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Application of grey wolf optimizer to develop new global GMPE for estimating peak ground acceleration

Ghalehjough Babak Karimi, Agahian Saeid

Acta Geophysica

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2023

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Vol. 71, no. 5

2149--2161

EN

Ground motion prediction equations (GMPEs) are open challenge problems that have been developed since 1964. Parametric and nonparametric methods predict ground motion characteristics such as peak ground acceleration (PGA), velocity, displacements, and spectral accelerations. In the present study, the grey wolf optimization (GWO) algorithm was used to obtain a new and developed GMPE for predicting PGA. Data from recorded earthquakes from all over the world were collected, and after filtering of Mw and distance parameters, close to 2000 data were used for modelling. Three parameters of Mw (4–7.9), epicentral distance (0.25–115 km) and geological conditions (soft soil, stiff soil, rock) were used as input parameters for estimating PGA. Many previous studies classified geological conditions based on shear wave velocity at the top 30 m (Vs30), without taking into account the effect of Vs30 at each group. In this study, the effects of Vs30 were considered separately for each geological group too. Results showed that PGA decreased by increasing Vs30 and moving from soft soil toward rock. Finally, the relationship was compared with the other two relations suggested for the local region and global earthquakes, and despite the simplicity of the suggested relation gained by the GWO method, it estimated PGA in terms of accuracy to a good and acceptable level.

2

Neural network based hybrid ground motion prediction equations for Western Himalayas and North Eastern India

Dhanya J., Raghukanth S. T. G.

Acta Geophysica

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2020

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Vol. 68, no. 2

303--324

EN

This work aims at developing a hybrid ground motion prediction equation (GMPE) for spectral acceleration in Western Himalayas and North-Eastern India. The GMPE is derived using an efcient nonparametric modelling based on neural network algorithm. In this study, owing to sparsity in the recorded ground motions (498 recordings) for the region, the available information is combined with 13,294 records from the well-tested NGA-West 2 database. For the methodology adopted in the study, regional fags are assigned to the records. Thus, given a magnitude, distance, shear wave velocity, fault type and region, the model is able to predict the possible spectral acceleration. The developed GMPE is observed to be unbiased with respect to region. Further, the inter- and intra-event standard deviations are also in acceptable ranges. It is observed that developed GMPE for Western Himalayas and North-Eastern India is able to capture all the known ground motion characteristics. Additionally, the GMPE is compared with the existing GMPE for rock-type soil condition available for the Western Himalayas and North-Eastern India. Furthermore, applicability of the developed GMPE model in estimating hazard is analysed by obtaining the uniform hazard response spectra for Delhi and Guwahati.

3

Site-specific Probabilistic Seismic Hazard Map of Himachal Pradesh, India. Part I. Site-specific Ground Motion Relations

Muthuganeisan P., Raghukanth S. T. G.

Acta Geophysica

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2016

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Vol. 64, no. 2

336--361

EN

This article presents four regional site-specific ground motion relations developed for the state of Himachal Pradesh in northwest Himalaya, situated in a seismically active region. These relations are developed from synthetic free surface ground motion databases obtained from a calibrated stochastic seismological model considering the characteristic properties of this specific region. The adopted methodology incorporates the site effects characterised through active MASW tests conducted in 22 important cities. The estimated ground motion levels from the developed relations are found to be in reasonable agreement with the recorded data.

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Site-specific Probabilistic Seismic Hazard Map of Himachal Pradesh, India. Part II. Hazard Estimation

Muthuganeisan P., Raghukanth S. T. G.

Acta Geophysica

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2016

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Vol. 64, no. 4

853--884

EN

This article presents site-specific probable seismic hazard of the Himachal Pradesh province, situated in a seismically active region of northwest Himalaya, using the ground motion relations presented in a companion article. Seismic recurrence parameters for all the documented probable sources are established from an updated earthquake catalogue. The contour maps of probable spectral acceleration at 0, 0.2, and 1 s (5% damping) are presented for 475 and 2475 years return periods. Also, the hazard curves and uniform hazard response spectrums are presented for all the important cities in this province. Results indicate that the present codal provision underestimates the seismic hazard at cities of Bilaspur, Shimla, Hamirpur, Chamba, Mandi, and Solan. In addition, regions near Bilaspur and Chamba exhibit higher hazard levels than what is reported in literature

5

New Ground Motion Prediction Equation for Peak Ground Velocity and Duration of Ground Motion for Mining Tremors in Upper Silesia

Chodacki J.

Acta Geophysica

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2016

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Vol. 64, no. 6

2449--2470

EN

This article presents a method of predicting the peak horizontal velocity of ground motion, PHV, and the duration of vibration, tH, for strong seismic events (E ≥ 5·106 J, ML > 2.5) in the Upper Silesian Coal Basin (USCB). For the prediction of PHV, a model proposed by Si and Midorikawa was used. The regression method takes into account the impact of the local geology under seismic stations on the ground motion according to the Eurocode 8 classification. The ground classification was based on the results of a seismic survey conducted near the seismometer stations. This method is of great practical use because it allows the degree of vibration intensity to be determined on the basis of the Mining Seismic Instrumental Intensity Scale MSIIS-15 (acronym GSIGZW in Polish version) at any distance from the epicentre of the seismic events induced or triggered by mining.

6

Seismic Monitoring of Poland - Description and Results of Temporary Seismic Project with Mobile Seismic Network

Trojanowski J., Plesiewicz B., Wiszniowski J.

Acta Geophysica

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2015

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Vol. 63, no. 1

17--44

EN

The paper describes a temporary seismic project aimed at developing the national database of natural seismic activity for seismic hazard assessment, officially called “Monitoring of Seismic Hazard of Territory of Poland” (MSHTP). Due to low seismicity of Poland, the project was focused on events of magnitude range 1-3 in selected regions in order to maximize the chance of recording any natural event. The project used mobile seismic stations and was divided into two stages. Five-year measurements brought over one hundred natural seismic events of magnitudes ML range 0.5-3.8. Most of them were located in the Podhale region in the Carpathians. Together with previously recorded events this made it possible to conduct a preliminary study on ground motion prediction equation for this region. Only one natural event, of magnitude ML = 3.8, was recorded outside the Carpathians in a surprising location in central-west Poland.