scholarly journals Diffuse soil CO_2 degassing from Linosa island

2014 ◽  
Vol 57 (3) ◽  
Author(s):  
Dario Cellura ◽  
Vincenzo Stagno ◽  
Marco Camarda ◽  
Mariano Valenza
Keyword(s):  
Sequential Gaussian Simulation ◽  
Rift System ◽  
Volcanic Complex ◽  
Tectonic Structures ◽  
Soil Degassing ◽  
Active Tectonic ◽  
Active Portion ◽  
Sicily Channel ◽  
Gaussian Simulation ◽  
First Time

<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:HyphenationZone>14</w:HyphenationZone> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]--><p class="MsoNormal" style="text-align: justify; line-height: 200%;"><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:TrackMoves/> <w:TrackFormatting/> <w:HyphenationZone>14</w:HyphenationZone> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:DoNotPromoteQF/> <w:LidThemeOther>IT</w:LidThemeOther> <w:LidThemeAsian>X-NONE</w:LidThemeAsian> <w:LidThemeComplexScript>X-NONE</w:LidThemeComplexScript> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> <w:SplitPgBreakAndParaMark/> <w:DontVertAlignCellWithSp/> <w:DontBreakConstrainedForcedTables/> <w:DontVertAlignInTxbx/> <w:Word11KerningPairs/> <w:CachedColBalance/> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> <m:mathPr> <m:mathFont m:val="Cambria Math"/> <m:brkBin m:val="before"/> <m:brkBinSub m:val="--"/> <m:smallFrac m:val="off"/> <m:dispDef/> <m:lMargin m:val="0"/> <m:rMargin m:val="0"/> <m:defJc m:val="centerGroup"/> <m:wrapIndent m:val="1440"/> <m:intLim m:val="subSup"/> <m:naryLim m:val="undOvr"/> </m:mathPr></w:WordDocument> </xml><![endif]--></p><p>Herein, we present and discuss the result of 148 measurements of soil CO<span><sub>2</sub></span> flux performed for the first time in Linosa island (Sicily Channel, Italy), a Plio-Pleistocene volcanic complex no longer active but still of interest owing to its location within a seismically active portion of the Sicily Channel rift system. The main purpose of this survey was to assess the occurrence of CO<span><sub>2</sub></span> soil degassing, and compare flux estimations from this island with data of soil degassing from worldwide active volcanic as well as non-volcanic areas. To this aim soil CO<span><sub>2</sub></span> fluxes were measured over a surface of about 4.2 km<span><sup>2</sup></span> covering ~80% of the island. The soil CO<span><sub>2</sub></span> degassing was observed to be mainly concentrated in the eastern part of the island likely due to volcano-tectonic lineaments, the presence of which is in good agreement with the known predominant regional faults system. Then, the collected data were interpreted using sequential Gaussian simulation that allowed estimating the total CO<span><sub>2</sub></span> emissions of the island. Results show low levels of CO<span><sub>2</sub></span> emissions from the soil of the island (~55 ton d<span><sup>-1</sup></span>) compared with CO<span><sub>2</sub></span> emissions of currently active volcanic areas, such as Miyakejima (Japan) and Vulcano (Italy). Results from this study suggest that soil degassing in Linosa is mainly fed by superficial organic activity with a moderate contribution of a deep CO<span><sub>2</sub></span> likely driven by NW-SE trending active tectonic structures in the eastern part of the island.</p>

Monitoring of diffuse CO2 degassing at NERZ, NWRZ and NSRZ volcanic systems of Tenerife, Canary Islands

2021 ◽  
Author(s):  
Fátima Rodríguez ◽  
Eleazar Padrón ◽  
Gladys Melián ◽  
María Asensio-Ramos ◽  
Mar Alonso ◽  
...  
Keyword(s):  
Rift Zone ◽  
Emission Rate ◽  
Interpolation Method ◽  
Sampling Site ◽  
Sequential Gaussian Simulation ◽  
Rift System ◽  
Volcanic Complex ◽  
North East ◽  
The North ◽  
Volcanic Seismicity

&lt;p&gt;One of the main volcano-structural and geomorphological feature in Tenerife (2,034 km&lt;sup&gt;2&lt;/sup&gt;) is the triple rift system, formed by aligned of hundreds of monogenetic eruptive products of shield basaltic volcanism. At the intersection of this triple rift system rises the Teide-Pico Viejo volcanic complex. These volcanic rifts are considered as active volcanic edifices. The North East volcanic Rift Zone (NERZ, 210 km&lt;sup&gt;2&lt;/sup&gt;) form a main NE-SW structure. The North West volcanic Rift Zone (NWRZ, 72 km&lt;sup&gt;2&lt;/sup&gt;) is oriented in NW-SE direction and the North South volcanic Rift Zone (NSRZ, 325 km&lt;sup&gt;2&lt;/sup&gt;) comprises a more scattered area on the south of these monogenetic cones. The most recent eruptive activity of Tenerife has taken place in these rift systems. NERZ host the fissural eruption of Arafo-Fasnia-Siete Fuentes (1704-1705). NWRZ host two historical eruptions: Arenas Negras in 1706 and Chinyero in 1909. Recently the eruption of Boca Cangrejo (1492) has been added to the historical register through &lt;sup&gt;14&lt;/sup&gt;C dating. NSRZ does not host historical volcanism, although it is recent, up to 10,000 years old.&lt;/p&gt;&lt;p&gt;In order to provide a multidisciplinary approach to monitor potential volcanic activity changes at the NERZ, NWRZ and NSRZ, diffuse CO&lt;sub&gt;2&lt;/sub&gt; emission surveys have been undertaken since 2000, in general in a yearly basis, but with a higher frequency when seismic swarms have occurred in and around NWRZ volcano. Each study area for NERZ, NWRZ and NSRZ comprises hundreds of sampling sites homogenously distributed. Soil CO&lt;sub&gt;2&lt;/sub&gt; efflux measurements at each sampling site were conducted at the surface environment by means of a portable non-dispersive infrared spectrophotometer (NDIR) LICOR Li820 following the accumulation chamber method. To quantify the CO&lt;sub&gt;2&lt;/sub&gt; emission rate from the NERZ, NWRZ and NSRZ a sequential Gaussian simulation (sGs) was used as interpolation method.&lt;/p&gt;&lt;p&gt;The diffuse CO&lt;sub&gt;2&lt;/sub&gt; emission rate for the NERZ ranged from 532 up to 2823 t d&lt;sup&gt;-1 &lt;/sup&gt;between 2001 and 2020, with the highest value measured in 2020. In the case of NWRZ, the diffuse CO&lt;sub&gt;2&lt;/sub&gt; emission rate ranged from 52 up to 867 t d&lt;sup&gt;-1 &lt;/sup&gt;between 2000 and 2020, with the highest value measured in one of the surveys of 2005. Finally, and for NSRZ, the diffuse CO&lt;sub&gt;2&lt;/sub&gt; emission rate ranged from 78 up to 819 t d&lt;sup&gt;-1 &lt;/sup&gt;between 2002 and 2020, with the highest value measured in 2019. The temporal evolution of diffuse CO&lt;sub&gt;2&lt;/sub&gt; emission at the NERZ, NWRZ and NSRZ shows a nice and clear relationship with the volcanic seismicity in and around Tenerife Island, which started to take place from the end of 2016. The good temporal correlation between the volcanic seismicity and the increase trend observed in the time series of diffuse CO&lt;sub&gt;2&lt;/sub&gt; emission rates at NERZ, NWRZ and NSRZ is also coincident with the observed increase of diffuse CO&lt;sub&gt;2&lt;/sub&gt; emission rate at the summit crater of Teide. This work demonstrates the importance of performing soil CO&lt;sub&gt;2&lt;/sub&gt; efflux surveys at active rift systems in volcanic oceanic islands as an effective geochemical monitoring tool.&lt;/p&gt;

scholarly journals Stratigraphic and structural control over permeability distribution in poorly consolidated siliciclastic rocks

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Thayssa Pereira de Andrade Andrade ◽  
Emilio Velloso Barroso ◽  
ConfiguraçõesLuis Paulo Vieira Braga ◽  
Claudio Limeira Mello ◽  
ConfiguraçõesJorge André Braz de Souza
Keyword(s):  
Structural Control ◽  
Flow Direction ◽  
Flow Analysis ◽  
Sequential Gaussian Simulation ◽  
Asymmetric Distribution ◽  
Tectonic Structures ◽  
Spatial Continuity ◽  
Permeability Distribution ◽  
Siliciclastic Rocks ◽  
Gaussian Simulation

Permeability models are very relevant for the characterization of oil systems. However, limitations related to the resolution of seismic data make it difficult to identify subseismic, sedimentary, and tectonic structures, which can significantly impact the flow pattern. This study analyzed the spatial variability of permeability according to stratigraphic and structural geology control to propose a useful model for poorly consolidated, fractured, and faulted siliciclastic reservoirs. In an outcrop analogue to this type of reservoir, air permeability was measured in 3 orthogonal directions at 24 points, spaced 2 m apart.The models were obtained by sequential Gaussian simulation (SGS) after statistical data treatment. The models were validated to ensure the consistency of the generated scenarios. Permeability values showed a positive asymmetric distribution and reduced medians toward tectonic structures. The fitted semivariogram model was exponential, with higher spatial continuity in the horizontal flow direction and lower in the vertical one. The permeability models emphasized the importance of considering subseismic structures in the flow analysis of reservoirs since they have proven to play a significant role in the permeability distribution in the outcrop assessed.

Long-term variations of diffuse CO2, He and H2 at the summit crater of Teide volcano, Tenerife, Canary Islands

2021 ◽  
Author(s):  
María Asensio-Ramos ◽  
Gladys Melián ◽  
Fátima Rodríguez ◽  
Nemesio M. Pérez ◽  
Mar Alonso ◽  
...  
Keyword(s):  
Canary Islands ◽  
Summit Crater ◽  
Sequential Gaussian Simulation ◽  
Rift System ◽  
Volcanic Complex ◽  
Sampling Point ◽  
Emission Rates ◽  
Volcanic System ◽  
Diffuse Degassing ◽  
Teide Volcano

&lt;p&gt;Tenerife (2,034 km&lt;sup&gt;2&lt;/sup&gt;) is the largest of the Canary Islands. Its structure is controlled by a volcano-tectonic rift-system with NW, NE and NS directions, with the volcanic system Teide-Pico Viejo located in the intersection. Teide is 3,718 m.a.s.l. high and its last eruption occurred in 1798 through an adventive cone of Teide-Pico Viejo volcanic complex. Persistent degassing activity, both visible and diffuse, takes place at the summit cone of the volcano, being the diffuse degassing the principle mechanism.&lt;/p&gt;&lt;p&gt;During the period 1999-2020, more than 200 diffuse CO&lt;sub&gt;2&lt;/sub&gt; ef&amp;#64258;ux surveys have been performed in the summit crater of Teide Volcano. For each survey, 38 sampling sites homogeneously distributed inside the crater covering an area of 6,972 m&lt;sup&gt;2&lt;/sup&gt; were selected. Diffuse CO&lt;sub&gt;2&lt;/sub&gt; emission was estimated in each point by means of a portable non dispersive infrared (NDIR) CO&lt;sub&gt;2&lt;/sub&gt; fluxmeter using the accumulation chamber method. Additionally, soil gas samples were taken at 40 cm depth and analyzed later in the lab for the He and H&lt;sub&gt;2&lt;/sub&gt; content by means of quadrupole mass spectrometry and micro-gas chromatography, respectively. To estimate the He and H&lt;sub&gt;2&lt;/sub&gt; emission rates at each sampling point, the diffusive component was estimated following the Fick&amp;#8217;s law and the convective emission component model was estimated following the Darcy&amp;#8217;s law. In all cases, spatial distribution maps were constructed averaging the results of 100 simulations following the sequential Gaussian simulation (sGs) algorithm, in order to determine CO&lt;sub&gt;2&lt;/sub&gt;, He and H&lt;sub&gt;2&lt;/sub&gt; emission rates.&lt;/p&gt;&lt;p&gt;During the study period, CO&lt;sub&gt;2&lt;/sub&gt; emissions ranged from 2.2 to 176.1 t/d, He emissions between 0.013 and 4.1 kg/d and H&lt;sub&gt;2&lt;/sub&gt; between 1.3 and 35.6 kg/d. On October 2, 2016, a seismic swarm of long-period events was recorded on Tenerife followed by a general increase of the seismic activity in and around the island (D&amp;#8217;Auria et al., 2019). Since then, relatively high values have been obtained in the diffuse CO&lt;sub&gt;2&lt;/sub&gt;, He and H&lt;sub&gt;2&lt;/sub&gt; emission rate the crater of Teide. This increase reflects a process of pressurization of the volcanic-hydrothermal system.&lt;/p&gt;&lt;p&gt;The variations in CO&lt;sub&gt;2&lt;/sub&gt;, He and H&lt;sub&gt;2&lt;/sub&gt; emissions indicate changes in the activity of the system and can be useful to understand the behaviour of the volcanic system and to forecast future volcanic activity. Monitoring the diffuse degassing rates at Teide volcano has demonstrated to be an essential tool for predicting future seismic&amp;#8211;volcanic unrest, and has become important to reduce volcanic risk in Tenerife (Meli&amp;#225;n et al., 2012; P&amp;#233;rez et al., 2013).&lt;/p&gt;&lt;p&gt;D'Auria .L, Barrancos J., Padilla G.D., P&amp;#233;rez N.M., Hern&amp;#225;ndez P.A., Meli&amp;#225;n G., Padron E., Asensio-Ramos M., Garc&amp;#237;a&amp;#8208;Hern&amp;#225;ndez R. (2019). J. Geophys. Res. 124, 8739-8752&lt;/p&gt;&lt;p&gt;P&amp;#233;rez N. M., Hern&amp;#225;ndez P. A., Padr&amp;#243;n E., Meli&amp;#225;n G., Nolasco D., Barrancos J., Padilla G., Calvo D., Rodr&amp;#237;guez F., Dionis S. and Chiodini G. (2013). J. Geol. Soc., 170(4), 585-592.&lt;/p&gt;&lt;p&gt;Meli&amp;#225;n G., Tassi F., P&amp;#233;rez N. M., Hern&amp;#225;ndez P., Sortino F., Vaselli O., Padr&amp;#243;n E., Nolasco D., Barrancos J., Padilla G., Rodriguez F., Dionis S., Calvo D., Notsu K., Sumino H. (2012).&amp;#160; Bull. Volcanol, 74(6), 1465-1483.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Diffuse H2 degassing studies: a useful geochemical tool for monitoring Cumbre Vieja volcano, La Palma, Canary Islands

2021 ◽  
Author(s):  
Nemesio M. Pérez ◽  
Gladys V. Melián ◽  
Pedro A. Hernández ◽  
María Asensio-Ramos ◽  
Eleazar Padrón ◽  
...  
Keyword(s):  
Canary Islands ◽  
Emission Rate ◽  
Monitoring Program ◽  
Hydrothermal Systems ◽  
Sequential Gaussian Simulation ◽  
Homogeneous Distribution ◽  
La Palma ◽  
Soil Degassing ◽  
Geothermal Activity ◽  
Cumbre Vieja

&lt;p&gt;Hydrogen (H&lt;sub&gt;2&lt;/sub&gt;) is one of the most abundant trace species in volcano-hydrothermal systems and is a key participant in many redox reactions occurring in the hydrothermal reservoir gas. Although H&lt;sub&gt;2&lt;/sub&gt; can be produced in soils by N&lt;sub&gt;2&lt;/sub&gt;-fixing and fertilizing bacteria, soils are considered nowadays as sinks of molecular hydrogen (Smith-Downey et al. 2006). Because of its chemical and physical characteristics, H&lt;sub&gt;2&lt;/sub&gt; generated within the crust moves rapidly and escapes to the atmosphere. These characteristics make H&lt;sub&gt;2&lt;/sub&gt; one of the best geochemical indicators of magmatic and geothermal activity at depth. Cumbre Vieja volcano (La Palma, Canary Islands) is the most active basaltic volcano in the Canaries with seven historical eruptions being Tenegu&amp;#237;a eruption (1971) the most recent one. Cumbre Vieja volcano is characterized by a main north&amp;#8211;south rift zone 20 km long, up to 1950 m in elevation and covering an area of 220 km&lt;sup&gt;2&lt;/sup&gt; with vents located at the northwest and northeast. Cumbre Vieja does not show any visible degassing (fumaroles, etc.). For that reason, the geochemical volcano monitoring program at Cumbre Vieja volcano has been focused on soil degassing surveys. &amp;#160;Here we show the results of soil H&lt;sub&gt;2&lt;/sub&gt; emission surveys that have been carried out regularly since 2001. Soil gas samples were collected in about 600 sampling sites selected to obtain a homogeneous distribution at about 40 cm depth using a metallic probe and 60 cc hypodermic syringes and stored in 10 cc glass vials. H&lt;sub&gt;2&lt;/sub&gt; content was analysed later by a VARIAN CP4900 micro-GC. A simple diffusive emission mechanism was applied to compute the emission rate of H&lt;sub&gt;2&lt;/sub&gt; at each survey. Diffuse H&lt;sub&gt;2&lt;/sub&gt; emission values were used to construct spatial distribution maps by using sequential Gaussian simulation (sGs) algorithm, allowing the estimation of the emission rate from the volcano. Between 2001-2003, the average diffuse H&lt;sub&gt;2&lt;/sub&gt; emission rate was &amp;#8764;2.5 kg&amp;#183;d&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; and an increase of this value was observed between 2013-2017 (&amp;#8764;16.6 kg&amp;#183;d&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;), reaching a value of 36 kg&amp;#183;d&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; on June 2017, 4 month before the first recent seismic swarm in October, 2017 at Cumbre Vieja volcano. Six additional seismic swarms had occurred at Cumbre Vieja volcano (February 2018, July-August 2020; October 8-10, 2020; October 17-19, 2020, November 21, 2020 and December 23-26, 2020) and changes of diffuse H&lt;sub&gt;2&lt;/sub&gt; emission related to this unrest had been observed reaching values up to &amp;#8764;70 kg&amp;#183;d&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;. Diffuse H&lt;sub&gt;2&lt;/sub&gt; emission surveys have demonstrated to be sensitive and excellent precursors of magmatic processes occurring at depth in Cumbre Vieja. Periodic diffuse H&lt;sub&gt;2&lt;/sub&gt; emission surveys provide valuable information to improve and optimize the detection of early warning signals of volcanic unrest at Cumbre Vieja volcano.&lt;/p&gt;

scholarly journals Features of ground inflow testing in the areas of double porosity aquifer development

2021 ◽  
Vol 44 (2) ◽  
pp. 116-124
Author(s):  
L. I. Auzinaa ◽  
Yu. K. Lankin
Keyword(s):  
Free Water ◽  
Double Porosity ◽  
Rift System ◽  
Eastern Siberia ◽  
Geological Exploration ◽  
Tectonic Structures ◽  
Fault Block ◽  
Study Results ◽  
Exploration Drilling ◽  
Block Structures

The purpose of the study is optimization of geological exploration at the groundwater deposits of the upper hydrodynamic zone formed in the fault-block structure conditions in Eastern Siberia. The authors analyze the structural and tectonic features of the areas under investigation, the results of areal geophysics studies, exploration drilling and the use of the author's methodology in carrying out of the ground inflow testing. The objects of research are groundwater deposits located in various tectonic structures of Eastern Siberia. The analysis of field study results involving researches of groundwater deposits located in various tectonic structures of Eastern Siberia made it possible to identify the double porosity in the aquifers of free water exchange in the region, which is due to the stresses arising during the inland Baikal rift system formation. As a result, the optimization of geological exploration work, methodology and processing methods of ground inflow testing in the areas of fault-block structures development were introduced on the basis of the features of structural-tectonic and hydrogeological conditions.

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