Attenuation Relationships Research Articles

Reconstruction of the acceleration field of ground vibrations taking into account the directivity of vibrations’ propagation

Many times, commonly used attenuation relations do not allow to obtain a sufficiently practicable accuracy of the results’ description of the observations. This may be an evidence of the attenuation directional nature of ground vibrations caused by tremors. In such cases, using the attenuation relationship that takes into account the directivity of the propagation of vibrations may allow to increase the accuracy of the reconstruction of ground vibrations accelerations. In the article there are presented the reconstruction’s results of recorded accelerations of ground vibrations caused by mine tremors, occurring in the area of one of the Polish mine. In all cases, the directivity of vibrations propagation was observed. The results of the calculations show that the direction of lower surface vibrations attenuation is parallel to the direction of the tectonic fault adjacent to the epicentre of the tremor inducing these vibrations.

Polarization of Near-fault Long-period Ground Motion

Through the analysis of typical near-fault ground motion, the inhomogeneity of the spatial distribution of long-period ground motion intensity on the fault parallel component (FP) and normal component (FN) is revealed. The study shows that the intensity of long-period ground motion on the fault parallel component is higher than that of on the fault normal component. This may be due to the fact that the velocity pulse is more easily formed on the fault parallel component higher than that of on the fault normal component, and the velocity pulse is more intense. The study is of great significance to the establishment of the attenuation relationship of near-fault ground motion and the seismic fortification of near fault structures.

Application of Existing Distance Attenuation Relationships Using PGAs Recorded during Earthquakes

Application of Existing Distance Attenuation Relationships Using PGAs Recorded during Earthquakes

Seismic loss estimation tool as rapid survey for prioritizing buildings for disaster preparedness: case study to hospital buildings

Hospital buildings must be fully operational after the earthquake to protect the lives of patients as well as to provide emergency care and medical treatment to the victims. Prioritization and justification of founding of such hospital buildings is an effective step under earthquake disaster preparedness. In this work, a seismic loss estimation tool (SRAI.SA) is used considering hazard on regional ground motion attenuation relation at micro-seismic level. The proposed tool is used to prioritize different hospital buildings of a metropolitan city of India during walk down survey. Rapid visual screening given by FEMA and structural vulnerability index by NORSAR questionnaires are also used for prioritization based on scoring during same walk down survey. It is found that prioritization graphs by all the three methods are almost at parity. Since rapid visual screening and structural vulnerability index methods are qualitative method and need experience and judgment of the expert, the loss estimation tool ensures effective tools for prioritizing buildings through which decision makers can be guided in prioritizing buildings and identifying buildings that require immediate attention for detailed investigation.

Peak ground acceleration attenuation relationship for Mazandaran province using GEP algorithm

The choice of attenuation relationships is one of the most important parts of seismic hazard analysis as using a different attenuation relationship will cause significant differences in the final result, particularly in near distances. This problem is responsible for huge sensibilities of attenuation relationships which are used in seismic hazard analysis. For achieving this goal, attenuation relationships require a good compatibility with the target region. Many researchers have put substantial efforts in their studies of strong ground motion predictions, and each of them had an influence on the progress of attenuation relationships. In this study, two attenuation relationships are presented using seismic data ofMazandaran province in the north of Iran by Genetic Expression Programming (GEP) algorithm. Two site classifications of soil and rock were considered regarding the shear wave velocity of top 30 meters of site. The quantity of primary data was 93 records; 63 of them were recorded on rock and 30 of them recorded on soil. Due to the shortage of records, a regression technique had been used for increasing them. Through using this technique, 693 data had been created; 178 data for soil and 515 data for rock conditions. The Results of this study show the observed PGA values in the region have high correlation coefficients with the predicted values and can be used in seismic hazard analysis studies in the region.

Attenuation relations for monsoonal rain at the X band from disdrometric measurements: Dependency on temperature, raindrop size distribution and drop shape models

Four years of disdrometric measurements made at Gadanki (13.5°N, 79.18°E), which receives rainfall during both southwest and northeast monsoons, have been used to (a) derive optimal attenuation relations for monsoonal rainfall at the X band, (b) study the impact of seasonal variation in raindrop size distribution (DSD) on attenuation relations and (c) analyze the dependency of these relations on the controlling parameters/models, such as temperature (T) and drop shape model. The results clearly show that the coefficients of these relations vary significantly with DSD (season and rain type), T and drop shape model, and are quite different for monsoonal rain than for those obtained elsewhere. The traditional relations that involve a specific attenuation (AH)‐reflectivity factor at horizontal polarization (ZH) and AH‐rain rate depend heavily on DSD and to some extent on T, while the relations involving a specific differential phase (KDP) and differential attenuation (ADP) show strong dependency on the drop shape model and DSD, but depend weakly on T. A detailed investigation has been carried out to decipher reasons for the observed intriguing seasonal variation in KDP‐based relations and their temperature dependency. The resonance scattering effects that are thought to be negligible at the X band in earlier studies appear to play a dominant role here and are primarily responsible for the observed features.

An improved input energy spectrum verified by the shake table tests

SummaryInput energy is the principal component of the energy balance equation. It is beneficial to determine, through its components, how the recoverable and irrecoverable energies are distributed within the structural elements. Several equations and attenuation relations to define mass‐normalized input energy spectra exist in the literature. They are mainly proposed for elastic systems subjected to far‐fault EQs. There is a lack of experimental verification of these proposed spectra. In this paper, experimental assessment was performed to the existing spectra, and further improvements were accomplished. For this purpose, steel cantilever columns were tested on the shake table for two specific historical EQs coincidently having similar spectral acceleration values. Based on the experimental results, a three‐part mass‐normalized relative input energy spectrum was formulated including soil type, EQ (corner period, intensity, duration, spectral acceleration, and velocity), and structural behavioral characteristics (period and structural damping). The proposed input energy spectrum was experimentally calibrated and numerically validated for various EQs featuring near‐ and far‐field types. Analytical and experimental comparisons were made between the previously developed spectrum and the newly proposed one. The validation studies and the statistical evaluations exposed that the proposed spectrum yielded better agreement with the experimental and numerical results.

PSHA of Van province for performance assessment using spectrally matched strong ground motion records

Within the framework of the performance based earthquake engineering, site specific earthquake spectra for Van province has been obtained. It is noteworthy that, in probabilistic seismic hazard assessment, as a first stage data from geological studies and records from the instrumental period were compiled to make a seismic source characterization for the study region. The probabilistic seismic hazard curves were developed based on selected appropriate attenuation relationships, at rock sites, with a probability of exceedance 2, 10 and 50% in 50 yrs period. The obtained results are compared with the spectral responses proposed for seismic evaluation and retrofit of building structure in Turkish Earthquake Code (2007), section 7. The acceleration response spectrums obtained from probabilistic seismic hazard analysis are matched to adjust earthquake accelerograms recorded during the 2011 Van earthquakes by using SeismoMatch v2.0 software. The aim of this procedure is to obtain a set of reasonable earthquake input motions for the seismic evaluation of existing buildings.

Shock attenuation by densely packed micro-particle wall

A wall densely packed with micro-particles is impacted by a planar shock wave in a horizontal multiphase shock tube to investigate the shock attenuation. The incident shock strength $${P_2}$$ is attenuated to the transmitted shock strength $${P_6}$$ . A dimensionless complex $$\theta$$ composed of the pressure drop coefficient $${f_{\text{m}}}$$ , the void fraction $$\varepsilon$$ , the packed particles length $$L$$ , and the particle diameter $$D$$ was derived from the previous experiments of the milli-particle walls to characterize the shock attenuation property of the particle wall. However, the data points of the micro-particle wall are located outside the region surrounded by the relationship of the shock attenuation $${{{P_6}} \mathord{\left/ {\vphantom {{{P_6}} {{P_2}}}} \right. \kern-0pt} {{P_2}}}$$ and the particle wall characteristic $$\theta$$ . Moreover, the data points of the micro-particle wall present a positive correlation between $${{{P_6}} \mathord{\left/ {\vphantom {{{P_6}} {{P_2}}}} \right. \kern-0pt} {{P_2}}}$$ and $$\theta$$ , which is contradictory to the negative correlation presented by the previous experiments. Comparison and analysis of the experimental results reveal that the key factor of the shock attenuation is not the size of the individual particle but of the skeleton densely packed with all particles. And then the individual particle diameter $$D$$ is replaced by the skeleton cross section size $$W$$ , the particle wall characteristic $$\theta$$ is modified. The experimental data points of Bakken et al., Wagner et al., Theofanous et al., and us are all located inside the region based on the modified particle wall characteristic $${\theta ^*}$$ and all obey the negative correlation between $${{{P_6}} \mathord{\left/ {\vphantom {{{P_6}} {{P_2}}}} \right. \kern-0pt} {{P_2}}}$$ and $${\theta ^*}$$ . The modified particle wall characteristic can describe the shock attenuation capability of both milli-particle and micro-particle walls. Numerous particles are densely packed to form a particle skeleton of void fraction $$\varepsilon$$ . The incident shock strength $${P_2}$$ is attenuated to the transmitted shock strength $${P_6}$$ . The circuitous pores among the skeleton provide the passages for the air shock wave. $$\varepsilon W$$ describes the total size of the void on the skeleton cross section, and $${\phi _{\text{p}}}L$$ describes the length of the circuitous pores among the skeleton. The modified particle skeleton characteristic $${\theta ^*}={{\left( {{f_{\text{m}}}{\phi _{\text{p}}}L} \right)} \mathord{\left/ {\vphantom {{\left( {{f_{\text{m}}}{\phi _{\text{p}}}L} \right)} {\varepsilon W}}} \right. \kern-0pt} {\varepsilon W}}$$ describes the shock wave attenuation capability of the particle skeleton and shows the negative correlation with the shock attenuation $${{{P_6}} \mathord{\left/ {\vphantom {{{P_6}} {{P_2}}}} \right. \kern-0pt} {{P_2}}}$$ .

A measurement campaign to assess sources of error in microwave link rainfall estimation

Abstract. We present a measurement campaign to address several error sources associated with rainfall estimates from microwave links in cellular communication networks. The core of the experiment is provided by three co-located microwave links installed between two major buildings on opposite sides of the small town of Wageningen, approximately 2 km apart: a 38 GHz formerly commercial microwave link, as well as 26 and 38 GHz (dual-polarization) research microwave links. Transmitting and receiving antennas have been attached to masts installed on the roofs of the two buildings, about 30 m above the ground. This setup was complemented with an infrared large-aperture scintillometer, installed over the same path, as well as five laser disdrometers positioned at several locations along the path and an automated rain gauge. Temporal sampling of the received signals was performed at a rate of 20 Hz. The setup was monitored by time-lapse cameras to assess the state of the antennas as well as the atmosphere. The experiment was active between August 2014 and December 2015. Data from an existing automated weather station situated just outside Wageningen was further used to compare and to interpret the findings. In addition to presenting the experiment, we also conduct a preliminary global analysis and show several cases highlighting the different phenomena affecting received signal levels: rainfall, solid precipitation, temperature, fog, antenna wetting due to rain or dew, and clutter. We also briefly explore cases where several phenomena play a role. A rainfall intensity (R) – specific attenuation (k) relationship was derived from the disdrometer data. We find that a basic rainfall retrieval algorithm without corrections already provides a reasonable correlation to rainfall as measured by the disdrometers. However, there are strong systematic overestimations (factors of 1.2–2.1) which cannot be attributed to the R–k relationship. We observe attenuations in the order of 3 dB due to antenna wetting under fog or dew conditions. We also observe fluctuations of a similar magnitude related to changes in temperature. The response of different makes of microwave antennas to many of these phenomena is significantly different even under the exact same operating conditions and configurations.

Seismicity of Batubesi Dam at Sorowako Region Based on Earthquake Data and Microtremor Measurement

Batubesi Dam which is located in Sorowako region in the middle part of Sulawesi island had been designed with seismic coefficient about 0.20g. The region constitutes an active earthquake zone with the recurrence frequency and magnitude of the earthquake are relatively high. The region is located on and active fault zone due to lateral fault movement (strike-slip) of Matano fault, Palukoro fault, and Walanea fault that categorized as shallow crustal earthquakes. To recognize characteristic of the earthquake at the site of interest, the historical earthquakes (background) data surrounding the study area and local microtremor measurements data are analyzed by means of a probabilistic seismic hazard analysis (PSHA) and deterministic seismic hazard analysis (DSHA) using some ground-motion models in attenuation relationship equations in resulting of seismic hazard parameter as represented by peak ground acceleration (PGA) values in earthquake scenario at operating basis earthquake (OBE), maximum design earthquake (MDE), and maximum credible earthquake (MCE) conditions. The PGA value in OBE condition is about 0.35g, in MDE about 0.45g, and in MCE about 0.49g. These values are used as reference to evaluate compliance of the current technical aspects with the new required design facing the updated seismicity parameters.

New Approach for Identification of Suitable Vibration Attenuation Relationship for Underground Blasts

New Approach for Identification of Suitable Vibration Attenuation Relationship for Underground Blasts

Global Attenuation Relationship for Estimating Peak Ground Acceleration

Abstract Peak Ground Acceleration (PGA) is a very important ground motion parameter which is used to define the degree of ground shaking during an earthquake. It is also very helpful for designing earthquake resistant structure. The PGA can be estimated by attenuation relationships using magnitude, distance, source type etc of a ground motion. In the past, several researchers have developed over 450 attenuation relationships for predicting PGA for a specific region. In the present study an attempt has been made to develop an attenuation relationship on the basis of these available previous relationships in rock site which will be applicable for any region of the world. In the present study, PGA has been expressed as a function of moment magnitude and hypo-central distance in rock site. Chi-square test have also been performed with available earthquake data in American and Indian region for verifying the accuracy of the generated attenuation relationship. Using multiple regression and Genetic Algorithm (GA) the attenuation relationship equations have also been generated. These equations will be very helpful for performing seismic hazard analysis and predicting earthquake force in any region of the world.

Seismic history of Pel la and the 1st century B.C. earthquake

Research and evaluation of past and recent seismic records is required in order to obtain an overall picture of the seismic history of a given region. To this aim, important information can be collected through the study of monuments and the damage that they may have experienced during their history. Consequently, the archaeological reports on a hitherto unknown earthquake of the Is' century B.C. in Pella (northern Greece) are particularly interesting. These reports are based on the findings that came to light after the excavations of I.Akamatis in the region where the ancient town of Pella was laying. Beginning with this earthquake, this study tries to reach useful conclusions on the seismicity of Pella, in terms of macroseismic intensities from all earthquakes that have affected the town. For all these events, the intensity attenuation relations were used to calculate the macroseismic intensity in Pella. Although it is known a priori that the area is characterized as a relatively low seismicity area, the picture of its seismic history indicates the existence of damaging earthquakes with relatively large return periods. More specifically, in Pella the maximum observed intensity was found to be 7/8 during its seismic history, indicating the picture of low-to-moderate seismic hazard in the region.

AN INVESTIGATION ON THE ATTENUATION CHARACTERISTICS OF DISTANT GROUND MOTIONS IN PENINSULAR MALAYSIA BY COMPARING VALUES OF RECORDED WITH ESTIMATED PGA AND PGV

The development of a design motion requires some input on ground motion characteristics. For a country such as Malaysia, where historical data is lacking and seismic activities are low, the information on characteristics of ground motion may be obtained by utilizing established attenuation relationships. This study aims to investigate the characteristics of distant ground motions in Peninsular Malaysia, which originated from the active tectonic plate of Sumatra, by comparing recorded peak ground acceleration (PGA) and peak ground velocity (PGV) values with those estimated using four attenuation models. Selected attenuation models are the Atkinson and Boore (1995), the Toro et al. (1997), the Dahle et al. (1990), and the Si and Midorikawa (1999) models. The analysis for comparison was made by employing a maximum of 46 horizontal component accelerograms, recorded at 14 seismic stations. These are data derived from 15 interplate earthquakes between May 2004 and July 2007. Recorded PGA and PGV values were plotted on respective attenuation curves to examine ground motion attenuation characteristics. Results indicated that attenuation models, established for stable tectonic regions, provide good estimation of PGA and PGV for Sumatran earthquakes for magnitude range of 5.9 to 9.0. The study shows that the Dahle et al. (1990) model best represents the characteristics of ground motions in terms of PGA, while the Atkinson and Boore (1995) model gives appropriately estimate ground motions in terms of PGV

Development of a Web-GIS based Decision Support System for earthquake warning service in Vietnam

This paper describes the development of a Decision support system (DSS) for earthquake warning service in Vietnam using Web GIS technology. The system consists of two main components: (1) an on-line database of earthquakes recorded from the national seismic network of Vietnam, and (2) a set of tools for rapid seismic hazard assessment. Using an online earthquake database, the system allows creating a shake map caused by a newly recorded earthquake. In addition, the Web GIS environment allows any user, including non-professional to get useful information about a just-occurred event and the possible impact caused by the earthquake shortly after its occurrence. A fault-source model developed for Vietnam was used as a part of the hazard calculation and mapping procedure. All information and results obtained from the system are automatically included in the earthquake bulletins, which will be disseminated national wide afterward by the Vietnam earthquake information and tsunami warning Center.The shake maps produced by the DSS in terms of both Peak Ground Acceleration and intensity values are rapidly available via the Web and can be used for emergency response, public information, loss estimation, earthquake planning, and post-earthquake engineering and scientific analyses. Application of the online decision support system in earthquake warning service can mitigate the earthquake risk and reduce the losses and damages due to earthquakes in Vietnam in future.ReferencesBoore D.M., Joyner W.B. and Fumal T.E., 1994. Estimation of Response Spectra and Peak Acceleration from Wester North American earthquakes: an interim report, USGS open file report, 94-127, Menlo Park, California, United States Geological Survey.Boore D.M. and Atkinson G.M., 2008. Ground-Motion Prediction Equations for the Average Horizontal Component of PGA, PGV, and 5%-Damped PSA at Spectral Periods between 0.01 s and 10.0 s. Earthquake Spectra, 24(1), 1-341.Bui Van Duan, Nguyen Anh Duong, 2017. The relation between fault movement potential and seismic activity of major faults in Northwestern Vietnam. Vietnam J. Earth Sci., 39, 240-255.Campbell K.W. and Bozorgnia Y., 1994. Near-Source Attenuation of Peak Horizontal Acceleration from Worldwide Accelerograms Recorded from 1957 to 1993, Proceedings, Fifth U.S. National Conference on Earthquake Engineering, Chicago, Illinois, July 10-14: V(III), 283-292.Campbell K.W. and Bozorgnia Y., 2008. NGA Ground Motion Model for the Geometric Mean Horizontal Component of PGA, PGV, PGD and 5% Damped Linear Elastic Response Spectra for Periods Ranging from 0.01 to 10s. Earthquake Spectra, 24(1), 1-341.Cauzzi C., Edwards B., Fäh D., Clinton J., Wiemer S., Kastli F., Cua G. and Giardini D., 2014. On the customisation of shakemap for optimised use in Switzerland, 2014. Proceedings of the 2nd European Conference on Earthquake Engineering and Seismology, Istanbul, August 25-29, 1-10.Center for International Earth Science Information Network - CIESIN - Columbia University, 2016. Documentation for the Gridded Population of the World, Version 4 (GPWv4). Palisades NY: NASA Socioeconomic Data and Applications Center (SEDAC). http://dx.doi.org/10.7927/H4D50JX4 Accessed April 2018.Chiou B.S.-J. and Youngs R.R., 2008. An NGA Model for the Average Horizontal Component of Peak Ground Motion and Response Spectra. Earthquake Spectra, 24(1), 1-341.Cornell, C.A., 1968. Engineering seismic risk analysis. Bull. Seis. Soc. Amer., 58(5), 1583-1606.Der Kiureghian and A. S-H. Ang, 1977. A fault rupture model for seismic risk analysis, Bull. Seim. Soc. Am., 67(4), 233-241.Douglas B.M. and Ryall A., 1977. Seismic risk in linear source regions, with application to the San Adreas fault, Bull. Seis. Soc. Amer., 67, 729-754.Marreiros, C. and Carrilho, F., 2012. The ShakeMap at the Instituto de Meteorologia. The proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal September 24-28.Nguyen Le Minh, et al., 2012. The first peak ground motion attenuation relationships for North of Vietnam. Journal of Asian Earth Sciences. Doi: 10.1016/j.jseaes.2011.09.012.Nguyen Dinh Xuyen and Tran Thi My Thanh, 1999. To find a formula for computing ground acceleration in strong earthquake in Vietnam, J. Sci. of the Earth, 21, 207-213 (in Vietnamese).Pacific Earthquake Engineering Research Center, 2008. NGA model for average horizontal component of peak ground motion and response spectra. Earthquake Spectra, 24(1), 1-341.Tran V.H. and Kiyomiya O., 2012. Ground motion attenuation relationship for shallow strike-slip earthquakes in northern Vietnam based on strong motion records from Japan, Vietnam and adjacent regions, Structural Eng./Earthquake Eng., JSCE, 29, 23-39.Toro G.R., Abrahamson N.A. and Schneider J.F., 1997. Engineering Model of Strong Ground Motions from Earthquakes in the Central and Eastern United States, Seismological Research Letters, January/February.Wald D.J., Worden B.C., Quitoriano V. and Pankow K.L., 2006. ShakeMap Manual. Technical manual, users guide, and software guide.Wald D.L., Wald B. Worden and Goltz J., 2003. ShakeMap - a tool for earthquake response. U.S. Geological Survey Fact Sheet 087-03.Wells D.L. and Coppersmith K.J., 1994. New Empirical Relationships Among Magnitude, Rupture Length, Rupture Width, and Surface Displacement, Bulletin of the Seismological Society of America, 84, 974-1002.

Comprehensive Seismicity, Seismic Sources and Seismic Hazard Assessment of Assam, North East India

ABSTRACTIn this study, an effort has been made to perform seismic hazard analysis (SHA) for the state of Assam, considering earthquake catalog collected since 1761–2015 using PSHA and DSHA methods at bed rock level. Earthquake catalog declustered and seismicity parameters (a & b) of faults estimated. The SHA performed using newly proposed modified attenuation relation and compared. Results are presented in the form of seismic hazard curve and peak ground acceleration (PGA) for each 33 district headquarters. The PGA at the bed rock level with 2%, 5%, and 10% probability of exceedance in 50 years and 100 years estimated.

ShakingAlarm: A Nontraditional Regional Earthquake Early Warning System Based on Time‐Dependent Anisotropic Peak Ground‐Motion Attenuation Relationships

Research Article| April 03, 2018 ShakingAlarm: A Nontraditional Regional Earthquake Early Warning System Based on Time‐Dependent Anisotropic Peak Ground‐Motion Attenuation Relationships Benjamin Ming Yang; Benjamin Ming Yang aDepartment of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, tingchunghuang@gmail.com, yihmin.wu@gmail.com, b98204032@gmail.com Search for other works by this author on: GSW Google Scholar Ting‐Chung Huang; Ting‐Chung Huang aDepartment of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, tingchunghuang@gmail.com, yihmin.wu@gmail.com, b98204032@gmail.combAlso at Institute of Earth Sciences, Academia Sinica 128, Section 2, Academia Road, Nangang, Taipei 11529, Taiwan. Search for other works by this author on: GSW Google Scholar Yih‐Min Wu Yih‐Min Wu aDepartment of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, tingchunghuang@gmail.com, yihmin.wu@gmail.com, b98204032@gmail.combAlso at Institute of Earth Sciences, Academia Sinica 128, Section 2, Academia Road, Nangang, Taipei 11529, Taiwan. Search for other works by this author on: GSW Google Scholar Author and Article Information Benjamin Ming Yang aDepartment of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, tingchunghuang@gmail.com, yihmin.wu@gmail.com, b98204032@gmail.com Ting‐Chung Huang aDepartment of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, tingchunghuang@gmail.com, yihmin.wu@gmail.com, b98204032@gmail.combAlso at Institute of Earth Sciences, Academia Sinica 128, Section 2, Academia Road, Nangang, Taipei 11529, Taiwan. Yih‐Min Wu aDepartment of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, tingchunghuang@gmail.com, yihmin.wu@gmail.com, b98204032@gmail.combAlso at Institute of Earth Sciences, Academia Sinica 128, Section 2, Academia Road, Nangang, Taipei 11529, Taiwan. Publisher: Seismological Society of America First Online: 03 Apr 2018 Online Issn: 1943-3573 Print Issn: 0037-1106 © Seismological Society of America Bulletin of the Seismological Society of America (2018) 108 (3A): 1219–1230. https://doi.org/10.1785/0120170105 Article history First Online: 03 Apr 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Benjamin Ming Yang, Ting‐Chung Huang, Yih‐Min Wu; ShakingAlarm: A Nontraditional Regional Earthquake Early Warning System Based on Time‐Dependent Anisotropic Peak Ground‐Motion Attenuation Relationships. Bulletin of the Seismological Society of America 2018;; 108 (3A): 1219–1230. doi: https://doi.org/10.1785/0120170105 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract The P‐alert seismic network, an on‐site low‐cost earthquake early warning system (EEWS) located in Taiwan, has proven useful in earthquake events since 2010. This dense network can produce detailed shakemaps and identify the direction of the source rupture in near‐real time. Based on real‐time acceleration signals and the proposed time‐dependent anisotropic attenuation relationship with peak ground acceleration (PGA), ShakingAlarm, a regional early warning system add‐on to the original P‐alert network, can immediately provide (1) an accurate predicted PGA, before the arrival of the observed PGA, that will give a consistent lead time for hazard assessment and emergency response, (2) a predicted shakemap (PSM) that will converge faster to the final reported shakemap than the regional EEWS, and (3) a shake contour area‐based magnitude estimation that is robust, even in the absence of a measured shake contour area such as in the case of an offshore earthquake. Taking the 2016 Mw 6.4 Meinong earthquake as an example, the 14th second PSM from ShakingAlarm converges on the final shakemap better than the regional EEWS from the Central Weather Bureau (CWB) in Taiwan. According to our tests, ShakingAlarm provides a warning using modified Mercalli intensity (MMI) V that is consistent with the results of another on‐site EEWS (Strategies and Tools for Real Time Earthquake Risk ReducTion [REAKT]). Further performance tests were conducted with another five ML>5.5 inland earthquakes from 2013 to 2014. Compared with traditional regional EEWSs, ShakingAlarm can effectively identify possible damage regions and provide valuable early warning information (PSM, predicted PGA, and magnitude) for risk mitigation. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Blind identification of site effects and bedrock motion from surface response signals

A method for blind identification of site effects from two nearby ground surface response signals is presented. The proposed approach makes use of ground surface accelerations from two nearby stations to back-calculate the transfer functions of both sites and their common bedrock motion. Seismic analysis of structures cannot be carried out accurately unless site effects are taken into account. Moreover, presently available empirical attenuation relationships for predicting ground surface motions are only useful if site effects are considered. While an extensive collection of analytical and numerical techniques is available to analyze ground responses induced by bedrock motions, their accuracy depends on a priori knowledge of site properties and the availability of bedrock motions. There are techniques based on direct/indirect measurements—such as spectral analysis of surface waves (SASW), and material testing of borehole samples—however, responses predicted by their output do not necessarily reflect site behavior during strong motions. As such, the estimation of site response from acceleration data recorded on the ground surface during real-life events is a key capability. In the method proposed herein, the site response is identified from recorded ground surface accelerations at two nearby stations through a blind identification technique, under the assumption that the unknown bedrock motion is identical for both stations and those two stations have different transfer functions. Most of the existing site response identification methods rely on a strategically chosen reference station, and the present approach obviates this limitation. We demonstrate the performance of this new approach using a synthetic, but adequately realistic, example.

Effect of clustered bubbly liquids on linear-wave propagation

The spatial distribution of bubble liquids strongly affect linear-wave propagation in bubbly liquids. The classical understanding suggests that using positional correlations of the bubbles, such as “hole correction” or Perkus-Yevick approximation, describes the spatial information of bubble clouds. However, bubbly liquids are observed experimentally with complex bubble ensembles that take the form of clusters, filaments, and clouds which cannot be intuitively described by these pair-correlation functions and need to be better clarified. To achieve this purpose, a three-dimensional random model, the Neyman-Scott point process, is proposed to describe bubbly liquids with clustering. Base on this method, we study the influence of such phenomenon on acoustic dispersion and attenuation relations. A formula for effective wavenumber in bubbly liquids is derived, based on self-consistent method. Comparing with the equation of Commander and Prosperetti [J. Acoust. Soc. Am. 85, 732 (1989)], our results show that the clustering can suppress peaks in the attenuation and the phase velocity as functions of the frequency. Further, we provide a numerical simulated method. A clustered bubbly liquid is simulated with strict mathematical method and the statistical informations are obtained through unbiased statistical approach. Through the results, we quantificationally analyze the influence of estimated value on predictions.