Preliminary Analysis of Strong-motion Recordings from the 28 September 2004 Parkfield, California Earthquake

Shakal, A. F.; Graizer, Vladimir; Huang, Moh; Borcherdt, Roger D.; Haddadi, Hamid R.; Lin, Kuan-Ting; Stephens, C. D.; Roffers, Peter

doi:10.1785/gssrl.76.1.27

Cited by 35 publications

(22 citation statements)

References 16 publications

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“…This event was recorded with a large number of near-field instruments deployed in a series of mostly fault-normal arrays. The Parkfield distribution of PGA with distance clearly demonstrates that the largest accelerations were not recorded at the stations closest to the fault (Shakal et al 2005). Similar observations can be also made about 1999 M7.6 Chi-Chi and the 1979 M6.5 Imperial Valley earthquakes.…”

Section: Attenuation-model Developmentsupporting

confidence: 72%

Ground Motion Attenuation Model for Peak Horizontal Acceleration from Shallow Crustal Earthquakes

Graizer

Kalkan

2007

Earthquake Spectra

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Spatial distribution of ground motion data of recent earthquakes unveiled some features of peak ground acceleration (PGA) attenuation with respect to closest distance to the fault ͑R͒ that current predictive models may not effectively capture. As such, PGA: (1) remains constant in the near-fault area, (2) may show an increase in amplitudes at a certain distance of about 3-10 km from the fault rupture, (3) attenuates with slope of R −1 and faster at farther distances, and (4) intensifies at certain distances due to basin effect (if basin is present). A new ground motion attenuation model is developed using a comprehensive set of ground motion data compiled from shallow crustal earthquakes. A novel feature of the predictive model is its new functional form structured on the transfer function of a single-degree-of-freedom oscillator whereby frequency square term is replaced with closest distance to the fault. We are proposing to fit ground motion amplitudes to a shape of a response function of a series (cascade) of filters, stacked separately one after another, instead of fitting an attenuation curve to a prescribed empirical expression. In this mathematical model each filter represents a separate physical effect.

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Section: Attenuation-model Developmentsupporting

confidence: 72%

Ground Motion Attenuation Model for Peak Horizontal Acceleration from Shallow Crustal Earthquakes

Graizer

Kalkan

2007

Earthquake Spectra

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“…Since the accelerations during the earthquake are estimated to be 0.2-0.45 g near Work Ranch (Shakal et al, 2005 , this issue), axial forces of up to 36 N were induced briefly on the eastern attachment point by the 8 kg mass of the invar rods. Forced displacement of this mount, or transient buckling of the rod, could thus be responsible for the observed coseismic signal.…”

Section: Alternative Explanation For Acoseismic Stepmentioning

confidence: 98%

Coseismic Strain and the Transition to Surface Afterslip Recorded by Creepmeters near the 2004 Parkfield Epicenter

Bilham

2005

Seismological Research Letters

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The M w 6 Parkfield earthquake at 11:15 local time, 28 September 2004 has dealt a possibly fatal blow to the notion that significant surface slip precedes earthquakes. In 1966, anecdotal reports of surface fissures along the fault zone had been reported in the preceding week, and a water pipe fractured 11.6 hours before the mainshock. This offered hope that substantial surface slip may have occurred had displacement sensors been in place to measure it. In the days, hours, and minutes prior to the 2004 Parkfield mainshock, displacement sensors were in place, and nothing happened. According to data from eight creepmeters crossing the fault, the fault remained effectively locked at the detection level of each sensor (6-20 urn) (Langbein et al., 2005, this issue). This absence of surface slip was accompanied by an absence of significant strain on the borehole dilatometer and shear-strainmeter array in the region, and by the absence of any unusual displacements on the GPS array embracing the 2004 epicenter. Although preseismic strain signals seen on some borehole strainmeters suggest that epicentral strain was not completely indifferent to the pending earthquake, the signals are close to instrumental noise levels and pose new challenges for their reliable future detection.In contrast to the absence of preseismic fault displacement, the creepmeters all recorded an abrupt coseismic dextral offset at the time of the mainshock. The step corresponds to dextral shear of the fault zone, but in the absence of surface rupture, the creepmeters during early afterslip acted as extensometers, measuring strain rather than fault creep. The serendipitous location of creepmeters at Work Ranch both across and eccentric to the fault zone has provided insight into the development of surface faulting. CREEPMETERS AND DATA PROCESSINGThe u.s. Geological Survey (USGS) has maintained a creepmeter array in Parkfield since the 1966 earthquake, increasing the number of sensors over the years to thirteen (Yamashita and Burford, 1973;Schultz, 1989;Schultz et al., 1990). Data from these instruments indicate that interseismic creep reduces in rate from more than 20 mm/year north of Middle Mountain to zero south of Highway 46 (Langbein et al., 1990). Ten of these now record afterslip with a displacement resolution of approximately 20 rm. The three University of Colorado extensometers discussed in this article were installed to capture coseismic slip and afterslip at Parkfield but were abandoned a decade ago due to funding difficulties. With the resumption of USGS funding this year, one was reactivated in April and two others shortly after the Parkfield earthquake. They measure linear displacements 30-60 em below the surface between attachment piers on the flanks of the fault. Each attachment pier consists of steel rods driven to refusal in the form of a buried tripod with a maximum depth of 2 m. The length standards of these original extensometers are solid I-em-diameter invar rods that slide within buried telescopic PVC pipes, although new instrumen...

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“…Accelerograms of the 2004 Parkfield earthquake were obtained from CISN (California Integrated Seismic Network) database. In calculating the metadata for records from this earthquake, various publications were considered, including Shakal et al (2005), Langbein et al (2005), Liu et al (2006), Dreger et al (2005), and Kim and Dreger (2008). Accelerograms at AQK station during the 2009 L'Aquila earthquake were obtained from the online database of the Italian accelerometric network (Luzi et al 2008).…”

Section: Data Sourcementioning

confidence: 99%

Quantification of ground-motion parameters and response spectra in the near-fault region

Rupakhety

Sigurdsson

Παπαγεωργιου

et al. 2011

Bull Earthquake Eng

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This study focuses on the characteristics of near-fault ground motions in the forward-direction and structural response associated with them. These ground motions are narrow-banded in nature and are characterized by a predominant period at which structures excited by them are severely affected. In this work, predominant period is defined as the undamped natural period of a single-degree-of-freedom (SDOF) oscillator at which its 5% damped linear elastic pseudo-spectral velocity (PSV) contains a clear and dominant peak. It is found that a linear relationship exists between predominant period and seismic moment. An empirical equation describing this relationship is presented by using a large set of accelerograms. Attenuation equations are developed to estimate peak ground velocity (PGV) as a function of earthquake magnitude and source-to-site distance. In addition, a predictive equation for spectral shapes of PSV (i.e., PSV normalized by PGV) is presented as a continuous function of the undamped natural period of SDOF oscillators. The model is independent of PGV, and can be used in conjunction with any available PGV attenuation relation applicable to near-fault ground motion exhibiting forward-directivity effects. Furthermore, viscous damping of the SDOF is included in the model as a continuous parameter, eliminating the use of so-called damping correction factors. Finally, simple equations relating force reduction factors and displacement ductility of elasto-plastic SDOF systems are presented.

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Preliminary Analysis of Strong-motion Recordings from the 28 September 2004 Parkfield, California Earthquake

Cited by 35 publications

References 16 publications

Ground Motion Attenuation Model for Peak Horizontal Acceleration from Shallow Crustal Earthquakes

Ground Motion Attenuation Model for Peak Horizontal Acceleration from Shallow Crustal Earthquakes

Coseismic Strain and the Transition to Surface Afterslip Recorded by Creepmeters near the 2004 Parkfield Epicenter

Quantification of ground-motion parameters and response spectra in the near-fault region

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