IODP Expedition 340 successfully drilled a series of sites offshore Montserrat, Martinique and Dominica in the Lesser Antilles from March to April 2012. These are among the few drill sites gathered ...around volcanic islands, and the first scientific drilling of large and likely tsunamigenic volcanic island‐arc landslide deposits. These cores provide evidence and tests of previous hypotheses for the composition and origin of those deposits. Sites U1394, U1399, and U1400 that penetrated landslide deposits recovered exclusively seafloor sediment, comprising mainly turbidites and hemipelagic deposits, and lacked debris avalanche deposits. This supports the concepts that i/ volcanic debris avalanches tend to stop at the slope break, and ii/ widespread and voluminous failures of preexisting low‐gradient seafloor sediment can be triggered by initial emplacement of material from the volcano. Offshore Martinique (U1399 and 1400), the landslide deposits comprised blocks of parallel strata that were tilted or microfaulted, sometimes separated by intervals of homogenized sediment (intense shearing), while Site U1394 offshore Montserrat penetrated a flat‐lying block of intact strata. The most likely mechanism for generating these large‐scale seafloor sediment failures appears to be propagation of a decollement from proximal areas loaded and incised by a volcanic debris avalanche. These results have implications for the magnitude of tsunami generation. Under some conditions, volcanic island landslide deposits composed of mainly seafloor sediment will tend to form smaller magnitude tsunamis than equivalent volumes of subaerial block‐rich mass flows rapidly entering water. Expedition 340 also successfully drilled sites to access the undisturbed record of eruption fallout layers intercalated with marine sediment which provide an outstanding high‐resolution data set to analyze eruption and landslides cycles, improve understanding of magmatic evolution as well as offshore sedimentation processes.
Key Points:
First drilling of large and likely tsunamigenic volcanic island‐arc landslides
Distal landslide deposits recovered seafloor sediment (turbidite, hemipelagic)
Debris avalanche emplacement can trigger voluminous seafloor sediment failure
We present here the first study of coral microatolls in the Caribbean. An exceptional site (Belloc reef) where dozens of microatolls were growing was uplifted and exposed during the 12 January 2010 ...Mw 7 Haiti earthquake. Total station measurements of the old pre-earthquake and the new post-earthquake coral highest level of survival (HLS) on two generations of Siderastrea siderea corals allowed us to estimate a value of 45±14cm for the coseismic uplift. In this small 90m×70m reef, microatolls of different shapes (cups, hats or flats) coexist, indicating long term submergence, emergence or stable relative sea-level. This variability in coral shape is uncommon. Two slices of microatolls, one cup-shaped (B8) and one hat-shaped (B10) were sampled with a chain saw and X-rayed to study their stratigraphy. B10 recorded a mean relative sea-level decrease of about −1mm/yr over the last five decades, whereas B8 has grown in a context of relative sea-level rise at a rate of about 1mm/yr over nine decades. Several sudden and temporary die downs simultaneously disrupted the growth of both corals in 1940±2, 1963±2, 1983±2, 1992±1, 2001±1 and 2009 and may be caused by oceanographic/climatic phenomena occurring in the tropical North Atlantic. The last one, in 2009, was associated with a clear sea-level height decrease (about 10cm) in the satellite data. B10 was strongly affected by these events and records die downs of systematically larger amplitude, which tended to delay its upward growth compared to B8. This makes B10 less reliable for the evaluation of the relative sea-level trend, its emergence rate being only an apparent estimate due to die downs. Fossil coral microatolls of Diploria strigosa which died between 1958 and 1966 (according to U/Th dating), probably during one of the strongest hurricane reported in Haiti (Flora, 1963), display a cup shape attesting for submergence. Their HLS is 1cm below the HLS of the S. siderea killed in 2010. The record of B8, the diversity in shape of the S. siderea microatolls and the position of fossil D. strigosa corals overall indicate stable to slightly increasing relative sea-level (about 1mm/yr). This is on the same order of magnitude, although slightly lower, as the rate we determined over the last 74years by using eight tide gauge records around Hispaniola (1.63±0.20mm/yr) and the mean rate of sea-level rise previously published (2.0±0.5mm/yr) in the area. This study demonstrates that coral microatolls can be used to infer relative sea-level changes over the last decades or centuries in the Caribbean, where tide gauge records are often sparse, incomplete or nonexistent. This is of prime importance for the numerous small and flat Caribbean islands, highly vulnerable to the threat of global sea-level rise.
•Coral microatolls can accurately document relative sea-level changes over centuries.•Study of a whole reef instead of one coral colony in a low relative sea-level setting•Uncommon shape variability among coral microatolls in Haiti•First study on coral microatolls in Caribbean•Coseismic uplift due to the 2010 Haitian earthquake estimated with microatolls
Context.
The extensive stellar spectroscopic datasets that are available for studies in Galactic Archeaology thanks to, for example, the
Gaia
-ESO Survey, now benefit from having a significant number ...of targets that overlap with asteroseismology projects such as
Kepler
, K2, and CoRoT. Combining the measurements from spectroscopy and asteroseismology allows us to attain greater accuracy with regard to the stellar parameters needed to characterise the stellar populations of the Milky Way.
Aims.
The aim of this
Gaia
-ESO Survey special project is to produce a catalogue of self-consistent stellar parameters by combining measurements from high-resolution spectroscopy and precision asteroseismology.
Methods.
We carried out an iterative analysis of 90 K2@
Gaia
-ESO red giants. The spectroscopic values of
T
eff
were used as input in the seismic analysis to obtain log
g
values. The seismic estimates of log
g
were then used to re-determine the spectroscopic values of
T
eff
and Fe/H. Only one iteration was required to obtain parameters that are in good agreement for both methods and, thus, to obtain the final stellar parameters. A detailed analysis of outliers was carried out to ensure a robust determination of the parameters. The results were then combined with
Gaia
DR2 data to compare the seismic log
g
with a parallax-based log
g
and to investigate instances of variations in the velocity and possible binaries within the dataset.
Results.
This analysis produced a high-quality catalogue of stellar parameters for 90 red giant stars from K2@
Gaia
-ESO that were determined through iterations between spectroscopy and asteroseismology. We compared the seismic gravities with those based on
Gaia
parallaxes to find an offset which is similar to other studies that have used asteroseismology. Our catalogue also includes spectroscopic chemical abundances and radial velocities, as well as indicators for possible binary detections.
We provide a database of the coseismic geological surface effects following the Mw 6.5 Norcia earthquake that hit central Italy on 30 October 2016. This was one of the strongest seismic events to ...occur in Europe in the past thirty years, causing complex surface ruptures over an area of >400 km
. The database originated from the collaboration of several European teams (Open EMERGEO Working Group; about 130 researchers) coordinated by the Istituto Nazionale di Geofisica e Vulcanologia. The observations were collected by performing detailed field surveys in the epicentral region in order to describe the geometry and kinematics of surface faulting, and subsequently of landslides and other secondary coseismic effects. The resulting database consists of homogeneous georeferenced records identifying 7323 observation points, each of which contains 18 numeric and string fields of relevant information. This database will impact future earthquake studies focused on modelling of the seismic processes in active extensional settings, updating probabilistic estimates of slip distribution, and assessing the hazard of surface faulting.
Grain dietary fiber content in wheat not only affects its end use and technological properties including milling, baking and animal feed but is also of great importance for health benefits. In this ...study, integration of association genetics (seven detected loci on chromosomes 1B, 3A, 3D, 5B, 6B, 7A, 7B) and meta-QTL (three consensus QTL on chromosomes 1B, 3D and 6B) analyses allowed the identification of seven chromosomal regions underlying grain dietary fiber content in bread wheat. Based either on a diversity panel or on bi-parental populations, we clearly demonstrate that this trait is mainly driven by a major locus located on chromosome 1B associated with a log of p value >13 and a LOD score >8, respectively. In parallel, we identified 73 genes differentially expressed during the grain development and between genotypes with contrasting grain fiber contents. Integration of quantitative genetics and transcriptomic data allowed us to propose a short list of candidate genes that are conserved in the rice, sorghum and Brachypodium chromosome regions orthologous to the seven wheat grain fiber content QTL and that can be considered as major candidate genes for future improvement of the grain dietary fiber content in bread wheat breeding programs.
IODP Expedition 340 successfully drilled a series of sites offshore Montserrat, Martinique and Dominica in the Lesser Antilles from March to April 2012. These are among the few drill sites gathered ...around volcanic islands, and the first scientific drilling of large and likely tsunamigenic volcanic island-arc landslide deposits. These cores provide evidence and tests of previous hypotheses for the composition and origin of those deposits. Sites U1394, U1399, and U1400 that penetrated landslide deposits recovered exclusively seafloor sediment, comprising mainly turbidites and hemipelagic deposits, and lacked debris avalanche deposits. This supports the concepts that i/ volcanic debris avalanches tend to stop at the slope break, and ii/ widespread and voluminous failures of preexisting low-gradient seafloor sediment can be triggered by initial emplacement of material from the volcano. Offshore Martinique (U1399 and 1400), the landslide deposits comprised blocks of parallel strata that were tilted or microfaulted, sometimes separated by intervals of homogenized sediment (intense shearing), while Site U1394 offshore Montserrat penetrated a flat-lying block of intact strata. The most likely mechanism for generating these large-scale seafloor sediment failures appears to be propagation of a decollement from proximal areas loaded and incised by a volcanic debris avalanche. These results have implications for the magnitude of tsunami generation. Under some conditions, volcanic island landslide deposits composed of mainly seafloor sediment will tend to form smaller magnitude tsunamis than equivalent volumes of subaerial block-rich mass flows rapidly entering water. Expedition 340 also successfully drilled sites to access the undisturbed record of eruption fallout layers intercalated with marine sediment which provide an outstanding high-resolution data set to analyze eruption and landslides cycles, improve understanding of magmatic evolution as well as offshore sedimentation processes.
The sequencing of individual chromosomes of common wheat is in progress. The molecular size of wheat chromosome 5B is nearly 870 Mb (5BL = 580 Mb and 5BS = 290 Mb). We produced the first low coverage ...454‐sequencing of the long and short arms of wheat chromosome 5B (110,793 and 39,695 reads, which compose 8 and 6% of total 5BL and 5BS length, respectively) and calculated the ratios of the different families of repetitive sequences, including transposable elements (TEs), satellite repeats (Afa, pSc119.2, 5S rDNA and 45S rDNA), and microsatellites, as well as direct and inverted repeat motifs. The TEs accounted for 70% of the total analyzed nucleotide sequences. The content of the Cereba retrotransposon family differed between the two arms of chromosome 5B. Comparing the reads of chromosome 5B with the data from chromosome 5A, we found the retrotransposons Fatima and Sakura and DNA transposon Jorge were prevalent in 5B. The hypothetical coding sequences accounted for 2.0% of the short arm and 2.07% of the long arm. Using in silico mapping, we identified the regions of synteny with rice and Brachypodium chromosomes (1,073,526 and 1,767,298 bp aligned, respectively), and the result was consistent with the data from the expressed sequence tag (EST) mapping of wheat 5B chromosome to the genomes of these grasses. Thus, these results show that low coverage survey sequencing can provide useful information about the composition and evolution of wheat chromosome 5B.
Abstract The SENTINEL study showed that the addition of natalizumab improved outcomes for patients with relapsing multiple sclerosis (MS) who had experienced disease activity while receiving ...interferon beta-1a (IFNβ-1a) alone. Previously unreported secondary and tertiary magnetic resonance imaging (MRI) measures are presented here. Patients received natalizumab 300 mg ( n = 589) or placebo ( n = 582) intravenously every 4 weeks plus IFNβ-1a 30 µg intramuscularly once weekly. Annual MRI scans allowed comparison of a range of MRI end points versus baseline. Over 2 years, 67% of patients receiving natalizumab plus IFNβ-1a remained free of new or enlarging T2-lesions compared with 30% of patients receiving IFNβ-1a alone. The mean change from baseline in T2 lesion volume over 2 years decreased in patients receiving natalizumab plus IFNβ-1a and increased in those receiving IFNβ-1a alone (–277.5 mm3 versus 525.6 mm3 ; p < 0.001). Compared with IFNβ-1a alone, add-on natalizumab therapy resulted in a smaller increase in mean T1-hypointense lesion volume after 2 years (1821.3 mm3 versus 2210.5 mm3 ; p < 0.001), a smaller mean number of new T1-hypointense lesions over 2 years (2.3 versus 4.1; p < 0.001), and a slower rate of brain atrophy during the second year of therapy (–0.31% versus –0.40%; p = 0.020). Natalizumab add-on therapy reduced gadolinium-enhancing, T1-hypointense, and T2 MRI lesion activity and slowed brain atrophy progression in patients with relapsing MS who experienced disease activity despite treatment with IFNβ-1a alone.
Abstract
IODP Expedition 340 successfully drilled a series of sites offshore Montserrat, Martinique and Dominica in the Lesser Antilles from March to April 2012. These are among the few drill sites ...gathered around volcanic islands, and the first scientific drilling of large and likely tsunamigenic volcanic island‐arc landslide deposits. These cores provide evidence and tests of previous hypotheses for the composition and origin of those deposits. Sites U1394, U1399, and U1400 that penetrated landslide deposits recovered exclusively seafloor sediment, comprising mainly turbidites and hemipelagic deposits, and lacked debris avalanche deposits. This supports the concepts that i/ volcanic debris avalanches tend to stop at the slope break, and ii/ widespread and voluminous failures of preexisting low‐gradient seafloor sediment can be triggered by initial emplacement of material from the volcano. Offshore Martinique (U1399 and 1400), the landslide deposits comprised blocks of parallel strata that were tilted or microfaulted, sometimes separated by intervals of homogenized sediment (intense shearing), while Site U1394 offshore Montserrat penetrated a flat‐lying block of intact strata. The most likely mechanism for generating these large‐scale seafloor sediment failures appears to be propagation of a decollement from proximal areas loaded and incised by a volcanic debris avalanche. These results have implications for the magnitude of tsunami generation. Under some conditions, volcanic island landslide deposits composed of mainly seafloor sediment will tend to form smaller magnitude tsunamis than equivalent volumes of subaerial block‐rich mass flows rapidly entering water. Expedition 340 also successfully drilled sites to access the undisturbed record of eruption fallout layers intercalated with marine sediment which provide an outstanding high‐resolution data set to analyze eruption and landslides cycles, improve understanding of magmatic evolution as well as offshore sedimentation processes.
Key Points:
First drilling of large and likely tsunamigenic volcanic island‐arc landslides
Distal landslide deposits recovered seafloor sediment (turbidite, hemipelagic)
Debris avalanche emplacement can trigger voluminous seafloor sediment failure
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