The High-Frequency Decay Slope of Spectra (Kappa) for M≥3.5 Earthquakes on Rock Sites in Eastern and Western Canada

2020 ◽  
Vol 110 (2) ◽  
pp. 471-488 ◽  
Author(s):  
Samantha M. Palmer ◽  
Gail M. Atkinson
Keyword(s):  
Ground Motion ◽  
Classical Method ◽  
Vertical Component ◽  
Western Canada ◽  
S Wave ◽  
Motion Modeling ◽  
Eastern Canada ◽  
General Observation ◽  
Anelastic Attenuation ◽  
Two Parameters

ABSTRACT Spectral decay of ground-motion amplitudes at high frequencies is primarily influenced by two parameters: site-related kappa (κ0) and regional Q (quality factor, inversely proportional to anelastic attenuation). We examine kappa and apparent Q-values (Qa) for M≥3.5 earthquakes recorded at seismograph stations on rock sites in eastern and western Canada. Our database contains 20 earthquakes recorded on nine stations in eastern Canada and 404 earthquakes recorded on eight stations in western Canada, resulting in 105 and 865 Fourier amplitude spectra, respectively. We apply two different methods: (1) a modified version of the classical S-wave acceleration method; and (2) a new stacking method that is consistent with the use of kappa in ground-motion modeling. The results are robust with respect to the method used and also with respect to the frequency band selected, which ranges from 9 to 38 Hz depending on the region, event, and method. Kappa values obtained from the classical method are consistent with those of the stacked method, but the stacked method provides a lower uncertainty. A general observation is that kappa is usually larger, and apparent Q is smaller, for the horizontal component in comparison to the vertical component. We determine an average regional κ0=7  ms (horizontal) and 0 ms (vertical) for rock sites in eastern Canada; we obtain κ0=19  ms (horizontal) and 14 ms (vertical) for rock sites in western Canada. We note that kappa measurements are quite sensitive to details of data selection criteria and methodology, and may be significantly influenced by site effects, resulting in large site-to-site variability.

Earthquake Magnitude and Lg Q Variations between the Grenville and Northern Appalachian Geologic Provinces of Eastern Canada

2020 ◽  
Vol 110 (2) ◽  
pp. 698-714 ◽  
Author(s):  
H. K. Claire Perry ◽  
Allison L. Bent ◽  
Daniel E. McNamara ◽  
Stephen Crane ◽  
Michal Kolaj
Keyword(s):  
Seismic Hazard ◽  
Hazard Analysis ◽  
Vertical Component ◽  
Earthquake Magnitude ◽  
Waveform Analysis ◽  
Eastern Canada ◽  
Frequency Dependent ◽  
Motion Models ◽  
Anelastic Attenuation ◽  
Specific Frequency

ABSTRACT This article assesses the ability of regionally specific, frequency-dependent crustal attenuation (1/Q) to reduce mean magnitude discrepancies between seismic stations in the northern Appalachian and Grenville provinces (NAP and GP) of Canada. LgQ(f) is an important parameter in ground-motion models used in probabilistic seismic hazard analysis. Discrepancies in regional magnitude estimates have long been noted to exist between stations in the two provinces for common event origins. Such discrepancies could arise from systematic site condition variations between the geologic provinces or from varying crustal attenuative properties. To evaluate the effect of frequency-dependent anelastic attenuation, LgQ(f) on estimated magnitudes, we analyze Lg amplitudes from >6000 waveforms recorded by Grenville and northern Appalachian receivers from 420 natural earthquakes of MN magnitude 3–5.6. Waveform analysis is strictly limited to analyst-reviewed, vertical-component waveforms in which Lg is clearly identified, ensuring that the datasets exhibit dominant, high-frequency energy in the Lg velocity window. LgQ(f) is found to be higher in the GP than in the northern Appalachians. In the Grenville, Q(f)=761(±145)f0.25(±0.014), and in the northern Appalachians, attenuation is higher: Q(f)=506(±172)f0.33(±0.310). Earthquake magnitude determined using the peak amplitude of the Lg phase (mbLg) for eastern Canada is corrected to incorporate the frequency-dependent, regionally specific LgQ(f) determined in this study. Using the new LgQ(f) values diminishes and nearly resolves magnitude discrepancies between the provinces. Correcting regional magnitude discrepancies between provinces is critical for reliable regional seismic hazard estimates because magnitude error in a particular region could lead to increased uncertainty in seismic hazard models.

Estimation Theory for Peak Ground Motion

1990 ◽  
Vol 61 (2) ◽  
pp. 99-107 ◽  
Author(s):  
Gwo-Bin Ou ◽  
Robert B. Herrmann
Keyword(s):  
Ground Motion ◽  
Vertical Component ◽  
Estimation Theory ◽  
Confidence Limits ◽  
Eastern Canada ◽  
Cumulative Energy ◽  
Distance Range ◽  
Peak Ground Motion

Abstract The application of estimation theory for predicting peak ground motion is critically examined in order to be more precise in its application. Estimation theory relates peak ground motion to the duration and spectrum of the signal. Using vertical component data from the Eastern Canada Telemetered Network, at distance range of 100–1000 km, we find that a duration must be defined by the interval where the cumulative energy of the main signal increases linearly, here between 5% and 75% of the cumulative power. This duration, when used with the spectra within this window, adequately replicates observed peak motions. This duration used differs significantly from that used by Herrmann (1985) and Toro and McGuire (1987) beyond 500 km. The estimation theory is extended to estimate confidence limits on the peak motion. Finally, the relation between various spectral level estimators, linear, logarithmic, and RMS, is considered to point out the need for consistency in spectral level estimation using smooth models.

Attenuation relations for strong seismic ground motion in Canada

1981 ◽  
Vol 71 (6) ◽  
pp. 1943-1962
Author(s):  
H. S. Hasegawa ◽  
P. W. Basham ◽  
M. J. Berry
Keyword(s):  
Ground Motion ◽  
Near Field ◽  
Strong Motion ◽  
Alternative Methods ◽  
Western Canada ◽  
Peak Acceleration ◽  
Eastern Canada ◽  
Attenuation Relations ◽  
Seismic Ground Motion ◽  
Hypocentral Distance

Abstract Strong seismic ground motion attenuation relations based primarily on Western United States data, in conjunction with intensity data from eastern and western Canada, are employed to derive new attenuation relations for horizontal strong seismic ground motion for application throughout Canada. The following peak acceleration (ap) and peak velocity (vp) relations are proposed for use in western Canada a p ( cm sec − 2 ) = 10 e 1.3 M R − 1.5 v p ( cm sec − 1 ) = 0.00040 e 2.3 M R − 1.3 where M is magnitude and R hypocentral distance (km). The difference in the distance attenuation of Modified Mercalli intensity in eastern and western Canada, and an assumption of equivalent strong motion in the near field in the two regions, is applied to the western relations to derive the following relations proposed for use in eastern Canada a p ( cm sec − 2 ) = 3.4 e 1.3 M R − 1.1 v p ( cm sec − 1 ) = 0.00018 e 2.3 M R − 1.0 . The proposed relations are in reasonable agreement with the small amount of strong motion data available for western and eastern Canada. Within the accuracy justified by very scattered experimental data, peak vertical and sustained horizontal acceleration and velocity can be estimated as 23 of the peak horizontal values. The magnitude and distance dependence of acceleration and velocity parameters are sufficiently different that the relative levels of ground motion bounds in different frequency ranges will depend on the dominant magnitudes of, and distance ranges to, the earthquakes contributing risk in various regions of Canada. The results indicate the importance of mapping risk for parameters in addition to simple peak acceleration, and suggest alternative methods of deriving ground motion bounds required for the development of design response spectra.

scholarly journals Site Response of the NARS-Baja and RESBAN Broadband Networks of the Gulf of California, México

2016 ◽  
Vol 55 (2) ◽  
Author(s):  
Lenin Ávila-Barrientos ◽  
Raúl R. Castro
Keyword(s):  
Ground Motion ◽  
Gulf Of California ◽  
Site Response ◽  
Vertical Component ◽  
Spectral Ratio ◽  
Ratio Method ◽  
S Wave ◽  
Amplification Factors ◽  
The Individual ◽  
Back Azimuth

We studied the seismic response of broadband stations located around the Gulf of California, Mexico, using the horizontal to vertical component spectral ratio method (HVSR). We analyzed 92 earthquakes recor-ded by the NARS-Baja and RESBAN networks, operated by CICESE. The database consists of events recorded between 2002 and 2006, with magnitudes ranging from 3.2 to 6.6. We rotated the records to find radial and transversal ground-motion components and we calculated Fourier spectra of S-wave windows recorded for the three ground-motion components. Then, we calculated HVSR for the individual components and the average of both horizontal components for every event. We analyze records from 20 stations located on sites with different geologic characteristics and we find azimuthal dependence on six of them that have amplification factors varying from 1.5 to up to 13 times at narrow back-azimuth ranges. We also find that sites with significant amplification factors (above three) show increasing amplification with increasing source magnitude.

Selection of random vibration theory procedures for the NGA-East project and ground-motion modeling

2021 ◽  
Vol 37 (1_suppl) ◽  
pp. 1420-1439
Author(s):  
Albert R Kottke ◽  
Norman A Abrahamson ◽  
David M Boore ◽  
Yousef Bozorgnia ◽  
Christine A Goulet ◽  
...  
Keyword(s):  
Ground Motion ◽  
Time Domain ◽  
Random Vibration ◽  
Amplitude Spectrum ◽  
Motion Modeling ◽  
Peak Response ◽  
Vibration Theory ◽  
Random Vibration Theory ◽  
The Time Domain ◽  
The Impact

Traditional ground-motion models (GMMs) are used to compute pseudo-spectral acceleration (PSA) from future earthquakes and are generally developed by regression of PSA using a physics-based functional form. PSA is a relatively simple metric that correlates well with the response of several engineering systems and is a metric commonly used in engineering evaluations; however, characteristics of the PSA calculation make application of scaling factors dependent on the frequency content of the input motion, complicating the development and adaptability of GMMs. By comparison, Fourier amplitude spectrum (FAS) represents ground-motion amplitudes that are completely independent from the amplitudes at other frequencies, making them an attractive alternative for GMM development. Random vibration theory (RVT) predicts the peak response of motion in the time domain based on the FAS and a duration, and thus can be used to relate FAS to PSA. Using RVT to compute the expected peak response in the time domain for given FAS therefore presents a significant advantage that is gaining traction in the GMM field. This article provides recommended RVT procedures relevant to GMM development, which were developed for the Next Generation Attenuation (NGA)-East project. In addition, an orientation-independent FAS metric—called the effective amplitude spectrum (EAS)—is developed for use in conjunction with RVT to preserve the mean power of the corresponding two horizontal components considered in traditional PSA-based modeling (i.e., RotD50). The EAS uses a standardized smoothing approach to provide a practical representation of the FAS for ground-motion modeling, while minimizing the impact on the four RVT properties ( zeroth moment, [Formula: see text]; bandwidth parameter, [Formula: see text]; frequency of zero crossings, [Formula: see text]; and frequency of extrema, [Formula: see text]). Although the recommendations were originally developed for NGA-East, they and the methodology they are based on can be adapted to become portable to other GMM and engineering problems requiring the computation of PSA from FAS.

Kernel colour varies with cultivars and environments in barley

1998 ◽  
Vol 78 (2) ◽  
pp. 217-222 ◽  
Author(s):  
M. J. Edney ◽  
T. M. Choo ◽  
D. Kong ◽  
T. Ferguson ◽  
K. M. Ho ◽  
...  
Keyword(s):  
Hordeum Vulgare ◽  
Key Words ◽  
Western Canada ◽  
Net Blotch ◽  
Hordeum Vulgare L ◽  
Eastern Canada ◽  
Key Words Barley

Kernel colour is an important marketing trait for both malting and feed barleys. Therefore a study was initiated to investigate the kernel colour of 75 Canadian barley (Hordeum vulgare L.) cultivars at three locations (Charlottetown, Ottawa and Bentley) across Canada in 1991 and 1992. Kernel colour was measured by an Instrumar Colormet Spectrocolorimeter. Kernel colour was found to be brighter at the two locations in eastern Canada (Charlottetown and Ottawa) than at the location in western Canada (Bentley). Two-row cultivars on average were more discoloured than six-row cultivars; eastern two-row were more discoloured than western two-row. Covered barleys were less discoloured than hulless barleys in five of the six environments, but covered barleys at Bentley in 1992 were more discoloured than hulless barleys. Kernel discolouration appeared to be associated with susceptibility to net blotch for six-row cultivars. More studies are needed on kernel discolouration of barley. Key words: Barley, Hordeum vulgare, kernel colour

A theoretical study of the radiation from small strikeslip earthquakes at close distances

1983 ◽  
Vol 73 (1) ◽  
pp. 83-96 ◽  
Author(s):  
Michel Campillo ◽  
Michel Bouchon
Keyword(s):  
Ground Motion ◽  
Epicentral Distance ◽  
Homogeneous Medium ◽  
Source Model ◽  
Strike Slip ◽  
Peak Ground Velocity ◽  
Corner Frequency ◽  
Crack Model ◽  
Sharp Change ◽  
S Wave

abstract We present a study of the seismic radiation of a physically realistic source model—the circular crack model of Madariaga—at close distance range and for vertically heterogeneous crustal structures. We use this model to represent the source of small strike-slip earthquakes. We show that the characteristics of the radiated seismic spectra, like the corner frequency, are strongly affected by the presence of the free surface and by crustal layering, and that they can be considerably different from the ones of the homogeneous-medium far-field solution. The vertical and radial displacement spectra are the most strongly affected. We use this source model to calculate the decay of peak ground velocity with epicentral distance and source depth for small strike-slip earthquakes in California. For distances between 10 and 80 km, the peak horizontal velocity decay is of the form r−1.25 for a 4-km hypocentral depth and r−1.65 for deeper sources. The predominance of supercritically reflected arrivals beyond epicentral distances of 70 to 80 km produces a sharp change in the rate of decay of the ground motion. For most of the cases considered, the peak ground velocity increases between 80 and 100 km. We also show that the S-wave velocity in the source layer is the lower limit of phase velocities associated with significant ground motion.

Are Near-Fault Fling Effects Captured in the New NGA West2 Ground Motion Models?

2015 ◽  
Vol 31 (3) ◽  
pp. 1629-1645 ◽  
Author(s):  
Ronnie Kamai ◽  
Norman Abrahamson
Keyword(s):  
Ground Motion ◽  
Vertical Component ◽  
Strong Motion ◽  
Motion Processing ◽  
Large Set ◽  
Pass Filter ◽  
Motion Models ◽  
Finite Fault ◽  
Maximum Period ◽  
Ground Motion Models

We evaluate how much of the fling effect is removed from the NGA database and accompanying GMPEs due to standard strong motion processing. The analysis uses a large set of finite-fault simulations, processed with four different high-pass filter corners, representing the distribution within the PEER ground motion database. The effects of processing on the average horizontal component, the vertical component, and peak ground motion values are evaluated by taking the ratio between unprocessed and processed values. The results show that PGA, PGV, and other spectral values are not significantly affected by processing, partly thanks to the maximum period constraint used when developing the NGA GMPEs, but that the bias in peak ground displacement should not be ignored.

scholarly journals Metode Seismik dalam Pemodelan Fisis Letusan Gunung Lumpur Bledug Kuwu

2019 ◽  
Vol 2 (2) ◽  
pp. 61-66
Author(s):  
Ahmad Fauzi Pohan ◽  
Rusnoviandi Rusnoviandi
Keyword(s):  
Wave Velocity ◽  
Physical Modeling ◽  
Vertical Component ◽  
Dominant Frequency ◽  
P Wave ◽  
Physical Parameters ◽  
S Wave ◽  
Interesting Phenomenon ◽  
Central Java ◽  
P Wave Velocity

Aktivitas gunung lumpur Bledug Kuwu di Jawa  Tengah merupakan fenomena yang menarik dikaji menggunakan pemodelan fisis. Tujuan penelitian ini adalah mengetahui parameter dari medium gunung lumpur Bledug Kuwu. Adapun pemodelan fisis yang dilakukan dengan menggunakan media fisis akuarium berukuran 59 × 59 × 37,3 cm yang diisi material dari lumpur Bledug Kuwu. Sumber letusan dihasilkan dari tekanan kompresor yang dapat diatur kedalaman (10.5, 13, dan 15.5 cm) dan sudut (30o, 45o dan 60o) sumbernya. Sensor yang digunakan geophone komponen vertikal sebanyak 3 buah dengan durasi perekaman selama 5 dan 2,5 detik. Data diambil dengan frekuensi sampel 2 dan 4 kHz untuk masing-masing durasi perekaman. Konfigurasi sumber dan geophone dibuat sesuai dengan pemodelan fisisnya. Pengukuran desnsitas lumpur menunjukkan angka sebesar 1200 kg/m3. Berdasarkan hasil analisis seismogram model fisis diperoleh kecepatan perambatan gelombang-P pada medium lumpur Bledug Kuwu adalah sebesar 48,74 m/s,dan gelombang-S sebesar 28,14 m/s dengan frekuensi dominan antara 20 sampai 25 Hz.   Bledug Kuwu mud volcano activity in Central Java is an interesting phenomenon to be studied using both physical  modeling. The objective of this study was to determine the physical parameters of the medium of Bledug Kuwu. The Physical model was an aquarium with a dimension of 59 × 59 × 37.3 cm filled with Bledug Kuwu’s mud. The eruption source is generated by a compressor pressure that can be controled both the depth(10.5, 13, and 15.5 cm) and the angel of the source (30o, 45o and 60o). The resulting seismic signals were recorded by using 3 vertical component geophones for 10 and 5 seconds durations at a frequency of 2 and 4 kHz respectivel, mud density 1200 kg/m3 . The physical modeling shows that the P-wave velocity of the Bledug Kuwu’s medium is 48.7 m/s, S-wave velocity of Bledug Kuwu’s is 28,14 m/s  with a dominant frequency of 20 to 25 Hz.

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