ascertain how the transducer’s makeup affect the transducer’s performance parameters. Two-dimensional axisymmetric model of the cymbal transducer was founded by finite element software-ANSYS, the application of the element type was discussed and the FEM models were built up under the far field condition. Eight groups of cymbal transducers of resonance frequency around 3kHz with different structural dimensions were designed. It was better for choosing the cymbal transducer of the 8mm cavity coping diameter, 20.8mm cavity bottom diameter and 26.8mm piezoelectric ceramic wafer diameter than others for reducing distortion degree of the signal and improving communication turnover in the researched cymbal transducers. It was appropriate for choosing the cymbal transducer of the 8mm cavity coping diameter, 22.4mm cavity bottom diameter and 26.4mm piezoelectric ceramic wafer diameter in order to improve the free-field voltage sensitivity and transmission efficient.

scholarly journals Facilitating the propagation of spiking activity in feedforward networks by including feedback

2019 ◽  
Author(s):  
Hedyeh Rezaei ◽  
Ad Aertsen ◽  
Arvind Kumar ◽  
Alireza Valizadeh
Keyword(s):  
Resonance Frequency ◽  
External Input ◽  
Network Activity ◽  
Inhibitory Neurons ◽  
Modular System ◽  
Feedforward Networks ◽  
Successful Transmission ◽  
Successful Communication ◽  
Resonance Frequencies ◽  
Feedback Connections

AbstractTransient oscillations in the network activity upon sensory stimulation have been reported in different sensory areas. These evoked oscillations are the generic response of networks of excitatory and inhibitory neurons (EI-networks) to a transient external input. Recently, it has been shown that this resonance property of EI-networks can be exploited for communication in modular neuronal networks by enabling the transmission of sequences of synchronous spike volleys (‘pulse packets’), despite the sparse and weak connectivity between the modules. The condition for successful transmission is that the pulse packet (PP) intervals match the period of the modules’ resonance frequency. Hence, the mechanism was termed communication through resonance (CTR). This mechanism has three sever constraints, though. First, it needs periodic trains of PPs, whereas single PPs fail to propagate. Second, the inter-PP interval needs to match the network resonance. Third, transmission is very slow, because in each module, the network resonance needs to build-up over multiple oscillation cycles. Here, we show that, by adding appropriate feedback connections to the network, the CTR mechanism can be improved and the aforementioned constraints relaxed. Specifically, we show that adding feedback connections between two upstream modules, called the resonance pair, in an otherwise feedforward modular network can support successful propagation of a single PP throughout the entire network. The key condition for successful transmission is that the sum of the forward and backward delays in the resonance pair matches the resonance frequency of the network modules. The transmission is much faster, by more than a factor of two, than in the original CTR mechanism. Moreover, it distinctly lowers the threshold for successful communication by synchronous spiking in modular networks of weakly coupled networks. Thus, our results suggest a new functional role of bidirectional connectivity for the communication in cortical area networks.Author summaryThe cortex is organized as a modular system, with the modules (cortical areas) communicating via weak long-range connections. It has been suggested that the intrinsic resonance properties of population activities in these areas might contribute to enabling successful communication. A module’s intrinsic resonance appears in the damped oscillatory response to an incoming spike volley, enabling successful communication during the peaks of the oscillation. Such communication can be exploited in feedforward networks, provided the participating networks have similar resonance frequencies. This, however, is not necessarily true for cortical networks. Moreover, the communication is slow, as it takes several oscillation cycles to build up the response in the downstream network. Also, only periodic trains of spikes volleys (and not single volleys) with matching intervals can propagate. Here, we present a novel mechanism that alleviates these shortcomings and enables propagation of synchronous spiking across weakly connected networks with not necessarily identical resonance frequencies. In this framework, an individual spike volley can propagate by local amplification through reverberation in a loop between two successive networks, connected by feedforward and feedback connections: the resonance pair. This overcomes the need for activity build-up in downstream networks, causing the volley to propagate distinctly faster and more reliably.

scholarly journals Structural analysis of S-wave seismics around an urban sinkhole; evidence of enhanced subrosion in a strike-slip fault zone

2017 ◽  
Author(s):  
Sonja H. Wadas ◽  
David C. Tanner ◽  
Ulrich Polom ◽  
Charlotte M. Krawczyk
Keyword(s):  
Strike Slip ◽  
Strike Slip Fault ◽  
Key Factors ◽  
S Wave ◽  
Seismic Profiles ◽  
Reflection Seismic ◽  
Dextral Strike Slip Fault ◽  
Seismic Sections ◽  
The Town ◽  
Dextral Strike Slip

Abstract. In November 2010, a large sinkhole opened up in the urban area of Schmalkalden, Germany. To determine the key factors which benefited the development of this collapse structure and therefore the subrosion, we carried out several shear wave reflection seismic profiles around the sinkhole. In the seismic sections we see evidence of the Mesozoic tectonic movement, in the form of a NW–SE striking, dextral strike-slip fault, known as the Heßleser Fault, which faulted and fractured the subsurface below the town. The strike-slip faulting created a zone of small blocks (

scholarly journals Innovative Seismic Microzonation Maps of Urban Areas for the Management of Building Heritage: A Catania Case Study

Geosciences ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 480
Author(s):  
Glenda Abate ◽  
Simone Bramante ◽  
Maria Rossella Massimino
Keyword(s):  
Urban Areas ◽  
Large Scale ◽  
Free Field ◽  
Ground Surface ◽  
Seismic Microzonation ◽  
Field Conditions ◽  
Seismic Retrofitting ◽  
Geotechnical Characteristics ◽  
Fixed Base ◽  
Scale Estimate

Several urban areas in the Mediterranean have already been subjected to seismic microzonation studies aimed at determining the acceleration expected on the ground surface, therefore mitigating the associated seismic risks. These studies have been generally related to free-field conditions. The present paper shows innovative seismic microzonation maps based on a large-scale estimate of soil-structure interaction (SSI) effects on design accelerations for some areas characterized by a high seismic risk in Catania, Italy. The proposed procedure combined: (1) geotechnical characteristics; (2) building features; and (3) 1-D seismic response analyses in free-field conditions. The seismic hazard and site effects were evaluated using artificial inputs and inputs recorded recently in Catania. Structural fundamental periods and related spectral accelerations, considering both the fixed-base building configuration and flexible-base configuration, were mapped in the Google My Maps environment. These results showed that SSI often had a beneficial effect, but sometimes it had detrimental effects, especially for some masonry buildings. These maps provided important information for planning the seismic retrofitting of investigated buildings, which were based on more detailed analyses of SSI and the developed maps requiring them.

scholarly journals Exploiting Elastically Supported Masses in Cantilever for Resonance Frequencies Down-Shifted Vibration Energy Harvester

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2207 ◽  
Author(s):  
Hai Wang ◽  
Bin Li ◽  
Yan Liu ◽  
Min Zhang ◽  
Wei Zhao ◽  
...  
Keyword(s):  
Resonance Frequency ◽  
Energy Harvester ◽  
Rubber Band ◽  
Resonant Peak ◽  
Vibration Energy ◽  
Equivalent Stiffness ◽  
Vibration Energy Harvester ◽  
Resonance Frequencies ◽  
Elastically Supported ◽  
Piezoelectric Vibration

This paper presents a piezoelectric vibration energy harvester (PVEH) with resonance frequencies shifted down by elastically supported masses. The added elastic supporters can diminish the equivalent stiffness of the whole structure, leading to an evident decline in the resonance frequency of the cantilever body. Meantime, a new resonant peak is generated in the lower frequency range. The resonant frequency of the proposed PVEH can be easily adjusted by replacing the rubber band of the elastic support. The constructed configuration is theoretically investigated and experimentally verified. Compared with the conventional cantilever, the proposed device achieved a 46% decrease in resonance frequency and 87% enhancement in output power.

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