Bernard Pelletier

Bernard Pelletier
Institute of Research for Development | IRD · 082 - GÉOAZUR

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252
Publications
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Publications

Publications (252)
Preprint
The Vanuatu subduction zone (VSZ) is known to be seismically very active, releasing a significant energy resulting of the quick convergence rate between the Australian and Pacific tectonic plates. That is not the case on its southernmost part south of latitude 22.5° S and east of longitude 170° E which is neither known as being highly tectonically...
Article
Full-text available
On 5 December 2018, a magnitude Mw 7.5 earthquake occurred southeast of Maré, an island of the Loyalty Islands archipelago, New Caledonia. This earthquake is located at the junction between the plunging Loyalty Ridge and the southern part of the Vanuatu Arc, in a tectonically complex and very active area regularly subjected to strong seismic crises...
Article
Full-text available
Serpentinization is a natural process that transforms ferromagnesian minerals such as olivine into serpentine and that produces waters at very high pH and gases enriched in methane (CH4) and hydrogen (H2). We report the composition of gases venting at two springs (Bain des Japonais and Rivière des Kaoris) of the serpentinizing environment of the Pr...
Article
Full-text available
(1) Background: The geothermal spring of La Crouen (New Caledonia) discharges warm (42 °C) alkaline water (pH~9) enriched in dissolved nitrogen with traces of methane, but its microbial diversity has not yet been studied. (2) Methods: Cultivation-dependent and -independent methods (e.g., Illumina sequencing and quantitative PCR based on 16S rRNA ge...
Article
A novel anaerobic, alkaliphilic, mesophilic, Gram-stain-positive, endospore-forming bacterium was isolated from an alkaline thermal spring (42 °C, pH 9.0) in New Caledonia. This bacterium, designated strain LB2 T , grew at 25–50 °C (optimum, 37 °C) and pH 8.2–10.8 (optimum, pH 9.5). Added NaCl was not required for growth (optimum, 0–1 %) but was to...
Article
In December 2018, an unusually large intra-and extra-caldera eruption took place at Ambrym volcano (Vanuatu). The eruption drained the volcano's five active lava lakes and terminated, at least momentarily, the surface activity that had been ongoing for decades to hundreds of years, sustaining the largest recorded persistent degassing on the planet....
Article
Full-text available
Neogene and Quaternary shallow-water carbonate records surrounding New Caledonia main island, Grande Terre, provide a good example for understanding the stratigraphic architecture of tropical mixed carbonate-siliciclastic systems. Due to a southeastern tilt of the eastern margin, the eastern shelf of Grande Terre has been better preserved from eros...
Preprint
Full-text available
On the 5th of December 2018, a magnitude Mw 7.5 earthquake occurred southeast of Maré, an island of the Loyalty Archipelago, New Caledonia. This earthquake is located at the junction between the plunging Loyalty ridge and the southernmost Vanuatu arc, in a tectonically very active area regularly subjected to strong seismic crises and events higher...
Research
Full-text available
https://www.dnr.wa.gov/publications/ger_tsuinfo_2021_v23_no1.pdf
Article
The lagoons of seven French Polynesia and Cook Islands pearl farming atolls (Raroia, Takume, Mopelia, Takapoto, Ahe, Takaroa and Manihiki) were surveyed using multibeam and mono-beam sounders. From the detailed bathymetry, morphometric variables (average and maximum depth, frequency-area of depth, lagoon area and volume) are computed and compared....
Article
The SW Pacific region consists of a succession of ridges and basins that were created by the fragmentation of Gondwana and the evolution of subduction zones since Mesozoic times. This complex geodynamic evolution shaped the geology of New Caledonia, which lies in the northern part of the Zealandia continent. Alternative tectonic models have been po...
Article
Full-text available
Eruptive activity shapes volcanic edifices. The formation of broad caldera depressions is often associated with major collapse events, emplacing conspicuous pyroclastic deposits. However, caldera subsidence may also proceed silently by magma withdrawal at depth, more difficult to detect. Ambrym, a basaltic volcanic island, hosts a 12-km wide calder...
Article
Full-text available
Fourteen years ago, the 26 December 2004 Indian Ocean tsunami demonstrated the destructional capability of tsunamis to the entire world. Since then, many research programs have been initiated to try to understand the phenomenon and its related hazards better and to improve the early warning systems for exposed coastal populations. Pacific Islands C...
Preprint
Eruptive activity shapes volcanic edifices. The formation of caldera depressions is often associated with major collapse events, emplacing conspicuous pyroclastic deposits. However, caldera subsidence may also proceed silently by magma withdrawal at depth, more difficult to detect. Ambrym, a basaltic volcanic island, hosts multiple intensely-degass...
Article
Full-text available
The Central Vanuatu forearc is characterized by a reduced convergence rate at the trench, significant uplift of the overriding plate and the presence of large forearc islands. Volcanic activity and intermediate‐depth seismicity behind the forearc are among the highest on Earth. These features are presumed to be associated with the subduction of a l...
Data
The ARC-VANUATU project was conducted between May 2008 and February 2009 using 20 onshore seismometers and 10 OBS. A total of 40,430 events were recorded. Arrivals were picked using an automatic picking routine program (Baillard et al., 2014) and 31,065 events were localized using a 1D velocity model (Baillard et al., 2015). Earthquake locations an...
Poster
Full-text available
At 4:18 UTC on December 5, 2018, New Caledonia, the Loyalty Islands and south Vanuatu have been struck by a powerful Mw 7.5 earthquake which epicenter has been located 168 km ESE of Tadine, Maré, Loyalty Islands. Between 30 and 45 minutes after the shake, a tsunami arrived on the coasts of Maré and Lifou where evacuation of low-lying areas has been...
Presentation
In the past 30 years, magmatic activity at the basaltic volcano of Ambrym (Vanuatu), which hosts a notable 12-km- diameter caldera, has been characterized by strombolian activity restricted to the two (or more) semi-permanent lava lakes. Little is known about the magma plumbing system of this volcano, due to its remote location (lack of instrumenta...
Article
Full-text available
14 years ago, the December 26, 2004 Indian Ocean tsunami brought to the entire World the destruction capability of tsunamis. Since then, many research programs have been initiated to try to better understand the phenomenon and its related hazards, and to improve the early warning systems for the exposed coastal populations. Pacific Islands Countrie...
Book
New Caledonia archipelago is located in the South West Pacific between Australia and the Vanuatu archipelago. The land covers 19,100 km2, and the EEZ and territorial waters extend to 1,450,000 km2. The main island, Grande Terre, is surrounded by a barrier reef of 1100 km length enclosing a large lagoon of 24,000 km2 and up to 60 m deep. The complex...
Poster
Full-text available
The distribution of intermediate-depth seismicity beneath the Vanuatu archipelago (South Pacific Ocean) includes several seismic clusters/alignments and gaps, including a remarkable 200 × 150 km gap beneath central Vanuatu. We show that a zone of enhanced seismicity beneath this gap corresponds to the most likely trace of the subducted D'Entrecaste...
Article
Full-text available
The distribution of intermediate-depth seismicity beneath the Vanuatu archipelago (South Pacific Ocean) includes several seismic clusters/alignments and gaps, including a remarkable 200 × 150 km gap beneath central Vanuatu. We show that a zone of enhanced seismicity beneath this gap corresponds to the most likely trace of the subducted D'Entrecaste...
Conference Paper
The western part of the Central Vanuatu subduction is characterized by the collision with bathymetric asperities of the Australian plate beneath the North-Fiji basin. This leads to the decrease of the convergence rate (from 16 cm/yr to the north to 3.5 cm/yr to the center segment) and to the uplift of the islands forearc (up to 6mm/yr). Collision i...
Poster
Full-text available
ReefTEMPS is a network of temperature, pressure and salinity sensors in the coastal area of the South, West and South-West Pacific, operated by GOPS (South Pacific integrated observatory for the environment, terrestrial and marine biodiversity). One of the initial objectives of the project was to provide different types of interoperable services, e...
Conference Paper
Le réseau Reeftemps de capteurs de température, pression, salinité dans le domaine côtier donne accès à la communauté scientifique au téléchargement (CSV, Netcdf, SOS/json) et à la visualisation (PNG, FS/openlayers, SOS/Highchart) de plus de 35M de mesures formant 160 séries temporelles (la plus ancienne recouvrant 40 années de mesures de températu...
Presentation
Full-text available
Le réseau Reeftemps de capteurs de température, pression, salinité dans le domaine côtier donne accès à la communauté scientifique au téléchargement (CSV, Netcdf, SOS/json) et à la visualisation (PNG, WFS/openlayers, SOS/Highchart) de plus de 35M de mesures formant 160 séries temporelles (la plus ancienne recouvrant 40 années de mesures de températ...
Article
New Caledonia's Loyalty Islands are located in the southwest region of the Pacific ocean in the highly seismogenic southern Vanuatu subduction zone and therefore may be subject to devastating local tsunamis. Over the past 150 years, two large tsunamis were triggered by major earthquakes on March 28th 1875 and September 20th 1920. In this study, we...
Article
Full-text available
Despite their potential importance as analogs of primitive microbial metabolisms, the knowledge of the structure and functioning of the deep ecosystems associated with serpentinizing environments is hampered by the lack of accessibility to relevant systems. These hyperalkaline environments are depleted in dissolved inorganic carbon (DIC), making th...
Article
ReefTEMPS est un réseau de capteurs de température, pression et salinité dans le domaine côtier du Pacifique Sud, Ouest et Sud-Ouest, opéré par le GOPS (Grand Observatoire de l'environnement et de la biodiversité terrestre et marine du Pacifique Sud). Un des objectifs initiaux du projet était de fournir différents types de services interopérables a...
Conference Paper
The 1 400 km long Vanuatu subduction zone marks the subduction of the oceanic Australia plate beneath the North-Fijian microplate. Seismic and volcanic activity is high, and several morphologic features enter into subduction, affecting seismicity and probably plate coupling. The Northern d'Entrecasteaux Ridge, West-Torres plateau, and Bougainville...
Conference Paper
Full-text available
The 1400-km long Vanuatu subduction zone results from subduction of the oceanic Australian plate (OAP) beneath the North-Fijian microplate (NFM). Seismic and volcanic activity are both high, and several morphologic features enter into subduction, affecting seismicity and probably plate coupling. The Entrecasteaux Ridge, West-Torres plateau, and Bou...
Conference Paper
Full-text available
Le réseau de capteurs Le réseau d’observation ReefTEMPS a pour objectifs 1/ de mesurer des paramètres physico chimiques sur le domaine côtier des différents états insulaires du Pacifique Sud, Sud- Ouest et Ouest (Polynésie française, Cook, Tonga, Wallis et Futuna, Samoa, Tokelau, Kiribati, Nauru, Etats Fédérés de Micronésie, Palau, Yap, Iles Salomo...
Article
Full-text available
High amounts of hydrogen are emitted in the serpentinite-hosted hydrothermal field of the Prony Bay (PHF, New Caledonia), where high-pH (~11), low-temperature (<40°C) and low-salinity fluids are discharged in both intertidal and shallow submarine environments. In this study, we investigated the diversity and distribution of potentially hydrogen-pro...
Article
Full-text available
High amounts of hydrogen are emitted in the serpentinite-hosted hydrothermal field of the Prony Bay (PHF, New Caledonia), where high-pH (~11), low-temperature (<40°C) and low-salinity fluids are discharged in both intertidal and shallow submarine environments. In this study, we investigated the diversity and distribution of potentially hydrogen-pro...
Article
Full-text available
A novel anaerobic, alkaliphilic, Gram-positive, spore-forming bacterium was isolated from a carbonaceous hydrothermal chimney in the Prony Bay, New Caledonia. This bacterium designated strain 3bT grew at temperatures from 30 to 43 °C (optimum 37°C) and at pH between 7.8 and 10.1 (optimum 9.5). Added NaCl was not required for growth (optimum 0-0.2%)...
Conference Paper
Full-text available
The Middle – Late Pleistocene (~1.2 – 0.125 Ma) climate is characterized by the intensification of cyclic oscillations between glacial (cool, low sea level) and interglacial (warm, high sea level) intervals. The fossil record, preserving a long-term dataset of coral reef communities composed of extant species, reveals that reef corals have persiste...
Article
We report the first helium isotope survey of volcanic gases, hot springs and some olivine phenocrysts along the Vanuatu island arc, from Tanna in the south to Vanua Lava in the north. Low CO2 content and low He-3/He-4 ratios in thermal fluids of Epi (4.0 +/- 0.1 R-a), Efate (4.5 +/- 0.1 R-a) and Pentecost (5.3 +/- 0.5 R-a) islands coherently indica...
Article
Ambrym volcano, in the Vanuatu arc, is one of the most active volcanoes of the Southwest Pacific region, where persistent lava lake and/or Strombolian activity sustains voluminous gas plume emissions. Here we report on the first comprehensive budget for the discharge of major, minor, trace and radioactive volatile species from Ambrym volcano, as we...
Poster
New Caledonia is located in the South West Pacific Ocean, on the Australian Plate just before its subduction under the North Fiji Basin. Because it is on the subducting side of the plate interface, New Caledonia is considered to be stable to first order and not to undergo rapid deformation. However, moderate seismicity is recorded close to the plat...
Article
Full-text available
Active carbonate chimneys from the shallow marine serpentinizing Prony Hydrothermal Field were sampled 3 times over a 6 years period at site ST09. Archaeal and bacterial communities composition was investigated using PCR-based methods (clone libraries, Denaturating Gel Gradient Electrophoresis, quantitative PCR) targeting 16S rRNA genes, methyl coe...
Article
Full-text available
New geophysical data acquired during three expeditions of the R/V Southern Surveyor in the southern part of the North Fiji Basin allow us to characterize the deformation of the upper plate at the southern termination of the New Hebrides subduction zone, where it bends eastward along the Hunter Ridge. Unlike the northern end of the Tonga subduction...
Article
Full-text available
We investigated the tsunami hazard in the remote French territory of Wallis and Futuna, Southwest Pacific, using the Gerris flow solver to produce numerical models of tsunami generation, propagation and inundation. Wallis consists of the inhabited volcanic island of Uvéa that is surrounded by a lagoon delimited by a barrier reef. Futuna and the isl...
Article
The Vanuatu Arc in the southwest Pacific Ocean is one of the world's most seismically active regions, with almost 39 magnitude 7+ earthquakes in the past 43 years. Convergence rates are around 90–120 mm/yr along most of the arc, but drop to 25–43 mm/yr in the central section, probably due to the subduction of the d'Entrecasteaux ridge. We character...
Poster
Full-text available
ReefTEMPS est un réseau de capteurs de température des eaux côtières de différents états insulaires du Pacifique Sud et Sud-Ouest pour le suivi à long terme du changement climatique et de ses effets sur l’état des récifs coralliens et de leurs ressources. Le système d’information SI-TEC-PSO permet la gestion et la valorisation de ces données d’obse...