Empirical Attenuation Relationships Research Articles

Horizontal ground-motion model for subduction slab earthquakes using offshore ground motions in the Japan Trench area

The S-net, a large-scale network of permanent ocean-bottom seismographs in the Japan Trench, consisting of 150 stations, has recorded a large number of offshore ground motions that can be used to establish the empirical attenuation relationship of offshore ground motions in the subduction zone. Due to the different attenuation characteristics among different earthquake types in subduction zones, the earthquakes are classified into four tectonic types of subduction slab, interface, shallow crustal, and upper-mantle earthquakes according to the classification scheme of Zhao et al. (2015). Predictive models and uncertainties in offshore ground motions were investigated for different earthquake types. This study establishes a horizontal offshore subduction slab earthquake ground-motion model (GMM) and compares the offshore and onshore slab earthquake GMMs. As the site conditions at ocean-bottom stations are different from those at land stations, the effects of water depth and sediment thickness are taken into account in the offshore slab earthquake GMM. Due to differences in the burial methods of ocean-bottom stations, stations were divided into buried and unburied to investigate the effects of the burial methods. Therefore, regression analysis was used to propose an offshore slab earthquake GMM considering the magnitude, focal depth, distance, water depth, sediment thickness, and burial method. By separating the within-event residuals, the single-station standard deviation is presented. Compared to the onshore GMM, the predicted spectra of the offshore GMM are significantly larger at long periods. For the attenuation rate, the offshore attenuation rate is lower than that of the onshore attenuation rate for short periods, but is basically consistent with the onshore attenuation rate for long periods. The proposed GMM can be used to predict the offshore ground motions for slab earthquakes with rupture distances less than 300 km, focal depths less than 110 km, and moment magnitude between 4 and 7.4.

Physically Based and Empirical Ground Motion Prediction Equations for Multiple Intensity Measures (PGA, PGV, Ia, FIV3, CII, and Maximum Fourier Acceleration Spectra) on Sakhalin Island

In the present study, empirical attenuation relations for multiple ground motion intensity measures (PGA, PGV, Ia, FIV3, CII, and MFAS) were developed for Sakhalin Island (in the far east of Russia). A recorded strong motion dataset was used, making GMPEs applicable in active crustal regions with an earthquake magnitude range of 4–6 and a distance range of up to 150 km. The hypocentral distance was used as a basic distance metric. For the first time in the research, an analytical representation of Arias intensity (Ia) was obtained in the framework of a multi-asperity source model. Asperities are considered as sub-sources of high-frequency incoherent radiation. The physical representation of the attenuation model in our study was based on a stress drop on the asperities and the ratio of the total rupture area to the combined area of asperities. The average stress drop on asperities for the examined earthquakes was approximately 13.4 MPa, and the ratio of the total rupture area to the asperity area was 0.22, which is generally close to similar estimates for crustal earthquakes. The coefficients and statistical scattering of the attenuation models were also analyzed. Moreover, a magnitude scale based on a modified Arias intensity is proposed in the present study. The new magnitude scale has an explicit physical meaning and is characterized by its simplicity of measurement. It is associated with the acceleration source spectrum level and can be successfully used in early warning systems.

Broadband Strong-Motion Prediction for Future Nankai-Trough Earthquakes Using Statistical Green’s Function Method and Subsequent Building Damage Evaluation

We used the Green’s function summation method together with the randomly perturbed asperity sources to sum up broadband statistical Green’s functions of a moderate-size source and predict strong ground motions due to the expected M8.1 to 8.7 Nankai-Trough earthquakes along the southern coast of western Japan. We successfully simulated seismic intensity distributions similar to the past earthquakes and strong ground motions similar to the empirical attenuation relations of peak ground acceleration and velocity. Using these results, we predicted building damage by non-linear response analyses and find that at the regions close to the source, as well as regions with relatively thick, soft sediments such as the shoreline and alluvium valleys along the rivers, there is a possibility of severe damage regardless of the types of buildings. Moreover, the predicted damage ratios for buildings built before 1981 are much higher than those built after because of the significant code modifications in 1981. We also find that the damage ratio is highest for steel buildings, followed by wooden houses, and then reinforced concrete buildings.

Empirical Attenuation Model for Predicting Peak Ground Acceleration in North Arm Sulawesi, Indonesia

The North Arm of Sulawesi is one of the areas that has very active tectonic conditions. The earthquake source in this area comes from the activity of several tectonic plates such as the North Sulawesi Subduction, the Molluca Sea Collision, the Philippine Sea Plate, the Pacific Plate and several local faults such as the Palu Koro Fault, Gorontalo Fault, Bolmong Fault and Manado Fault. The purpose of this study was to determine the peak ground acceleration value using several empirical attenuation models such as the Fukushima-Tanaka, Donovan, McGuire, Campbell, and Crouse. The peak ground acceleration is the value of the greatest acceleration a place has ever occurred which describes the strength of the tremor or shock of an earthquake. Geographically, this research area is located at 1180E to 1270E and 0.50S to 40N. The data used are data from the ISC-EHB and USGS catalog during the observation interval 1964-2020. Data processing includes the uniformity of the magnitude scale into the Surface Magnitude (Ms) scale, determining the main shock, sorting earthquake data with a magnitude greater than M6.0 and a depth of less than 100 km, creating a grid measuring 0.05 x 0.05 degree. Next step, determine the peak ground acceleration using an empirical attenuation relationships. The analysis results show that the peak ground acceleration in the North Arm Sulawesi is as follows: McGuire Method 0.4295g, Fukushima-Tanaka 0.3595g method, Crouse method 0.314g, Donovan method 0.3149g, and Campbell method 0.2550g.

A Bayesian Method for Real‐Time Earthquake Location Using Multiparameter Data

AbstractA primary task of a network‐based, earthquake early warning system is the prompt event detection and location, needed to assess the magnitude of the event and its potential damage through the predicted peak ground shaking amplitude using empirical attenuation relationships. Most of real‐time, automatic earthquake location methods ground on the progressive measurement of the first P‐wave arrival time at stations located at increasing distances from the source but recent approaches showed the feasibility to improve the accuracy and rapidity of the earthquake location by using the additional information carried by the P‐wave polarization or amplitude, especially with unfavorable seismic network lay‐outs.Here, we propose an evolutionary, Bayesian method for the real‐time earthquake location which combines the information derived from the differential P‐wave arrival times, amplitude ratios and back‐azimuths measured at a minimum of two stations. As more distant stations record the P‐wave, the posterior pdf is updated and new earthquake location parameters are determined along with their uncertainty. To validate the location method, we performed a retrospective analysis of mainshocks (M > 4.5) occurred during the 2016–2017 Central Italy earthquake sequence by simulating the typical acquisition layouts of in‐land, coastal and linear array of stations.Results show that with the combined use of the three parameters, 2–4 s after the first P‐wave detection, the method converges to stable and accurate determinations of epicentral coordinates and depth even with a nonoptimal coverage of stations. The proposed methodology can be generalized and adapted to the off‐line analysis of seismic records collected by standard local networks.

Quantifying and addressing uncertainties in empirical vibration attenuation relationship for underground blast by re-sampling

For efficient and timely execution of deep excavations, tunnelling or mining activities in rock, controlled blasting often becomes essential. For design of the controlled blasting operation, scaled distance regression analysis of trial blast data, namely, distance, charge weight, and peak particle velocity (PPV), is the regular industrial practice. Due to limited number of input data from trial blasts, and further due to variability of underlying media, multiple uncertainties creep into expressions thus developed. To account for these uncertainties in design of safe controlled blasting, therefore, 95 percent confidence expression obtained from trail blast data is generally preferred in industry. However, this approach lacks statistical quantification or treatment of the parameter uncertainty and there is no methodology suggested in literature, codes or standards to address this aspect. The present article proposes to estimate the parameter uncertainties in the empirical vibration attenuation relationship for underground blast using re-sampling approach. With blast data from literature, multiple samples are randomly selected and empirical parameters are evaluated for each set by least square principle. It is found that both empirical parameters in power form of expression (popular in industry) follow Normal distribution. Using the 95 percentile value for each parameter, the safe charges are calculated and thereafter are compared to the traditional industrial practice of employment of 95 percent confidence expression from trail blast data. Re-sampling approach yielded conservative charge weight for lower limiting values (PPV ≤ 15 mm/s) and efficient charge weights for higher limiting values (PPV ≥ 50 mm/s) of PPV.

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.

Prediction of Near-Field Wave Attenuation Due to a Spherical Blast Source

Empirical and theoretical far-field attenuation relationships, which do not capture the near-field response, are most often used to predict the peak amplitude of blast wave. Jiang et al. (Vibration due to a buried explosive source. PhD Thesis, Curtin University, Western Australian School of Mines, 1993) present rigorous wave equations that simulates the near-field attenuation to a spherical blast source in damped and undamped media. However, the effect of loading frequency and velocity of the media have not yet been investigated. We perform a suite of axisymmetric, dynamic finite difference analyses to simulate the propagation of stress waves induced by spherical blast source and to quantify the near-field attenuation. A broad range of loading frequencies, wave velocities, and damping ratios are used in the simulations. The near-field effect is revealed to be proportional to the rise time of the impulse load and wave velocity. We propose an empirical additive function to the theoretical far-field attenuation curve to predict the near-field range and attenuation. The proposed curve is validated against measurements recorded in a test blast.

Empirical Attenuation relationship for Peak Ground Horizontal Acceleration for North-East Himalaya

Empirical Attenuation relationship for Peak Ground Horizontal Acceleration for North-East Himalaya

Seismic landslide hazard assessment in the Tianshui area, China, based on scenario earthquakes

This work represents a regional potential seismic landslide hazard assessment for the Tianshui area, southeastern Gansu Province, China. The peak ground accelerations for two specific seismic scenarios (Ms 7.0 and 8.0) are estimated through empirical attenuation relationships. They are then combined with the slope threshold accelerations to calculated cumulative displacements through the Newmark’s sliding rigid-block model. Potentially unstable areas are identified based on the predicted Newmark displacement. The results show that both of the scenarios are capable of producing widespread slope instabilities, mainly loess landslides in the near-fault region, and that the Ms 7.0 earthquake would induce more slope instabilities around Tianshui city. The high-risk zones are concentrated mainly in the loess or mudstone areas with slope greater than 30°, especially on the banks of the Wei River, Xi River, and Niutou River, and pose a threat to the Longhai Railway line and the surroundings of Tianshui city. The potential damage to traffic networks and to built-up areas in Tianshui city is also mapped. These maps represent a preliminary assessment that can be utilized by local government to define the seismic landslide hazard better for future detailed risk evaluation, emergency plans, and engineering design.

Physically based probabilistic seismic hazard analysis using broadband ground motion simulation: a case study for the Prince Islands Fault, Marmara Sea

The main motivation for this study was the impending occurrence of a catastrophic earthquake along the Prince Island Fault (PIF) in the Marmara Sea and the disaster risk around the Marmara region, especially in Istanbul. This study provides the results of a physically based probabilistic seismic hazard analysis (PSHA) methodology, using broadband strong ground motion simulations, for sites within the Marmara region, Turkey, that may be vulnerable to possible large earthquakes throughout the PIF segments in the Marmara Sea. The methodology is called physically based because it depends on the physical processes of earthquake rupture and wave propagation to simulate earthquake ground motion time histories. We included the effects of all considerable-magnitude earthquakes. To generate the high-frequency (0.5–20 Hz) part of the broadband earthquake simulation, real, small-magnitude earthquakes recorded by a local seismic array were used as empirical Green’s functions. For the frequencies below 0.5 Hz, the simulations were obtained by using synthetic Green’s functions, which are synthetic seismograms calculated by an explicit 2D/3D elastic finite difference wave propagation routine. By using a range of rupture scenarios for all considerable-magnitude earthquakes throughout the PIF segments, we produced a hazard calculation for frequencies of 0.1–20 Hz. The physically based PSHA used here followed the same procedure as conventional PSHA, except that conventional PSHA utilizes point sources or a series of point sources to represent earthquakes, and this approach utilizes the full rupture of earthquakes along faults. Furthermore, conventional PSHA predicts ground motion parameters by using empirical attenuation relationships, whereas this approach calculates synthetic seismograms for all magnitudes of earthquakes to obtain ground motion parameters. PSHA results were produced for 2, 10, and 50 % hazards for all sites studied in the Marmara region.

Broadband NDSHA computations and earthquake ground motion observations for the Italian territory

The aim of this work is two-fold: 1) to compare the results of national scale NDSHA modelling for the Italian region at 10 Hz cut-off, based on the relevant available knowledge, with observations (e.g., peak ground motion values) and existing empirical attenuation relations; 2) to update the scaling law for source spectra (SLSS) to be used for the selected area. The new set of source spectra, defined along the lines suggested by the comparison with empirical attenuation relations, produces acceptable results in terms of PGV and spectral acceleration at long periods. Synthetic PGA and SA at short periods show a faster attenuation with respect to the observed ones and, therefore, the effect of complex attenuation factors should be explored in future ad hoc studies.

Seismic hazard assessment for Iceland in terms of macroseismic intensity using a site approach

We present the results of probabilistic seismic hazard assessment for Iceland in the framework of the EU project UPStrat-MAFA using the so-called site approach implemented in the SASHA computational code. This approach estimates seismic hazard in terms of macroseismic intensity by basically relying on local information about documented effects of past seismic events in the framework of a formally coherent and complete treatment of intensity data. In the case of Iceland, due to the lack of observed intensities for past earthquakes, local seismic histories were built using indirect macroseismic estimates deduced from epicentral information through an empirical attenuation relationship in probabilistic form. Seismic hazard was computed for four exceedance probabilities for an exposure time of 50 years, equivalent to average return periods of 50, 200, 475 and 975 years. For some localities, further return periods were examined and deaggregation analysis was performed. Results appear significantly different from previous seismic hazard maps, though just a semi-qualitative comparison is possible because of the different shaking measure considered (peak ground acceleration versus intensity), and the different computational methodology and input data used in these studies.

Numerical modelling of drop load tests

Assessment of the attenuation of induced vibrations in the ground plays an important role in evaluating comfort and structural safety. Analytical and empirical wave attenuation relationships of increasing complexity and detail are presented in the paper, as well as a numerical model that accurately reproduces wave attenuation for a well-documented site, namely the one of the Tower of Pisa, Italy. A new source model is calibrated on near-field data and used as input for the dynamic coupled consolidation finite element analysis to achieve a satisfactory simulation. The accuracy of simpler analytical and empirical approaches is then comprehensively assessed through comparison with the validated numerical model and the field data obtained from geophones at various distances from the impact source.

Empirical Arias Intensity Attenuation Relationships For The Seismic Hazard Analysis Of Greece

New empirical attenuation relationships of Arias Intensity for various site conditions based on the strong-motion data recorded in Greece are presented. With regard to attenuation relationships, for the region of Greece, there are no Arias Intensity empirical attenuation models available today that may be used in seismic hazard analysis. For each site class, the attenuation relationship of Arias Intensity is expressed as a function of moment magnitude (M) and epicentral distance (R) and it is derived using a mixed effects regression analysis method. As a final result probabilistic seismic hazard maps in terms of Arias Intensity have been developed for the territory of Greece.

Synthetic seismic intensity for historic earthquakes in the North China Plain: implications for the regional seismic hazard

Multiple approaches are used to study the potential seismic hazard in the North China Craton (NCC, or North China Plain), where approximately 15 % of the Chinese population resides and under which active faults are located. In this study, we develop a new modified Mercalli intensity (MMI) attenuation relationship for the NCC using intensity data from 10 instrumentally recorded events. We then utilize this relationship to infer the magnitude and epicentral location of historic events based on the method proposed by Bakun and Wentworth (Bull Seismol Soc Am 87(6):1502–1521, 1997). In addition, a modified stochastic finite fault model is employed to simulate the strong ground motions caused by these historic events. The simulated peak ground accelerations and velocities are then converted into regional MMI distributions through empirical relationships, and these synthetic MMI maps are compared to field observations. The resultant MMI attenuation versus distance models of the 1976 Mw 7.6 Tangshan event and the 1679 M 8.0 Sanhe-Pinggu event are consistent with the empirical attenuation relationships, and the location and size of the meizoseismal area (>VIII) are consistent with observations. The successful modeling of these historic events indicates that a stochastic finite fault model constrained by the regional MMI attenuation relationship can be used to evaluate a wide range of scenarios based on modern computational simulations. These findings may also provide useful information for the estimation and mitigation of potential seismic hazards in this region.

A study of the Newmark sliding block displacement functions

The Newmark sliding block displacement function, the curve showing the relation between the sliding response and the critical acceleration ratio, is important because its applications have been widespread in seismic designs of earth structures. The aims of this article are twofold: (a) to give a new point of view on the related abscissa parameter, and (b) to provide a new methodology for better understanding the displacement functions. Regarding the new methodology, the study of the properties of the displacement functions is divided into two parts: one is the property of the amplitude at a specific abscissa, and the other is the shape property. After derivations, validations and calibrations, the authors have obtained a simple expression for the characteristic slippage. Simple expressions have also been obtained for the shapes of the displacement functions using observations and derivations. The authors compare their results for the characteristic slippage predictions and for the shapes of displacement functions with related previous studies. Finally, empirical attenuation relationships of the characteristic slippage for different ground types are developed.

Ground-Motion Attenuation Relationship for East Central Iran

Predictive attenuation relationships have been developed for peak ground acceleration and spectral coordinates based on observed and simulated records for East Central Iran. First, the predictive relationships are derived based on observed records. The observed data set, which was considered, includes a total of 258 records from 109 earthquakes with a magnitude range of 5.0–7.4 on rock site. Then a suite of ground motions has been simulated for a range of magnitude and distances based on the stochastic finite fault ground‐motion model. The theoretical–empirical attenuation relationship, which has been developed for the horizontal component of peak ground acceleration and spectral acceleration, is applicable to earthquakes of M w 5.0–7.4 at a distance up to 100 km. Online Material Earthquake catalog.

Estimation of Coda Wave Attenuation Quality Factor from Digital Seismogram Using Statistical Approach

The main objective of the paper is to estimate seismic wave attenuation from the decay rate of coda wave amplitudes of digital seismogram of local earthquakes (epicentral distance < 100 km) following statistical approach. Three earthquake events have been selected for estimation of coda wave attenuation quality factor (Q<SUB>c</SUB>). The coda wave of 9 seismograms from 3 local earthquakes recorded digitally by three seismic stations in the region have been analyzed for this purpose at ten central frequencies (1, 1.5, 2, 3, 4, 6, 8, 12, 16 and 18Hz) and three lapse time windows of 20, 30 and 40 seconds duration. Single backscattering model proposed by Aki (1969) and extended by Aki and Chouet (1975) and Sato (1977) is employed to determine Q<SUB>c</SUB> values. The mean values of the estimated Q<SUB>c</SUB> vary from 31+12 (at 1Hz) to 1974+211 (at 18Hz) for 20 seconds coda window length. For 30 seconds coda window length Q<SUB>c</SUB> vary from 46+16 (at 1Hz) to 1977+ 256(at 18Hz). Similarly for 40 seconds coda window length Q<SUB>c</SUB> vary from 97+ 22 to 2552 +312. It is observed that Q<SUB>c</SUB> value for the study area is frequency dependent and increase with increase in frequency. Moreover the observed Q<SUB>c</SUB> values increase with increasing lapse time at all frequency bands. The estimated Q<SUB>c</SUB> values show a frequency dependent relationship of the form Q<SUB>c</SUB>=Q<SUB>o</SUB>f<SUP> n</SUP>, where Q<SUB>0</SUB> is Q<SUB>c</SUB> at 1Hz and n represents degree of frequency dependence. The frequency dependent empirical attenuation relationship for 20, 30 and 40 seconds window lengths are obtained as Q<SUB>c</SUB> = 21.49+1.17 <i>f</i> <SUP>1.48+0.08</SUP>, Q<SUB>c</SUB> = 48.6+1.11 <i>f</i> <SUP>1.29+0.06</SUP><SUP> </SUP>and Q<SUB>c</SUB> = 88.86+1.12 <i>f</i> <SUP>1.19+0.06</SUP> respectively.

Proposed modification on velocity attenuation relationships in West of with special respect to Dorood fault

As a routine procedure, the estimation of source parameters such as focal mechanism and magnitude is known for moderate to great earthquakes, however some of them such as directivity effect and filing step are rarely taking into account. According to the radiation pattern, directivity effect is a source parameter, which causes significant spatial variations in near field strong ground motion. Its significant variations could be obtained on strike normal component of velocity in forward and backward directions. This study has an attempt on estimation of a modification factor, which can define the effect of directivity in empirical attenuation relationships in Dorood fault. In order to model unilateral and bila- teral rupturing Finite Elements Method (FEM) is applied to achieve reliable functions.The authors used Somervill et al. (1997) directivity model parameter with some changes as variable parameter. To obtain modified ground motion parame- ters, these models were applied for earthquakes which Dorood fault caused them. These parameters consist of fault normal component to fault parallel component of velocity ratio ( Vn/Vp ) and fault normal component to average horizontal veloc- ity ratio (Vn/V ). It shows Vn/V is controlled by directivity angle, distance between the site, epicenter and rupture length. This ratio has the same trend in studied region earthquakes velocity data.