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  • 1
    Publication Date: 2020-12-23
    Description: Slow slip events (SSEs) at the northern Hikurangi subduction margin, New Zealand, are among the best-documented shallow SSEs on Earth. International Ocean Discovery Program Expedition 375 was undertaken to investigate the processes and in situ conditions that underlie subduction zone SSEs at the northern Hikurangi Trough by (1) coring at four sites, including an active fault near the deformation front, the upper plate above the high-slip SSE sourc e region, and the incoming sedimentary succession in the Hikurangi Trough and atop the Tūranganui Knoll Seamount, and (2) installing borehole observatories in an active thrust near the deformation front and in the upper plate overlying the slow slip source region. Logging-while-drilling (LWD) data for this project were acquired as part of Expedition 372 (26 November 2017-4 January 2018; see th e Expedition 372 Preliminary Report for further details on the LWD acquisition program). Northern Hikurangi subduction margin SSEs recur every 1-2 years and thus provide an ideal opportunity to monitor deformation and associated changes in chemical and physical properties throughout the slow slip cycle. Sampling of material from the sedimentary section and oceanic basement of the subducting plate reveals the rock properties, composition, lithology, and structural character of material that is transported downdip into the SSE source region. A recent seafloor geodetic experiment raises the possibility that SSEs at northern Hikurangi may propagate all the way to the trench, indicating that the shallow thrust fault zone targeted during Expedition 375 may also lie in the SSE rupture area. Hence, sampling at this location provides insights into the composition, physical properties, and architecture of a shallow fault that may host slow slip. Expedition 375 (together with the Hikurangi subduction LWD component of Expedition 372) was designed to address three fundamental scientific objectives: (1) characterize the state and composition of the incoming plate and shallow plate boundary fault near the trench, which comprise the protolith and initial conditions for fault zone rock at greater depth and which may itself host shallow slow slip; (2) characterize material properties, thermal regime, and stress conditions in the upper plate above the core of the SSE source region; and (3) install observatories at an active thrust near the deformation front and in the upper plate above the SSE source to measure temporal variations in deformation, temperature, and fluid flow. The observatories will monitor volumetric strain (via pore pressure as a proxy) and the evolution of physical, hydrological, and chemical properties throughout the SSE cycle. Together, the coring, logging, and observatory data will test a suite of hypotheses about the fundamental mechanics and behavior of SSEs and their relationship to great earthquakes along the subduction interface.
    Type: Report , NonPeerReviewed
    Format: text
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  • 2
    Publication Date: 2019-09-23
    Description: Slow slip events (SSEs) at the northern Hikurangi subduction margin, New Zealand, are among the best-documented shallow SSEs on Earth. International Ocean Discovery Program Expeditions 372 and 375 were undertaken to investigate the processes and in situ conditions that underlie subduction zone SSEs at the northern Hikurangi Trough. We accomplished this goal by (1) coring and geophysical logging at four sites, including penetration of an active thrust fault (the Pāpaku fault) near the deformation front, the upper plate above the SSE source region, and the incoming sedimentary succession in the Hikurangi Trough and atop the Tūranganui Knoll seamount; and (2) installing borehole observatories in the Pāpaku fault and in the upper plate overlying the slow slip source region. Logging-while-drilling (LWD) data for this project were acquired as part of Expedition 372, and coring, wireline logging, and observatory installations were conducted during Expedition 375. Northern Hikurangi subduction margin SSEs recur every 1–2 y and thus provide an ideal opportunity to monitor deformation and associated changes in chemical and physical properties throughout the slow slip cycle. In situ measurements and sampling of material from the sedimentary section and oceanic basement of the subducting plate reveal the rock properties, composition, lithology, and structural character of material that is transported downdip into the SSE source region. A recent seafloor geodetic experiment raises the possibility that SSEs at northern Hikurangi may propagate to the trench, indicating that the shallow thrust fault (the Pāpaku fault) targeted during Expeditions 372 and 375 may also lie in the SSE rupture area and host a portion of the slip in these events. Hence, sampling and logging at this location provides insights into the composition, physical properties, and architecture of a shallow fault that may host slow slip. Expeditions 372 and 375 were designed to address three fundamental scientific objectives: Characterize the state and composition of the incoming plate and shallow fault near the trench, which comprise the protolith and initial conditions for fault zone rock at greater depth and which may itself host shallow slow slip; Characterize material properties, thermal regime, and stress conditions in the upper plate directly above the SSE source region; and Install observatories in the Pāpaku fault near the deformation front and in the upper plate above the SSE source to measure temporal variations in deformation, temperature, and fluid flow. The observatories will monitor volumetric strain (via pore pressure as a proxy) and the evolution of physical, hydrological, and chemical properties throughout the SSE cycle. Together, the coring, logging, and observatory data will test a suite of hypotheses about the fundamental mechanics and behavior of SSEs and their relationship to great earthquakes along the subduction interface.
    Type: Article , NonPeerReviewed
    Format: archive
    Format: archive
    Format: other
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  • 3
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    Texas A&M Univ.
    In:  In: Creeping Gas Hydrate Slides. Proceedings of the International Ocean Discovery Program, 372A . Texas A&M Univ., College Station, TX, pp. 1-40.
    Publication Date: 2021-08-17
    Description: International Ocean Discovery Program (IODP) Site U1517(proposed Site TLC-04B) is located at 38°49.772ʹS, 178°28.557ʹE inthe extensional, creeping part of the Tuaheni Landslide Complex(TLC) (Figure F1; see Figure F2 in the Expedition 372A summarychapter [Barnes et al., 2019a]) (Mountjoy et al., 2014b). HoleU1517A was drilled in a water depth of 725 meters below sea level(mbsl); Holes U1517B and U1517C lie at 720 mbsl. The primarydrilling objective was to log and sample through the landslide massand the gas hydrate stability zone to understand the mechanismsbehind creeping. Therefore, we planned to log the sediment columnto 205 meters below seafloor (mbsf ) using logging-while-drilling(LWD) tools, followed by advanced piston corer (APC) coring, pres-sure coring, and temperature dual pressure probe (T2P) deploy-ments.
    Type: Book chapter , NonPeerReviewed
    Format: text
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  • 4
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    Texas A&M Univ.
    In:  In: Creeping Gas Hydrate Slides. Proceedings of the International Ocean Discovery Program, 372A . Texas A&M Univ., College Station, TX, pp. 1-11.
    Publication Date: 2021-08-17
    Type: Book chapter , NonPeerReviewed
    Format: text
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  • 5
    Publication Date: 2015-12-19
    Description: Aims It remains controversial whether cardiovascular magnetic resonance imaging with gadolinium only enhances acutely infarcted or also salvaged myocardium. We hypothesized that enhancement of salvaged myocardium may be due to altered extracellular volume (ECV) and contrast kinetics compared with normal and infarcted myocardium. If so, these mechanisms could contribute to overestimation of acute myocardial infarction (AMI) size. Methods and results Imaging was performed at 1.5T ≤ 7 days after AMI with serial T 1 mapping and volumetric early (5 min post-contrast) and late (20 min post-contrast) gadolinium enhancement imaging. Infarcts were classified as transmural (〉75% transmural extent) or non-transmural. Patients with non-transmural infarctions ( n = 15) had shorter duration of symptoms before reperfusion ( P = 0.02), lower peak troponin ( P = 0.008), and less microvascular obstruction ( P 〈 0.001) than patients with transmural infarcts ( n = 22). The size of enhancement at 5 min was greater than at 20 min (18.7 ± 12.7 vs. 12.1 ± 7.0%, P = 0.003) in non-transmural infarctions, but similar in transmural infarctions (23.0 ± 10.0 vs. 21.9 ± 9.9%, P = 0.21). ECV of salvaged myocardium was greater than normal (39.5 ± 5.8 vs. 24.1 ± 3.1%) but less than infarcted myocardium (50.5 ± 6.0%, both P 〈 0.001). In kinetic studies of non-transmural infarctions, salvaged and infarcted myocardium had similar T 1 at 4 min but different T 1 at 8–20 min post-contrast. Conclusion The extent of gadolinium enhancement in AMI is modulated by ECV and contrast kinetics. Image acquisition too early after contrast administration resulted in overestimation of infarct size in non-transmural infarctions due to enhancement of salvaged myocardium.
    Print ISSN: 1525-2167
    Electronic ISSN: 1532-2114
    Topics: Medicine
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  • 6
    Publication Date: 2015-02-10
    Description: Determining the association between adipokine expression in multiple tissues and phenotypic features of non-alcoholic fatty liver disease in obesity Nutrition & Diabetes 5, e146 (February 2015). doi:10.1038/nutd.2014.43 Authors: M G M Wolfs, N Gruben, S S Rensen, F J Verdam, J W Greve, A Driessen, C Wijmenga, W A Buurman, L Franke, L Scheja, D P Y Koonen, R Shiri-Sverdlov, T W van Haeften, M H Hofker & J Fu
    Electronic ISSN: 2044-4052
    Topics: Medicine
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  • 7
    Publication Date: 2016-08-09
    Description: Background: Evidence for treating hypertension in patients with asymptomatic aortic valve stenosis is scarce. We used data from the SEAS trial (Simvastatin Ezetimibe in Aortic Stenosis) to assess what blood pressure (BP) would be optimal. Methods: A total of 1767 patients with asymptomatic aortic stenosis and no manifest atherosclerotic disease were analyzed. Outcomes were all-cause mortality, cardiovascular death, heart failure, stroke, myocardial infarction, and aortic valve replacement. BP was analyzed in Cox models as the cumulative average of serially measured BP and a time-varying covariate. Results: The incidence of all-cause mortality was highest for average follow-up systolic BP ≥160 mm Hg (4.3 per 100 person-years; 95% confidence interval [CI], 3.1–6.0) and lowest for average systolic BP of 120 to 139 mm Hg (2.0 per 100 person-years; 95% CI, 1.6–2.6). In multivariable analysis, all-cause mortality was associated with average systolic BP 〈120 mm Hg (hazard ratio [HR], 3.4; 95% CI, 1.9–6.1), diastolic BP ≥90 mm Hg (HR, 1.8; 95% CI, 1.1–2.9), and pulse pressure 〈50 mm Hg (HR, 1.8; 95% CI, 1.1–2.9), with systolic BP of 120 to 139 mm Hg, diastolic BP of 70 to 79 mm Hg, and pulse pressure of 60 to 69 mm Hg taken as reference. Low systolic and diastolic BPs increased risk in patients with moderate aortic stenosis. With a time-varying systolic BP from 130 to 139 mm Hg used as reference, mortality was increased for systolic BP ≥160 mm Hg (HR, 1.7; P =0.033) and BP of 120 to 129 mm Hg (HR, 1.6; P =0.039). Conclusions: Optimal BP seems to be systolic BP of 130 to 139 mm Hg and diastolic BP of 70 to 90 mm Hg in these patients with asymptomatic aortic stenosis and no manifest atherosclerotic disease or diabetes mellitus. Clinical Trial Registration: URL: http://www.clinicaltrials.gov . Unique identifier: NCT00092677.
    Keywords: Valvular Heart Disease, High Blood Pressure, Mortality/Survival
    Electronic ISSN: 1524-4539
    Topics: Medicine
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  • 8
    Publication Date: 2016-09-14
    Description: We present a detailed palaeomagnetic study from 35 sites on Holocene lava flows of the Tongariro Volcanic Centre, central North Island, New Zealand. Prior to the study the eruption ages of these flows were constrained to within a few thousand years by recently published high-precision 40 Ar/ 39 Ar geochronological data and tephrostratigraphic controls. Correlation of flow mean palaeomagnetic directions with a recently published continuous sediment record from Lake Mavora, Fiordland, allows us to reduce the age uncertainty to 300–500 yr in some cases. Our refined ages significantly improve the chronology of Holocene effusive eruptions of the volcanoes of the Tongariro Volcanic Centre. For instance, differences in the palaeomagnetic directions recorded by lavas from the voluminous Iwikau and Rangataua members suggest that individual effusive periods lasted up to thousands of years and that these bursts have been irregularly spaced over time. While over the last few millennia the effusive eruptive activity from Mt Ruapehu has been relatively quiet, the very young age (200–500 BP) of a Red Crater sourced flow suggests that effusive activity around Mt Tongariro lasted into the past few centuries. This adds an important hazard context to the historical record, which has otherwise comprised frequent relatively small, tephra producing, explosive eruptions without the production of lava flows.
    Keywords: Geomagnetism, Rock Magnetism and Palaeomagnetism
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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