Structural Inheritance Control on Intraplate Present‐Day Deformation: GPS Strain Rate Variations in the Saint Lawrence Valley, Eastern Canada

Tarayoun, Alizia; Mazzotti, S.; Craymer, M.; Henton, J. A.

doi:10.1029/2017jb015417

Cited by 26 publications

(39 citation statements)

References 56 publications

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“…Liu and Stein () argue that weakening from rifting is neither necessary nor sufficient for intraplate deformation based on observed seismicity in the NMSZ and north China. Recent quantitative analysis suggests, however, that structural inheritance from past tectonic cycles observed in the Saint Lawrence Valley in eastern Canada is an important factor in driving present‐day intraplate deformation, where the strain rate can be 2 to 11 times higher than the surrounding region (Tarayoun et al, ). This latter study assumes that no other process contributes to observed high deformation rates.…”

Section: Discussionmentioning

confidence: 99%

Interacting Intraplate Fault Systems in Australia: The 2012 Thorpdale, Victoria, Seismic Sequences

Attanayake

Sandiford

Schleicher³

et al. 2019

JGR Solid Earth

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Using a new seismic waveform data set, we locate 234 earthquakes and estimate source parameters (focal mechanisms, magnitude, and stress drop) of the two largest earthquakes (E1 and E2) in the 2012 seismic sequence in Thorpdale, Victoria. The focal mechanisms suggest thrust faulting, consistent with previous observations in southeast Australia. The estimated magnitudes are M w 4.9 ± 0.14 (E1) and 4.3 ± 0.1 (E2). The estimates of stress drop 57 ± 7.4 MPa (E1) and 28 ± 2.4 MPa (E2) reflect strength of faults in an intraplate environment. By analyzing spatiotemporal distribution of aftershocks, we show that E1 and E2 reflect two separate seismic sequences about a month apart. E1 and E2 ruptured two adjacent faults with orientations 218°/78°/78°(Fault 1) and 134°/27°/171°(Fault 2), respectively, where angles indicate strike/dip/slip rake. To test causal mechanism of fault interaction, we performed Coulomb stress modeling, which shows very weak unloading of E2 by E1. Thus, we infer that fault interaction might instead reflect remotely triggered fluid diffusion. Also, a local rotation of the stress field proceeding E1 might have favorably reoriented Fault 2 for failure. Finally, we identify an apparent correlation between high heat flow and seismicity in southeastern Australia, suggesting a combination of mechanisms including transient stress perturbations and lithospheric thermal weakening associated with high heat flow as the principal factors localizing intraplate seismicity.Plain Language Summary The 2012 earthquake sequence in Thorpdale is the most recent and significant seismic activity in southeast Australia, during which two moderate-sized earthquakes were felt in the region with the second earthquake thought to be an aftershock of the first. Using a newly assembled data set, we estimate source parameters of these earthquakes and locate 232 smaller earthquakes associated with this seismic sequence. In this study, we show that faults ruptured with thrust motion, the moment magnitude of the two largest earthquakes are 4.9 and 4.3, and the stress release per fault length (57 and 28 MPa) is larger than the global average. By locating aftershocks, we also show that the two largest earthquakes ruptured two separate faults rather than one. The absence of any plausible Coulomb stress loading suggests that these different faults interacted with each other through other mechanisms such as a fluid diffusion. Key Points:• The two largest earthquakes (M w 4.9 and 4.3) in the seismic sequence indicate thrust faulting in southeast Australia • Higher than average stress drop (57 and 28 MPa) suggests the rupture of strong faults with longer recurrence intervals • Adjacent fault planes ruptured, implying fault interaction through interplay between stress conditions and fluid diffusion Supporting Information:• Supporting Information S1

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Section: Discussionmentioning

confidence: 99%

Interacting Intraplate Fault Systems in Australia: The 2012 Thorpdale, Victoria, Seismic Sequences

Attanayake

Sandiford

Schleicher³

et al. 2019

JGR Solid Earth

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“…Because of their sporadic and sparse point density, campaign time series are not amenable to noise model estimation and computation of formal uncertainties. There is no standard method for estimating campaign velocity uncertainty, but most of them rely scaling based on the nearby continuous GNSS sites (Tarayoun et al, 2018;Beavan et al, 2016;Reilinger et al, 2006). In this study, we use synthetic time series constructed from permanent-station parameters (Masson et al, 2019) to 30 generate synthetic campaign time series with the Alps and Pyrenees campaign characteristics (dates and number of surveys).…”

Section: Campaign Datamentioning

confidence: 99%

“…The Global Navigation Satellite System (GNSS) is a primary dataset to study present-day crustal deformation, for example through the computation of strain rate tensors, both in active tectonics areas (e.g., Indonesia or Greece; Gunawan et al,20 2019; Chousianitis et al, 2015) and in very low deformation areas (e.g., Eastern Canada or India; Tarayoun et al, 2018;Banerjee et al, 2008). However, the analysis of regional and local deformation is commonly restricted by several factors, such as the precision of individual GNSS velocities, the presence of non-tectonic transient signals or the methods used to compute strain rates on different spatial scales (e.g., Cardozo et al, 2009;Zhu et al, 2011;Carafa and Bird, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…However, the analysis of regional and local deformation is commonly restricted by several factors, such as the precision of individual GNSS velocities, the presence of non-tectonic transient signals or the methods used to compute strain rates on different spatial scales (e.g., Cardozo et al, 2009;Zhu et al, 2011;Carafa and Bird, 2016). In particular, the precision of individual GNSS velocities is a strong limitation in intraplate regions, where the amplitude of the 25 tectonic signal is of the same order of magnitude as the measurement uncertainties (e.g., Calais and Stein, 2009;Tarayoun et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

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Extracting small deformation beyond individual station precision from dense GNSS networks in France and Western Europe

Masson

Mazzotti

Vernant

et al. 2019

Preprint

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Abstract. We use dense geodetic networks and large GPS datasets to extract regionally coherent velocities and deformation rates in France and neighboring Western Europe. This analysis is combined with statistical tests on synthetic data to quantify the deformation detection thresholds and significance levels. By combining two distinct methods, Gaussian smoothing and k-means clustering, we extract horizontal deformations with a 95% confidence level ca. 0.1–0.2 mm yr−1 (ca. 0.5–1 × 10-9 yr−1) on spatial scales of 100–200 km or more. From these analyses, we show that the regionally average velocity and strain rate fields are statistically significant in most of our study area. The first order deformation signal in France and neighboring Western Europe is a belt of N-S to NE-SW shortening ca. 0.2–0.4 mm yr−1 (1–2 × 10−9 yr−1) in central and eastern France. In addition to this large-scale signal, patterns of orogen-normal extension are observed in the Alps and the Pyrenees, but methodological biases, mainly related to GPS solution combinations, limit the spatial resolution and preclude associations with specific geological structures. The patterns of deformation in western France show either tantalizing correlation (Brittany) or anti-correlation (Aquitaine Basin) with the seismicity. Overall, more detailed analyses are required to address the possible origin of these signals and the potential role of aseismic deformation.

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“…In geodynamic GPS applications, failure to take offsets into account can have major consequences. For example, Thomas et al (2011) estimated velocities of about 2.1 mm yr −1 lower than those of Argus et al (2011), leading to very different interpretations of the data for estimating uplift rates in East Antarctica. Multiple automatic methods exist for offset detection in GPS position time series, but their reliability is limited.…”

Section: Introductionmentioning

confidence: 97%

Precision of continuous GPS velocities from statistical analysis of synthetic time series

2019

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Abstract. We use statistical analyses of synthetic position time series to estimate the potential precision of GPS (Global Positioning System) velocities. The synthetic series represent the standard range of noise, seasonal, and position offset characteristics, leaving aside extreme values. This analysis is combined with a new simple method for automatic offset detection that allows an automatic treatment of the massive dataset. Colored noise and the presence of offsets are the primary contributor to velocity variability. However, regression tree analyses show that the main factors controlling the velocity precision are first the duration of the series, second the presence of offsets, and third the noise level (dispersion and spectral index). Our analysis allows us to propose guidelines, which can be applied to actual GPS data, that constrain velocity precisions, characterized as a 95 % confidence limit of the velocity biases, based on simple parameters: (1) series durations over 8.0 years result in low-velocity biases in the horizontal (0.2 mm yr−1) and vertical (0.5 mm yr−1) components; (2) series durations of less than 4.5 years are not suitable for studies that require precisions lower than mm yr−1; (3) series of intermediate durations (4.5–8.0 years) are associated with an intermediate horizontal bias (0.6 mm yr−1) and a high vertical one (1.3 mm yr−1), unless they comprise no offset. Our results suggest that very long series durations (over 15–20 years) do not ensure a significantly lower bias compared to series of 8–10 years, due to the noise amplitude following a power-law dependency on the frequency. Thus, better characterizations of long-period GPS noise and pluri-annual environmental loads are critical to further improve GPS velocity precisions.

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Structural Inheritance Control on Intraplate Present‐Day Deformation: GPS Strain Rate Variations in the Saint Lawrence Valley, Eastern Canada

Cited by 26 publications

References 56 publications

Interacting Intraplate Fault Systems in Australia: The 2012 Thorpdale, Victoria, Seismic Sequences

Interacting Intraplate Fault Systems in Australia: The 2012 Thorpdale, Victoria, Seismic Sequences

Extracting small deformation beyond individual station precision from dense GNSS networks in France and Western Europe

Precision of continuous GPS velocities from statistical analysis of synthetic time series

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