scholarly journals Vulnerability and site effects in earthquake disasters in Armenia (Colombia) – Part 2 : Observed damage and vulnerability

2021 ◽  
Vol 21 (8) ◽  
pp. 2345-2354
Author(s):  
Francisco J. Chávez-García ◽  
Hugo Monsalve-Jaramillo ◽  
Joaquín Vila-Ortega
Keyword(s):  
Peak Ground Acceleration ◽  
Relative Frequency ◽  
Site Effects ◽  
Building Stock ◽  
Ground Acceleration ◽  
Vulnerability Evaluation ◽  
Observed Damage ◽  
Made In

Abstract. Damage in Armenia, Colombia, for the 25 January 1999 (Mw=6.2, peak ground acceleration (PGA) 580 Gal) event was disproportionate. We analyze the damage report as a function of number of stories and construction age of buildings. We recovered two vulnerability evaluations made in Armenia in 1993 and in 2004. We compare the results of the 1993 evaluation with damage observed in 1999 and show that the vulnerability evaluation made in 1993 could have predicted the relative frequency of damage observed in 1999. Our results show that vulnerability of the building stock was the major factor behind damage observed in 1999. Moreover, it showed no significant reduction between 1999 and 2004.

scholarly journals Vulnerability and Site Effects in Earthquake Disasters in Armenia (Colombia). II – Observed Damages and Vulnerability

2020 ◽  
Author(s):  
Francisco J. Chávez-García ◽  
Hugo Monsalve-Jaramillo ◽  
Joaquín Vila-Ortega
Keyword(s):  
Relative Frequency ◽  
Site Effects ◽  
Building Stock ◽  
Vulnerability Evaluation ◽  
Made In

Abstract. Damage in Armenia, Colombia, for the 1999 (Mw6.2) event was disproportionate. We analyse the damage report as a function of number of storeys and construction age. We recovered two vulnerability evaluations made in Armenia in 1993 and in 2004. We compare the results of the 1993 evaluation with damages observed in 1999 and show that the vulnerability evaluation made in 1993 could have predicted the relative frequency of damage observed in 1999. Our results show that vulnerability of the building stock was the major factor behind damage observed in 1999. Moreover, it showed no significant reduction between 1999 and 2004.

Evaluation of Peak Ground Acceleration and Response Spectra Considering the Local Site Effects

2010 ◽  
Vol 1 (1) ◽  
pp. 25-41 ◽  
Author(s):  
T. G. Sitharam ◽  
K. S. Vipin
Keyword(s):  
Seismic Hazard ◽  
Peak Ground Acceleration ◽  
Site Effects ◽  
Response Spectra ◽  
Probabilistic Logic ◽  
Site Classification ◽  
Ground Acceleration ◽  
Entire Study ◽  
Local Site Effects ◽  
Local Site

The local site effects play an important role in the evaluation of seismic hazard. The proper evaluation of the local site effects will help in evaluating the amplification factors for different locations. This article deals with the evaluation of peak ground acceleration and response spectra based on the local site effects for the study area. The seismic hazard analysis was done based on a probabilistic logic tree approach and the peak horizontal acceleration (PHA) values at the bed rock level were evaluated. Different methods of site classification have been reviewed in the present work. The surface level peak ground acceleration (PGA) values were evaluated for the entire study area for four different site classes based on NEHRP site classification. The uniform hazard response spectrum (UHRS) has been developed for the city of Bangalore and the details are presented in this work.

The power of the little ones: Computed and observed aftershock hazard in Central Italy

2021 ◽  
pp. 875529302110369
Author(s):  
Robin Gee ◽  
Laura Peruzza ◽  
Marco Pagani
Keyword(s):  
Seismic Hazard ◽  
Peak Ground Acceleration ◽  
Site Effects ◽  
Hazard Analysis ◽  
Central Italy ◽  
Current Approach ◽  
Time Dependent ◽  
Ground Acceleration ◽  
Key Features ◽  
Hazard Curves

Seismic hazard in Central Italy due to the 2016–2017 seismic sequence is modeled using a standard probabilistic aftershock seismic hazard model. Two key features of the model are the consideration of time-dependent aftershock occurrence, modeled by stacking Omori decay curves associated with the three largest ( Mw > 5.5) events, and the incorporation of geologic information by modeling the locations of expected seismicity along realistic fault surfaces. The computed seismic hazard at Amatrice indicates higher hazard values compared to those computed using a conventional time-independent hazard analysis. We then compare the computed hazard curves against empirical hazard curves constructed for 12 individual recording stations in terms of peak ground acceleration, each with at least 35 (and up to 231) recordings. At eight sites, the observed exceedances fall within one standard deviation of the expected mean, while at the remaining sites, the observed exceedances fall outside this range indicating a poorer match. The soil sites are among the stations with the poorest match, suggesting that site effects may not be accurately modeled with the current approach.

Evaluation of Peak Ground Acceleration and Response Spectra Considering the Local Site Effects

2012 ◽  
pp. 1-17
Author(s):  
Sitharam T. G. ◽  
Vipin K. S.
Keyword(s):  
Seismic Hazard ◽  
Peak Ground Acceleration ◽  
Site Effects ◽  
Response Spectrum ◽  
Response Spectra ◽  
Site Classification ◽  
Ground Acceleration ◽  
Local Site Effects ◽  
Local Site ◽  
Uniform Hazard Response Spectrum

The local site effects play an important role in the evaluation of seismic hazard. The proper evaluation of the local site effects will help in evaluating the amplification factors for different locations. This article deals with the evaluation of peak ground acceleration and response spectra based on the local site effects for the study area. The seismic hazard analysis was done based on a probabilistic logic tree approach and the peak horizontal acceleration (PHA) values at the bed rock level were evaluated. Different methods of site classification have been reviewed in the present work. The surface level peak ground acceleration (PGA) values were evaluated for the entire study area for four different site classes based on NEHRP site classification. The uniform hazard response spectrum (UHRS) has been developed for the city of Bangalore and the details are presented in this work.

scholarly journals Risk-adjusted Design Basis Earthquake’s Adequacy for use in Seismic Design Codes

2021 ◽  
Author(s):  
Mohammad Zaman ◽  
Mohammad Reza Ghayamghamian
Keyword(s):  
Seismic Design ◽  
Peak Ground Acceleration ◽  
Design Parameters ◽  
Design Codes ◽  
Acceptance Criteria ◽  
Ground Acceleration ◽  
Seismic Codes ◽  
Residual Drift ◽  
Design Basis ◽  
Made In

Abstract In most buildings’ seismic design codes design basis peak ground acceleration (PGADBE) is provided by employing a uniform-hazard approach. However, a new trend in updating seismic codes is to adopt a risk-informed method to estimate the PGADBE so-called risk-adjusted design basis peak ground acceleration (PGARDBE). An attempt is made here to examine the adequacy of the PGARDBE to fulfill the assumptions made in seismic codes for converting the maximum considered earthquake’s (MCE) intensity to PGADBE. To this end, the performance of regular intermediate steel moment frames (IMF) is assessed in terms of collapse margin (CMR) and residual drift ratios in the event of MCE and design basis earthquake (DBE), respectively. The PGARDBEs are computed for Karaj County, Iran. A set of 96 index archetypes of regular IMF are designed considering four design parameters, which include the number of stories (2, 3, 6, 9, 12, and 15), span lengths (4 and 8 meters), occupancies (residential and commercial), and seismic demands (0.15, 0.25, 0.35 and 0.45g). The PGADBE prescribed by Standard No. 2800 for Karaj neither meets the assumed acceptance criteria nor stands on the safe side. Meanwhile, PGARDBE fulfills the acceptance criteria but does not necessarily satisfy the implicit assumption made in codes that the code-conforming buildings have at least a CMR of 1.5 if the MCE occurs. This emphasizes that the PGARDBE should not be used without examining the CMR fulfillment. The results recommend that a lower limit need to be set on PGARDBEs, which is found to be 0.35g for Karaj. Outcomes also reveal that the code-conforming buildings designed with the proposed PGARDBE can fulfill both repairability and life safety performances at the DBE and MCE, respectively. These buildings also have a high chance to be even considered as repairable ones at the seismic demand of MCE. Furthermore, regardless of the employed method for estimating PGADBE, various relationships between design parameters with different performance indicators such as CMR, residual drift ratio, ductility demand, imposed drift ratio, and building’s normalized weight are presented. These relationships can be used to evaluate the buildings’ safety factor against collapse and repairability, justification of using IMF in regions with high seismicity, level of structural and nonstructural damage as well as the economic consequence of changes in PGADBE. The presented relationships provide a multi-criteria decision-making tool to decide on the optimum PGADBE leading to an affordable alternative and tolerable damage.

Analisis Percepatan Tanah Puncak Akibat Gempa Pada Kota Sorong Sebagai Upaya Mitigasi Bencana

2018 ◽  
Vol 4 (2) ◽  
pp. 14
Author(s):  
Imam Trianggoro Saputro ◽  
Mohammad Aris
Keyword(s):  
Peak Ground Acceleration ◽  
Ground Acceleration ◽  
Papua Barat

Sorong merupakan salah satu kota yang terletak di Provinsi Papua Barat. Daerah ini memiliki tingkat kerentanan yang tinggi terhadap ancaman bahaya gempa bumi karena lokasinya terletak di antara pertemuan lempengan tektonik dan beberapa sesar aktif. Tingkat kerawanan terhadap gempa pada daerah ini cukup tinggi. Pada September 2016, BMKG mencatat bahwa terjadi gempa bumi dengan skala magnitudo sebesar 6,8 SR (Skala Ritcher) dengan kedalaman 10 meter dari permukaan laut dan berjarak 31 km arah timur laut kota Sorong. Gempa ini bersifat merusak. Akibat gempa ini, sebanyak 62 orang terluka dan 257 rumah rusak. Untuk itu diperlukan suatu analisis terhadap percepatan tanah puncak (Peak Ground Acceleration) terbaru sebagai langkah mitigasi yang nantinya dapat digunakan untuk perencanaan gedung tahan gempa.Pengumpulan data gempa pada peneltian ini yaitu data gempa yang terjadi sekitar kota Sorong pada rentang waktu 1900-2017. Data gempa yang diambil adalah yang berpotensi merusak struktur yaitu dengan magnitudo (Mw) ≥ 5 dengan radius gempa 500 km dari kota Sorong dan memiliki kedalaman antara 0 - 300 km. Setelah diperoleh data gempa maka dibuat peta sebaran gempa di wilayah kota Sorong. Percepatan tanah puncak dihitung berdasarkan fungsi atenuasi matuscha (1980) dan menggunakan pendekatan metode Gumbel.Hasil penelitian menunjukkan bahwa nilai percepatan tanah puncak (PGA) di wilayah kota Sorong pada periode ulang 2500 tahun atau menggunakan probabilitas terlampaui 2% dalam 50 tahun umur rencana bangunan diperoleh sebesar 708.9520 cm/dt2 atau 0.7227 g. Apabila melihat peta gempa SNI 1726-2012 yang menggunakan probabilitas yang sama maka nilai percepatan tanah puncak (PGA) ketika gempa bumi berkisar antara 0.4 g - 0.6 g. Nilai ini mengalami peningkatan yang berarti tingkat resiko terhadap gempa bumi pada wilayah kota Sorong meningkat.

scholarly journals I. Notices of some conclusions derived from the photographic records of the Kew declinometer, in the years 1858,1859, 1860, and 1861

1862 ◽  
Vol 11 ◽  
pp. 585-590
Keyword(s):  
Relative Frequency ◽  
Magnetic Force ◽  
Total Force ◽  
Magnetic Disturbances ◽  
Different Parts ◽  
Made In ◽  
Photographic Records

The discussion of the magnetic observations which have been made in different parts of the globe may now be considered to have established the three following important conclusions in regard to the magnetic disturbances: viz., 1. That these phenomena, whether of the declination, inclination, or total force, are subject in their mean effects to periodical laws, which determine their relative frequency and amount at different hours of the day and night. 2. That the disturbances which occasion westerly and those which occasion easterly deflections of the compass-needle, those which increase and those which decrease the inclination, and those which increase and those which decrease the magnetic force have all distinct and generally different periodical laws.

Site effects of the Denis-Perron dam (SM-3): A case study in Eastern North America

2021 ◽  
pp. 875529302110194
Author(s):  
Daniel Verret ◽  
Denis LeBœuf ◽  
Éric Péloquin
Keyword(s):  
North America ◽  
Ground Motion ◽  
Site Effects ◽  
Transfer Functions ◽  
Ground Motions ◽  
Published Data ◽  
Eastern North America ◽  
Ground Acceleration ◽  
Large Dams ◽  
Moderate Seismicity

Eastern North America (ENA) is part of a region with low-to-moderate seismicity; nonetheless, some significant seismic events have occurred in the last few decades. Recent events have reemphasized the need to review ENA seismicity and ground motion models, along with continually reevaluating and updating procedures related to the seismic safety assessment of hydroelectric infrastructures, particularly large dams in Québec. Furthermore, recent researchers have shown that site-specific characteristics, topography, and valley shapes may significantly aggravate the severity of ground motions. To the best of our knowledge, very few instrumental data from actual earthquakes have been published for examining the site effects of hydroelectric dam structures located in eastern Canada. This article presents an analysis of three small earthquakes that occurred in 1999 and 2002 at the Denis-Perron (SM-3) dam. This dam, the highest in Québec, is a rockfill embankment structure with a height of 171 m and a length of 378 m; it is located in a narrow valley. The ground motion datasets of these earthquakes include the bedrock and dam crest three-component accelerometer recordings. Ground motions are analyzed both in the time and frequency domains. The spectral ratios and transfer functions obtained from these small earthquakes provide new insights into the directionality of resonant frequencies, vibration modes, and site effects for the Denis-Perron dam. The crest amplifications observed for this dam are also compared with previously published data for large dams. New statistical relationships are proposed to establish dam crest amplification on the basis of the peak ground acceleration (PGA) at the foundation.

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