scholarly journals Analysis of Volcanic Thermohaline Fluctuations of Tagoro Submarine Volcano (El Hierro Island, Canary Islands, Spain)

Geosciences ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 374
Author(s):  
Anna Olivé Abelló ◽  
Beatriz Vinha ◽  
Francisco Machín ◽  
Francesco Zerbetto ◽  
Evangelos Bakalis ◽  
...  
Keyword(s):  
Time Series ◽  
Canary Islands ◽  
Hydrothermal Vents ◽  
Hydrothermal Process ◽  
Structure Functions ◽  
Submarine Volcano ◽  
Normal Behaviour ◽  
System A ◽  
Moments Method ◽  
Stochastic Events

Temperature and conductivity fluctuations caused by the hydrothermal emissions released during the degasification stage of the Tagoro submarine volcano (Canary Islands, Spain) have been analysed as a robust proxy for characterising and forecasting the activity of the system. A total of 21 conductivity-temperature-depth time series were gathered on a regular high-resolution grid over the main crater of Tagoro volcano. Temperature and conductivity time series, as manifestations of stochastic events, were investigated in terms of variance and analysed by the Generalised Moments Method (GMM). GMM provides the statistical moments, the structure functions of a process whose shape is an indicator of the underlying stochastic mechanisms and the state of activity of the submarine volcano. Our findings confirm an active hydrothermal process in the submarine volcano with a sub-normal behaviour resulting from anti-persistent fluctuations in time. Its hydrothermal emissions are classified as multifractal processes whose structure functions present a crossover between two time scales. In the shorter time scale, findings point to the multiplicative action of two random processes, hydrothermal vents, which carries those fluctuations driving the circulation over the crater, and the overlying aquatic environment. Given that both temperature and conductivity fluctuations are nonstationary, Tagoro submarine volcano can be characterised as an open system exchanging energy to its surroundings.

scholarly journals Temperature and Conductivity as Indicators of the Morphology and Activity of a Submarine Volcano: Avyssos (Nisyros) in the South Aegean Sea, Greece

2018 ◽  
Author(s):  
Evangelos Bakalis ◽  
Theo J. Mertzimekis ◽  
Paraskevi Nomikou ◽  
Francesco Zerbetto
Keyword(s):  
Time Series ◽  
Open System ◽  
Morphological Structure ◽  
Aegean Sea ◽  
Submarine Volcano ◽  
The South ◽  
Hand Temperature ◽  
Moments Method ◽  
Generalized Moments ◽  
Shed Light

The morphology and the activity of a submarine caldera, Avyssos, at the northern part of Nisyros volcano in the South Aegean Sea (Greece), has been studied by means of remotely operated underwater vehicle dives. The recorded time series of temperature and conductivity over the submarine volcano have been analyzed in terms of the Generalized Moments Method. The findings of the mathematical analysis shed light on the volcanic activity, but also on the morphology (shape) of the submarine volcano. The conductivity time series indicates the volcano is at rest in agreement with other types of observations. On the other hand, temperature fluctuations, which in general describe a multifractal process, show that the submarine caldera operates as an open system that interacts with its surroundings. This type of analysis can be used as an indicator for the state of activity and the morphological structure (closed or open system) of a submarine volcano.

scholarly journals The Hydrothermal Vent Field at the Eastern Edge of the Hellenic Volcanic Arc: The Avyssos Caldera (Nisyros)

Geosciences ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 290
Author(s):  
Ana Dura ◽  
Theo J. Mertzimekis ◽  
Paraskevi Nomikou ◽  
Andreas Gondikas ◽  
Martín Manuel Gómez Míguez ◽  
...  
Keyword(s):  
Time Series ◽  
Volcanic Activity ◽  
Hydrothermal Vent ◽  
Natural Hazard ◽  
Risk Mitigation ◽  
Aegean Sea ◽  
Submarine Volcano ◽  
Moments Method ◽  
The Impact ◽  
Generalized Moments

Almost three-quarters of known volcanic activity on Earth occurs in underwater locations. The presence of active hydrothermal vent fields in such environments is a potential natural hazard for the environment, society, and economy. Despite its importance for risk assessment and risk mitigation, the monitoring of volcanic activity is impeded by the remoteness and the extreme conditions of many underwater volcanoes. The morphology and the activity of the submarine caldera, Avyssos, at the northern part of Nisyros volcano in the South Aegean Sea (Greece), were studied using a remotely operated underwater vehicle. The recorded time series of temperature and conductivity over the submarine volcano have been analyzed in terms of the Generalized Moments Method. This type of analysis can be used as an indicator for the state of activity of a submarine volcano. Here, we expand the work conducted for the first time in 2018. We present the findings of the geological exploration and the mathematical analysis, obtained from the data collected in October 2010. The temperature and conductivity time series show minor fluctuations in a rather stable environment. Based on these results, the impact of developing appropriate mechanisms and policies to avoid the associated natural hazard is expected to be important.

scholarly journals First Macro-Colonizers and Survivors Around Tagoro Submarine Volcano, Canary Islands, Spain

Geosciences ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 52 ◽  
Author(s):  
Ana Sotomayor-García ◽  
José Rueda ◽  
Olga Sánchez-Guillamón ◽  
Javier Urra ◽  
Juan Vázquez ◽  
...  
Keyword(s):  
Canary Islands ◽  
Hydrothermal Vents ◽  
Hard Substrate ◽  
Volcanic Complex ◽  
Substrate Type ◽  
Submarine Volcano ◽  
Sea Floor ◽  
Biological Communities ◽  
Bacterial Mats ◽  
New Habitats

Tagoro, the youngest submarine volcano of the Canary Islands, erupted in 2011 South of El Hierro Island. Pre-existing sea floor and inhabiting biological communities were buried by the newly erupted material, promoting the appearance of new habitats. The present study pursues to describe the first metazoans colonizing different new habitats formed during the eruption and to create precedent on this field. Through dredge and remote operated vehicle samplings, five main habitat types have been detected based on the substrate type and burial status after the eruption. Inside the Tagoro volcanic complex (TVC), two new habitats are located in and around the summit and main craters—hydrothermal vents with bacterial mats and sulfurous-like fields mainly colonized by small hydrozoan colonies. Two other habitats are located downslope the TVC; new hard substrate and new mixed substrate, holding the highest biodiversity of the TVC, especially at the mixed bottoms with annelids (Chloeia cf. venusta), arthropods (Monodaeus couchii and Alpheus sp.), cnidarians (Sertularella cf. tenella), and molluscs (Neopycnodonte cochlear) as the first colonizers. An impact evaluation was done comparing the communities of those habitats with the complex and well-established community described at the stable hard substrate outside the TVC, which is constituted of highly abundant hydrozoans (Aglaophenia sp.), antipatharians (Stichopates setacea and Antipathes furcata), and colonizing epibionts (e.g., Neopycnodonte cochlear). Three years after the eruption, species numbers at Tagoro were still low compared to those occurring at similar depths outside the TVC. The first dominant species at the TVC included a large proportion of common suspension feeders of the circalittoral and bathyal hard bottoms of the area, which could have exploited the uncolonized hard bottoms and the post eruptive fertilization of water masses.

scholarly journals Characterizing sand ripples at equilibrium phases

2013 ◽  
Vol 61 (4) ◽  
pp. 293-298 ◽  
Author(s):  
Jie Qin ◽  
Deyu Zhong ◽  
Guangqian Wang
Keyword(s):  
Time Series ◽  
Random Fields ◽  
Morphological Characteristics ◽  
Structure Functions ◽  
Second Order ◽  
Order Structure ◽  
Two Dimensional ◽  
Sand Ripples ◽  
Digital Elevation ◽  
Equilibrium Phases

Abstract Morphological characteristics of ripples are analyzed considering bed surfaces as two dimensional random fields of bed elevations. Two equilibrium phases are analyzed with respect to successive development of ripples based on digital elevation models. The key findings relate to the shape of the two dimensional second-order structure functions and multiscaling behavior revealed by higher-order structure functions. Our results suggest that (1) the two dimensional second-order structure functions can be used to differentiate the two equilibrium phases of ripples; and (2) in contrast to the elevational time series of ripples that exhibit significant multiscaling behavior, the DEMs of ripples at both equilibrium phases do not exhibit multiscaling behavior.

scholarly journals Recent changes and drivers of the atmospheric evaporative demand in the Canary Islands

2016 ◽  
Author(s):  
S. M. Vicente-Serrano ◽  
C. Azorin-Molina ◽  
A. Sanchez-Lorenzo ◽  
A. El Kenawy ◽  
N. Martín-Hernández ◽  
...  
Keyword(s):  
Time Series ◽  
Relative Humidity ◽  
Canary Islands ◽  
Temporal Variability ◽  
Meteorological Factors ◽  
Negative Consequences ◽  
Evaporative Demand ◽  
High Quality ◽  
Radiative Component ◽  
Main Driver

Abstract. We analysed recent evolution and meteorological drivers of the atmospheric evaporative demand (AED) in the Canary Islands for the period 1961–2013. We employed long and high quality time series of meteorological variables to analyze current AED changes in this region and found that AED has increased during the investigated period. Overall, the annual ETo increased significantly by 18.2 mm decade−1 on average, with a stronger trend in summer (6.7 mm decade−1). The radiative component showed much lower temporal variability than the aerodynamic component did. Thus, more than 90 % of the observed ETo variability at the seasonal and annual scales can be associated with the variability of the aerodynamic component. The variable that recorded more significant changes in the Canary Islands was relative humidity, and among the different meteorological factors used to calculate ETo, relative humidity was the main driver of the observed ETo trends. The observed trend could have negative consequences in a number of water-depending sectors if it continues in the future.

Fluctuation complexity of agent-based financial time series model by stochastic Potts system

2015 ◽  
Vol 26 (11) ◽  
pp. 1550123 ◽  
Author(s):  
Weijia Hong ◽  
Jun Wang
Keyword(s):  
Time Series ◽  
Dynamic System ◽  
Financial Time Series ◽  
Composite Index ◽  
Time Series Model ◽  
Agent Based ◽  
Financial Time ◽  
System A ◽  
Challenging Tasks ◽  
Financial Research

Financial market is a complex evolved dynamic system with high volatilities and noises, and the modeling and analyzing of financial time series are regarded as the rather challenging tasks in financial research. In this work, by applying the Potts dynamic system, a random agent-based financial time series model is developed in an attempt to uncover the empirical laws in finance, where the Potts model is introduced to imitate the trading interactions among the investing agents. Based on the computer simulation in conjunction with the statistical analysis and the nonlinear analysis, we present numerical research to investigate the fluctuation behaviors of the proposed time series model. Furthermore, in order to get a robust conclusion, we consider the daily returns of Shanghai Composite Index and Shenzhen Component Index, and the comparison analysis of return behaviors between the simulation data and the actual data is exhibited.

Sign in / Sign up

Export Citation Format

Share Document