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Due to challenges involved in mapping the seafloor at high‐resolution (e.g., < 2 m), data are lacking to understand processes that control the evolution of submarine normal fault scarps, which cover large parts of the global seafloor. Here, we use data from autonomous deep‐sea vehicles to quantify local erosion and deposition associated with a pronounced tectonic surface scarp formed by slip on the submarine Roseau normal fault (Lesser Antilles). We use high‐resolution video imagery, photomosaics, and high‐resolution bathymetry data (0.1–10 m/pixel) to identify active erosional features on the scarp including channels, steep gullies, small scarps, and debris cones. We compare volumes of erosion and deposition and find that under certain depositional conditions, debris cones effectively record the erosion signal of mass wasting from the footwall with a ratio of hanging wall deposition to footwall erosion of 0.80. We use eroded volumes to estimate earthquake‐induced landslide erosion rates for the Roseau fault of 14–46 m Ma‐1. Assuming mass wasting of the Roseau fault scarp is mostly coseismic, the erosion rates for the Roseau fault imply that submarine earthquake induced mass‐wasting can occur at similar rates to various terrestrial lithological and tectonic settings. We present a process‐based model of submarine scarp degradation via retrogressive erosion in basement lithology where scarps have a gravitational stability threshold height of 20–40 m and a long‐term average slope of 30–40°. More generally, the results presented here may be applicable to develop models of submarine landscape evolution based on degradation of normal fault scarps on the seafloor.
Alex Hughes; Javier Escartín; Jean‐Arthur Olive; Jeremy Billant; Christine Deplus; Nathalie Feuillet; Frédérique Leclerc; Luca Malatesta. Quantification of Gravitational Mass Wasting and Controls on Submarine Scarp Morphology Along the Roseau Fault, Lesser Antilles. Journal of Geophysical Research: Earth Surface 2021, 126, 1 .
AMA StyleAlex Hughes, Javier Escartín, Jean‐Arthur Olive, Jeremy Billant, Christine Deplus, Nathalie Feuillet, Frédérique Leclerc, Luca Malatesta. Quantification of Gravitational Mass Wasting and Controls on Submarine Scarp Morphology Along the Roseau Fault, Lesser Antilles. Journal of Geophysical Research: Earth Surface. 2021; 126 (4):1.
Chicago/Turabian StyleAlex Hughes; Javier Escartín; Jean‐Arthur Olive; Jeremy Billant; Christine Deplus; Nathalie Feuillet; Frédérique Leclerc; Luca Malatesta. 2021. "Quantification of Gravitational Mass Wasting and Controls on Submarine Scarp Morphology Along the Roseau Fault, Lesser Antilles." Journal of Geophysical Research: Earth Surface 126, no. 4: 1.
On 30 October 2020 11:51 UTC a large Mw = 7.0 earthquake occurred offshore of the island of Samos, Greece. In this contribution we present the characteristics of the seismic fault (location, geometry, geodetic moment) as inferred from the processing of geodetic data (InSAR and GNSS). We use the InSAR displacement data from Sentinel-1 interferograms (ascending orbit 29 and descending 36) and the GNSS offsets from eleven (11) permanent stations in Greece and Turkey to invert for the fault parameters. Our inversion modeling indicates the activation of a normal fault north of Samos with a length of 32 km, width of 17 km, average slip of 2.1 m, a moderate dip-angle (37°) and with a dip-direction towards North. The inferred fault is located adjacent to Samos northern coastline, with the top of the slip ~1 km below surface, and ~2 km off-shore at its closest to the island. The earthquake caused the permanent uplift of the island up to 10 cm with the exception of a coastal strip along the NE part of the northern shore (near Kokkari) that subsided 2-6 cm. The effects of the earthquake included liquefaction, rock falls, rock slides, road cracks and deep-seated landslides, all due to the strong ground motion and associated down-slope mobilization of soil cover and loose sediments.
Panagiotis Elias; Athanassios Ganas; Pierre Briole; Sotiris Valkaniotis; Javier Escartin; Varvara Tsironi; Ilektra Karasante; Chrysanthi Kosma. Co-seismic deformation, field observations and seismic fault model of the Oct. 30, 2020 Mw=7.0 Samos earthquake, Aegean Sea. 2021, 1 .
AMA StylePanagiotis Elias, Athanassios Ganas, Pierre Briole, Sotiris Valkaniotis, Javier Escartin, Varvara Tsironi, Ilektra Karasante, Chrysanthi Kosma. Co-seismic deformation, field observations and seismic fault model of the Oct. 30, 2020 Mw=7.0 Samos earthquake, Aegean Sea. . 2021; ():1.
Chicago/Turabian StylePanagiotis Elias; Athanassios Ganas; Pierre Briole; Sotiris Valkaniotis; Javier Escartin; Varvara Tsironi; Ilektra Karasante; Chrysanthi Kosma. 2021. "Co-seismic deformation, field observations and seismic fault model of the Oct. 30, 2020 Mw=7.0 Samos earthquake, Aegean Sea." , no. : 1.
The Milos hydrothermal field is one of the largest known shallow water hydrothermal systems, and shows both fluid and gas outflow through the seafloor. Recent studies based on imagery acquired by both aerial and submarine drones (Puzenat et al., submitted) reveal several types of fluid outflow associated with bacterial mats along the SE coast of the island (Paleochori, Spathi, and Agia Kyriaki bays). From these observations? include: a) zones of polygonal hydrothermal outflow and associated bacterial mats, b) extended white (bacterial) patches, and c) isolated ones. Subseafloor hydrothermal circulation is hosted in sediments with subseafloor temperatures >50°C, and there is a clear association between hydrothermal circulation and active degassing.
To understand the controls on and relationships between fluid and gas outflow in the area, we need to characterise: a) the nature of the subseafloor (sediment thickness, composition & permeability); b) the distribution of gas and subseafloor fluids, and c) the distribution of gas flares emanating from the seafloor. In November 2020, we conducted a short pilot geophysical study at Paleochori Bay, deploying a towed catamaran with a multibeam echo sounder (iXblue Seapix) to obtain seafloor bathymetry, acoustic backscatter and water column detection of gas flares. We also deployed a sub-bottom profiler (iXblue Echoes 3500 T1) to image sediment architecture and gas/fluid diffusion within the sediment. Our survey focused on Paleochori Bay, surveing areas from ~5 m (nearshore) to ~100 m waterdepth (offshore).
Preliminary results of this geophysical survey suggest that subseafloor gas accumulations play a major role on the nature and structure of hydrothermal activity at Milos. These gas accumulations within the sediments develop along an onshore/offshore fault system, and likely control the shallow subseafloor thermal structure, establishing a thin thermal conductive layer between the roof of gas pockets and the seafloor.[GJ1] [je2] We will report on the link between the distribution and geometry (extent, depth, acoustic nature of the accumulations) of gas pockets, fluid outflows, and gas outflows, all of which will be characterised from both seafloor imagery and subsurface geophysical surveys. We will also discuss how gas pocket geometry may be linked to both fluid flow and subseafloor temperature structure. [HA3]
Javier Escartín; Alex Hughes; Jean-Emmanuel Martelat; Valentine Puzenat; Thibaut Barreyre; Paraskevi Nomikou; Guillaume Jouvé; Alban Bouchard; Remi Stephan; Alain Philippe; Mathias Delescluse. Tectonic constraints on submarine hydrothermal activity, degassing, and subseafloor gas storage (Milos Shallow Water Hydrothermal System, Greece). 2021, 1 .
AMA StyleJavier Escartín, Alex Hughes, Jean-Emmanuel Martelat, Valentine Puzenat, Thibaut Barreyre, Paraskevi Nomikou, Guillaume Jouvé, Alban Bouchard, Remi Stephan, Alain Philippe, Mathias Delescluse. Tectonic constraints on submarine hydrothermal activity, degassing, and subseafloor gas storage (Milos Shallow Water Hydrothermal System, Greece). . 2021; ():1.
Chicago/Turabian StyleJavier Escartín; Alex Hughes; Jean-Emmanuel Martelat; Valentine Puzenat; Thibaut Barreyre; Paraskevi Nomikou; Guillaume Jouvé; Alban Bouchard; Remi Stephan; Alain Philippe; Mathias Delescluse. 2021. "Tectonic constraints on submarine hydrothermal activity, degassing, and subseafloor gas storage (Milos Shallow Water Hydrothermal System, Greece)." , no. : 1.
The MAR 13°20’N corrugated detachment fault is composed of pervasively silicified mafic cataclastic breccias, instead of ultramafics and gabbros commonly found at other detachments. These breccias record overplating of hangingwall diabases, with syntectonic silicification due to important influx of silica‐iron‐rich fluids, able to leach alkalis and calcium. Fluids trapped in quartz inclusions show important salinity variations (2.1‐10 wt.% NaCl eq.) indicating supercritical phase separation. Fluid inclusions also contain minor amounts of H2±CO2±CH4±H2S, with high H2/CO2 and H2/H2S ratios, signatures typical of ultramafic‐hosted vent fluids. We propose that seawater infiltrated the hangingwall upper crust at the axis adjacent to the active detachment, reaching a reaction zone at the dyke complex base (∼2 km). At >500°C, fluids become Si‐rich during diabase alteration (amphibolite‐facies alteration in clasts), and undergo phase‐separation. Brines, preferentially released in the nearby detachment fault during diabase brecciation, mix with serpentinite‐derived fluids bearing H2 and CH4. Cooling during detachment deformation and fluid upward migration triggers silica precipitation at greenschist‐facies conditions (quartz+Fe‐rich‐chlorite±pyrite). Important variations in fluid inclusion salinity and gas composition at both sample and grain scales record heterogeneous fluid circulation at small spatial and short temporal scales. This heterogeneous fluid circulation operating at <2 km depth, extending both along‐axis and over time, is inconsistent with models of fluids channeled along detachments from heat sources at the base of the crust at the fault root. Present‐day venting at detachment footwall, including Irinovskoe, is instead likely underlain by fluid circulation within the footwall, with outflow crossing the inactive detachment fault near‐surface.
A. Verlaguet; D. Bonnemains; C. Mével; J. Escartín; M. Andreani; F. Bourdelle; M.‐C. Boiron; V. Chavagnac. Fluid Circulation Along an Oceanic Detachment Fault: Insights From Fluid Inclusions in Silicified Brecciated Fault Rocks (Mid‐Atlantic Ridge at 13°20′N). Geochemistry, Geophysics, Geosystems 2021, 22, 1 .
AMA StyleA. Verlaguet, D. Bonnemains, C. Mével, J. Escartín, M. Andreani, F. Bourdelle, M.‐C. Boiron, V. Chavagnac. Fluid Circulation Along an Oceanic Detachment Fault: Insights From Fluid Inclusions in Silicified Brecciated Fault Rocks (Mid‐Atlantic Ridge at 13°20′N). Geochemistry, Geophysics, Geosystems. 2021; 22 (1):1.
Chicago/Turabian StyleA. Verlaguet; D. Bonnemains; C. Mével; J. Escartín; M. Andreani; F. Bourdelle; M.‐C. Boiron; V. Chavagnac. 2021. "Fluid Circulation Along an Oceanic Detachment Fault: Insights From Fluid Inclusions in Silicified Brecciated Fault Rocks (Mid‐Atlantic Ridge at 13°20′N)." Geochemistry, Geophysics, Geosystems 22, no. 1: 1.
Across the seismogenic zone, the transition from brittle to plastic deformation corresponds to a semi‐brittle regime where brittle fracturing and plastic flow coexist at high strength conditions. Thorough experimental investigations on brittle‐plastic transition are crucial to understand why natural faults behave in stable or unstable ways at varying crustal depths and why large earthquakes generally nucleate at the base of the seismogenic zone. To investigate semi‐brittle deformation in carbonates and the conditions promoting it, we reported here the results of experiments performed on Carrara marble saw‐cut faults in triaxial conditions. We studied the influence of the confining pressure (ranging between 45 and 180 MPa), axial loading rates (0.01 μm s‐1 and 1 μm s‐1) and initial fault roughness (smooth and rough) on fault (in‐)stability across the brittle‐plastic transition. We conclude that laboratory earthquakes may nucleate on inherited fault interfaces at brittle‐plastic transition conditions. The occurrence of laboratory earthquakes associated with increasing plastic deformation are promoted at high confining pressure, on smooth fault interfaces, or when the loading rate is slow. In a rather counterintuitive manner, increasing initial roughness promotes stable sliding and a larger amount of plastic deformation. Furthermore, we show that stable sliding tends to produce mirror‐like surfaces, while stick‐slips are associated with matte surfaces, on which the size of the asperities grows with increasing confining pressure. Finally, our results seem to reveal the influence of asperity hardness and melt viscosity on fault weakening.
J. Aubry; F. X. Passelègue; Javier Escartin; Julien Gasc; D. Deldicque; A. Schubnel. Fault Stability Across the Seismogenic Zone. Journal of Geophysical Research: Solid Earth 2020, 125, 1 .
AMA StyleJ. Aubry, F. X. Passelègue, Javier Escartin, Julien Gasc, D. Deldicque, A. Schubnel. Fault Stability Across the Seismogenic Zone. Journal of Geophysical Research: Solid Earth. 2020; 125 (8):1.
Chicago/Turabian StyleJ. Aubry; F. X. Passelègue; Javier Escartin; Julien Gasc; D. Deldicque; A. Schubnel. 2020. "Fault Stability Across the Seismogenic Zone." Journal of Geophysical Research: Solid Earth 125, no. 8: 1.
Oxide gabbros are a minor but diffuse component of the lower oceanic crust. Their presence poses questions on lower crust exhumation processes and magma differentiation at mid ocean ridges because they are systematically associated with shear zones and are hardly explained by classical fractionation and melt migration models. Here, we report on a study of lower-crust gabbros recovered from the Vema Lithospheric Section at 11°N along the Mid Atlantic Ridge, where oxide gabbros are abnormally abundant relative to ridge centred magmatic intrusives and where we found a peculiar lithological occurrence represented by deformed diorites extremely enriched in Fe-Ti-oxides and apatites. Their complex genetic history reveals a hybrid nature consistent with derivation from high pressure injections of Fe-Ti-P saturated nelsonitic melts in a primitive gabbroic groundmass that induced fracturing, de-compaction, mineral resorption and chemical re-equilibration. Melt injections may occur after intense ductile shearing at the edges of the axial magma chamber following lateral differentiation of primitive melts injected at the centre of the ridge axis segment. We propose a regime of lateral, instead of vertical, melt differentiation along the ridge axis and a possible role for melt immiscibility in the formation of Fe-Ti-P melt pockets in oceanic domains.
Daniele Brunelli; Alessio Sanfilippo; Enrico Bonatti; Sergei Skolotnev; Javier Escartin; Marco Ligi; Giorgia Ballabio; Anna Cipriani. Origin of oceanic ferrodiorites by injection of nelsonitic melts in gabbros at the Vema Lithospheric Section, Mid Atlantic Ridge. Lithos 2020, 368-369, 105589 .
AMA StyleDaniele Brunelli, Alessio Sanfilippo, Enrico Bonatti, Sergei Skolotnev, Javier Escartin, Marco Ligi, Giorgia Ballabio, Anna Cipriani. Origin of oceanic ferrodiorites by injection of nelsonitic melts in gabbros at the Vema Lithospheric Section, Mid Atlantic Ridge. Lithos. 2020; 368-369 ():105589.
Chicago/Turabian StyleDaniele Brunelli; Alessio Sanfilippo; Enrico Bonatti; Sergei Skolotnev; Javier Escartin; Marco Ligi; Giorgia Ballabio; Anna Cipriani. 2020. "Origin of oceanic ferrodiorites by injection of nelsonitic melts in gabbros at the Vema Lithospheric Section, Mid Atlantic Ridge." Lithos 368-369, no. : 105589.
Risk assessment at active volcanic islands link to populated areas is of first importance. We evaluate the potential of satellite imagery to map and monitor the activity of shallow-water hydrothermal systems, which are often found at volcanic islands. For this study, we used publicly available data and proprietary WorldView-2 satellites images, with spectral bands that can penetrate up to water depths of 30 m. Shallow water hydrothermal sites are visible on satellite imagery, primarily with publicly available data, demonstrating the potential of satellite imagery to study and monitor shallow water hydrothermal activity. We focus our work on volcanic islands, showing intense near-shore, shallow-water hydrothermal activity, and distinct styles of hydrothermal venting. Satellite imagery constrains regional outflow geometry and the temporal variability or stability of these systems. Milos Island shows hydrothermal outflow associated with reflective mineral precipitates and/or bacterial mats, which are stable over time (2010-2014). These outflows locally define polygonal patterns likely associated with hydrothermal convection in porous media. In Kueishantao Island individual hydrothermal plumes charged with particles are visible at the sea surface, and display great variability in intensity and distribution of plume sources (2002-2019). Worldwide we have identified ~15 shallow water hydrothermal sites with satellite imagery, that are similar to either the Milos system (e.g., Vulcano and Panarea, Italy), or the Kueishantao system (numerous sites in Pacific volcanic islands). This study demonstrates that satellite imagery can be used to map and monitor different types of shallow-water hydrothermal systems, at regional scale, and monitor their evolution. Satellite data provides not only regional and temporal information on these systems, unavailable to date, but also the regional context for follow-up in situ field data and observations (e.g., instrumental monitoring, sampling, observations and mapping with divers or AUVs) to understand both the nature and dynamics of these systems, and ultimately the associated fluxes.
Jean-Emmanuel Martelat; Javier Escartin; Thibaut Barreyre. Volcanic submarine hydrothermal activity from satellites : regional mapping and temporal evolution in shallow water systems. 2020, 1 .
AMA StyleJean-Emmanuel Martelat, Javier Escartin, Thibaut Barreyre. Volcanic submarine hydrothermal activity from satellites : regional mapping and temporal evolution in shallow water systems. . 2020; ():1.
Chicago/Turabian StyleJean-Emmanuel Martelat; Javier Escartin; Thibaut Barreyre. 2020. "Volcanic submarine hydrothermal activity from satellites : regional mapping and temporal evolution in shallow water systems." , no. : 1.
The pioneering seafloor mapping by Marie Tharp played a key role in the acceptance of the plate tectonic theory. Her physiographic maps, published with Bruce Heezen, covered the Earth’s oceans and revealed with astonishing accuracy the submarine landscape. She exposed the full extent of the global mid-ocean ridge system, documented features such as seamounts and volcanic chains, trenches, and transform faults. Marie Tharp co-authored the first papers describing the major fracture zones in the Central Atlantic (Chain, Romanche, Vema). In 1952, she also discovered that the Atlantic ridge has a central valley (the axial valley), and convinced her colleague Bruce Heezen that it, which corresponds to sustained seismicity (highlighted by other researchers at the same time thanks to the worldwide networking of seismological stations), is a rift that separates the eastern and western provinces of the Atlantic Ocean. Tharp and Heezen were not yet talking about plate tectonics at this time. But when, at the beginning of the 1960s, the first magnetic anomaly maps showed that the oceans were "young", and that the age of the seabed increased with the distance from the ridges, their physiographic map became an essential element in understanding the role that these ridges play, as well as the distribution of the main current terrestrial plates. In this poster, we present original maps and sketches that document this key contribution to the understanding of the Earth's tectonics.
Mathilde Cannat; Deborah Smith; Daniel Fornari; Vicki Ferrini; Javier Escartin. Marie Tharp: Seafloor mapping and ocean plate tectonics. 2020, 1 .
AMA StyleMathilde Cannat, Deborah Smith, Daniel Fornari, Vicki Ferrini, Javier Escartin. Marie Tharp: Seafloor mapping and ocean plate tectonics. . 2020; ():1.
Chicago/Turabian StyleMathilde Cannat; Deborah Smith; Daniel Fornari; Vicki Ferrini; Javier Escartin. 2020. "Marie Tharp: Seafloor mapping and ocean plate tectonics." , no. : 1.
Submarine hydrothermal activity is common at the flanks of volcanic islands, and in some cases, occurring at very shallow water (0-100 meter depth). These sites are a key target for systematic seafloor mapping to understand the location, geometry and nature of hydrothermal discharge. These data are also critical for monitoring the temporal variability of these dynamic systems, while providing a context for instrumental measurements, sampling and other observations (e.g., temperature of outflow, chemistry, etc.). Here we present a systematic mapping of the Milos hydrothermal system in the Hellenic volcanic Arc, characterized by submarine gas emissions, high-temperature outflow, bacterial mats, precipitation of hydrothermal minerals, and small hydrothermal constructs and edifices. We have mapped this site at regional scales using satellite imagery (World-View2 images from the DigitalGlobe foundation), complemented with aerial photography acquired with drones, and high-resolution seafloor photomosaics (<1 cm resolution) from underwater imagery acquired by the autonomous underwater vehicle Sparus II (University of Girona).
Our drone and AUV mapping ground truths the correlation between patterns in satellite imagery and hydrothermal outflow, associated to mineral precipitates and/or bacterial mats at the seafloor. This mapping also reveals a clear organization of the hydrothermal outflow in sandy areas. In particular, polygonal patterns are common and often associated with inactive or actively bubbling pockmarks. These areas, showing white bacterial mats and hydrothermal precipitates, are rippled, suggesting that the hydrothermal precipitates do not consolidate the sediment. White precipitates display subseafloor temperatures >50°C at depths of 10 to 50 cm. The white areas are bound by bands of seafloor with a hummocky structure due to intense bioturbation, that obliterates the ripples, with widths of up to a few meters. This area shows subseafloor temperatures of 20-40°C, and corresponds to a transition from the high-temperature white zones and the seafloor with ripples and no hydrothermal precipitates. This area exhibits subseafloor temperatures similar to those of seawater, and can be associated with seagrass. These patterns reveal a clear organization of a narrowly focused hydrothermal outflow that controls the biological communities at the seafloor and subseafloor. We will discuss the implications of these observations to quantify hydrothermal fluxes in the study area.
Valentine Puzenat; Jean-Emmanuel Martelat; Javier Escartin; Thibaut Barreyre; Nuno Gracias; Guillem Vallicrosa; Rafael Garcia; Lluís Magí; Paraskevi Nomikou; Philippe Grandjean; Pascal Allemand; Anders Schouw; Sven Le Moine Bauer; Steffen Leth Jørgensen; Varvara Antoniou; Othonas Vlasopoulos; Paraskevi Polymenakou; Manolis Mandalakis; Omer Coskun; William Orsi. Integrated regional scale view of Milos submarine hydrothermalism. 2020, 1 .
AMA StyleValentine Puzenat, Jean-Emmanuel Martelat, Javier Escartin, Thibaut Barreyre, Nuno Gracias, Guillem Vallicrosa, Rafael Garcia, Lluís Magí, Paraskevi Nomikou, Philippe Grandjean, Pascal Allemand, Anders Schouw, Sven Le Moine Bauer, Steffen Leth Jørgensen, Varvara Antoniou, Othonas Vlasopoulos, Paraskevi Polymenakou, Manolis Mandalakis, Omer Coskun, William Orsi. Integrated regional scale view of Milos submarine hydrothermalism. . 2020; ():1.
Chicago/Turabian StyleValentine Puzenat; Jean-Emmanuel Martelat; Javier Escartin; Thibaut Barreyre; Nuno Gracias; Guillem Vallicrosa; Rafael Garcia; Lluís Magí; Paraskevi Nomikou; Philippe Grandjean; Pascal Allemand; Anders Schouw; Sven Le Moine Bauer; Steffen Leth Jørgensen; Varvara Antoniou; Othonas Vlasopoulos; Paraskevi Polymenakou; Manolis Mandalakis; Omer Coskun; William Orsi. 2020. "Integrated regional scale view of Milos submarine hydrothermalism." , no. : 1.
During the ODEMAR 2013 and SUBSAINTES 2017 cruises we mapped the full extent of the seafloor rupture associated with the 2004 Mw 6.3 Les Saintes extensional earthquake. Near-bottom bathymetry acquired both with ROVs and AUVs along the Roseau Fault reveal a normal fault scarp developing in an extensional graben within the Caribbean volcanic arc, between the islands of Guadeloupe and Dominica. Optical inspection during ROV dives along the scarp’s base, where fault mirrors are well-preserved, allowed us to identify and characterize the coseismic fault rupture, and measure the coseismic displacements using both laser calipers and measurements performed on video-derived, textured 3D models, with accuracies better than 1 cm.
The 2004 rupture extends ~20 km along the Roseau Fault, with a vertical displacement exceeding 2.5 m at its center, and tapering towards its ends. Local variations in apparent fault slip within a single 3D model (fault lengths of ~10 to 300 m) document local deposition of gravity debris cones at the base of the scarp, extending laterally between a few to tens of m, and covering the coseismic markers. Gullies eroding the footwall and depositing debris cones on the hanging wall do not show any significant displacement. Fault scarps on either side of the gully mouth instead record significant displacements, suggesting that either erosion or deposition along the gully bottom efficiently obliterated markers of coseismic deformation.
We inspected all overlapping seafloor imagery acquired in December 2013 and April 2017, >10 years after the 2004 Les Saintes earthquake, extending laterally over >3 km of the Roseau Fault rupture. Neither the bed of gullies crossing the rupture, nor the debris and rubble at the base of the fault scarp show any noticeable seafloor change indicating mass wasting and transport, and only changes in mobile sediment (e.g., ripples) can be detected between both image sets. We identified a single area, ~2m wide, with apparent deposition of pebbles during these 3.25 years period, and associated with a local mass-wasting event.
These observations point towards a systematic triggering of mass-wasting during seismic events, with deposition of rubble and rocks both at dejection cones at the mouth of gullies, or at the base of fault scarp sections displaying fault mirrors, covering or obliterating the coseismic markers. Therefore, long-term erosion and deposition processes here are gravity-driven and triggered by the history and magnitude of seismic events. Similar seismic controls may enable denudation of exposed oceanic lithosphere at fault scarps developing along and flanking mid-ocean ridges.
Javier Escartin; Jeremy Billant; Frédérique Leclerc; Jean-Arthur Olive; Klemen Istenic; Nuno Gracias; Rafael Garcia; Aurelien Arnaubec; Christine Deplus; Nathalie Feuillet; SUBSAINTES Science Party. Connecting seismicity, gravity-driven erosion and deposition at submarine normal faults: Insights from mapping of the 2004 Mw 6.3 Les Saintes earthquake rupture (French Antilles). 2020, 1 .
AMA StyleJavier Escartin, Jeremy Billant, Frédérique Leclerc, Jean-Arthur Olive, Klemen Istenic, Nuno Gracias, Rafael Garcia, Aurelien Arnaubec, Christine Deplus, Nathalie Feuillet, SUBSAINTES Science Party. Connecting seismicity, gravity-driven erosion and deposition at submarine normal faults: Insights from mapping of the 2004 Mw 6.3 Les Saintes earthquake rupture (French Antilles). . 2020; ():1.
Chicago/Turabian StyleJavier Escartin; Jeremy Billant; Frédérique Leclerc; Jean-Arthur Olive; Klemen Istenic; Nuno Gracias; Rafael Garcia; Aurelien Arnaubec; Christine Deplus; Nathalie Feuillet; SUBSAINTES Science Party. 2020. "Connecting seismicity, gravity-driven erosion and deposition at submarine normal faults: Insights from mapping of the 2004 Mw 6.3 Les Saintes earthquake rupture (French Antilles)." , no. : 1.
At the scale of individual faults, few studies have investigated fundamental interactions between active faulting, erosion, and deposition in submarine landscapes dominated by magmatic and volcaniclastic deposits with thin sedimentary cover. Such landscapes comprise a high percentage of the global seafloor. Therefore, there is a significant gap in our understanding of first-order processes of erosion and deposition for a large portion of the Earth’s surface. The paucity of studies derives mainly from challenges involved in the acquisition of high-resolution bathymetry and seafloor data in a deep-marine environment. In this study, we use bathymetry data obtained with autonomous deep-sea vehicles and processed to obtain a 1-m resolution digital elevation model along the active Roseau normal fault, in the Lesser Antilles volcanic arc. The Roseau fault was the source of the 2004 Mw6.3 Les Saintes earthquake, and Mw 5-6 events are thought to occur on the Roseau fault every few thousand years. Building on the work of Vilaseca (MSc Thesis, 2015), we quantify the height, slope, and volume eroded from a well-defined fault scarp created by the Roseau fault and calculate volumes for a series of erosional footwall catchments developed in the scarp. We also quantify the volume and morphology of a series of dejection cones in the hanging wall of the Roseau fault to facilitate mass-balancing between the hanging wall and footwall of the scarp.
Mass-balancing indicates that in isolated basins, where the primary supply of sediment is from the adjacent footwall scarp, dejection cone volumes are around half of the total volume of material eroded from the individual footwall catchments. Geomorphological analyses show that dejection cones have surface slopes as high as 30°and form as radial depositional features adjacent to catchment outlets. The results of the mass-balancing, the high slope values for the cone surface, and the identification of >1 m sized blocks of eroded material present on the cone surfaces indicate that dejection cones form through episodic, coseismic and/or post-seismic, gravitationally driven mass-wasting of the uplifting footwall scarp. Preliminary morphometric analysis of the Roseau fault scarp potentially indicates that erosion of normal fault scarps in volcaniclastic and magmatic deposits may primarily occur beyond a threshold in fault scarp height between ~40–70 m. Above ~40–70 m height, erosional catchments may begin to develop on the footwall scarp and average scarp slope decreases with increasing scarp height until average slope values reach an equilibrium of ~35°. The quantitative survey of the Roseau fault scarp in this study demonstrates that episodic earthquake-related mass-wasting is a key erosional process for volcanic and sedimentary deposits in submarine landscapes. Furthermore, the results presented here will be used as first-order inputs to develop models of seafloor erosion and apply them to understand submarine landscape evolution of the oceanic lithosphere.
Alex Hughes; Javier Escartín; Jean-Arthur Olive; Jeremy Billant; Christine Deplus; Nathalie Feuillet; Frédérique Leclerc; Luca Malatesta. Quantifying submarine mass-wasting and links to seismicity along the Roseau normal fault, Lesser Antilles. 2020, 1 .
AMA StyleAlex Hughes, Javier Escartín, Jean-Arthur Olive, Jeremy Billant, Christine Deplus, Nathalie Feuillet, Frédérique Leclerc, Luca Malatesta. Quantifying submarine mass-wasting and links to seismicity along the Roseau normal fault, Lesser Antilles. . 2020; ():1.
Chicago/Turabian StyleAlex Hughes; Javier Escartín; Jean-Arthur Olive; Jeremy Billant; Christine Deplus; Nathalie Feuillet; Frédérique Leclerc; Luca Malatesta. 2020. "Quantifying submarine mass-wasting and links to seismicity along the Roseau normal fault, Lesser Antilles." , no. : 1.
We investigate the potential of satellite imagery to map and monitor the activity of shallow-water hydrothermal systems, which are often found around volcanic islands. For this study, we used publicly available data and proprietary WorldView-2 satellites images, with spectral bands that can penetrate up to water depths of 30 m. Shallow water hydrothermal sites are visible on satellite imagery, primarily with publicly available data, demonstrating the potential of satellite imagery to study and monitor shallow water hydrothermal activity. We focus our work on volcanic islands, showing intense near-shore, shallow-water hydrothermal activity, and distinct styles of hydrothermal venting. Satellite imagery constrains regional outflow geometry and the temporal variability or stability of these systems. Milos Island shows hydrothermal outflow associated with reflective mineral precipitates and/or bacterial mats, which are stable over time (2010–2014). These outflows locally define polygonal patterns likely associated with hydrothermal convection in porous media. In Kueishantao Island individual hydrothermal plumes charged with particles are visible at the sea surface, and display great variability in intensity and distribution of plume sources (2002–2019). Worldwide we have identified ~15 shallow water hydrothermal sites with satellite imagery, that are similar to either the Milos system (e.g., Vulcano and Panarea, Italy), or the Kueishantao system (numerous sites in Pacific volcanic islands). This study demonstrates that satellite imagery can be used to map and monitor different types of shallow-water hydrothermal systems, at regional scale, and monitor their evolution. Satellite data provide not only regional and temporal information on these systems, unavailable to date, but also the regional context for follow-up in situ field data and observations (e.g., instrumental monitoring, sampling, observations and mapping with divers or AUVs) to understand both the nature and dynamics of these systems, and ultimately the associated fluxes.
Jean-Emmanuel Martelat; Javier Escartin; Thibaut Barreyre. Terrestrial shallow water hydrothermal outflow characterized from out of space. Marine Geology 2020, 422, 106119 .
AMA StyleJean-Emmanuel Martelat, Javier Escartin, Thibaut Barreyre. Terrestrial shallow water hydrothermal outflow characterized from out of space. Marine Geology. 2020; 422 ():106119.
Chicago/Turabian StyleJean-Emmanuel Martelat; Javier Escartin; Thibaut Barreyre. 2020. "Terrestrial shallow water hydrothermal outflow characterized from out of space." Marine Geology 422, no. : 106119.
Improvements in structure-from-motion techniques are enabling many scientific fields to benefit from the routine creation of detailed 3D models. However, for a large number of applications, only a single camera is available for the image acquisition, due to cost or space constraints in the survey platforms. Monocular structure-from-motion raises the issue of properly estimating the scale of the 3D models, in order to later use those models for metrology. The scale can be determined from the presence of visible objects of known dimensions, or from information on the magnitude of the camera motion provided by other sensors, such as GPS. This paper addresses the problem of accurately scaling 3D models created from monocular cameras in GPS-denied environments, such as in underwater applications. Motivated by the common availability of underwater laser scalers, we present two novel approaches which are suitable for different laser scaler configurations. A fully unconstrained method enables the use of arbitrary laser setups, while a partially constrained method reduces the need for calibration by only assuming parallelism on the laser beams and equidistance with the camera. The proposed methods have several advantages with respect to existing methods. By using the known geometry of the scene represented by the 3D model, along with some parameters of the laser scaler geometry, the need for laser alignment with the optical axis of the camera is eliminated. Furthermore, the extremely error-prone manual identification of image points on the 3D model, currently required in image-scaling methods, is dispensed with. The performance of the methods and their applicability was evaluated both on data generated from a realistic 3D model and on data collected during an oceanographic cruise in 2017. Three separate laser configurations have been tested, encompassing nearly all possible laser setups, to evaluate the effects of terrain roughness, noise, camera perspective angle and camera-scene distance on the final estimates of scale. In the real scenario, the computation of 6 independent model scale estimates using our fully unconstrained approach, produced values with a standard deviation of 0.3%. By comparing the values to the only other possible method currently usable for this dataset, we showed that the consistency of scales obtained for individual lasers is much higher for our approach (0.6% compared to 4%).
Klemen Istenič; Nuno Gracias; Aurélien Arnaubec; Javier Escartín; Rafael Garcia. Automatic scale estimation of structure from motion based 3D models using laser scalers in underwater scenarios. ISPRS Journal of Photogrammetry and Remote Sensing 2019, 159, 13 -25.
AMA StyleKlemen Istenič, Nuno Gracias, Aurélien Arnaubec, Javier Escartín, Rafael Garcia. Automatic scale estimation of structure from motion based 3D models using laser scalers in underwater scenarios. ISPRS Journal of Photogrammetry and Remote Sensing. 2019; 159 ():13-25.
Chicago/Turabian StyleKlemen Istenič; Nuno Gracias; Aurélien Arnaubec; Javier Escartín; Rafael Garcia. 2019. "Automatic scale estimation of structure from motion based 3D models using laser scalers in underwater scenarios." ISPRS Journal of Photogrammetry and Remote Sensing 159, no. : 13-25.
Along with the intracrustal heat source, crustal permeability is considered as the controlling factor for hydrothermal circulation within zero‐age oceanic crust. To obtain fine‐scale, 2‐D models of upper crustal permeability along the East Pacific Rise 9°50′N, known for prolific hydrothermal activity, we use recently‐derived high‐resolution seismic velocity and examine a number of the existing velocity‐permeability relationships. To constrain our preferred permeability model, we compare thus derived permeability models with collocated permeability estimates from poroelastic response to tidal loading at L‐vent. Furthermore, using the preferred permeability result, we model hydrothermal convection in 2‐D and find that the distribution of recharge and discharge zones are in good agreement with seafloor observations, including locations of the vent fields. Our results suggest that seismic velocities can be used as a tool for deriving spatial variation of permeability, which must be considered in modeling of hydrothermal flow.
Milena Marjanović; Thibaut Barreyre; Fabrice J. Fontaine; Javier Escartín. Investigating Fine‐Scale Permeability Structure and Its Control on Hydrothermal Activity Along a Fast‐Spreading Ridge (the East Pacific Rise, 9°43′–53′N) Using Seismic Velocity, Poroelastic Response, and Numerical Modeling. Geophysical Research Letters 2019, 46, 11799 -11810.
AMA StyleMilena Marjanović, Thibaut Barreyre, Fabrice J. Fontaine, Javier Escartín. Investigating Fine‐Scale Permeability Structure and Its Control on Hydrothermal Activity Along a Fast‐Spreading Ridge (the East Pacific Rise, 9°43′–53′N) Using Seismic Velocity, Poroelastic Response, and Numerical Modeling. Geophysical Research Letters. 2019; 46 (21):11799-11810.
Chicago/Turabian StyleMilena Marjanović; Thibaut Barreyre; Fabrice J. Fontaine; Javier Escartín. 2019. "Investigating Fine‐Scale Permeability Structure and Its Control on Hydrothermal Activity Along a Fast‐Spreading Ridge (the East Pacific Rise, 9°43′–53′N) Using Seismic Velocity, Poroelastic Response, and Numerical Modeling." Geophysical Research Letters 46, no. 21: 11799-11810.
Rapid developments in the field of underwater photogrammetry have given scientists the ability to produce accurate 3D models which are now increasingly used in the representation and study of local areas of interest. This paper addresses the lack of systematic analysis of 3D reconstruction and navigation fusion strategies, as well as associated error evaluation of models produced at larger scales in GPS-denied environments using a monocular camera (often in deep sea scenarios). Based on our prior work on automatic scale estimation of SfM-based 3D models using laser scalers, an automatic scale accuracy framework is presented. The confidence level for each of the scale error estimates is independently assessed through the propagation of the uncertainties associated with image features and laser spot detections using a Monte Carlo simulation. The number of iterations used in the simulation was validated through the analysis of the final estimate behavior. To facilitate the detection and uncertainty estimation of even greatly attenuated laser beams, an automatic laser spot detection method was developed, with the main novelty of estimating the uncertainties based on the recovered characteristic shapes of laser spots with radially decreasing intensities. The effects of four different reconstruction strategies resulting from the combinations of Incremental/Global SfM, and the a priori and a posteriori use of navigation data were analyzed using two distinct survey scenarios captured during the SUBSAINTES 2017 cruise (doi: 10.17600/17001000). The study demonstrates that surveys with multiple overlaps of nonsequential images result in a nearly identical solution regardless of the strategy (SfM or navigation fusion), while surveys with weakly connected sequentially acquired images are prone to produce broad-scale deformation (doming effect) when navigation is not included in the optimization. Thus the scenarios with complex survey patterns substantially benefit from using multiobjective BA navigation fusion. The errors in models, produced by the most appropriate strategy, were estimated at around 1 % in the central parts and always inferior to 5 % on the extremities. The effects of combining data from multiple surveys were also evaluated. The introduction of additional vectors in the optimization of multisurvey problems successfully accounted for offset changes present in the underwater USBL-based navigation data, and thus minimize the effect of contradicting navigation priors. Our results also illustrate the importance of collecting a multitude of evaluation data at different locations and moments during the survey.
Klemen Istenič; Nuno Gracias; Aurélien Arnaubec; Javier Escartín; Rafael Garcia. Scale Accuracy Evaluation of Image-Based 3D Reconstruction Strategies Using Laser Photogrammetry. Remote Sensing 2019, 11, 2093 .
AMA StyleKlemen Istenič, Nuno Gracias, Aurélien Arnaubec, Javier Escartín, Rafael Garcia. Scale Accuracy Evaluation of Image-Based 3D Reconstruction Strategies Using Laser Photogrammetry. Remote Sensing. 2019; 11 (18):2093.
Chicago/Turabian StyleKlemen Istenič; Nuno Gracias; Aurélien Arnaubec; Javier Escartín; Rafael Garcia. 2019. "Scale Accuracy Evaluation of Image-Based 3D Reconstruction Strategies Using Laser Photogrammetry." Remote Sensing 11, no. 18: 2093.
Geomorphological and geological studies of the seafloor benefit today from both ROV exploration and from acquisition of high resolution bathymetric data. Although both represent significant improvements to study submarine domains, the understanding of the studied objects is made more difficult than on land given the limited visual perception provided by the ROV camera due to the attenuation of light in the water and the need to use artificial illumination. Likewise, mapping can be performed using GIS software for digital elevation models and its derivatives (e.g. slope or shade raster), mostly in a 2D map view only. So, the submarine studies lack the field survey stage performed in classical onshore works that allows clear visualization and appreciation of the studied objects.Our aim is to develop a solution allowing the visualization of Digital Elevation Models (DEM) and 3D models derived from Structure-from-Motion (SfM) within a virtual reality environment, and to use these data for geomorphological and geological analysis. For this, we use an Oculus Rift headset, Touch controllers, and the Unity game engine, with GIS-like interaction capabilities.The free and open Unity package that we are developing allows, at this stage, data visualization and working at a 1:1 scale in a georeferenced system. The user can therefore move freely within a 3D immersive environment that includes custom topographic data. For quantitative observations, we develop tools (ruler, compass) allowing measurements similar to those performed during geomorphological or geological field work. We also add the possibility to map objects. Digitizing in 3D is achieved with a laser pointed towards the data, providing great precision. The user can thus create pseudo shapefiles using the same three graphic primitives, and that are compatible with standard GIS software. Beside these functionalities, we also implement a spatial user interface displaying help and information and a teleportation tool preventing motion sickness.The users that have tested this solution are enthusiastic and agree that it helps to better appreciate and understand the shape and geometry of the studied objects. It was also used to present and explain 3D models of outcrops to master students. Further developments will port the solution for other headsets, facilitate the data import (e.g., standard file formats for 3D objects and DEMs), create and manage of multiple layers of shapefiles, and include multiplayer online gaming capabilities to allow remote co-working with colleague(s) at other distant locations, or a whole classroom.
Jeremy Billant; Julia Bozzinio; Frederique Leclerc; Javier Escartin; Nuno Gracias; Klemen Istenic; Aurelien Arnaubec; Rafael Garcia. Performing submarine field survey without scuba gear using GIS-like mapping in a Virtual Reality environment. OCEANS 2019 - Marseille 2019, 1 -6.
AMA StyleJeremy Billant, Julia Bozzinio, Frederique Leclerc, Javier Escartin, Nuno Gracias, Klemen Istenic, Aurelien Arnaubec, Rafael Garcia. Performing submarine field survey without scuba gear using GIS-like mapping in a Virtual Reality environment. OCEANS 2019 - Marseille. 2019; ():1-6.
Chicago/Turabian StyleJeremy Billant; Julia Bozzinio; Frederique Leclerc; Javier Escartin; Nuno Gracias; Klemen Istenic; Aurelien Arnaubec; Rafael Garcia. 2019. "Performing submarine field survey without scuba gear using GIS-like mapping in a Virtual Reality environment." OCEANS 2019 - Marseille , no. : 1-6.
Subduction zones are areas with significant tectonic activity, complex fault systems, volcanic edifices and growth of islands. Earthquakes in this context are associated with sudden subsidence or uplift of the sea floor with the potential to trigger landslides and tsunamis. A tsunami initiated by a megathrust earthquake can generate strong currents, and is able to carry massive quantities of sediments. The inhabited islands and coasts near subduction areas are threatened by those destructive earthquakes and tsunamis. The arc of the Lesser Antilles which formed due to the plunge of the Atlantic oceanic plate under the Caribean plate, is one of them. The tsunamigenic earthquakes in this region are rare, poorly documented and the only available data are qualitative (observations of coseismic displacement, intensity of the damages). Quantitative data is lacking as no seismograms or tide-gauge were set up before 1968. This lack of data increases the uncertainty on the existent fault models and the shortness of the catalog of seismicity does not enable a good analysis of the recurence cycle of the megathrust earthquakes. The most recent tsunamigenic earthquake occured in 2004 in the area of Les Saintes normal fault system. This Mw6.3 earthquake generated small waves with 2m of run-up in several bays of Les Saintes, a group of island in the South of Guadeloupe. A recent survey done on the fault scarp revealed important coseismic displacement at the surface which had not been predicted in the seismic source models resulting from the joint inversion of teleseismic and GPS data. Tsunami simulations of those different models of fault enable the calculation of the associated time arrivals and water heights of the waves. Compared to the reported observation, those results give complementary informations and additional constrains on the source parameters.
Louise Cordrie; Javier Escartin; Audrey Gailler; Nathalie Feuillet; Philippe Heinrich. Simulation of the 2004 tsunami of Les Saintes in Guadeloupe (Lesser Antilles). OCEANS 2019 - Marseille 2019, 1 -9.
AMA StyleLouise Cordrie, Javier Escartin, Audrey Gailler, Nathalie Feuillet, Philippe Heinrich. Simulation of the 2004 tsunami of Les Saintes in Guadeloupe (Lesser Antilles). OCEANS 2019 - Marseille. 2019; ():1-9.
Chicago/Turabian StyleLouise Cordrie; Javier Escartin; Audrey Gailler; Nathalie Feuillet; Philippe Heinrich. 2019. "Simulation of the 2004 tsunami of Les Saintes in Guadeloupe (Lesser Antilles)." OCEANS 2019 - Marseille , no. : 1-9.
The stability of a horizontally and vertically sheared surface jet is examined, with a focus on the vertical structure of the resultant eddies. Over a flat bottom, the instability is mixed baroclinic/barotropic, producing strong eddies at depth that are characteristically shifted downstream relative to the surface eddies. Baroclinic instability is suppressed over a large slope for retrograde jets (with a flow antiparallel to topographic wave propagation) and to a lesser extent for prograde jets (with flow parallel to topographic wave propagation), as seen previously. In such cases, barotropic (lateral) instability dominates if the jet is sufficiently narrow. This yields surface eddies whose size is independent of the slope but proportional to the jet width. Deep eddies still form, forced by interfacial motion associated with the surface eddies, but they are weaker than under baroclinic instability and are vertically aligned with the surface eddies. A sinusoidal ridge acts similarly, suppressing baroclinic instability and favoring lateral instability in the upper layer. A ridge with a 1-km wavelength and an amplitude of roughly 10 m is sufficient to suppress baroclinic instability. Surveys of bottom roughness from bathymetry acquired with shipboard multibeam echo sounding reveal that such heights are common beneath the Kuroshio, the Antarctic Circumpolar Current, and, to a lesser extent, the Gulf Stream. Consistent with this, vorticity and velocity cross sections from a 1/50° HYCOM simulation suggest that Gulf Stream eddies are vertically aligned, as in the linear stability calculations with strong topography. Thus, lateral instability may be more common than previously thought, owing to topography hindering vertical energy transfer.
J. H. LaCasce; Javier Escartin; Eric. P. Chassignet; Xiaobiao Xu. Jet Instability over Smooth, Corrugated, and Realistic Bathymetry. Journal of Physical Oceanography 2019, 49, 585 -605.
AMA StyleJ. H. LaCasce, Javier Escartin, Eric. P. Chassignet, Xiaobiao Xu. Jet Instability over Smooth, Corrugated, and Realistic Bathymetry. Journal of Physical Oceanography. 2019; 49 (2):585-605.
Chicago/Turabian StyleJ. H. LaCasce; Javier Escartin; Eric. P. Chassignet; Xiaobiao Xu. 2019. "Jet Instability over Smooth, Corrugated, and Realistic Bathymetry." Journal of Physical Oceanography 49, no. 2: 585-605.
Analyses of fault attributes have contributed to unraveling fault growth processes in diverse tectonic settings. By integrating such analysis at the scale of a fault population, we propose to investigate the characteristics of a rift that has evolved up to a stage typical of a continent‐ocean transition. We address this problem by considering Dabbahu‐Manda‐Hararo (DMH) rift segment (Central Afar, Ethiopia), recognized for being in a late rifting stage. We quantify fault azimuth, length, and throw attributes for 668 normal faults. Along DMH rift, the mean fault density is 0.87 ± 0.7 km/km2 and the median tectonic strain ranges from 1.8% to 3.1% assuming a fault dip of 60° and 45°, respectively. Maximum tectonic strain (>10%) is found where the rift azimuth changes. Along‐rift variations in fault azimuth, length, and scaling relationships suggest a different stage of rifting in the northern part of the rift. We show that this difference can be attributed to the influence of the Dabbahu volcano located at the northern tip of the rift, which captured the propagating Manda‐Hararo rift in the last ~100 kyr. The morpho‐tectonic analysis reveals numerous common features with slow‐spreading ridge segments, such as the Lucky Strike segment located along the Mid‐Atlantic ridge (segment length, spreading rate, associated magmatic system) but also with intermediate and fast ones (axial valley, fault throws, and diking). This study reveals that a rift at the continent‐ocean transition may be characterized by a transient and evolutionary behavior that shares features with oceanic ridges from slow‐ to fast‐spreading rates.
S. Dumont; Y. Klinger; A. Socquet; Javier Escartin; R. Grandin; E. Jacques; S. Medynski; C. Doubre. Rifting Processes at a Continent‐Ocean Transition Rift Revealed by Fault Analysis: Example of Dabbahu‐Manda‐Hararo Rift (Ethiopia). Tectonics 2019, 38, 190 -214.
AMA StyleS. Dumont, Y. Klinger, A. Socquet, Javier Escartin, R. Grandin, E. Jacques, S. Medynski, C. Doubre. Rifting Processes at a Continent‐Ocean Transition Rift Revealed by Fault Analysis: Example of Dabbahu‐Manda‐Hararo Rift (Ethiopia). Tectonics. 2019; 38 (1):190-214.
Chicago/Turabian StyleS. Dumont; Y. Klinger; A. Socquet; Javier Escartin; R. Grandin; E. Jacques; S. Medynski; C. Doubre. 2019. "Rifting Processes at a Continent‐Ocean Transition Rift Revealed by Fault Analysis: Example of Dabbahu‐Manda‐Hararo Rift (Ethiopia)." Tectonics 38, no. 1: 190-214.
While oceanic detachment faults have been proposed to account for the accretion of ∼40% of new seafloor in the North Atlantic ocean, clear exposures of large-offset, often-corrugated fault surfaces remain scarce and spatially limited. To help resolve this paradox, we examine the conditions under which detachment fault growth may or may not lead to extensive exposure of corrugated fault planes at the seafloor. Using high-resolution bathymetry from four detachment faults at the northern Mid-Atlantic Ridge, we investigate the rafting of hanging wall-derived debris over emerging fault scarps, which can lead to covering shallow-dipping corrugated fault surfaces. We model this process using critical taper theory, and infer low effective friction coefficients (∼0.2) on the shallowest portion of detachment faults. A corollary to this result is that detachments emerging from the seafloor at angles <13° are more likely to become blanketed under an apron of hanging wall material. We generalize these findings as a simple model for the progressive exposure and flexural rotation of detachment footwalls, which accounts for the continued action of seafloor-shaping processes. Our model suggests that many moderate-offset, hidden detachment faults may exist along slow mid-ocean ridges, and do not feature an exposed fault surface.
Jean-Arthur Olive; Ross Parnell-Turner; Javier Escartín; Deborah K. Smith; Sven Petersen. Controls on the seafloor exposure of detachment fault surfaces. Earth and Planetary Science Letters 2018, 506, 381 -387.
AMA StyleJean-Arthur Olive, Ross Parnell-Turner, Javier Escartín, Deborah K. Smith, Sven Petersen. Controls on the seafloor exposure of detachment fault surfaces. Earth and Planetary Science Letters. 2018; 506 ():381-387.
Chicago/Turabian StyleJean-Arthur Olive; Ross Parnell-Turner; Javier Escartín; Deborah K. Smith; Sven Petersen. 2018. "Controls on the seafloor exposure of detachment fault surfaces." Earth and Planetary Science Letters 506, no. : 381-387.