Composite Megathrust Rupture From Deep Interplate to Trench of the 2016 Solomon Islands Earthquake

Lee, Shiann‐Jong; Lin, Te-Hsien; Feng, Kuan‐Fu; Liu, Ting‐Yu

doi:10.1002/2017gl076347

Cited by 9 publications

(8 citation statements)

References 24 publications

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“…To correct for static coseismic displacements at our sites due to regional large earthquakes (e.g., Banerjee et al, 2005;Tregoning et al, 2013), we used STATIC1D (Pollitz, 1996) to calculate the surface displacement at each site due to static elastic interactions from planar dislocations in a spherical layered half-space with PREM elastic stratification (Dziewonski & Anderson, 1981), representing fault slip in the 2007 M w 8.1 Solomon Islands earthquake and all M w 6.9 + earthquakes from 2009 to July 2018 (Hayes, 2017;Lay et al, 2017;Lee et al, 2018;Strasser et al, 2010;F. W. Taylor et al, 2008;U.S.…”

Section: Gps Data and Velocitiesmentioning

confidence: 99%

Mechanical Implications of Creep and Partial Coupling on the World's Fastest Slipping Low-angle Normal Fault in Southeastern Papua New Guinea

Biemiller

Boulton

Wallace

et al. 2020

Preprint

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We use densely spaced campaign GPS observations and laboratory friction experiments on fault rocks from one of the world's most rapidly slipping low-angle normal faults, the Mai'iu fault in Papua New Guinea, to investigate the nature of interseismic deformation on active low-angle normal faults. GPS velocities reveal 8.3 ± 1.2 mm/year of horizontal extension across the Mai'iu fault, and are fit well by dislocation models with shallow fault locking (above 2 km depth), or by deeper locking (from ~5-16 km depth) together with shallower creep. Laboratory friction experiments show that gouges from the shallowest portion of the fault zone are predominantly weak and velocity-strengthening, while fault rocks deformed at greater depths are stronger and velocity-weakening. Evaluating the geodetic and friction results together with geophysical and microstructural evidence for mixed-mode seismic and aseismic slip at depth, we find that the Mai'iu fault is most likely strongly locked at depths of ~5-16 km and creeping updip and downdip of this region. Our results suggest that the Mai'iu fault and other active low-angle normal faults can slip in large (M w > 7) earthquakes despite near-surface interseismic creep on frictionally stable clay-rich gouges. Plain Language SummaryIn regions of extension, where tectonic plates pull apart, the Earth's crust breaks along fractures, or "normal faults", that allow parts of the crust to slip past each other. Many of these faults intersect the Earth's surface at a steep angle, but some anomalously low-angle normal faults are oriented at a shallower angle to the surface. Faults can slip during infrequent fast earthquakes or through slower gradual fault creep. Because active low-angle normal faults are rare and typically have low long-term slip-rates, it is not clear whether they cause large earthquakes or creep gradually. Using two approaches, this study addresses whether earthquakes occur on one of the fastest-slipping of these types of faults, the Mai'iu fault in Papua New Guinea. One approach uses GPS measurements to track patterns of displacement of the Earth's surface near the Mai'iu fault over 3 years. Surface displacements confirm that the Mai'iu fault slips actively and are used to constrain models of fault slip at depth. The second approach uses laboratory experiments on rocks from the Mai'iu fault zone to test whether these rocks tend to slip unstably in earthquakes, or creep stably under conditions similar to those in the fault zone. Laboratory results show that rocks from the shallowest parts of the fault tend to creep stably, while deeper fault rocks tend to slip unstably. Combining laboratory, geological, and GPS results to map slip behaviors to different fault zone depths, we find that the Mai'iu fault most likely creeps near the Earth's surface but can generate larger earthquakes at greater depths.

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Section: Gps Data and Velocitiesmentioning

confidence: 99%

Mechanical Implications of Creep and Partial Coupling on the World's Fastest Slipping Low-angle Normal Fault in Southeastern Papua New Guinea

Biemiller

Boulton

Wallace

et al. 2020

Preprint

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“…Other multiplets ruptured a single segment, such as those beneath Guadalcanal in 1977 (Wesnouski et al., 1986). The 2016 Mw 7.9 earthquake west of Buka was not a multiplet, but was itself a composite event whose source‐time function shows that it ruptured asperities in three separate depth ranges, starting from 100 km up to the trench axis (Lee et al., 2017). Three magnitude M ≥ 7.2 earthquakes occurred in 1926, one each under west Guadalcanal and Makira, and the largest at the intersection of the Itina Trough with the SCT (Figure 4; Newman et al., 2011).…”

Section: Primary Datamentioning

confidence: 99%

“…Lay and Kanamori (1980) were the first to point out the quarter century recurrence interval of the NBT trench corner, which increases to ∼35 and 40–45 years for south Bougainville and Makira, respectively (Figure 4). Since the 2007 earthquake, sequentially adjoining segments ruptured in the 2010 Mw 7.1 tsunami earthquake adjacent to Rendova and Tetepare (Newman et al., 2011), the 2015 Bougainville sequence, and the 2016 Mw 7.9 earthquake west of Buka (Lee et al., 2017). The SCT also ruptured adjacent to Makira in the 2014 and 2016 earthquakes (Figure 4).…”

Section: Primary Datamentioning

confidence: 99%

Oceanic Plateau and Spreading Ridge Subduction Accompanying Arc Reversal in the Solomon Islands

Taylor,

Benyshek

2024

Geochem Geophys Geosyst

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We study the collision of the Ontong Java Plateau, reversal of the Solomon Islands arc, and subduction of the Woodlark Basin spreading ridge in the southwest Pacific. Double‐sided subduction and intra‐arc deformation, not just polarity reversal, characterize the rapid Australia‐Pacific plate convergence. The rifted margins of the 0–6.2‐Ma Woodlark Basin separate its unflexed young lithosphere without a trench from the older flexed lithosphere with >8‐km‐deep trenches subducting to either side. A gap evident in the seismicity and tomography between the NE‐subducted slabs of the Solomon Sea and Australia plates indicates that the Woodlark lithosphere likely melts and/or is quickly (<1 m.y.) resorbed into the mantle. A section of the Pacific Plate remains attached within the gap and provides the slab pull to form the Malaita accretionary prism. Quaternary arc‐composition volcanoes that occur on both sides of the Woodlark Basin subduction front are not sourced from a mantle wedge overlying a Wadati‐Benioff zone, but come from and through breaks in the young incoming and subducting lithosphere and the overturning mantle beneath. Though the basin is too weak to sustain plate flexure, arc volcanoes on the subducting crust result in locally strong coupling to the forearc, manifest by tsunamigenic earthquakes. At 150–400‐km depth, the subducted slabs under the Solomon Islands are near vertical. They are near‐horizontal between the 410 and 660‐km mantle discontinuities beneath the Woodlark Basin and further south, whereas beneath the Solomon Sea Basin they dip southwest and penetrate the 660‐km discontinuity, having been detached by the north‐dipping Solomon Sea slab.

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“…One new event (2002 Papua New Guinea) with shallow slip occurred in a region with no deep trench, giving a total of three such cases (cyan). Two new events have moderately high RMS_C/P but uncertain slip models; 17 December 2016 Solomon Islands (e.g., Lay et al, ; https://earthquake.usgs.gov/earthquakes/search/; Lee et al, ) and 5 May 2015 Papua New Guinea (e.g., Ye et al, ; https://earthquake.usgs.gov/earthquakes/search/), giving three such cases. The two new events involve initially deep ruptures (the 2016 Solomon Islands event likely begins as an intraplate rupture) that propagate or trigger updip, and while the finite‐fault models do suggest that some slip may extend to near the trench, the resolution is limited and the amount of shallow slip varies among the finite‐fault models.…”

Section: Rms Coda Measures For Interplate Thrust Eventsmentioning

confidence: 99%

Enhancing Tsunami Warning UsingPWave Coda

2019

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Most large tsunamis are generated by earthquakes on offshore plate boundary megathrusts.The primary factors influencing tsunami excitation are the seismic moment, faulting geometry, and depth of the faulting. Efforts to provide rapid tsunami warning have emphasized seismic and geodetic methods for quickly determining the event size and faulting geometry. It remains difficult to evaluate the updip extent of rupture, which has significant impact on tsunami excitation. Teleseismic P waves can constrain this issue; slip under deep water generates strong pwP water reverberations that persist as ringing P coda after the direct P phases from the faulting have arrived. Event-averaged P coda /P amplitude measures at large epicentral distances (>80°), tuned to the dominant periods of deep water pwP (~12-15 s), correlate well with independent models of whether slip extends to near the trench or not. Data at closer ranges (30°to 80°) reduce the time lag needed for inferring the updip extent of rupture to <15 min. Arrival of PP and PPP phases contaminates closer distance P coda measures, but this can be suppressed by azimuthal or distance binning of the measures. Narrowband spectral ratio measures and differential magnitude measures of P coda and direct P (m B ) perform comparably to broader band root-mean-square (RMS) measures. P coda /P levels for large nonmegathrust events are also documented. Rapid measurement of P coda /P metrics after a large earthquake can supplement quick moment tensor determinations to enhance tsunami warnings; observation of large P coda levels indicates that shallow submarine rupture occurred and larger than typical tsunami (for given M W ) can be expected. Key Points:• Teleseismic P coda amplitude generated by water reverberations (pwP) increases relative to the direct P for shallow slip under deep water • Measurement of high or low P coda /P ratios in the distance range from 30°t o 80°can reliably identify events with or without shallow slip • Tsunami warning for subduction zone thrust earthquakes can be improved by rapidly measuring P coda to constrain the updip extent of slip Supporting Information:• Supporting Information S1• Figure Bundle S1• Figure Bundle S2

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Composite Megathrust Rupture From Deep Interplate to Trench of the 2016 Solomon Islands Earthquake

Cited by 9 publications

References 24 publications

Mechanical Implications of Creep and Partial Coupling on the World's Fastest Slipping Low-angle Normal Fault in Southeastern Papua New Guinea

Mechanical Implications of Creep and Partial Coupling on the World's Fastest Slipping Low-angle Normal Fault in Southeastern Papua New Guinea

Oceanic Plateau and Spreading Ridge Subduction Accompanying Arc Reversal in the Solomon Islands

Enhancing Tsunami Warning UsingPWave Coda

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