Continuous Borehole Strain and Pore Pressure in the Near Field of the 28 September 2004 M 6.0 Parkfield, California, Earthquake: Implications for Nucleation, Fault Response, Earthquake Prediction, and Tremor

Johnston, M. J. S.; Borcherdt, Roger D.; Linde, A. T.; Gladwin, M. T.

doi:10.1785/0120050822

Cited by 83 publications

(58 citation statements)

References 50 publications

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“…[] attributed to preseismic dilation. This raises a fundamental question as to why changes of groundwater chemistry apparently coupled with preseismic dilation were seen at Hafralækur, 76 km from the epicenters of two M > 5 earthquakes, while geodetic measurements made along the San Andreas Fault, less than 10 km from the epicenter of the M 6.0 Parkfield earthquake revealed no evidence of preseismic change of dilational strain [ Johnston et al ., ]. This paradox could be resolved if both chemical changes in groundwater and the earthquakes could be related to magma movement.…”

Section: Discussionmentioning

confidence: 99%

Coupling between mineral reactions, chemical changes in groundwater, and earthquakes in Iceland

et al. 2016

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Chemical analysis of groundwater samples collected from a borehole at Hafralækur, northern Iceland, from October 2008 to June 2015 revealed (1) a long‐term decrease in concentration of Si and Na and (2) an abrupt increase in concentration of Na before each of two consecutive M > 5 earthquakes which occurred in 2012 and 2013, both 76 km from Hafralækur. Based on a geochemical (major elements and stable isotopes), petrological, and mineralogical study of drill cuttings taken from an adjacent borehole, we are able to show that (1) the long‐term decrease in concentration of Si and Na was caused by constant volume replacement of labradorite by analcime coupled with precipitation of zeolites in vesicles and along fractures and (2) the abrupt increase of Na concentration before the first earthquake records a switchover to nonstoichiometric dissolution of analcime with preferential release of Na into groundwater. We attribute decay of the Na peaks, which followed and coincided with each earthquake to uptake of Na along fractured or porous boundaries between labradorite and analcime crystals. Possible causes of these Na peaks are an increase of reactive surface area caused by fracturing or a shift from chemical equilibrium caused by mixing between groundwater components. Both could have been triggered by preseismic dilation, which was also inferred in a previous study by Skelton et al. (2014). The mechanism behind preseismic dilation so far from the focus of an earthquake remains unknown.

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Section: Discussionmentioning

confidence: 99%

Coupling between mineral reactions, chemical changes in groundwater, and earthquakes in Iceland

et al. 2016

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“…The cumulative time signatures we develop enable us to rigorously assess this observation through a statistical analysis of the spatial correlations of the LFE occurrence patterns. To this end, we use a hierarchical clustering algorithm (Kaufmen and Rousseeuw, 2005) to sort the sources into clusters based on the similarity of their cumulative time signatures (equation (1)). Sources within a given cluster therefore have occurrence patterns that are quantitatively similar in form.…”

Section: Clustering Of Nearby Lfe Sourcesmentioning

confidence: 99%

Synchronous low frequency earthquakes and implications for deep San Andreas Fault slip

Trugman

Guyer

et al. 2015

Earth and Planetary Science Letters

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Low Frequency Earthquakes (LFEs) are slip events that occur repeatedly at source locations within the lower crust. LFEs, and the associated seismic broadcast known as tremor, have been observed in a diverse array of tectonic environments. Here we develop a suite of statistical tools to conduct a systematic study of the spatial and temporal correlations of the event occurrence patterns of the 88 LFE sources beneath the greater Parkfield section of the San Andreas Fault. We first examine correlations in the occurrence patterns on long time scales to show that the regions to the north and south of Parkfield behave independently. We next use the cumulative event signatures of each source to characterize the individual occurrence patterns on shorter time scales. Through application of a statistical clustering algorithm, we demonstrate that individual LFE sources form spatially coherent clusters that may represent localized elastic structures or asperities on the deep fault interface. We conclude by examining the fine-scale features of the event rates within the LFE occurrence patterns. Through quantitative comparison to analogous laboratory shear experiments on granular, fault gouge-like materials, we infer that the distinctive features of LFE occurrence patterns reflect variations in the insitu stress and frictional conditions at the individual LFE source locations. These observations provide a framework to understand the spatial and temporal diversity of fault slip that occurs within the lower crust beneath Parkfield and that may influence seismic hazard in the region.

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“…Regional‐scale (approximately kilometers) seismological studies have sometimes identified slow, possibly premonitory, phenomena embedded in the main shock seismograms [ Iio , ; Ellsworth and Beroza , ; Beroza and Ellsworth , ]. However, these motions are difficult to detect [e.g., Tullis , ; Johnston et al , ], and whether they are intrinsic to an earthquake is yet unproven [ Olson and Allen , ]. In certain cases, clusters and swarms of small earthquakes and/or foreshocks have been detected weeks to minutes before the eventual main shock [e.g., Mogi , ; Ohnaka , ; Nadeau et al , ; Dodge et al , , ; Ando and Imanishi , ; Bouchon et al , ; Chiaraluce et al , ; Chen and Shearer , ; Govoni et al , ; Tape et al , ].…”

Section: Introductionmentioning

confidence: 99%

Laboratory‐developed contact models controlling instability on frictional faults

Selvadurai

Glaser

2015

JGR Solid Earth

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Laboratory experiments were performed on a polymethyl methacrylate (PMMA)-PMMA frictional interface in a direct shear apparatus in order to gain understanding of fault dynamics leading to gross rupture. Actual asperity sizes and locations along the interface were characterized using a pressure-sensitive film. Slow aseismic slip accumulated nonuniformly along the fault and showed dependency on the applied normal force-increased normal force resulted in higher slip gradients. The slow slip front propagated from the trailing (pushed) edge into a region of more densely distributed asperities at rates between 1 and 9.5 mm/s. Foreshocks were detected and displayed impulsive signals with source radii ranging between 0.21 and 1.09 mm; measurements made using the pressure-sensitive film were between 0.05 and 1.2 mm. The spatiotemporal clustering of foreshocks and their relation to the elastodynamic energy released was dependent on the normal force. In the region where foreshocks occurred, qualitative optical measurements of the asperities along the interface were used to visualize dynamic changes occurring during the slow slip phase. To better understand the nucleation process, a quasi-static asperity finite element (FE) model was developed and focused in the region where foreshocks clustered. The FE model consisted of 172 asperities, located and sized based on pressure-sensitive film measurements. The numerical model provides a plausible explanation as to why foreshocks cluster in space and observed a normal force dependency and lend credence to Ohnaka's nucleation model.

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Continuous Borehole Strain and Pore Pressure in the Near Field of the 28 September 2004 M 6.0 Parkfield, California, Earthquake: Implications for Nucleation, Fault Response, Earthquake Prediction, and Tremor

Cited by 83 publications

References 50 publications

Coupling between mineral reactions, chemical changes in groundwater, and earthquakes in Iceland

Coupling between mineral reactions, chemical changes in groundwater, and earthquakes in Iceland

Synchronous low frequency earthquakes and implications for deep San Andreas Fault slip

Laboratory‐developed contact models controlling instability on frictional faults

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