A Sample Generation of Scenario Earthquake Shaking Maps via a Combination of Modal Decomposition and Empirical Copula toward Seismic Hazard Assessment

ABSTRACT To quantify variations in seismic hazard assessment, a large number of scenario earthquake shaking maps (hereafter referred to as s-EQ maps for short) are required. In this article, we propose a method to easily generate a large number of s-EQ maps by combining modal decomposition and empirical copula. First, by applying modal decomposition to a set of existing s-EQ maps, we identify a scenario set with a parameter space to reduce the dimensionality of models. Next, we model a probability distribution of the modal coordinates, which we regard as random variables to allow us to induce a probability measure on the parameter space. By applying an empirical copula for modeling the probability distributions, the dependence structure between modal coordinates and the probability distribution of an individual modal coordinate can be discussed independently. Some simulations show that the dependence structure between modal coordinates is important to not distort the seismic hazard assessment. The proposed method can be applied to actual existing s-EQ maps to easily generate a large number of new s-EQ maps that follow the original probability distribution. We also show that variations can be added to the newly generated s-EQ maps by adjusting the empirical copula. Furthermore, we give a generalization of the proposed method to cases with nonequal probabilities of occurrence of existing scenarios.

A Multidimension Source Model for Generating Broadband Ground Motions with Deterministic 3D Numerical Simulations

ABSTRACT A multidimension source model for generating broadband ground motions with deterministic 3D numerical simulations is proposed in this article. In this model, the source is composed of several superimposed layers, and the total seismic moment is assigned to these layers in different proportions. Each layer exactly fills up the seismic fault and is uniformly divided into subsources with size decreased progressively to reflect different levels of rupture details. Hence, the proposed multidimension source model may consider the realistic rupture process of an earthquake, that is, the spatial and temporal heterogeneity of source parameters, and generate broadband ground motions. To verify this source model, the 1994 Northridge earthquake is simulated with four multidimension source models, based on different source inversion results. The amplitudes, durations, and spectral characteristics of the observed ground motions of the 1994 Northridge earthquake are respectably reproduced in a range of frequencies up to 5 Hz. In addition, a scenario earthquake is also simulated with four multidimension source models, with different synthetic rupture process. The simulated ground motions of the scenario earthquake are generally in good agreement with the Next Generation Attenuation-West 2 ground-motion prediction equations. This demonstrates that it is promising to simulate realistic broadband ground motions of strong earthquakes with a proper source description and realistic Earth models.

Safety Evaluation of High Concrete-Faced Rockfill Dam Based on Site-Related Response Spectrum Using Scenario Earthquake

To clarify how to arrive at earthquake ground motion parameters for use in evaluating the high rockfill dams during seismic loading conditions, as well as to evaluate reasonably the seismic response of dams subjected to strong earthquake, the differences of design response spectra determined by scenario earthquake and uniform hazard spectra theory are investigated in detail. Coupled with the safety evaluation of the Houziyan concrete-faced rockfill dam (CFRD) with a height of 200 m located in meizoseismal regions, comprehensive comparisons of key safety evaluation indices are performed using input motions determined from the abovementioned two design response spectra. The key safety evaluation indices include dynamic response acceleration, permanent deformation, safety of the impervious body, safety factor, and sliding displacement of the potential failure sliding body. Additionally, the ultimate seismic capability of the high CFRD is discussed based on the two response spectra. More considerable results can be achieved and offered to the engineers for the seismic design. It is obvious that the uniform hazard spectra, which are used to adopt in the safety evaluation of high CFRD, typically result in conservative evaluations and unnecessary economic cost for seismic design and reinforcements.

Development of Simulation-Based Approach Using Frame Models Generated From GIS Features and BIM Data for Application to City Seismic Response Analysis of Low- to Mid-Rise RC Structures in Metro Manila

Many cities in the Philippines are situated near fault systems that can generate large magnitude of earthquakes. This paper describes the development of a city seismic response analysis approach for Metro Manila’s low- to mid-rise RC structures using frame models which are generated from GIS feature or BIM data. To create the three-dimensional (3D) models, features and structural details from BIM are used. Finite element method was used to discretize the models with mesh of line elements. Validations of generated models were conducted by comparing the results with those obtained using solid finite element model, commercial software and experimental test. The developed approach was applied to a scenario earthquake analysis wherein the causative fault is the West Valley Fault. Two cities within Metro Manila, that vary in distribution of low- and mid-rise building and site condition, were analyzed. The results of statistical analysis show that the variations in distribution of maximum interstory drift (ISD) between cities and between floor levels, are influenced by the height and floor plan area of the structures. Visualizations in both city-level and building-level reveal the areas that are critical for the considered scenario earthquake. Analysis of the computation costs shows that using frame models for response analysis of each city in Metro Manila leads to million-order degrees-of-freedom (DoF) to solve, and necessitates the implementation of data partitioning and high performance computing techniques.

Earthquake-induced site effect in the oil field deposit of Absheron peninsula (Azerbaijan)

<p>Absheron peninsula (Azerbaijan) area was hit by the strong Caspian earthquakes on November 25, 2000 with Mw6.1 and 6.2 magnitudes. The seismic networks successfully recorded the foreshock, main shock and many aftershocks at respective locations. By using probabilistic analysis, magnitude of design earthquake for the current study in the oilfield was taken as 6.3. From this concept design (scenario) earthquake, accelerations were estimated for the distance of 35 km. In the second phase of the study, soil amplification factors and site characteristics data from boreholes were determined and estimated. In the next phase, the study uses synthesized accelerograms formed on the basis of simulation of the seismic wave propagation processes through ground layer aiming to determine the quantitative characteristics of seismic effect on the oilfield region. Soil amplification values estimated by empirical relationships in terms of shear wave velocities are in the range of 0.7 and 1.9 values. Shear wave velocity (Vs, 30) values are 100 and 110 (m/s). The PGA values for the study area were evaluated by considering the local site effects. Peak ground acceleration varies between 100 – 380 gal. On the basis of the empirical relationship between MSK-64 and peak ground acceleration, the special distribution of intensity of the design earthquake with intensity of >8 is represented. Finally, the study presents possible relationship between seismic effect and daily oil recovery which states the direct proportional characteristics.</p><p><strong>Keywords: </strong>ground classification, oilfield, scenario earthquake, Vs30, amplification factor, peak ground acceleration</p>

Estimation of seismic ground motions and attendant potential human fatalities from a scenario earthquake on the Sanchiao fault in northern Taiwan

<p>The purpose of this study is to estimate maximum ground motions in northern Taiwan in the form of ShakeMaps as well as to assess potential human fatalities from a scenario earthquake on the Sanchiao active fault in this area. Analysis of seismic hazard potential becomes necessary in northern Taiwan for the Central Geological Survey (CGS) announced the Sanchiao active fault as Category II. The resultant ShakeMap patterns of maximum ground motion by using ground motion prediction equation (GMPE) method in a case of Mw6.88 show the areas of PGA above 400 gals are located in the regions inside the yellow lines in the corresponding figure. Furthermore, the areas of PGA greater than 637 gal are located in the northern Bali and the border area of Sinjhuang and Shulin. Likewise, the high PGV area greater than 60 cm/s are located in the border area of Sinjhuang, Taishan and Shulin. In addition, seismic hazards in terms of PGA and PGV in the vicinity of the Sanchiao fault are not completely dominated by the Sanchiao fault. The main reason is that some areas located in the vicinity of the Sanchiao fault are marked with low site response amplification values of 0.61 and 0.74 for PGA and PGV, respectively in northwestern Beitou. Finally, from estimation of potential human fatalities from scenario earthquakes on the Sanchiao active fault, it is noted that potential fatalities increase rapidly in people above age 45. Total fatalities reach a high peak in age groups of 55–64. Another to pay special attention by Taipei City Government is the number and percentage of fatalities above age 85 are more in Taipei City with values 419 and 8.54% than New than Taipei City with values of 319 and 5.02%. In addition, it is surprising that the number and percentage of fatalities are 1234 and 9.75%, respectively in Taoyuan City. Finally, the results of this paper will enable both local and central governments in Taiwan to take notice of potential earthquake threat in these areas, as well as to improve decision making with respect to emergency preparedness, response, and recovery activities for earthquakes in northern Taiwan.</p>