Characteristics on fault coupling along the Solomon megathrust based on GPS observations from 2011 to 2014

Kuo, Yu‐Ting; Ku, Cheng-Yuan; Chen, Yue‐Gau; Wang, Yu; Lin, Yunung Nina; Chuang, R. Y.; Hsu, Ya‐Ju; Taylor, Frederick W.; Huang, Bor‐Shouh; Tung, Hsin

doi:10.1002/2016gl070188

Cited by 4 publications

(2 citation statements)

References 46 publications

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“…The Solomon Island forearc occupies an 800 km long segment of the Australia-Pacific plate boundary in the southwest Pacific Ocean (Mann et al, 1998;Cowley et al, 2004;Kuo et al, 2016). Formed of a collage of crustal units, the islands are surrounded by deep ocean floor and sit on an uplifted tectonic block (Figure 1).…”

Section: Geological Backgroundmentioning

confidence: 99%

“…The convergence direction along this segment is oblique, with the Australian Plate subducting along the San Cristobal Trench at 93 mm/yr (Figure 1). As a consequence, the Guadalcanal -Makira segment can be effected by large megathrust earthquakes along the trench and has experienced a number of Mw > 7.0 earthquakes, including an Mw 7.9 earthquake on the 30th April 1939 (Thirumalai et al, 2015;Kuo et al, 2016). In addition, the region experiences frequent lower magnitude seismicity along the subduction zone interface and in the upper plate (Figure 1).…”

Section: Geological Backgroundmentioning

confidence: 99%

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Geomorphic Response to Differential Uplift: River Long Profiles and Knickpoints From Guadalcanal and Makira (Solomon Islands)

Boulton

2020

Front. Earth Sci.

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Knickpoints have long been recognized as key geomorphic features that can be used to reveal the landscape evolution of a region. In particular, mobile knickpoints resulting from relative base-level fall record a landscape in the process of change and can encode information about the timing and rate of landscape response. Here, digital elevation model analysis is undertaken to; (a) identify topographic lineaments related to active faulting, and (b) extract geomorphic metrics and document associated knickpoints for rivers on Guadalcanal and Makira (San Cristobal) part of the Solomon Island chain. These islands have been experiencing uplift of up to 2 mm/year since at least the mid Holocene on the upper (Pacific) plate of the San Cristobal Trench of the Solomon Island Forearc. For Guadalcanal, 23 out of 53 studied rivers exhibit slopebreak knickpoints, characteristic of base-level fall, and 27 new topographic lineaments with ∼E-W orientation are identified. By contrast, on Makira 14 of 41 studied rivers have slope-break knickpoints, where the rivers are steeper below the knickpoint than above. In addition, 76 new lineaments are inferred, trending NE-SW and likely to be extensional faults. For both Guadalcanal and Makira there is a good correlation between knickpoint elevation/catchment area and distance upstream from the sea, and a weak correlation between relief and knickpoint elevation. There are no clear relationships between the knickpoints and the new topographic lineaments. These data indicate that both islands are undergoing active river incision caused by regional tectonic uplift along an active subduction zone. On Makira, river steepness (k sn) scales with uplift, and K, coefficient of erosion, is in the range 1 × 10 −5-7 × 10 −6 m 0.1 yr −1 , while K can be estimated as 1 × 10 −5-5 × 10 −8 m 0.1 yr −1 for Guadalcanal. Calculation of K for steady-state rivers demonstrates a rock strength control on the fluvial response and highlights the importance of lithology on river evolution. Furthermore, the distinct landscape response of the two islands supports the hypothesis that there are different arc segments present along the Solomon Arc and suggests that the Holocene uplift rates for Guadalcanal may not be representative of long-term uplift.

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Section: Geological Backgroundmentioning

confidence: 99%

Section: Geological Backgroundmentioning

confidence: 99%

Geomorphic Response to Differential Uplift: River Long Profiles and Knickpoints From Guadalcanal and Makira (Solomon Islands)

Boulton

2020

Front. Earth Sci.

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Seismic velocity structure beneath the Western Solomon Islands from the joint inversion of receiver functions and surface-wave dispersion curves

Kuo

Huang

et al. 2020

Journal of Asian Earth Sciences

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PSHA of the southern Pacific Islands

Johnson

Pagani

Styron

2020

Geophysical Journal International

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Summary The southern Pacific Islands region is highly seismically active, and includes earthquakes from four major subduction systems, seafloor fracture zones and transform faults, and other sources of crustal seismicity. Since 1900, the area has experienced >350 earthquakes of M > 7.0, including 11 of M ≥ 8.0. Given the elevated threat of earthquakes, several probabilistic seismic hazard analyses have been published for this region or encompassed subregions; however, those that are publicly accessible do not provide complete coverage of the region using homogeneous methodologies. Here, we present a probabilistic seismic hazard model for the southern Pacific Islands that comprehensively covers the Solomon Islands in the northwest to the Tonga islands in the southeast. The seismic source model accounts for active shallow crustal seismicity with seafloor faults and gridded smoothed seismicity, subduction interfaces using faults with geometries defined based on geophysical datasets and models, and intraslab seismicity modelled by a set of ruptures that occupy the slab volume. Each source type is assigned occurrence rates based on sub-catalogues classified to each respective tectonic context. Subduction interface and crustal fault occurrence rates also incorporate a tectonic component based on their respective characteristic earthquakes. We demonstrate the use of non-standard magnitude-frequency distributions to reproduce the observed occurrence rates. For subduction interface sources, we use various versions of the source model to account for epistemic uncertainty in factors impacting the maximum magnitude earthquake permissible by each source, varying the interface lower depth and segmentation as well as the magnitude scaling relationship used to compute the maximum magnitude earthquake and subsequently its occurrence rate. The ground motion characterisation uses a logic tree that weights three ground motion prediction equations for each tectonic region. We compute hazard maps for 10% and 2% probability of exceedance in 50 years on rock sites, discussing the regional distribution of peak ground acceleration and spectral acceleration with a period of 1.0 s, honing in on the hazard curves and uniform hazard spectra of several capital or populous cities and drawing comparisons to other recent hazard models. The results reveal that the most hazardous landmasses are the island chains closest to subduction trenches, as well as localised areas with high rates of seismicity occurring in active shallow crust. We use seismic hazard disaggregation to demonstrate that at selected cities located above subduction zones, the PGA with 10% probability of exceedance in 50 years is controlled by Mw > 7.0 subduction interface and intraslab earthquakes, while at cities far from subduction zones, Mw < 6.5 crustal earthquakes contribute most. The model is used for southern Pacific Islands coverage in the Global Earthquake Model Global Hazard Mosaic.

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Characteristics on fault coupling along the Solomon megathrust based on GPS observations from 2011 to 2014

Cited by 4 publications

References 46 publications

Geomorphic Response to Differential Uplift: River Long Profiles and Knickpoints From Guadalcanal and Makira (Solomon Islands)

Geomorphic Response to Differential Uplift: River Long Profiles and Knickpoints From Guadalcanal and Makira (Solomon Islands)

Seismic velocity structure beneath the Western Solomon Islands from the joint inversion of receiver functions and surface-wave dispersion curves

PSHA of the southern Pacific Islands

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