Function Of Peak Ground Acceleration Research Articles

Empirical relationships between Arias Intensity and peak ground acceleration for western China

There is little available attenuation relationship for Arias Intensity (AI) in China. Empirical relationships between AI and peak ground acceleration (PGA) provide another option for predicting AI. We establish empirical relationships for AI and PGA for western China, utilizing 3,169 horizontal and 979 vertical strong motion records with PGA ≥0.01 g from 274 earthquakes (MS 4.0–8.0), originating in eight provinces in southwest (Yunnan, Sichuan) and northwest China (Gansu, Shaanxi, Ningxia, Qinghai, Inner Mongolia, and Xinjiang). The influences of MS epicenter distance, and site conditions indicators VS30, generic site classes (i.e., rock and soil) are explored. The results show that the logarithm of AI increases linearly with the increase of the logarithm of PGA and MS, and decreases with the logarithm of VS30. However, the influence of site conditions on AI-PAG relationships can't be recognized by the simple generic rock and soil site classes. The epicenter distance has little effect on the AI-PAG relationships. Empirical relationships are developed to estimate horizontal or vertical AI as a function of PGA (basic model), PGA and MS (model 2) for southwest, northwest, and western China, using all the records. Empirical relationships for AI as a function of PGA, MS, and VS30 (model 1) are established using the 2,248 horizontal (70.9% of the total) and 670 vertical (68.4% of the total) records with VS30 between 148 and 841m/s. The notable disparity between model 1 of the southwest and northwest regions is chiefly attributed to local site conditions, indicating that the AI-PGA correlation is region-dependent. These findings enable one way of estimating AI for western China and will contribute to a better understanding of AI attenuation.

Predictive model for seismic displacements of flexible sliding block subjected to near-fault pulse-like ground motions

A post investigation of landslides induced by strong earthquake events in recent years shows that near-fault pulse-like ground motions have a considerable impact on slopes. Accurate evaluation of the stability of slopes under near-fault earthquakes has become a crucial issue in seismic-prone areas. Permanent displacement is widely recognized as an effective index for evaluating the stability of slope. Based on the coupled analysis, an empirical earthquake-induced permanent displacement prediction model was developed. A displacement database of 318 pulse-like ground motions from 50 earthquake events was established. The proposed predictive model is a function of the maximum seismic coefficient-time history (kmax), maximum velocity coefficient of velocity-time history of the k-time history (kv-max), yield acceleration (ky), and period ratio (ratio of the natural period of the slope to the mean period of input motion, Ts/Tm). The dynamic responses (kmax and kv-max) are represented by two different functions. At small period ratios (Ts/Tm≤1.8), it is a function of peak ground acceleration (PGA), peak ground velocity (PGV) and ky. At large period ratios (Ts/Tm > 1.8), it is a function of PGV, Ts and ky. It successfully captured the velocity pulse and long period characteristics of pulse-like ground motions. Compared to the existing model, it is found that the model is more accurate when considering pulse-like ground motions. This prediction model can be used not only for the preliminary evaluation of slope stability but also for probabilistic seismic demand analysis of flexible slopes considering pulse-like ground motion in near-fault regions.

A probabilistic seismic hazard model for Greenland

Greenland belongs to a stable continental region where seismic activity is low. Due to this factor and low population, only one probabilistic seismic hazard model of Greenland has been published, showing only a peak ground acceleration map. We constructed a probabilistic seismic hazard model for Greenland in order to complete our global earthquake risk map. We used a smoothed seismicity method due to the lack of recognized active faults. An earthquake magnitude-frequency distribution was derived based on the recorded earthquakes from 1933 to 2013. We assumed a maximum earthquake magnitude of 7.0 for the distribution, given that the magnitude of the largest recorded tectonic earthquake in the region is about 6.0. The NGA-East ground motion models were employed for ground shaking calculations. Finally, we presented seismic hazard maps in terms of peak ground acceleration, spectral acceleration at 0.2 ​s and 1.0 ​s, and hazard curves for several of the major cities.

Typological fragility curves for RC buildings: influence of damage index and building sample selection

The recent earthquakes occurred in the last years in Italy registered a great number of casualties and large economic losses. In this perspective, the effective seismic risk assessment has become crucial for the Government mitigation policies that have to allocate the limited economic sources for the risk reduction.In this paper, data collected after the 2012 Emilia and the 2009 L’Aquila, Italy, earthquakes were used to derive novel fragility curves for RC frame buildings classes. Compared to previous studies, different aspects affecting the fragility curves parameters were investigated. First of all, data are completed accounting for the presence of undamaged buildings that are generally uninspected after the seismic events, considering alternative criteria to complete the database. Then, the influence of the building damage index definition was considered by selecting four damage indices available in the literature that allow converting the damage data collected with the post-earthquake form into one of the five damage states, according to the European macroseismic scale. Separate sets of fragility curves, as a function of peak ground acceleration, were developed for the building stock of the two regions. The results reveal that the database correction with the uninspected buildings is relevant to avoid the overestimation of the exceedance probability, especially at lower peak ground acceleration values, resulting in less steep curves. Then, the building damage indices accounting for the damage of both structural and non-structural elements led to a higher exceedance probability with respect to damage indices based on damage of only structural elements, especially for the lower damage states.

Stability Evaluation of Diversion Tunnel Portal Slopes at Lau Simeme Dam Site, Indonesia, using Limit Equilibrium Method

Construction of the Lau Simeme Dam used a tunnel as a diversion channel. Slopes at the diversion tunnel portals were prone to failure due to the tunnel excavation and earthquake. Earthquake load was not considered in the designs of the inlet and outlet portal slopes. This research evaluated stability of the tunnel portal slopes under static and earthquake loads using limit equilibrium methods of the Bishop Simplified and Morgenstern-Price. Input material properties for the slope stability analyses were obtained from evaluations of soil and rock cores, including determination of lithology type and rock mass quality based on Geology Strength Index (GSI), and laboratory testing. Evaluations of soil and rock cores indicated that the inlet portal slope consisted of residual soil, good quality tuff breccia, and good quality sandstone. The outlet portal slope consisted of residual soil, poor quality sandstone, poor quality tuff breccia, fair quality sandstone, fair quality tuff breccia, and good quality tuff breccia. The earthquake load coefficient determined by the seismic analyses based on the peak ground acceleration map for 10% probability exceedance in 50 year was 0.125 g. The slope stability analyses showed that the designed inlet and outlet portal slopes were stable under static and earthquake loads. The Bishop Simplified and Morgenstern-Price resulted in relatively similar Fs values. The Fs values of the inlet and outlet portal slopes decreased with the earthquake load application. Although Fs values of the outlet slope under static and earthquake loads met the requirements specified by SNI 8460:2017, the rock mass conditions, particularly the poor rock masses of layers 2 and 3, required special attention. Application of slope reinforcement methods, such as shotcrete, is suggested to further increase the slope stability.

High-resolution peak ground acceleration modeling using geographic information systems: A case study of the potentially active Central Cebu Fault System, Philippines

The heavily populated Cebu Island is cut by the Central Cebu Fault System (CCFS). While the CCFS has not produced any MW > 5.0 earthquakes in the past century, recent strong earthquakes in the adjacent islands have brought attention to the seismic hazards in the region. Fault properties such as strike, dip, slip direction, and surface trace length were determined based on literature review, fieldwork, and analysis of geomorphic features. Empirical relations were utilized to estimate down-dip width and magnitude. The gathered data were used to create a three-dimensional model of the four major faults in the CCFS: Balamban Fault, Central Highland Fault, Uling-Masaba Fault, and Lutac-Jaclupan Fault. The 3D model was used to generate peak ground acceleration maps of central Cebu, should an earthquake occur along any of the major faults. Site corrections were made based on the seismic velocity of the upper 30 m of the subsurface. The major faults are estimated to be capable of generating MW 6.4 to 7.1 earthquakes. Worst-case scenarios in densely populated areas show 0.40 to 0.70 g of PGA, suggesting the potential for severe damage in central Cebu. We explored the advantages of using raster mathematics in a GIS platform for calculating and presenting ground motion. These advantages include rapid calculations for tens of millions of points, reducing the effects of interpolation artifacts in final map products. This study emphasizes the importance of detailed structural, geological, and geomorphological data in modeling seismic hazards. Further investigations on the seismogenesis of the CCFS segments are recommended.

Census-based typological usability fragility curves for Italian unreinforced masonry buildings

The main vulnerability models available in the literature aim to develop damage fragility curves to estimate the damage level suffered by a building after a seismic event. However, recent earthquakes have highlighted the great importance of predicting the usability of residential buildings, i.e. the condition of a building being habitable or occupiable after a seismic event. The building usability performance can be used as an indicator for allocating economic funding after a seismic event because recent researches have demonstrated a stronger correlation between repair costs and usability assessment rather than between repair costs and structural damage. Therefore, this work focused on the development of census-based fragility curves for the preventive forecast of the usability of Italian unreinforced-masonry buildings. The proposed usability model was calibrated based on the 2009 L'Aquila earthquake database, including almost 60,000 unreinforced-masonry buildings, and this database was increased by adding data from the Italian census to account for uninspected constructions. Six typological classes were defined considering two parameters available both in the post-earthquake and Italian census databases: construction timespan and state of repair. Additionally, it was highlighted in which cases the number of stories was also relevant. The usability fragility curves were defined as a function of peak ground acceleration for two building usability states: partially unusable and unusable. The results confirmed that older buildings are more vulnerable and clearly pointed out the crucial role of the state of repair as a parameter influencing the building usability.

Multi-hazard spatial modeling via ensembles of machine learning and meta-heuristic techniques

Considering the large number of natural disasters on the planet, many areas in the world are at risk of these hazards; therefore, providing an integrated map as a guide map for multiple natural hazards can be applied to save human lives and reduce financial losses. This study designed a multi-hazard map for three important hazards (earthquakes, floods, and landslides) to identify endangered areas in Kermanshah province located in western Iran using ensemble SWARA-ANFIS-PSO and SWARA-ANFIS-GWO models. In the first step, flood and landslide inventory maps were generated to identify at-risk areas. Then, the occurrence places for each hazard were divided into two groups for training susceptibility models (70%) and testing the models applied (30%). Factors affecting these hazards, including altitude, slope aspect, slope degree, plan curvature, distance to rivers, distance to roads, distance to the faults, rainfall, lithology, and land use, were used to generate susceptibility maps. The SWARA method was used to weigh the subclasses of the influencing factors in floods and landslides. In addition, a peak ground acceleration (PGA) map was generated to investigate earthquakes in the study area. In the next step, the ANFIS machine learning algorithm was used in combination with PSO and GWO meta-heuristic algorithms to train the data, and SWARA-ANFIS-PSO and SWARA-ANFIS-GWO susceptibility maps were separately generated for flood and landslide hazards. The predictive ability of the implemented models was validated using the receiver operating characteristics (ROC), root mean square error (RMSE), and mean square error (MSE) methods. The results showed that the SWARA-ANFIS-PSO ensemble model had the best performance in generating flood susceptibility maps with ROC = 0.936, RMS = 0.346, and MSE = 0.120. Furthermore, this model showed excellent results (ROC = 0.894, RMS = 0.410, and MSE = 0.168) for generating a landslide map. Finally, the best maps and PGA map were combined, and a multi-hazard map (MHM) was obtained for Kermanshah Province. This map can be used by managers and planners as a practical guide for sustainable development.

Census-Based Typological Damage Fragility Curves and Seismic Risk Scenarios for Unreinforced Masonry Buildings

Seismic risk assessment has become a crucial issue for optimal management of economic resources allocated to mitigation. For this purpose, in the last decades, several research activities were aimed to update hazard, exposure, and vulnerability models that contribute to seismic risk assessment. From this perspective, the present work focuses on developing new empirical damage fragility curves for census-based typological unreinforced masonry buildings. In particular, damage data observed after the 2009 L’Aquila earthquake, Italy, related to almost 57,000 residential buildings, were used to calibrate the fragility functions. These data were complemented with the census data with the aim of obtaining an accurate estimation of the number of undamaged buildings. Damage fragility curves were identified for typological building classes, defined considering parameters present in both post-earthquake observations and census data with the aim of extending the results to the whole national territory. Six typological classes were defined considering the categories of the construction timespan and of the state of repair parameters. Then, a further distinction of the typological classes considering the number of stories parameter was included where relevant. The fragility curves were defined as a function of peak ground acceleration for five damage states, defined according to the European macroseismic scale. The results confirmed that older buildings are more vulnerable than newer ones and highlighted the crucial role of the state of repair on the damage fragility curves. Finally, the new set of damage fragility functions was uploaded in the Italian Risk Maps information technology platform, used by the Civil Protection Department for risk evaluation, as an exemplification of the potential application of the fragility curves.

Capturing the footprints of ground motion in the spatial distribution of rainfall-induced landslides

The coupled effect of earthquakes and rainfall is rarely investigated in landslide susceptibility assessments although it could be crucial to predict landslide occurrences. This is even more critical in the context of early warning systems and especially in cases of extreme precipitation regimes in post-seismic conditions, where the rock masses are already damaged due to the ground shaking. Here, we investigate this concept by accounting for the legacy of seismic ground shaking in rainfall-induced landslide (RFIL) scenarios. We do this to identify whether ground shaking plays a role in the susceptibility to post-seismic rainfall-induced landslides and to identify whether this legacy effect persists through time. With this motivation, we use binary logistic regression and examine time series of landslides associated with four earthquakes occurred in Indonesia: 2012 Sulawesi (Mw = 6.3), 2016 Reuleut (Mw = 6.5), 2017 Kasiguncu (Mw = 6.6) and 2018 Palu (Mw = 7.5) earthquakes. The dataset includes one co-seismic and three post-seismic landslide inventories for each earthquake. We use the peak ground acceleration map of the last strongest earthquake in each case as a predisposing factor of landslides representing the effect of ground shaking. We observe that, at least for the study areas under consideration and in a probabilistic context, the earthquake legacy contributes to increase the post-seismic RFIL susceptibility. This positive contribution decays through time. Specifically, we observe that ground motion is a significant predisposing factor controlling the spatial distribution of RFIL in the post-seismic period 110 days after an earthquake. We also show that this effect dissipates within 3 years at most.

Probabilistic seismic hazard map analysis for Aceh Tenggara district and microzonation for Kutacane city

The Aceh Tenggara (Southeast Aceh) District, especially Kutacane, is located along with the main GSF (Great Sumatra Fault) system and the Tripa segment in particular based on seismic hazard map of Indonesia 2017. Therefore, the seismic hazard map needs to be updated based on the recent seismotectonic information and the latest active fault investigations. This paper discusses the updated seismic hazard map for the Aceh Tenggara district. In seismic hazard calculation, input source definition including fault characteristics, subduction zone, and seismicity background. Ground Motion Prediction Equation (GMPE) is used by the Indonesian official seismic hazard map 2017 to compute the hazard curve of strong ground shaking. Probability exceeding 2% and 10% for 50 years is chosen to calculate PGA (Peak Ground Acceleration) map on bedrock. On the other hand, Kutacane is located on a younger alluvium basin in the Holocene epoch thus site sediment amplification effect is taken into account in the microzonation calculations (local scale). The geomorphological slope is used to estimate the Vs30 distribution map. The site amplification is calculated based on PGA value on bedrock and Vs30 value on each site location. The Probabilistic Seismic Hazard Analysis (PSHA) is applied to produce seismic hazard maps as also used since many scientists and engineers in Indonesia although for critical infrastructure Neo-Deterministic Seismic Hazard Analysis (NDSHA) is suggested to be applied. The newly updated seismic hazard map can be used for the reference of infrastructure development in order to reduce the risk of disaster.

Seismic source modeling and probabilistic seismic hazard analysis for Bangladesh

The probabilistic seismic hazard analysis (PSHA) has been performed for Bangladesh using background seismicity, crustal fault, and subduction zone source models. The latest ground motion prediction equations (GMPEs) that are developed using global data sets have been used to estimate ground motion. The uncertainties in seismic sources and GMPEs to estimate ground motion are accounted using the logic tree approach. The activity rates of the background and regional seismicity sources are estimated using a declustered and complete catalog of the study regions. The activity rates of the crustal fault and subduction zone sources are estimated from the geodetic strain rates using the well-accepted relationships. The peak ground acceleration (PGA) and spectral acceleration (SA) at spectral periods of 0.2, 0.5, 1.0, 2.0, 5.0, and 10.0 s have been estimated at a grid size of 0.250 at the bedrock ground condition. The PGA and SA maps of various spectral periods have been prepared for Bangladesh for both 10% and 2% probability of exceedance in 50 years. These seismic hazard maps can be used for seismic risk management of Bangladesh.

Middle value ground acceleration map and site effect in the Merapi sedimentary basin under the 2006 Yogyakarta, Indonesia earthquake

The purpose of this paper is to develop a ground acceleration map in Yogyakarta Special Province under the 2006 Yogyakarta earthquake and look for evidence of site effects that affect to the ground response and building damage. The earthquake was more than one and half decade away, but its ground acceleration map and soil-site effects are still unclear. An estimation of the peak ground acceleration map under the Yogyakarta earthquake was conducted but limited for upper bound value and not including the influence of the site effects (Widodo in Bull N Z Soc Earthq Eng 51(2):92–104, 2018). Middle value PGA map at YSP including the site effects has been successfully developed. The development of PGA map is based on the maximum ground acceleration at two control points, i.e., at YOGI and BJI stations (see Box 2 in Fig. 1) and the result of earthquake intensity Imm field surveying (Wijaya in Isoseismal, Kerentanan dan Rasio Kerusakan Bangunan Rumah Tinggal; Studi Kasus Gempa Bumi Yogyakarta 27 Mei 2006, 2009). Two ground motion prediction equations have been used to interpolate ground acceleration between two control points and produce an equation of the relationship between ground acceleration with earthquake intensity. The relationship between earthquake intensity Imm with distance L (Wijaya 2009) is then combined with the previous equation and lead to final equation. The ground acceleration in all point data in the field is computed by using the final equation. The contours of the PGA as obtained apparently do not form a circle but tend to follow the path of Opak river fault. Moreover, the maximum ground acceleration does not occur in the epicenter area but shifts about 14 km west of the epicenter. The maximum ground acceleration in Imogiri sub-district reaches 0.45 g, while in the epicenter is only around 0.17 g. Site effects phenomena have occurred in the field both based on the result of analysis and the result of horizontal–vertical spectral ratio (HVSR) tests in the field. HVSR results from field tests by using microtremor showed that in the epicenter was obtained that the site period T = 0.078 s (rocky site), sediment thickness H = 6.6 m and percentages of housing collapsed was only 14.5%. Meanwhile, in the Imogiri sub-district (about 14 km west of the epicenter) the value of site period T = 1.52 s (soft soil), sediment thickness H = 86.6 m and the percentage of collapsed building reached 77.6%. This means that irregularities have occurred in earthquake intensity, ground acceleration and building damage, which are the characteristic of the site effect occurrence (Montalva et al. in Earthq Spectra 32(3):1469–1488, 2016).

Analysis of peak ground acceleration (PGA) using the probabilistic seismic hazard analysis (PSHA) method for Bengkulu earthquake of 1900 – 2017 period

This study was aimed to find out and analyze Peak Ground Acceleration (PGA) in order to mitigate the earthquake. The PGA map resulted was an acceleration map on bedrock with a probability exceeding 10% and 2% with the Probabilistic Seismic Hazard Analysis (PSHA) method for PGA in 50 years. The software used to analyze the Probabilistic Seismic Hazard Analysis (PSHA) method is USGS-PSHA. The data used was in the form of historical earthquake data from 1900 to 2017 and a depth of 1 km to 300 km. Earthquake magnitude ≥ 4.5 Mw with a research limit of 2.53° - 7.58° SL and 96.1° - 106.1° EL from the International Seismological Center (ISC) earthquake catalog, ISC-EHB Bulletin, United States Geological Survey (USGS) and The Geophysical Climatology Meteorology Institution (BMKG), a radius of 500 km from the border of Bengkulu Province. The results show that the most earthquakes for shallow depths with a magnitude of 4.5 Mw - 5.9 Mw as much as 2805 times, while for medium depths at magnitude 4.5 Mw - 5.9 Mw as much as 642 times. The probabilistic calculations exceeding 10% are 0.24 gal - 0.86 gal and probabilistic calculation exceeding 2% is 0.36 gal - 1.35 gal. The areas exposed to the danger zone are Lebong, Rejang Lebong, Kepahiang, Mukomuko, North Bengkulu and Bengkulu City. Whereas the regions included in the medium zone are Seluma and Bengkulu Tengah. And the areas of the safe zone are Kaur and South Bengkulu.

Curved surface sliders with friction damping, linear viscous damping, bow tie friction damping, and semiactively controlled properties

This paper investigates the isolation performance of curved surface sliders (CSSs) with different damping mechanisms. The following passive damping mechanisms are considered: passive friction damping as commonly present in CSSs, linear viscous damping as linear damping mechanism, and bow tie friction as adaptive, that is, position-dependent, but passive approach; CSSs with adaptive behaviour based on different sliding regimes are not considered. From the field of CSSs with semiactive dampers, two control strategies are considered: amplitude proportional friction damping aiming at linearizing the friction damping over one cycle and semiactively controlled damping and stiffness properties to enhance the decoupling between ground and structure by the emulation of zero dynamic stiffness. The CSSs under consideration are assessed in terms of peak structural acceleration, peak CSS horizontal force and displacement, and recentring error as function of peak ground acceleration (PGA) of the accelerograms. The results demonstrate that (a) friction damping can be optimized at one PGA only due to its nonlinearity, (b) the optimization of linear viscous damping does not depend on PGA, (c) optimized bow tie friction improves the isolation at low PGA while the isolation at medium to high PGAs worsens, (d) optimized amplitude proportional friction damping does not improve the isolation compared with optimized linear viscous damping, and (e) zero dynamic stiffness is preferably emulated only for a certain range of CSS relative motion amplitude to keep the recentring error within acceptable limits.

The estimated PGA map of the Mw6.4 2006 Yogyakarta Indonesia earthquake, constructed from the Modified Mercalli intensity IMM

Many moderate and strong earthquakes have occurred in Indonesia. However, since ground motion records are unavailable, a concise earthquake peak ground acceleration (PGA) map has never before been constructed. Several efforts have been made to construct PGA maps after the Mw6.4 2006 Yogyakarta earthquake, i.e. earthquake PGA maps by researchers [1–4]. However, due to their use of completely different earthquake sources, methods of analysis and by using exclusion criteria of ground motion prediction equations (GMPE), the maps differed greatly and did not match the actual structural damage found in the field. Estimation of a 2006 Yogyakarta earthquake PGA map became possible after field surveying of the Imm conducted by Wijaya [5]. The estimated PGA map was constructed based on the isoseimic lines, intensity prediction equation (IPE) by Wijaya [5] and peak ground acceleration at YOGI and BJI station control points, as published by Elnashai et al [6]. A set of most recent GMPEs were chosen, as they closely predicted the PGA at two control points. An Extrapolation Method was developed in which the PGA between YOGI and BJI stations would be extrapolated to all data points in the field to yield the 2006 Yogyakarta seismic PGA map. Result of the investigation indicated that the pattern of the new PGA map does not form a circle with radius R, but occurs longitudinally following the direction of the Opak River fault trace and closely follows the pattern of Imm map and damage to buildings in the field. It was found that the maximum upperbound PGA reached ±0.50-0.51g and it did not occur at the epicenter area but instead took place in relatively deep soil deposit approximately ±2 km west of the Opak River fault.

Role of Post-tensioned Coconut-fibre Ropes in Mortar-free Interlocking Concrete Construction During Seismic Loadings

This paper mainly presents the experimental work on studying the effect of post-tensioned coconut-fibre ropes in controlling uplifts of interlocking blocks in mortar-free concrete construction during seismic loadings. Interlocking blocks are capable of returning back to their original positions after the ground motion because of provided inclined key between the blocks. Coconut fibre reinforced concrete was used to make interlocking blocks. To simulate a single degree-of-freedom system, a mass of 200 kg is attached at the column top. The seismic response of structure is measured in terms of induced accelerations, block uplift, top relative displacement and rope tension. Generally, induced acceleration is increased up to the column mid-height and then decreased a little bit at the column top. The trends of block uplift and rope tension are somewhat similar i.e. non-linear with respect to the applied incremental seismic loadings. Empirical relations, as a function of peak ground acceleration, are also developed from the experimental results to envisage the structure seismic response. There is a percentage difference up to 35% in predicting the structure response which can be attributed towards the complicated nature of the structure versus the simple approach developed. But still, this can help in understanding the behaviour of mortar-free interlocking structure having post-tensioned coconut-fibre rope in a systematic manner.

Application of Gumbel I and Monte Carlo methods to assess seismic hazard in and around Pakistan

A proper assessment of seismic hazard is of considerable importance in order to achieve suitable building construction criteria. This paper presents probabilistic seismic hazard assessment in and around Pakistan (23° N–39° N; 59° E–80° E) in terms of peak ground acceleration (PGA). Ground motion is calculated in terms of PGA for a return period of 475 years using a seismogenic-free zone method of Gumbel’s first asymptotic distribution of extreme values and Monte Carlo simulation. Appropriate attenuation relations of universal and local types have been used in this study. The results show that for many parts of Pakistan, the expected seismic hazard is relatively comparable with the level specified in the existing PGA maps.

The revised Thiel–Zsutty earthquake damage model—Reformulated and extended—Part 2

SummaryThe revised Thiel–Zsutty model predicts the probability distribution function for earthquake damageability of a building as a function of peak ground acceleration and parameters that represent the site soils, building damageability, and uncertainty of the basis for parameter selection. Guidance is provided on how to assign revised Thiel–Zsutty parameters and for procedures to determine these parameters for a given building and site. Parameter base values are given for ASCE 7 structural systems and soil classes. The model includes representation of the uncertainty in the parameter evaluations according to level and quality of investigation through an uncertainty factor. It is keyed to ASTM investigation levels and determined by either a constructive or descriptive approach from the characteristics of the building and its design and construction. Procedures are developed for cases where the damageability factor changes as the buildings or site's response changes its character as the level of excitation increases. Guidance is provided on how to incorporate nonlinear time history analyses for performance‐based design of tall buildings and other structures.

Comparative Analysis of Peak Ground Acceleration Before and After Padang Earthquake 2009 Using Mc. Guirre Method

We have analyzed the earthquakes data in West Sumatra province to determine peak ground acceleration value. The peak ground acceleration is a parameter that describes the strength of the tremor that ever happened. This paper aims to compare the value of the peak ground acceleration by considering the b-value before and after the Padang earthquake 2009. This research was carried out in stages, starting by taking the earthquake data in West Sumatra province with boundary coordinates 0.923° LU - 2.811° LS and 97.075° - 102.261° BT, before and after the 2009 Padang earthquake with a magnitude ≥ 3 and depth of ≤ 300 km, calculation of the b-value, and ended by creating peak ground acceleration map based on Mc. Guirre empirical formula with Excel and Surfer software.Based on earthquake data from 2002 until before Padang earthquake 2009, the b-value is 0.874 while the b-value after the Padang earthquake in 2009 to 2016 is 0.891. Considering b value, it can be known that peak ground acceleration before and after the 2009 Padang earthquake might be different. Based on the seismic data before 2009, the peak ground acceleration value of West Sumatra province is ranged from 7,002 to 308.875 gal. This value will be compared by the value of the peak ground acceleration after the Padang earthquake in 2009 which ranged from 7,946 to 372,736 gal.