Automated detection and location of tectonic tremor along the entire Cascadia margin from 2005 to 2011

Boyarko, D. C.; Brudzinski, M. R.; Porritt, R. W.; Allen, R. M.; Tréhu, A. M.

doi:10.1016/j.epsl.2015.06.026

Cited by 18 publications

(31 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Brudzinski and Allen [] further suggested that the effects of locking on megathrust asperities can transmit to deeper fault where ETS appears. Boyarko et al [] have also reported the along‐strike nonvolcanic tremor segmentation is related with megathrust asperities. These studies suggest that both the source properties of megathrust seismic and ETS zones are largely affected by the overlying continent.…”

Section: Discussionmentioning

confidence: 99%

“…Gravity anomalies along the margin may represent the loading of the overlying continental plate, which may influence the source parameters of ETS [ Brudzinski and Allen , ]. Studies of marine sediments in fore‐arc basins [ Wells et al , ; Goldfinger et al , ] also indicate that offshore paleoearthquake “patches” could affect the along‐strike tremor segmentation in Cascadia [ Boyarko et al , ]. These observations suggest a relation between shallow and deep fault slip, which may help to investigate the faulting mechanism in subduction zones.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Modeling slow‐slip segmentation in Cascadia subduction zone constrained by tremor locations and gravity anomalies

Liu

2017

JGR Solid Earth

View full text Add to dashboard Cite

Along‐strike segmentation of slow‐slip events (SSEs) and nonvolcanic tremors in Cascadia may reflect heterogeneities of the subducting slab or overlying continental lithosphere. However, the nature behind this segmentation is not fully understood. We develop a 3‐D model for episodic SSEs in northern and central Cascadia, incorporating both seismological and gravitational observations to constrain the heterogeneities in the megathrust fault properties. The 6 year automatically detected tremors are used to constrain the rate‐state friction parameters. The effective normal stress at SSE depths is constrained by along‐margin free‐air and Bouguer gravity anomalies. The along‐strike variation in the long‐term plate convergence rate is also taken into consideration. Simulation results show five segments of ∼Mw6.0 SSEs spontaneously appear along the strike, correlated to the distribution of tremor epicenters. Modeled SSE recurrence intervals are equally comparable to GPS observations using both types of gravity anomaly constraints. However, the model constrained by free‐air anomaly does a better job in reproducing the cumulative slip as well as more consistent surface displacements with GPS observations. The modeled along‐strike segmentation represents the averaged slip release over many SSE cycles, rather than permanent barriers. Individual slow‐slip events can still propagate across the boundaries, which may cause interactions between adjacent SSEs, as observed in time‐dependent GPS inversions. In addition, the moment‐duration scaling is sensitive to the selection of velocity criteria for determining when SSEs occur. Hence, the detection ability of the current GPS network should be considered in the interpretation of slow earthquake source parameter scaling relations.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modeling slow‐slip segmentation in Cascadia subduction zone constrained by tremor locations and gravity anomalies

Liu

2017

JGR Solid Earth

View full text Add to dashboard Cite

show abstract

“…The largest ETS zone in Cascadia is immediately landward from a paleoseismic asperity (Goldfinger et al, 2008;Song & Simons, 2003;Wells et al, 2003), and marine sediments studies in the forearc basins also indicate that offshore paleoseismic "patches" could affect the along-strike segmentation of tremors in Cascadia (Boyarko et al, 2015). The largest ETS zone in Cascadia is immediately landward from a paleoseismic asperity (Goldfinger et al, 2008;Song & Simons, 2003;Wells et al, 2003), and marine sediments studies in the forearc basins also indicate that offshore paleoseismic "patches" could affect the along-strike segmentation of tremors in Cascadia (Boyarko et al, 2015).…”

Section: Compositional Changes Of the Upper Geological Terranementioning

confidence: 98%

Segmentation of Slow Slip Events in South Central Alaska Possibly Controlled by a Subducted Oceanic Plateau

Wei

et al. 2018

JGR Solid Earth

View full text Add to dashboard Cite

Recent GPS observations show that slow slip events in south central Alaska are segmented along strike. Here we review several mechanisms that might contribute to this segmentation and focus on two: along‐strike variation of slab geometry and effective normal stress. We then test them by running numerical simulations in the framework of rate‐and‐state friction with a nonplanar fault geometry. Results show that the segmentation is most likely related to the along‐strike variation of the effective normal stress on the fault plane caused by the Yakutat Plateau. The Yakutat Plateau could affect the effective normal stress by either lowering the pore pressure in Upper Cook Inlet due to less fluids release or increasing the normal stress due to the extra buoyancy caused by the subducted Yakutat Plateau. We prefer the latter explanation because it is consistent with the relative amplitudes of the effective normal stress in Upper and Lower Cook Inlet and there is very little along‐strike variation in Vp/Vs ratio in the fault zone from receiver function analysis. However, we cannot exclude the possibility that the difference in effective normal stress results from along‐strike variation of pore pressure due to the uncertainties in the Vp/Vs estimates. Our work implies that a structural anomaly can have a long‐lived effect on the subduction zone slip behavior and might be a driving factor on along‐strike segmentation of slow slip events.

show abstract

“…For instance, if the main event has an along-dip width of 50 or 75 km, not 60 km as we have assumed, the main event peak slip will be 20% larger or smaller. Observed along-dip tremor extents are mostly between 50 and 60 km [e.g., Wech et al, 2009;Houston et al, 2011;Bostock et al, 2012;Armbruster et al, 2014;Royer and Bostock, 2014;Boyarko et al, 2015], while geodetic along-dip extents reach about 75 km [Szeliga et al, 2008;Wech et al, 2009;Schmidt and Gao, 2010]. Similarly, if the lengths and widths of the RTRs are a factor of 1.4 larger or smaller than we have estimated, as would seem a limiting scenario for most RTRs given the tremor locations [Royer et al, 2015 and see supporting information Figures S19-S52], the RTR peak slips will be a factor of 2 smaller or larger.…”

Section: Slipmentioning

confidence: 99%

Variations in slow slip moment rate associated with rapid tremor reversals in Cascadia

Hawthorne

Bostock

Royer

et al. 2016

Geochem Geophys Geosyst

View full text Add to dashboard Cite

During large slow slip events, tremor sometimes propagates in the reverse along‐strike direction for a few hours, at speeds 10 to 40 times faster than the forward propagation. We examine the aseismic slip that underlies this rapidly propagating tremor. We use PBO (Plate Boundary Observatory) borehole strainmeter data to search for variations in the slow slip moment rate during 35 rapid tremor reversals (RTRs) that occurred beneath Vancouver Island. The strain records reveal that, on average, the strain rate increases by about 100% ( ±30%) during RTRs. Given the Green's functions expected for slip in the RTR locations, these strain rate increases imply 50 to 130% increases in the aseismic moment rate. The median moment released per RTR is between 8 and 21% of the daily slow slip moment, equivalent to that of a MW 5.0 to 5.1 earthquake. By combining the RTR moments with the spatial extents suggested by tremor, we estimate that a typical RTR has peak slip of roughly one‐sixth of the peak slip in the main slow slip event, near‐front slip rate of a few to ten times the main front slip rate, stress drop around half the main event stress drop, and strain energy release rate around one‐tenth that of the main front. Our observations support a picture of RTRs as aseismic subevents with high slip rates but modest strain energy release. RTRs appear to contribute to but not dominate the overall slow slip moment, though they may accommodate most of the slip in certain locations.

show abstract

Automated detection and location of tectonic tremor along the entire Cascadia margin from 2005 to 2011

Cited by 18 publications

References 45 publications

Modeling slow‐slip segmentation in Cascadia subduction zone constrained by tremor locations and gravity anomalies

Modeling slow‐slip segmentation in Cascadia subduction zone constrained by tremor locations and gravity anomalies

Segmentation of Slow Slip Events in South Central Alaska Possibly Controlled by a Subducted Oceanic Plateau

Variations in slow slip moment rate associated with rapid tremor reversals in Cascadia

Contact Info

Product

Resources

About