Active oceanic spreading in the northern north Fiji basin : results of the NOFI cruise of R/V l'Atalante (Newstarmer project)

The South Pandora and the Tripartite Ridges are active spreading centers located in the northern part of the North Fiji Basin. These spreading centers were surveyed over a distance of 750 km during the NOFI cruise of R/V L'Atalante (August-September 1994) which was conducted in the frame of the french-japanese Newstarmer cooperation project. SIMRAD EM12-dual full coverage swath bathymetric and imagery data as well as airgun 6-channel seismic, magnetics and gravity profiles were recorded along an off-axis from 170°40'E to 178°E. Dredging and piston coring were also performed along and off-axis. The axial domain of the South Pandora Ridge is divided into 5 first-order segments characterized by contrasted morphologies. The average width of the active domain is 20 km and corresponds either to bathymetric highs or to deep elongated grabens. The bathymetric highs are volcanic constructions, locally faulted and rifted, which can obstruct totally the axial valley. The grabens show the typical morphology of slow spreading axes, with two steep walls flanking a deep axial valley. Elongated lateral ridges may be present on both sides of the grabens. Numerous volcanoes, up to several kilometers in diameter, occur on both flanks of the South Pandora Ridge. The Tripartite Ridge consists of three main segments showing a sigmoid shape. Major changes in the direction of the active zones are observed at the segment discontinuities. These discontinuities show various geometrical patterns which suggest complex transform relay zones. Preliminary analysis of seismic reflection profiles suggest that the Tripartite Ridge is a very young feature which propagates into an older oceanic domain characterized by a significant sedimentary cover. By contrast, a very thin to absent sedimentary cover is observed about 100 km on both flanks of the South Pandora Ridge active axis. The magnetic anomaly profiles give evidence of long and continuous lineations, parallel to the South Pandora Ridge spreading axis. (Résumé d'auteur

Topographic and Bathymetric Effects on the Seismic Response of the Nice Bay Region, France

The eastern part of the French Mediterranean coast represents a moderate but sustained seismogenic region. This area comprises both the Alpine Arc and the Liguria See geological provinces. In the last half century, destructive earthquakes with intensities ranging between VII and IX have been experienced several times. Among them, the biggest earthquake registered in France during the XX century in 1963 of magnitude Ml=6.0. Nice, one of the biggest cities in France lies in this region, between the see and the Maritime Alps Mountains which reach about 600 m of altitude in only 10 km from the coast. Such an abrupt morphology of the Earth's surface goes under the see and describes scarped depressions in the bathymetry becoming deep quickly. As a consequence, we have relief of about 1200 m along a small region of about 400 km2. To assess the effect on the seismic response of both the Earth's surface and its interaction with the see water, we performed numerical simulations for different earthquakes scenarios in the Nice region by applying a partly-staggered finite-difference approach. Comparisons with semi-analytical solutions in heterogeneous media containing a superficial water layer validate our numerical approach. Peak-velocities and accelerations maps were determined as a function of the dominant frequencies of source spectrum. Continental wavefield scattering is induced by topography for frequencies higher than ~0.8 Hz. Trapped waves in the water column acts as a sustained energy supplier which strongly affects the see bottom ground-motion

Triggering factors and tsunamogenic potential of a large submarine mass failure on the western Nile margin (Rosetta area, Egypt)

A large-scale mass-transport deposit (MTD) called Sl6 was recognized on the upper slope of the western Nile margin, downslope from of a 30 km-long scarp located along the outer shelf. Regional mapping indicated that this MTD extends on nearly 505 km2 and involved about 14 km3 of Pleistocene-Holocene sediment. Sl6 was triggered between 10 and 9 kyr BP, during the Holocene sea-level rise and coeval pluvial period (increased river flow). The consequent enhanced sediment supply on the upper slope and the outer shelf area caused local overburdening. This factor combined with the potential accumulation of gas in the sediment and earthquake activity is thought to have been the main factor triggering the Sl6 MTD. From the estimated volume of the MTD, a potential slide-generated tsunami was numerically simulated using the GEOWAVE software. The results indicate that the ~80 km wide Egyptian continental shelf protects the main part of the coastline from a slide-induced tsunami coming from the Rosetta area. An exception is the part of the coastline around Alexandria because focussing and shoaling processes can be simulated very close to the coast

Segmentation d'une dorsale océanique en domaine arrière-arc : l'axe d'accrétion Sud Pandora - Tripartite (bassin Nord-Fidjien) : résultats de la campagne NOFI de l'Atalante

La campagne NOFI du NIO L'Atalante (Programme franco-japonais NEW STARMER, 25 août - 19 septembre, 1994), avait pour objectif l'étude bathymétrique et géophysique des axes d'accrétion dans la partie septentrionale du bassin arrière-arc nord-fidjien. Les dorsales actives "Sud Pandora" et "Tripartite", orientées de N75 à N110, ont été cartographiées à l'aide du sondeur multifaisceaux SIMRAD EM12-dual, de 171°E à 178°E et de 13°S à 15°S. L'axe actif des dorsales est découpé en segments de 80 à 120 km de long, présentant des caractères morphologiques très variés; il s'agit soit d'un graben parfois occupé par une ride néovolcanique ou obstrué par un volcan, soit d'un puissant dôme volcanique allongé. Les segments sont décalés de 10 à 30 km par des zones de relais de natures variées (décalages simples, "OSC", propagateurs, ...). La dorsale Sud Pandora fonctionne au moins depuis 3 Ma, tandis que la dorsale Tripartite est une structure très récente se propageant au sein d'une croûte plus ancienne jusqu'à 178°E, où elle disparaît. Bien que ressemblant aux centres d'accrétion des grands océans, ce système actif se distingue par l'absence de véritables failles transformantes et par sa position orthogonale à la fois au système central N-S d'accrétion du bassin nord-fidjien et à la frontière convergente des Nouvelles Hébrides. (Résumé d'auteur

Active oceanic spreading in the northern north Fiji basin : results of the NOFI cruise of R/V l'Atalante (Newstarmer project)

The South Pandora and the Tripartite Ridges are active spreading centers located in the northern part of the North Fiji Basin. These spreading centers were surveyed over a distance of 750 km during the NOFI cruise of R/V L'Atalante (August-September 1994) which was conducted in the frame of the french-japanese Newstarmer cooperation project. SIMRAD EM12-dual full coverage swath bathymetric and imagery data as well as airgun 6-channel seismic, magnetics and gravity profiles were recorded along an off-axis from 170°40'E to 178°E. Dredging and piston coring were also performed along and off-axis. The axial domain of the South Pandora Ridge is divided into 5 first-order segments characterized by contrasted morphologies. The average width of the active domain is 20 km and corresponds either to bathymetric highs or to deep elongated grabens. The bathymetric highs are volcanic constructions, locally faulted and rifted, which can obstruct totally the axial valley. The grabens show the typical morphology of slow spreading axes, with two steep walls flanking a deep axial valley. Elongated lateral ridges may be present on both sides of the grabens. Numerous volcanoes, up to several kilometers in diameter, occur on both flanks of the South Pandora Ridge. The Tripartite Ridge consists of three main segments showing a sigmoid shape. Major changes in the direction of the active zones are observed at the segment discontinuities. These discontinuities show various geometrical patterns which suggest complex transform relay zones. Preliminary analysis of seismic reflection profiles suggest that the Tripartite Ridge is a very young feature which propagates into an older oceanic domain characterized by a significant sedimentary cover. By contrast, a very thin to absent sedimentary cover is observed about 100 km on both flanks of the South Pandora Ridge active axis. The magnetic anomaly profiles give evidence of long and continuous lineations, parallel to the South Pandora Ridge spreading axis. (Résumé d'auteur

Pediatric Acute Promyelocytic Leukemia: Epidemiology, Molecular Features, and Importance of GST-Theta 1 in Chemotherapy Response and Outcome.

Previous studies have suggested a variation in the incidence of acute promyelocytic leukemia (APL) among the geographic regions with relatively higher percentages in the Latin American population. We aimed to explore the population burden of pediatric APL, gathering information from the population-based cancer registry (PBCR) and the diagnosis of APL obtained through incident cases from a hospital-based cohort. The homozygous deletion in glutathione S-transferases (GSTs) leads to a loss of enzyme detoxification activity, possibly affecting the treatment response. Mutations in the RAS pathway genes are also considered to be a key component of the disease both in the pathogenesis and in the outcomes. We have assessed mutations in a RAS-MAP kinase pathway (FLT3, PTPN11, and K-/NRAS) and GST variant predisposition risk in the outcome. Out of the 805 children and adolescents with acute myeloid leukemia (AML) who are registered in the PBCR, 35 (4.3%) were APL cases. The age-adjusted incidence rate (AAIR) was 0.03 per 100,000 person-years. One-hundred and sixty-three patients with APL were studied out of 931 AML cases (17.5%) from a hospital-based cohort. Mutations in FLT3, KRAS, and NRAS accounted for 52.1% of the cases. Patients with APL presented a 5-year probability of the overall survival (OS) of 67.3 ± 5.8%. A GST-theta 1 (GSTT1) null genotype conferred adverse prognosis, with an estimated hazard ratio of 2.8, 95% confidence interval (CI) 1.2-6.9. We speculate that the GSTT1 polymorphism is associated with therapeutics and would allow better OS of patients with APL with a GSTT1 null genotype