Early Estimation of Seismic Hazard for Strong Earthquakes in Taiwan (original) (raw)
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Natural Hazards Review, 2019
The method of on-site earthquake early warning was proposed in the past decade to enhance seismic preparedness and safety measures for areas close to the earthquake epicenter. The method leverages critical information contained in the initial 3 s of a P wave that arrives early to predict possibly intense ground shaking at a site. In this study, two types of empirical relationships are developed: (1) Pd 3-PGV relationship for predicting the horizontal peak ground velocity (PGV) based on the peak displacement in the first 3 s of the vertical motion (Pd 3); and (2) τ c − M w relationship for estimating the moment magnitude (Mw) of an earthquake based on a groundmotion period parameter (τ c). Performance of these empirical relationships in on-site earthquake early warning framework is examined using global earthquake records from the most updated Next Generation Attenuation (NGA-West2) strong-motion database. Region-specific empirical predictive equations for California and Japan are proposed based on the state of the art mixed-effect regression to separate ground-motion variability between different earthquakes and that within an earthquake. Applicability and inapplicability of the empirical models in the near-fault condition are investigated using ground motions with strong velocity pulses. The overarching goal of study is to leverage the comprehensive database and state of the art regression techniques to facilitate understanding and engineering practice of on-site earthquake early warning in a variety of regions and in the near-fault condition.
On Estimation of Earthquake Magnitude and Intensity of Shaking
Determination of earthquake magnitude and the strength of shaking at a site from the initial P-wave portion of ground notion is the key problems for earthquake Early Warning (EEW). In this study we selected two parameters of ground motion, namely - characteristic period, which is used for magnitude estimation, and instrumental JMA intensity, which characterizes the level of shaking. We analyzed performance of the parameters scaling relations using datasets collected in various seismic regions in respect of (a) characteristics of datasets accumulated in the regions; (b) variation of initial conditions applying when determining the parameters (length of P-wave windows, number of stations used); (c) possible combinations of the parameters. The used datasets include more than 5350 records that were obtained from more than 130 earthquakes (moment magnitude range 4.1 - 7.6) occurred in Japan, Taiwan and California. We give a particular attention to the problem of proper consideration of e...
Natural Hazards, 2000
The paper describes an integrated approach to seismic hazard assessment, which was applied to the Taiwan region. First, empirical models for ground motion estimation in the region were obtained on the basis of records from recent (1993)(1994)(1995)(1996)(1997)(1998)(1999) earthquakes. The database includes strong-motion data collected during the recent Chi-Chi earthquake (M = 7.6, 21 September 1999) and large (M = 6.8) aftershocks. The ground-motion database was also used for evaluation of generalised site amplification functions for typical soil classes (B, C and D). Second, the theoretical seismic catalogue (2001-2050) for the Taiwan region had been calculated using the 4D-model (location, depth, time) for dynamic deformation of the Earth' crust and 5D-model (location, depth, time, magnitude) for seismic process. The models were developed on the basis of available geophysical and geodynamic data that include regional seismic catalogue. Third, the region and site and timedependent seismic analysis, which is based on schemes of probable earthquake zones evaluated from the theoretical catalogue, regional ground motion models, and local site response characteristics, has been performed. The seismic hazard maps are compiled in terms of Peak Ground Acceleration (PGA) and Response Spectra (RS) amplitudes. The maps show distribution of amplitudes that will not be exceeded with certain probability in condition of typical soil classes during all possible earthquakes that may occur in the region during time period of 2003-2025. The approach allows introduction of a new parameter that describes the dependency of seismic hazard on time, the so-called "period of maximum hazard". The parameter shows the period, during which every considered site will be subjected by the maximum value of ground motion characteristic (PGA or RS).
Estimation of Moment Magnitude and Stress Parameter from ShakeMap Ground‐Motion Parameters
Bulletin of the Seismological Society of America, 2015
We describe a method to determine moment magnitude and stress parameter in near real-time from ShakeMap ground motion parameters (5%-damped pseudo spectral acceleration [PSA] at 1 Hz, peak ground acceleration [PGA] or PSA at 10 Hz), suitable for regions having a sparse network, in the immediate aftermath of a small to moderate earthquake. The methodology is based on relating ShakeMap parameters to source and attenuation parameters within the context of a stochastic point-source model, in order to provide an event-specific ground-motion prediction equation (GMPE) that will reliably predict amplitudes across the region. An example application is provided for southern Ontario. Here, we initially develop a simulation-guided regional generic GMPE model based on the available database. Then, using the estimated regional attenuation and source parameters, we are able to invert ShakeMaps parameters to estimate moment magnitude and stress parameter in near real-time, in order to provide reliable eventspecific GMPEs. The event-specific GMPE are then used to provide robust, calibrated ShakeMaps that are fully consistent with ground-motion observations.
Bulletin of Earthquake Engineering, 2012
We analysed the within-earthquake correlation of ground motion using the strong-motion records accumulated by the TSMIP (Taiwan Strong Motion Instrumentation Program) network in Taiwan during 1993-2009. Two ground-motion prediction equations, which were recently developed for peak ground acceleration (PGA) in the region and based on moment and local magnitude and hypocentral distance, were used for the calculation and analysis of ground-motion residuals. We also used the database containing shear-wave velocity data averaged for the top 30 m of the soil column (Vs30) for the TSMIP stations. We showed that the within-earthquake correlation may vary significantly depending on site classes, gross geological features of the area, and magnitude of earthquakes, records of which dominate the analysed dataset. On the one hand, there is a prominent correspondence between the within-earthquake correlation of PGA residuals and spatial correlation of Vs30 values, which was estimated for particular geological structures (e.g., sedimentary filled basins and large plain areas). On the other hand, the high level of ground-motion correlation (or significant non-random component of residuals) may be caused by the joint influence of soft surface soil and thick sediments and by the path or azimuthal effects. The point-source approximation of extended fault and neglected hanging-and foot-wall effects may also result in non-random residuals. The application of empirical correction factors, which consider the magnitude of earthquakes, source-to-site distance and Vs30 value for given stations, allows for the effective reduction in the level of within-earthquake correlation, as well as the within-earthquake standard deviation. The results of the analysis may be used in practical estimates of seismic
Uncertainty and Spatial Correlation of Earthquake Ground Motion in Taiwan
Terrestrial, Atmospheric and Oceanic Sciences, 2010
In this work we analyzed characteristics of aleatory variability with regard to intra-event and inter-event components in the prediction of peak ground acceleration in Taiwan and the spatial (site-to-site) correlation of ground motion residuals. The characteristics are very important for an assessment of seismic hazard and loss for regionally located building assets (portfolio) and spatially distributed systems (lifelines) and Shake Map generation. The strong-motion database collected by the TSMIP network in Taiwan, which includes about 4650 records from 66 shallow earthquakes (M(L) > 4.5, focal depth < 30 km) occurred in 1993 - 2004, was used for this purpose. The results of the analysis show that the ground motion correlation structure is highly dependent on local geology and on peculiarities of the propagation path (azimuth-dependent attenuation). Thus, a single generalized spatial correlation model may not be adequate for all of Taiwan territory or similar large areas.
Magnitude estimation using the covered areas of strong ground motion in earthquake early warning
Geophysical Research Letters, 2010
1] We collected the strong-motion accelerograms with peak ground acceleration (PGA) larger than 100 Gal (1 Gal = 1.0 cm/s 2 ) from large crustal earthquakes in Taiwan recorded by the Taiwan Strong Motion Instrumentation Program (TSMIP) stations to find an empirical relationship between the area of high PGA and the corresponding earthquake magnitude. We found that the logarithms of the areas inside the PGA contours have a linear relation to the corresponding earthquake magnitudes. We propose that this relationship might be able to rapidly define the earthquake magnitude while providing sufficient seismic station coverage and might have practical application in earthquake early warning (EEW) and rapid reporting systems. The proposed magnitude estimation method is directly related to the level of strong surface shaking and is inherently suitable for the purpose of the EEW and rapid reporting systems.
Eskişehir Technical University Journal of Science and Technology A - Applied Sciences and Engineering, 2020
Together with the ever-increasing number of global and local Ground Motion Prediction Equations (GMPEs) and the complexity of the functional forms, incompatibility problems arise in the selection of the most appropriate GMPE for a specific location. Associated with the incompatibility issues, practitioners face a compromise over the precision of prediction because the functional form of the used GMPE that might be developed by considering influential parameters, which might not be available for the considered location. Hence, a modification is required to adjust the considered GMPE to local conditions by using the local ground motion data. The sensitivity of the parameters of the selected GMPEs to the local seismic propagation patterns can be determined only after the adjustment. Together with the attempts to solve the incompatibility and sensitivity problem, the selection of the most appropriate GMPE becomes the selection of the most suitable functional form. The aim of this study is to select the most appropriate GMPE form for Eskişehir through the guidance of the above statements. A number of GMPEs are selected according to the criteria of wider utilization and recognition. All the candidate GMPEs were subjected to adjustments, including some minor modifications and the calibration of the coefficients by using the indigenous data. Then, a number of statistical and visual procedures were applied including the performance test of the adjusted GMPEs with the records of the two largest earthquakes that occurred in the region. The study highlights the influence of the local seismic behavior on the performance of various functional forms of the candidate GMPEs.