Microplate Evolution in the Queen Charlotte Triple Junction &amp; Explorer Region: New Insights From Microseismicity

Littel, Geena; Bostock, M. G.; Schaeffer, A. J.; Roecker, S. W.

doi:10.1029/2022tc007494

Cited by 4 publications

(4 citation statements)

References 132 publications

(467 reference statements)

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“…The REST algorithm has been used successfully in other studies involving hypocenter catalog generation (e.g., Comte et al., 2017, 2019, 2023; Lanza et al., 2019; Littel et al., 2023; Merrill et al., 2022; Yarce et al., 2023) but is still a relatively untested procedure and its efficacy has not been extensively documented. In any event, its performance is likely to be somewhat dependent on the specifics of a given data set.…”

Section: Data and Processingmentioning

confidence: 99%

Are Volatiles From Subducted Ridges on the Pampean Flat Slab Fracking the Crust? Evidence From an Enhanced Seismicity Catalog

Maharaj,

Roecker,

Alvarado

et al. 2023

Geochem Geophys Geosyst

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Seamounts and ridges are often invoked to explain subduction‐related phenomena such as flat slab generation, but the extent of their involvement remains controversial. An analysis of seismicity in the region of the Pampean flat slab through an application of an automated catalog generation algorithm resulted in 35,924 well constrained local earthquake hypocenters and a total of 12,172 focal mechanisms. Several new features related to the subduction of the Juan Fernandez Ridge (JFR) were discovered, including (a) a series of parallel lineaments of seismicity in the subducted Nazca plate separated by about 50 km and trending about 20°, and (b) a strong spatial correlation between these deeper (>80 km depth) regions of intense seismicity and concentrations of activity in the crust almost directly above it. Focal mechanisms of the deeper events are almost exclusively (∼81%) normal, while those in the crust are predominantly (∼70%) reverse. The deeper lineaments mirror the orientation and spacing of several seamount chains seen on the Nazca plate, suggesting that these patterns are caused by the same types of features at depth. This would imply that relatively minor features persist as slab anomalies long after they are subducted. The correlation of the deeper seismicity that defines these features with seismicity in the mid to lower crust suggests a genetic relation between the two. We postulate that volatiles from the subducted ridges percolate into the South American crust and induce seismicity essentially by fracking it.

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Section: Data and Processingmentioning

confidence: 99%

Are Volatiles From Subducted Ridges on the Pampean Flat Slab Fracking the Crust? Evidence From an Enhanced Seismicity Catalog

Maharaj,

Roecker,

Alvarado

et al. 2023

Geochem Geophys Geosyst

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“…Farther south, there is a shallow cluster of earthquakes near the Tuzo‐Wilson seamounts (T1 in Figure 2) which Littel et al. (2023) discuss in detail.…”

Section: Resultsmentioning

confidence: 98%

“…Near Moresby Island, we identify three clusters of interest, labeled C1, C2, C3 in Figure 2. Farther south, there is a shallow cluster of earthquakes near the Tuzo-Wilson seamounts (T1 in Figure 2) which Littel et al (2023) discuss in detail.…”

Section: Other Earthquake Clustersmentioning

confidence: 92%

Incipient Subduction and Slip Partitioning at High Obliquity: The Haida Gwaii Plate Boundary

Oliva,

Bostock,

Schaeffer

et al. 2024

JGR Solid Earth

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Plate motion obliquity along the dominantly transform Queen Charlotte plate boundary (QCPB) peaks offshore Haida Gwaii. To investigate the effects of obliquity on plate boundary deformation, we analyze continuous seismic waveforms from temporary and permanent stations from 1998 to 2020 to generate a catalog of ∼50,000 earthquakes across Haida Gwaii. We use an automated technique based on auto‐regressive phase detection and onset estimation to obtain the initial seismic catalog, integrate existing catalogs, invert for 3D velocity structure using data from the best constrained period, and relocate the entire catalog using the new 3D velocity model. We investigate the seismically active sections of the transcurrent Queen Charlotte fault (QCF), noting that little seismicity locates directly along its bathymetrically defined trace. Instead, seismicity illuminates a complex system of segmented structures with variable geometries along strike. Other clusters highlight active shallow faults within the highly deformed Queen Charlotte terrace. Few aftershocks appear on the thrust plane of the 2012 Mw 7.8 Haida Gwaii earthquake except near its inferred intersection with the QCF at 15–20 km depths, suggesting elevated residual stress at the juncture of slip‐partitioning. Deep crustal seismicity (up to ∼20 km depths) beneath central Haida Gwaii aligned parallel to the strike of the thrust plane may represent landward underthrusting of the Pacific plate. Our results suggest possible coseismic strike‐slip rupture on the QCF during the 2012 earthquake and add support to the thesis that highly oblique transform boundaries are viable settings for subduction initiation.

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“…Farther south, there is a shallow cluster of earthquakes near the Tuzo-Wilson seamounts (T1 in Fig. 2) which Littel et al (2023) discuss in detail.…”

Section: Other Earthquake Clustersmentioning

confidence: 90%

A complex Queen Charlotte Plate Boundary offshore Haida Gwaii

Oliva,

Bostock,

Schaeffer

et al. 2023

Preprint

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The Queen Charlotte plate boundary marks a transpressional system between the Pacific and North American plates, extending from offshore Haida Gwaii in Canada into southeastern Alaska. Using continuous seismic waveforms from temporary and permanent seismic networks from 1998–2020, we produced a comprehensive catalog of ~50,000 earthquakes across the region near Haida Gwaii. We used an automated processing technique of auto-regressive phase detection and onset estimation to obtain the initial seismic catalog, integrated existing catalogs, inverted for 3D velocity structure using data from the most well constrained period, and relocated the entire catalog using the new 3D velocity model. We investigate the seismically active sections of the transcurrent Queen Charlotte fault (QCF), noting that little seismicity locates directly along the bathymetrically defined QCF trace. Instead, the seismicity illuminates a complex system of multiple segmented structures, featuring variable geometries along strike. Clustered shallow seismicity could indicate active shallow faults within the highly deformed Queen Charlotte terrace. Few aftershocks appear on the thrust plane of the 2012 Mw 7.8 Haida Gwaii earthquake except near its inferred intersection with the QCF between 15 and 20 km depths, suggesting elevated residual stress. Deep (up to ~20 km) crustal seismicity below central Haida Gwaii aligned parallel to the strike of the thrust plane may manifest the landward underthrusting of the Pacific plate. We also explore the possibility of coseismic strike-slip rupture on the QCF during the 2012 earthquake. Our results provide insights into postseismic strain accommodation and partitioning across this complex oblique transpressive system.

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Microplate Evolution in the Queen Charlotte Triple Junction & Explorer Region: New Insights From Microseismicity

Cited by 4 publications

References 132 publications

Are Volatiles From Subducted Ridges on the Pampean Flat Slab Fracking the Crust? Evidence From an Enhanced Seismicity Catalog

Are Volatiles From Subducted Ridges on the Pampean Flat Slab Fracking the Crust? Evidence From an Enhanced Seismicity Catalog

Incipient Subduction and Slip Partitioning at High Obliquity: The Haida Gwaii Plate Boundary

A complex Queen Charlotte Plate Boundary offshore Haida Gwaii

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