THE STRONG MOTION RECORDS OF THE Ms 8.0 WENCHUAN EARTHQUAKE BY THE DIGITAL STRONG EARTHQUAKE NETWORK IN SICHUAN AND THE NEIGHBORING REGION

2011 ◽  
Vol 05 (04) ◽  
pp. 343-361 ◽  
Author(s):  
RONGJUN ZHOU ◽  
YONG LI ◽  
ALEXANDER L. DENSMORE ◽  
MIN LAI ◽  
YI ZHANG ◽  
...  

The M s 8.0 Wenchuan Earthquake of May 12, 2008 resulted in oblique dextral-thrust motion in the Longmen Shan tectonic belt resulted. During this earthquake event, 133 sets of three-component acceleration records were collected by the digital earthquake network in Sichuan Province. By using these records and some strong motion records from the networks in Shanxi and Gansu provinces, contours of peak ground acceleration were determined. These contours are elliptically shaped with the major axis oriented in a northeast direction. The peak acceleration decayed more gradually toward the northeast, parallel to the rupture propagation than toward the southwest, indicating a directivity effect. The peak acceleration also decayed more gradually toward the northwest, on the hanging wall, than toward the southeast on the footwall. A relatively high rate of attenuation in the peak acceleration was also evident on the Yingxiu-Beichuan section of the fault; this can be attributed to the seismic source fracture pattern and rupture progress. The measured peak vertical and horizontal ground acceleration components were far larger than the design values prescribed by the Code for Seismic Design of Buildings (GB50011-2001). As distance from the rupture increased, the acceleration response spectrum gradually became dominated by long-period motions. A large velocity pulse was also measured at a distance of about 80–100 km from the fault.

1961 ◽  
Vol 51 (2) ◽  
pp. 191-202
Author(s):  
D. E. Hudson ◽  
J. L. Alford ◽  
W. D. Iwan

Abstract Ground acceleration-time measurements have been made within 2000 ft. of two quarry blasts of total charge weight 185 tons and 673 tons. Ground accelerations were of a character and magnitude similar to those associated with damaging earthquakes. Complete response spectrum curves calculated from the acceleration records are presented. Direct comparisons are made between these results and previous similar measuements and calculations using identical instruments, which have been made of strong-motion earthquakes, H. E. blasts, and the Rainier nuclear blast.


2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Deyu Yin ◽  
Yun Dong ◽  
Qifang Liu ◽  
Yuexin She ◽  
Jingke Wu ◽  
...  

In order to reproduce the rupture history of the 2008 Mw8.0 Wenchuan earthquake, the teleseismic and strong-motion records are adopted. Based on a multiple-segment, variable-slip model, the finite fault inversion method is utilized to recover the rupture process. The results are as follows: (1) the rupture duration of the Wenchuan earthquake is about 100 s, and the released seismic moment is 1.24 × 1021 N·m, equal to the moment magnitude Mw8.0. There are 5 asperities on the fault plane, indicating that the earthquake is composed of at least 5 subevents. (2) The slip is mainly distributed on the Beichuan fault, indicating that the Beichuan fault is the main rupture fault. On the southern part of the Beichuan fault, the dislocation underside the Longmenshan area and Hongkou-Yingxiu near-surface area is dominated by thrust, and the maximum slip is 11.8 m. Slip between the Yuejiashan and Qingping area is dominated by thrust. On the northern part of the Beichuan fault, the area under Beichuan is dominated by thrust, the slip under Nanba is thrust and strike, near Qingchuan, the slip turns into the strike slip, and the maximum slip is 13.1 m. The dislocation under Bailu is also dominated by thrust, with maximum slip 8.9 m. (3) The rupture of the Wenchuan earthquake is mainly a unilateral rupture to the northeast. The rupture started at the low dip angle part of the Beichuan fault, and after 3 s, it propagated to the Pengguan fault. After 10 s, the largest asperity under Longmenshan in the south section of the Beichuan fault began to break, lasting for about 24 s. Then, the Xiaoyudong fault was triggered by the Pengguan fault, and the bilateral rupture of the high dip angle part of the Beichuan fault started at about 6 s. South section of the Beichuan fault began to break at about 35 s, and at 43 s, 63 s, and 80 s, the rupture extended to Beichuan, Nanba, and Qingchuan areas.


1988 ◽  
Vol 4 (1) ◽  
pp. 75-100 ◽  
Author(s):  
A. Shakal ◽  
M. J. Huang ◽  
T. Q. Cao

The Whittier Narrows earthquake of October 1, 1987 generated the largest set of strong-motion records ever obtained from a single earthquake. The California Strong Motion Instrumentation Program (CSMIP) recovered 128 strong-motion records from 101 stations. Of these 101 stations, 63 are ground-response stations and 38 are extensively-instrumented structures. The structures include 27 buildings, eight dams, a suspension bridge, an airport tower, and a power plant. This paper summarizes that data set and highlights records of particular interest. The duration of strong shaking was approximately 3 to 4 seconds at most stations. The maximum peak acceleration values in the CSMIP data set are 0.62 g on the ground and 0.54 g in a structure. The largest acceleration (0.62 g) was recorded at a station near Tarzana, approximately 45 km from the epicenter. Other records of particular interest discussed here include the record from a soft-story building on the Los Angeles State University campus and the records from the Vincent Thomas suspension bridge near Long Beach. Digitization and processing of the accelerograms are underway, and accelerograms from 12 ground-response stations have been digitized as of this writing. The spectra show that the motion at the Tarzana station was dominated by 3 Hz energy. Spectra from other sites are relatively flat and do not show this spectral peak. The attenuation of peak acceleration with distance for this earthquake is compared with the relationship of Joyner and Boore (1981) derived from past earthquakes. On average, the peak acceleration data from this earthquake are higher than would be predicted by the Joyner-Boore model.


2014 ◽  
Vol 915-916 ◽  
pp. 122-125
Author(s):  
Xiao Fei Li ◽  
Rui Sun ◽  
Xiao Bo Yu

In order to test the applicable of the seismic response analysis procedures SHAKE2000 and LSSRLI-1 for class ІІ site, 17 stations and 35 underground strong motion records of KiK-net are selected from Class ІІ site. 210 working conditions are used to verify the applicability of the two soil seismic response analysis programs at Class ІІ site. These two programs are used to calculate the selected working conditions, giving the peak acceleration of the ground, the shear strain and the ground acceleration response spectra. By analyzing the results of the two programs and the measured results to assess the degree of difference between the two methods and which program is closer to the real situation. Studies have shown that in class ІІ site, in most cases, the results of SHAKE2000 and LSSRLI-1 differ little. While comparing with the actual records, SHAKE2000 is closer to the strong motion records.


Author(s):  
G. H. McVerry

Probabilistic techniques for seismic hazard analysis have
come into vogue in New Zealand for both the assessment of major projects and the development and review of seismic design codes. However, there are considerable uncertainties in the modelling
 of the strong-motion attenuation, which is necessarily based largely on overseas data. An excellent agreement is obtained between an average 5% damped response spectrum for New Zealand alluvial sites in the 20 to 59 km distance range and 5.4 to 6.0 magnitude class and that given by a Japanese model. Unfortunately, this corresponds to only about half the amplitude levels of 150 year spectra relevant to code design. The much more rapid decay
of ground shaking with distance in New Zealand has led to a considerable modification based on maximum ground acceleration
data from the Inangahua earthquake of the distance-dependence
of the Japanese response spectra model. Less scatter in New Zealand data has resulted in adopting a lower standard deviation for the attenuation model, which is important in reducing the considerable "probabilistic enhancement" of the hazard estimates. Regional differences in attenuation shown by intensities are difficult to resolve from the strong-motion acceleration data, apart from lower accelerations in Fiordland.


2013 ◽  
Vol 4 (1) ◽  
pp. 83-101 ◽  
Author(s):  
Shiv Shankar Kumar ◽  
A. Murali Krishna

In this study, one dimensional equivalent–linear ground response analyses were performed for some typical sites in the Guwahati city, India. Six bore locations covering about 250 km2 area of the city were considered for the analyses. As the strong motion significantly influences the ground response, seven different recorded ground motions, varying in magnitude (6.1 to 8.1) and other ground motion parameters, were adopted. Seismic site analyses were carried out for all layers of borelogs using all the seven earthquakes. Results are presented in terms of surface acceleration histories, strain and shear stress ratio variation, response spectrum, Fourier amplitude ratio versus frequency. The results indicate that accelerations were amplified the most at the surface level. The range of peak ground acceleration (PGA) values obtained at the ground surface is about 0.2 g to 0.79 for a range of PGA considered at bedrock level (rigid half space at bottom of borelog) of 0.1 g to 0.34 g. The Fourier amplifications of ground motion at surface are in the range of 4.14 – 8.99 for a frequency band of 1.75 Hz to 3.13 Hz. The maximum spectral acceleration at six locations varies in the range of 1.0 g – 4.71 g for all the seven earthquakes. The study clearly demonstrated the role for site effect and the type of ground motion on the ground response. For a given earthquake motion, amplification factors at surface level change by almost about 20% to 70% depending on local site conditions.


2015 ◽  
Vol 2015 ◽  
pp. 1-17
Author(s):  
Baofeng Zhou ◽  
Haiyun Wang ◽  
Lili Xie ◽  
Yanru Wang

This paper collects a rich set of strong motion records in some typical earthquakes domestic and abroad, checks its seismic events, converts the data format, corrects the zeroline and draws the waveform. Four kinds of abnormal phenomena on the acceleration waveform are revealed, such as spike, asymmetric waveform, obvious baseline drift, and strong motion records packets separation. Then reasonable processing approaches are derived from the preliminary analysis of the generation mechanism for abnormal phenomena. In addition to the effects on time history, Fourier amplitude spectrum and response spectrum are studied before and after strong motion records correction. It is shown that (1) mechanism of spikes is rather complicated; however spikes can be eliminated by “jerk” method, ratio method, and the consistency of the three-component PGA time; (2) mechanism of the asymmetric waveform is of diversity; however, to some extent, the Butterworth low-pass filtering can be applied to correct it; (3) two pieces of strong motion record packets can be connected by searching continuous and repeated data; (4) the method of cumulative adding can be used to find the clear baseline drift; (5) the abnormal waveform directly affects the characteristics of time history and frequency spectrum.


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