scholarly journals Revisiting the tsunamigenic volcanic flank collapse of Fogo Island in the Cape Verdes, offshore West Africa

2019 ◽  
Vol 500 (1) ◽  
pp. 13-26 ◽  
Author(s):  
Rachel Barrett ◽  
Elodie Lebas ◽  
Ricardo Ramalho ◽  
Ingo Klaucke ◽  
Steffen Kutterolf ◽  
...  
Keyword(s):  
Large Scale ◽  
Debris Avalanche ◽  
Volcanic Material ◽  
Flank Collapse ◽  
Bathymetric Data ◽  
Medium Resolution ◽  
History Of ◽  
Seafloor Sediments ◽  
Multi Phase ◽  
Mass Transport Deposits

AbstractVolcanic archipelagos are a source of numerous on- and offshore geohazards, including explosive eruptions and potentially tsunamigenic large-scale flank collapses. Fogo Island in the southern Cape Verdes is one of the most active volcanoes in the world, making it both prone to collapse (as evidenced by the c. 73 ka Monte Amarelo volcanic flank collapse), and a source of widely distributed tephra and volcanic material. The offshore distribution of the Monte Amarelo debris avalanche deposits and the surrounding volcaniclastic apron were previously mapped using only medium-resolution bathymetric data. Here, using recently acquired, higher-resolution acoustic data, we revisit Fogo's flank collapse and find evidence suggesting that the deposition of hummocky volcanic debris originating from the failed eastern flank most likely triggered the contemporaneous, multi-phase failure of pre-existing seafloor sediments. Additionally, we identify, for the first time, multiple mass-transport deposits in the southern part of the volcaniclastic apron of Fogo and Santiago based on the presence of acoustically chaotic deposits in parametric echo sounder data and volcaniclastic turbiditic sands in recovered cores. These preliminary findings indicate a long and complex history of instability on the southern slopes of Fogo and suggest that Fogo may have experienced multiple flank collapses.

scholarly journals Syn-Eruptive Lateral Collapse of Monogenetic Volcanoes: The Case of Mazo Volcano from the Timanfaya Eruption (Lanzarote, Canary Islands)

2020 ◽  
Author(s):  
Carmen Romero ◽  
Inés Galindo ◽  
Nieves Sánchez ◽  
Esther Martín-González ◽  
Juana Vegas
Keyword(s):  
Canary Islands ◽  
Great Part ◽  
Volcanic Hazards ◽  
Debris Avalanche ◽  
Mitigation Strategies ◽  
Morphological Data ◽  
Flank Collapse ◽  
Tectonic Process ◽  
Eruptive Style ◽  
History Of

The evolution of complex volcanic structures usually includes the occurrence of flank collapse events. Monogenetic cones, however, are more stable edifices with minor rafting processes that remove part of the cone slopes. We present the eruptive history of Mazo volcano (Lanzarote, Canary Islands), including the first detailed description of a syn-eruptive debris avalanche affecting a volcanic monogenetic edifice. The study and characterization, through new geological and morphological data and the analysis of a great number of documentary data, have made it possible to reinterpret this volcano and assign it to the Timanfaya eruption (1730–1736). The eruptive style evolved from Hawaiian to Strombolian until a flank collapse occurred, destroying a great part of the edifice, and forming a debris avalanche exhibiting all the features that define collapsing volcanic structures. The existence of blocks from the substrate suggests a volcano-tectonic process associated with a fracture acting simultaneously with the eruption. The sudden decompression caused a blast that produced pyroclasts that covered most of the island. This study forces to change the current low-hazard perception usually linked to monogenetic eruptions and provides a new eruptive scenario to be considered in volcanic hazards analysis and mitigation strategies development.

scholarly journals Modeling of partial dome collapse of La Soufrière of Guadeloupe volcano: implications for hazard assessment and monitoring

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Marc Peruzzetto ◽  
Jean-Christophe Komorowski ◽  
Anne Le Friant ◽  
Marina Rosas-Carbajal ◽  
Anne Mangeney ◽  
...  
Keyword(s):  
Coulomb Friction ◽  
Hazard Analysis ◽  
Debris Avalanche ◽  
Flank Collapse ◽  
Barrier Effects ◽  
History Of ◽  
Assessment And Monitoring ◽  
Coulomb Friction Law ◽  
Dome Collapse ◽  
Best Fit

Abstract Over the past 9,150 years, at least 9 flank collapses have been identified in the history of La Soufrière of Guadeloupe volcano. On account of the volcano’s current unrest, the possibility of such a flank collapse should not be dismissed in assessing hazards for future eruptive magmatic as well as non-magmatic scenarios. We combine morphological and geophysical data to identify seven unstable structures (volumes ranging from 1 × 106 m3 to 100 × 106 m3), including one that has a volume compatible with the last recorded flank collapse in 1530 CE. We model their dynamics and emplacement with the SHALTOP numerical model and a simple Coulomb friction law. The best-fit friction coefficient to reproduce the 1530 CE event is tan(7°) = 0.13, suggesting the transformation of the debris avalanche into a debris flow, which is confirmed by the texture of mapped deposits. Various friction angles are tested to investigate less water-rich and less mobile avalanches. The most densely populated areas of Saint-Claude and Basse-Terre, and an area of Gourbeyre south of the Palmiste ridge, are primarily exposed in the case of the more voluminous and mobile flank collapse scenarios considered. However, topography has a prominent role in controlling flow dynamics, with barrier effects and multiple channels. Classical mobility indicators, such as the Heim’s ratio, are thus not adequate for a comprehensive hazard analysis.

Internal architecture of the two-fold nature Monte Amarelo volcanic flank-collapse deposit offshore Fogo Island in the southern Cape Verdean Archipelago

2020 ◽  
Author(s):  
Elodie Lebas ◽  
Elisa Klein ◽  
Rachel Barrett ◽  
Ricardo Ramalho ◽  
Katja Lindhorst ◽  
...  
Keyword(s):  
Seismic Data ◽  
Large Scale ◽  
Distal Part ◽  
Debris Avalanche ◽  
Acoustic Energy ◽  
Sidescan Sonar ◽  
Cape Verdean ◽  
Hazard Potential ◽  
Flank Collapse ◽  
Internal Architecture

<p>Volcanic islands are the sites of some of the largest submarine landslides observed on Earth. Individual landslide deposits can contain several hundreds to few thousands of cubic kilometers of mobilized material and, therefore, represent significant hazards. They can generate destructive tsunamis which may have devastating impacts on coastal areas and populations. Hazard potential of volcanic flank-collapses is widely recognized, but the magnitude, and therefore the hazard potential of tsunamis triggered by such collapses have been much debated over the past decades. Hence, a better understanding and a full characterization of volcanic landslide deposits and emplacement dynamics is crucial. Fogo Island, situated in the southern part of the Cape Verdean Archipelago, is one of the most active oceanic intraplate volcanoes in the world. Fogo Volcano experienced a catastrophic flank-collapse event as witnessed by up-to-1 km high, eastward-opened horseshoe-shape depression. Tsunami deposits found on the nearby islands of Santiago and Maio indicate that the flank-collapse was tsunamigenic <em>(Ramalho et al. 2015; Madeira et al. 2019)</em>. To better constrain the tsunamigenic hazard potential of this large, volcanic flank-collapse, we collected in 2019 a dense network of marine geophysical datasets offshore Fogo. Our dataset includes high-resolution multi-beam swath bathymetry, parametric sediment echo-sounder, multi-channel seismic reflection, sidescan sonar data and sediment gravity cores. Here, we present the key results of the seismic data. We show – for the first time – the internal architecture of the Monte Amarelo flank-collapse deposit in unprecedented detail. Our data reveal a two-fold nature of the deposit with hummocky terrains in the proximal area – typical of blocky debris avalanche deposits – and finer-grained, acoustically transparent deposits in the southern distal part. Our observations support recently-proposed failure models, where the loading of seafloor sediment by volcanic debris avalanche deposits triggered sediment destabilization and progressive downslope-propagating failure along a décollement surface <em>(Le Friant et al. 2015, 2020)</em>. The basal surface of the Monte Amarelo deposits along with a series of strong internal reflections have also been captured in the seismic data, both in the proximal and distal part. This suggests a multi-phase event in the emplacement of the Monte Amarelo deposit offshore and allows us to reassess the volume of failed and remobilized material. Such details are particularly unusual on submarine volcanic flanks, as it is rather difficult to image the base of debris avalanche deposits due to their hummocky nature that instantly diffract/scatter the acoustic energy. This makes Fogo’s Monte Amarelo volcanic flank-collapse deposit a perfect study case to investigate the emplacement dynamics of large-scale, volcanic flank collapses and better constrain their tsunamigenic hazard potential.</p>

Materials for the history of the gospel-Baptist movement in Ukraine

1996 ◽  
pp. 4-15
Author(s):  
S. Golovaschenko ◽  
Petro Kosuha
Keyword(s):  
Large Scale ◽  
Religious Studies ◽  
Theological Seminary ◽  
National Academy Of Sciences ◽  
Evangelical Christians ◽  
Evangelical Christian ◽  
First Results ◽  
History Of ◽  
Fruitful Cooperation ◽  
Academy Of Sciences

The report is based on the first results of the study "The History of the Evangelical Christians-Baptists in Ukraine", carried out in 1994-1996 by the joint efforts of the Department of Religious Studies at the Institute of Philosophy of the National Academy of Sciences of Ukraine and the Odessa Theological Seminary of Evangelical Christian Baptists. A large-scale description and research of archival sources on the history of evangelical movements in our country gave the first experience of fruitful cooperation between secular and church researchers.

Integration of Ecological and Engineering Aspects in Planning Large Scale Tidal Power Development in the Bay of Fundy, Canada

1984 ◽  
Vol 16 (1-2) ◽  
pp. 281-295 ◽  
Author(s):  
Donald C Gordon
Keyword(s):  
Large Scale ◽  
Feasibility Studies ◽  
Bay Of Fundy ◽  
Final Decision ◽  
Power Development ◽  
Tidal Power ◽  
History Of ◽  
Scientists And Engineers ◽  
The Many ◽  
University Scientists

Large-scale tidal power development in the Bay of Fundy has been given serious consideration for over 60 years. There has been a long history of productive interaction between environmental scientists and engineers durinn the many feasibility studies undertaken. Up until recently, tidal power proposals were dropped on economic grounds. However, large-scale development in the upper reaches of the Bay of Fundy now appears to be economically viable and a pre-commitment design program is highly likely in the near future. A large number of basic scientific research studies have been and are being conducted by government and university scientists. Likely environmental impacts have been examined by scientists and engineers together in a preliminary fashion on several occasions. A full environmental assessment will be conducted before a final decision is made and the results will definately influence the outcome.

scholarly journals A Survey on Edge Performance Benchmarking

2021 ◽  
Vol 54 (3) ◽  
pp. 1-33
Author(s):  
Blesson Varghese ◽  
Nan Wang ◽  
David Bermbach ◽  
Cheol-Ho Hong ◽  
Eyal De Lara ◽  
...  
Keyword(s):  
Large Scale ◽  
Future Internet ◽  
Coupled Systems ◽  
Operational Conditions ◽  
Loosely Coupled ◽  
Performance Benchmarking ◽  
The Past ◽  
Geographically Dispersed ◽  
Tightly Coupled ◽  
History Of

Edge computing is the next Internet frontier that will leverage computing resources located near users, sensors, and data stores to provide more responsive services. Therefore, it is envisioned that a large-scale, geographically dispersed, and resource-rich distributed system will emerge and play a key role in the future Internet. However, given the loosely coupled nature of such complex systems, their operational conditions are expected to change significantly over time. In this context, the performance characteristics of such systems will need to be captured rapidly, which is referred to as performance benchmarking, for application deployment, resource orchestration, and adaptive decision-making. Edge performance benchmarking is a nascent research avenue that has started gaining momentum over the past five years. This article first reviews articles published over the past three decades to trace the history of performance benchmarking from tightly coupled to loosely coupled systems. It then systematically classifies previous research to identify the system under test, techniques analyzed, and benchmark runtime in edge performance benchmarking.

scholarly journals Efficacy and safety of Si-Jun-Zi-Tang-based therapies for functional (non-ulcer) dyspepsia: a meta-analysis of randomized controlled trials

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yaping Wang ◽  
Bin Liu ◽  
Xiuqiong Fu ◽  
Tiejun Tong ◽  
Zhiling Yu
Keyword(s):  
Relapse Rate ◽  
Large Scale ◽  
Primary Outcome ◽  
Response Rate ◽  
Meta Analysis ◽  
Risk Of Bias ◽  
Efficacy And Safety ◽  
History Of ◽  
Non Ulcer Dyspepsia

Abstract Background The traditional Chinese medicine formula Si-Jun-Zi-Tang (SJZT) has a long history of application in the treatment of functional dyspepsia (non-ulcer dyspepsia, FD)-like symptoms. SJZT-based therapies have been claimed to be beneficial in managing FD. This study aimed to assess the efficacy and safety of SJZT-based therapies in treating FD by meta-analysis. Methods Systematic searches for RCTs were conducted in seven databases (up to February 2019) without language restrictions. Data were analyzed using Cochrane RevMan software version 5.3.0 and Stata software version 13.1, and reported as relative risk (RR) or odds ratio (OR) with 95% confidence intervals (CIs). The primary outcome was response rate and the secondary outcomes were gastric emptying, quality of life, adverse effects and relapse rate. The quality of evidence was evaluated according to criteria from the Cochrane risk of bias. Results A total of 341 potentially relevant publications were identified, and 12 RCTs were eligible for inclusion. For the response rate, there was a statically significant benefit in favor of SJZT-based therapies (RR = 1.23; 95% CI 1.17 to 1.30). However, the benefit was limited to modified SJZT (MSJZT). The relapse rate of FD patients received SJZT-based therapies was lower than that of patients who received conventional medicines (OR = 0.23; 95% CI 0.10 to 0.51). No SJZT-based therapies-related adverse effect was reported. Conclusion SJZT-based prescriptions may be effective in treating FD and no serious side-effects were identified, but the effect on response rate appeared to be limited to MSJZT. The results should be interpreted with caution as all the included studies were considered at a high risk of bias. Standardized, large-scale and strictly designed RCTs are needed to further validate the benefits of SJZT-based therapies for FD management. Trial registration Systematic review registration: [PROSPERO registration: CRD42019139136].

Line length balancing to evaluate multi-phase submarine landslide development: an example from the Storegga Slide, Norway

2019 ◽  
Vol 500 (1) ◽  
pp. 531-549 ◽  
Author(s):  
Suzanne Bull ◽  
Joseph A. Cartwright
Keyword(s):  
Seismic Data ◽  
Large Scale ◽  
Line Length ◽  
Proximal Region ◽  
Submarine Landslide ◽  
Landslide Development ◽  
Multi Phase ◽  
Storegga Slide ◽  
2D And 3D ◽  
3D Seismic Data

AbstractThis study shows how simple structural restoration of a discrete submarine landslide lobe can be applied to large-scale, multi-phase examples to identify different phases of slide-lobe development and evaluate their mode of emplacement. We present the most detailed analysis performed to date on a zone of intense contractional deformation, historically referred to as the compression zone, from the giant, multi-phase Storegga Slide, offshore Norway. 2D and 3D seismic data and bathymetry data show that the zone of large-scale (>650 m thick) contractional deformation can be genetically linked updip with a zone of intense depletion across a distance of 135 km. Quantification of depletion and accumulation along a representative dip-section reveals that significant depletion in the proximal region is not accommodated in the relatively mild amount (c. 5%) of downdip shortening. Dip-section restoration indicates a later, separate stage of deformation may have involved removal of a significant volume of material as part of the final stages of the Storegga Slide, as opposed to the minor volumes reported in previous studies.

Seismic geomorphology of early North Atlantic sediment waves, offshore northwest Africa

2013 ◽  
Vol 1 (1) ◽  
pp. SA75-SA91 ◽  
Author(s):  
Dallas B. Dunlap ◽  
Lesli J. Wood ◽  
Lorena G. Moscardelli
Keyword(s):  
Seismic Survey ◽  
Entire Study ◽  
Sediment Waves ◽  
Northwest Africa ◽  
Stable Slope ◽  
Wave Forms ◽  
History Of ◽  
Wave Heights ◽  
Slope Currents ◽  
Mass Transport Deposits

The lower continental rise of Morocco’s Atlantic Margin contains three varying morphologies of buried deepwater sediment waves. The 3D mapping of a [Formula: see text] seismic survey acquired in the Safi Haute Mer seismic block revealed numerous linear features that range from small, less than 17-m-thick Jurassic-age amplitude striations up to 110-m-thick migrating Cretaceous contourite sediment waves. Early proto-Atlantic deposition in Safi Haute Mer initiated in the Triassic, with syn- and postrift accumulation in basement half-grabens basinward of the modern Moroccan salt front. Sedimentation continued through the Mesozoic with deposition of turbidites, progradation of clinoforms, and culminating in multiple Late Cretaceous, regionally expansive, mass-transport deposits ([Formula: see text]). Tertiary stratigraphy consists of multiple thin, pelagic drapes and unconformities. The complex history of sedimentation and tectonics gave rise to three styles of sediment waves found within the study area: (1) type J1 — small and poorly imaged, Jurassic age, locally generated wave forms that have wavelengths of up to 12 km and crest-to-crest separations of less than 1 km with little or no vertical expression; (2) type K1 — early Aptian constructional sediment waves ([Formula: see text] thick) built by contour currents that traveled in and near a contourite moat at the base of a seafloor high produced by shallowly buried mobile salt; and (3) type K2 — latest Albian and earliest post-Albian sediment waves built by along-slope currents on a relatively stable slope, showing evidence of updip migration. The type K2 sediment wavefield exhibits wave heights of 40 m and crest-to-crest separations of 1 km, and it is continuous over the entire study area.

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