Erratum: “Model for Basin Effects on Long-Period Response Spectra in Southern California” [Earthquake Spectra 24, 257–277 (2008)]

2010 ◽  
Vol 26 (4) ◽  
pp. 1139-1139
Author(s):  
Steven M. Day ◽  
Robert Graves ◽  
Jacobo Bielak ◽  
Douglas Dreger ◽  
Shawn Larsen ◽  
...  
Keyword(s):  
Southern California ◽  
Response Spectra ◽  
Long Period ◽  
Basin Effects

Fling-step recovering from near-source waveforms and ground displacement attenuation models

2020 ◽  
Author(s):  
Maria D'Amico ◽  
Erika Schiappapietra ◽  
Giovanni Lanzano ◽  
Sara Sgobba ◽  
Francesca Pacor
Keyword(s):  
Low Frequency ◽  
Time History ◽  
Strong Motion ◽  
Response Spectra ◽  
Ground Displacement ◽  
Permanent Displacement ◽  
Processing Scheme ◽  
Long Period ◽  
Fling Step ◽  
Attenuation Models

<p>We present a processing scheme (eBASCO, extended BASeline COrrection) to remove the baseline of strong-motion records by means of a piece-wise linear de-trending of the velocity time history. Differently from standard processing schemes, eBASCO does not apply any filtering to remove the low-frequency content of the signal. This approach preserves both the long-period near-source ground-motion, featured by one-side pulse in the velocity trace, and the offset at the end of the displacement trace (fling-step). Hence, the software is suitable for the identification of fling-containing strong-motion waveforms. Here, we apply eBASCO to reconstruct the ground displacement of more than 400 three-component near-source waveforms recorded worldwide (NESS1, http://ness.mi.ingv.it/; Pacor et al., 2019) with the aim of: 1) extensively testing the eBasco capability to capture the long-period content of near-source records; 2) calibrating attenuation models for peak ground displacement (PGD), 5% damped displacement response spectra (DS), permanent displacement amplitude (PD) and period (Tp). The results could provide a more accurate estimate of ground motions, to be adopted for different engineering purposes such as performance-based seismic design of structures.</p><p>Pacor F., Felicetta C., Lanzano G., Sgobba S., Puglia R., D’Amico M., Russo E., Baltzopoulos G., Iervolino I. (2018). NESS v1.0: A worldwide collection of strong-motion data to investigate near source effects. Seismological Research Letters. https://doi.org/10.1785/0220180149</p>

Link Between Long-Term Variability in Upwelling and Fish Production in the Northeast Pacific Ocean

1991 ◽  
Vol 48 (12) ◽  
pp. 2296-2306 ◽  
Author(s):  
Daniel M. Ware ◽  
Richard E. Thomson
Keyword(s):  
Time Series ◽  
Primary Production ◽  
Southern California ◽  
Coastal Upwelling ◽  
Pelagic Fish ◽  
Biological Time ◽  
Long Period ◽  
Pacific Sardine ◽  
The Individual

The biomass of pelagic fish in the Coastal Upwelling Domain off the west coast of North America decreased by a factor of 5 in the first half of this century. We assemble several physical and biological time series spanning this period to determine what may have caused this decline in productivity. Based on an observed link between time series of the coastal wind and primary production, we conclude that there was a strong relaxation in wind-induced upwelling and primary production between 1916 and 1942 off southern California. The fact that the individual biomasses of the dominant pelagic fish species tend to rise and fall in phase through the sediment record off southern California is consistent with our belief that these species are responding to a long-period (40–60 yr) oscillation in primary and secondary production, which, in turn, is being forced by a long-period oscillation in wind-induced upwelling. Our extended sardine recruitment time series indicates that there is a nonlinear relationship between Pacific sardine (Sardinops sagax) recruitment and upwelling and suggests that optimal recruitment occurs when the wind speed during the first few months of life averages 7–8 m/s.

scholarly journals Continuous monitoring of seismic energy release associated with the 1994 Northridge earthquake and the 1992 Landers earthquake

1996 ◽  
Vol 86 (1A) ◽  
pp. 255-258 ◽  
Author(s):  
Sharon Kedar ◽  
Hiroo Kanamori
Keyword(s):  
Frequency Band ◽  
Southern California ◽  
Seismic Energy ◽  
Northridge Earthquake ◽  
Time Frequency ◽  
Landers Earthquake ◽  
Long Period ◽  
1992 Landers Earthquake ◽  
Large Earthquakes ◽  
1994 Northridge Earthquake

Abstract We have developed a method to detect long-period precursors for large earthquakes observed in southern California, if they occur. The method allows us to continuously monitor seismic energy radiation over a wide frequency band to investigate slow deformation in the crust (e.g., slow earthquakes), especially before large earthquakes. We used the long-period records (1 sample/sec) from TERRAscope, a broadband seismic network in southern California. The method consists of dividing the record into a series of overlapping 30-min-long windows, computing the spectra over a frequency band of 0.00055 to 0.1 Hz, and plotting them in the form of a time-frequency diagram called spectrogram. This procedure is repeated daily over a day-long record. We have analyzed the 17 January 1994 Northridge earthquake (Mw = 6.7), and the 28 June 1992 Landers earthquake (Mw = 7.3). No slow precursor with spectral amplitude measured over a duration of 30 min larger than that of a magnitude 3.7 was detected prior to either event. In other words, there was no precursor whose moment was larger than ∼0.003% of the mainshock.

Significance of Ground Motion Scaling Parameters on Amplitude of Scale Factors and Seismic Response of Short- and Long-Period Structures

2019 ◽  
Vol 35 (4) ◽  
pp. 1663-1688 ◽  
Author(s):  
Esengul Cavdar ◽  
Gokhan Ozdemir ◽  
Beyhan Bayhan
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Ground Motions ◽  
Response Spectra ◽  
Scaling Method ◽  
Period Range ◽  
Long Period ◽  
Scale Factors ◽  
Short Period ◽  
Response History Analysis

In this study, an ensemble of ground motions is selected and scaled in order to perform code-compliant bidirectional Nonlinear Response History Analysis for the design purpose of both short- and long-period structures. The followed scaling method provides both the requirements of the Turkish Earthquake Code regarding the scaling of ground motions and compatibility of response spectra of selected ground motion pairs with the target spectrum. The effects of four parameters, involved in the followed scaling method, on both the amplitude of scale factors and seismic response of structures are investigated. These parameters are the number of ground motion records, period range, number of periods used in the related period range, and distribution of weight factors at the selected periods. In the analyses, ground motion excitations were applied to both fixed-base and seismically isolated structure models representative of short- and long-period structures, respectively. Results revealed that both the amplitudes of scale factors and seismic response of short-period structures are more prone to variation of investigated parameters compared to those of long-period structures.

scholarly journals Assessment of the Design Spectrum with Aggravation Factors by 2D Nonlinear Numerical Analyses: A Case Study in Gemlik Basin, Turkey

2021 ◽  
Author(s):  
BİLAL ÖZASLAN ◽  
Recep Iyisan ◽  
Emre Murat Hasal ◽  
Hadi Khanbabazadeh ◽  
Hiroaki Yamanaka
Keyword(s):  
Seismic Waves ◽  
Plastic Material ◽  
Site Response ◽  
Response Spectra ◽  
Considerable Effect ◽  
Design Spectrum ◽  
The North ◽  
Basin Effects ◽  
Stratification Effect ◽  
A Site

Abstract The response spectra of multidimensional analyses are compared with the one-dimensional (1D) local models to couple the irregular soil stratification effect in a site. In recent studies, the surface motion spectra ratios of 2D/1D or 3D/1D are defined as spectral aggravation factors for each region in a site. Particularly in alluvial basins, where the soil media is typically formed by fault ruptures or topographic depressions filled with sediments, the inclination of the rock outcrop in the edge of the basin has a considerable effect on the site response, and such effect has not yet been taken into consideration of recent seismic building codes and general engineering applications. In this study, the natural alluvial basin near the North Anatolian Fault in Gemlik, Maramara Region, Turkey, was investigated by 40 seismic site tests and 4 validation borings. The 2D and 1D nonlinear response history analyses in north-south and east-west directions of the Gemlik basin were performed by numerical model on finite difference scheme considering nonlinear elasto-plastic material behaviors and geometric discontinuities. 22 strong ground motions recorded on rock site are excited vertically as SH waves. The numerical results exhibited the narrow basin effects are derived not only by reflection, refraction, and shifting behavior but also by focusing and superposition of the seismic waves propagating from both opposite basin edges. As a result, the site-specific spectral aggravation factors, SAF2D/1D defined by the ratio between the 2D and 1D acceleration response spectra for each period and any location on the site, were proposed for the Gemlik basin. The variations of the aggravation factors were observed as increasing values to 1.2–2.2 on the near edge and basin center.

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