Slow slip events and the 2016 Te AraroaMw7.1 earthquake interaction: Northern Hikurangi subduction, New Zealand

Koulali, Achraf; McClusky, S.; Wallace, Laura; Allgeyer, S.; Tregoning, Paul; D’Anastasio, E.; Benavente, Roberto

doi:10.1002/2017gl074776

Cited by 27 publications

(31 citation statements)

References 41 publications

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“…Further to the North, at the western edge of the forearc beneath the Raukumara Peninsula, both Qp and Qs are low (100–300), with Qs slightly lower than Qp (Figure 5). This low Q corresponds to the downdip edge of an SSE induced by the coulomb stress change from a M W 7.1 earthquake (Koulali et al., 2017). Although the resolution is limited, Eberhart‐Phillips et al.…”

Section: Discussionmentioning

confidence: 99%

Near Trench 3D Seismic Attenuation Offshore Northern Hikurangi Subduction Margin, North Island, New Zealand

et al. 2021

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We image seismic attenuation near the Hikurangi trench offshore New Zealand, using ocean bottom and land‐based seismometers, revealing high attenuation above a recurring shallow slow‐slip event and within the subducting Hikurangi Plateau. The Hikurangi subduction margin east of the North Island, New Zealand is the site of frequent shallow slow slip events. Overpressured fluids are hypothesized to lead to slow slip at shallow depths close to the oceanic trench. Seismic attenuation, energy loss of seismic waves, can be used to detect high temperatures, melt, the presence of fluids, and fractures. We use local earthquake P‐ and S‐waves from 180 earthquakes to invert for t*, and subsequently invert for Qp and Qs, offshore the North Island directly above the area of slow slip. We image Qp and Qs to ∼25 km depth, increasing resolution of previously identified coastal low Q (100–300), and finding a new region of even higher attenuation (Qp and Qs < 50–100) directly above the shallow slow slip event of 2014–2015, beneath the offshore seismic array. This highest attenuation is downdip of a subducting seamount, and is spatially correlated with a high seismic reflectivity zone and Vp/Vs > 1.85, all of which provide evidence for the presence of fluids. The Qp and Qs is low at the trench (<50–100) and in the subducting plate (100–200), suggesting that seismic wave scattering due to faults, fractures, and the inherent heterogeneous composition of the Hikurangi Plateau, a large igneous province, plays a role in seismic attenuation.

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Section: Discussionmentioning

confidence: 99%

Near Trench 3D Seismic Attenuation Offshore Northern Hikurangi Subduction Margin, North Island, New Zealand

et al. 2021

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“…Different parameterizations of a low‐velocity wedge discussed above lead to similar increases in dynamic‐stressing durations on the plate interface (Figure S11). Enhanced triggering potential provided by such a strong basin effect suggests that slow slip events in the northern Hikurangi might be commonly triggered by regional large ( M >7) earthquakes (Koulali et al, ) including those from the Kermadec‐Tonga subduction zone.…”

Section: Discussionmentioning

confidence: 99%

Ultra‐long Duration of Seismic Ground Motion Arising From a Thick, Low‐Velocity Sedimentary Wedge

et al. 2019

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Sedimentary basins are known to amplify and increase the duration of ground motions that accompany earthquakes. A similar phenomenon is expected, but not as well documented, in low seismic-velocity accretionary prisms along subduction margins. In this study, we report anomalously long duration of long-period ground motions observed in the North Island of New Zealand during seismic wave propagation from the M7.8 Kaikoura earthquake ∼600 km away. Unique waveform data captured by strong-motion, high-rate GPS and ocean bottom pressure sensors reveal that long-period ground motions lasted longer than 450 s in the northeastern North Island. These waveforms indicate one of the longest durations of long-period (>10 s) ground motions ever recorded at similar epicentral distances for comparable, large earthquakes. To understand the underlying mechanism, we use numerical simulations of seismic wave propagation. We find that a velocity model that includes an accretionary prism, modeled as a large-scale (∼30,000 km 2 ) wedge characterized by extremely low seismic wave speeds, can explain the observed long durations of long-period ground motions as the reverberations of seismic waves within the low-velocity wedge. We show that the long duration of long-period ground motions leads to prolonged dynamic stressing on the plate interface, likely accentuating the triggering of slow slip that occurred following the Kaikoura earthquake. Accretionary prisms characterized by extremely low seismic velocities may enhance the generation of tsunami earthquakes and dynamic triggering of slow slip events observed in the northern Hikurangi and other subduction margins.

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“…SSEs are considered important due to their impact on the seismic cycle; however, the exact nature of the relationship between slow slip and seismic slip is unclear. In some cases, SSEs are thought to increase earthquake hazard by loading adjacent fault patches (Kaneko et al, ; Koulali et al, ; Mazzotti & Adams, ; Reyners & Bannister, ; Wech & Creager, ). Earthquakes can also trigger SSEs (Wallace et al, , ) even if the triggering earthquake is small (Han et al, ); conversely, they can also arrest SSEs (Wallace et al, ).…”

Section: Introductionmentioning

confidence: 99%

Observations of Laboratory and Natural Slow Slip Events: Hikurangi Subduction Zone, New Zealand

Ikari

Wallace

Rabinowitz

et al. 2020

Geochem Geophys Geosyst

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Slow slip events (SSEs) are recognized as an important component of plate boundary fault slip, and there is a need for laboratory friction data on natural samples to guide comparisons with natural SSEs. Here, we compile a comprehensive catalog of SSEs observed geodetically at the Hikurangi subduction zone offshore northern New Zealand, and compare it with results of laboratory friction experiments that produce laboratory SSEs under plate tectonic driving rates (5 cm/yr). We use samples from Ocean Drilling Program Site 1124 seaward of the Hikurangi subduction zone to represent the plate boundary that hosts shallow SSEs at Hikurangi. We find that laboratory SSEs exhibit a similar displacement record and range of stress drops as the natural SSEs. Results of velocity step tests, which can be used to evaluate frictional instability based on the critical stiffness criterion, indicate that the slow slip activity at Hikurangi is a form of stably‐accelerating slip. Our laboratory SSEs provide an alternative method of quantifying (in)stability by direct measurement of the unloading stiffness during the stress drop. The observed dependence of laboratory SSE parameters on effective normal stress is consistent with critical stiffness theory; however, depth‐increasing projections based on laboratory data do not match observations from natural SSEs. These differences are likely related to changing temperature and fault rock composition downdip but also complications related to scaling and/or limited sampling. Scientific drilling recently undertaken at the Hikurangi subduction zone should serve to improve and guide future studies of the role of frictional properties for the occurrence of SSEs.

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Slow slip events and the 2016 Te AraroaM_w7.1 earthquake interaction: Northern Hikurangi subduction, New Zealand

Cited by 27 publications

References 41 publications

Near Trench 3D Seismic Attenuation Offshore Northern Hikurangi Subduction Margin, North Island, New Zealand

Near Trench 3D Seismic Attenuation Offshore Northern Hikurangi Subduction Margin, North Island, New Zealand

Ultra‐long Duration of Seismic Ground Motion Arising From a Thick, Low‐Velocity Sedimentary Wedge

Observations of Laboratory and Natural Slow Slip Events: Hikurangi Subduction Zone, New Zealand

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