Diffuse CO2 degassing monitoring of the Tenerife North–South Rift Zone (NSRZ) volcano, Canary Islands

Tenerife (2,034 km2) is the largest of the Canary Islands and the North South Rift Zone (NSRZ) is one of the three active volcanic rift-zones of the island. The NSRZ (325 km2) is characterized mainly by effusive activity of basaltic lavas forming spatter and cinder cones and comprises 139 monogenetic cones representing the most common eruptive activity occurred on the island during the last 1Ma. In order to provide a multidisciplinary approach to monitor potential volcanic activity changes at the NSRZ volcano, diffuse CO2 emission surveys have been undertaken since 2002. This study shows the results of the last soil CO2 efflux survey undertaken in summer 2019, with &#8275;600 soil gas sampling sites homogenously distributed in the study area. Soil CO2 efflux measurements were performed at the surface environment by means of a portable non-dispersive infrared spectrophotometer (NDIR) LICOR Li820 following the accumulation chamber method. Soil CO2 efflux values ranged from non-detectable (&#8275;0.5 g m-2 d-1) up to 30 g m-2 d-1, with an average value of 2.6 g m-2 d-1. In order to distinguish the existence of different geochemical populations on the soil CO2 efflux data, a Sinclair graphical analysis was done. The average value of background population was 2.1 g m-2 d-1 and that of peak population was 18.5 g m-2 d-1, representing the 97% and the 1% of the total data, respectively. To quantify the total CO2 emission rate from the NSRZ volcano a sequential Gaussian simulation (sGs) was used as interpolation method. The diffuse CO2 emission rate for the studied area was estimated in 2019 in 819 &#177; 18 t d-1, ranging from 466 to 819 t d-1 between 2002 and 2019, with the highest value measured in 2015 (707 t d-1). The temporal evolution of diffuse CO2 emission at the NSRZ shows a clear relationship with the volcano seismic activity in and around Tenerife Island, which started to taking place from the end of 2016. This study demonstrates the importance of studies of soil CO2 efflux at the NSRZ volcano of Tenerife island as an effective volcanic monitoring tool, especially in areas where there is no visible degassing (fumaroles, etc.)

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Surface diffuse degassing monitoring of the Tenerife Northeastern Rift Zone (NERZ) volcano, Canary Islands

10.5194/egusphere-egu2020-11604 ◽

2020 ◽

Author(s):

Lucía Sáez-Gabarrón ◽

Jazlyn Beeck ◽

Sian Reilly ◽

Mar Alonso ◽

Víctor Ortega-Ramos ◽

...

Keyword(s):

Interpolation Method ◽

Graphical Analysis ◽

Point Of View ◽

Sequential Gaussian Simulation ◽

Contour Maps ◽

Average Value ◽

North East ◽

The North ◽

Tenerife Island ◽

Total Data

The North East Rift volcanic Zone (NERZ) of Tenerife Island is one of the three volcanic rift-zones of the island, oriented NW-SE (NWRZ), NE-SW (NERZ) and a more scattered area on the south (NSRZ). From a volcano-structural point of view, NERZ is more complex than NW or NS rifts due the existence of Pedro Gil stratovolcano that broke the main NE-SW structure. Pedro Gil Caldera was formed&#160; 0.8&#160; Ma ago by a vertical collapse of this stratovolcano. The most recent eruptive activity along the NERZ took place during 1704 and 1705 along a 13 km of fissural eruption of Arafo-Fasnia-Siete Fuentes. Diffuse CO2 emission surveys have been undertaken in a yearly basis since 2001 in order to provide a multidisciplinary approach to monitor potential volcanic activity changes at the NERZ. The aim of this study is to report the results of the last soil CO2 efflux survey undertaken in summer 2019, with 639 measuring sites homogeneously distributed in an area of 210 km2. In-situ measurements of CO2 efflux from the surface environment of NERZ were performed by means of a portable non-dispersive infrared spectrophotometer (NDIR) following the accumulation chamber method. Soil CO2 efflux contour maps were constructed to identify spatio-temporal anomalies and to quantify the total CO2 emission using the sequential Gaussian simulation (sGs) interpolation method. The CO2 efflux values ranged from non-detectable (0.5 g m-2 d-1) up to 72,3 g m-2 d-1, with an average value of 10,9 g m-2 d-1. Statistical-graphical analysis of the 2019 data show two different geochemical populations; background (B) and peak (P) represented by 70.4% and 1.9% of the total data, respectively. The geometric means of the B and P populations are 0.4 and 4.3 g m-2 d-1, respectively. The diffuse CO2 emission rate was estimated in 2,205 t d-1. Studying the long-term variations on the diffuse CO2 emission since 2001, two main pulses are identified: one in 2007 and a second one sustained over time between 2014 and 2019. Enhanced endogenous contributions of deep-seated CO2 might have been responsible for the higher CO2 emissions values observed during those pulses. The 2014-2019 pulse appears to be related to the seismic activity that started taking place in Tenerife at the end of 2016. This study denotes the importance of soil CO2 efflux surveys at the NERZ volcano of Tenerife Island as an effective volcanic monitoring tool.

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

10.5194/egusphere-egu21-15427 ◽

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

One of the main volcano-structural and geomorphological feature in Tenerife (2,034 km2) 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 km2) form a main NE-SW structure. The North West volcanic Rift Zone (NWRZ, 72 km2) is oriented in NW-SE direction and the North South volcanic Rift Zone (NSRZ, 325 km2) 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 14C dating. NSRZ does not host historical volcanism, although it is recent, up to 10,000 years old.In order to provide a multidisciplinary approach to monitor potential volcanic activity changes at the NERZ, NWRZ and NSRZ, diffuse CO2 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 CO2 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 CO2 emission rate from the NERZ, NWRZ and NSRZ a sequential Gaussian simulation (sGs) was used as interpolation method.The diffuse CO2 emission rate for the NERZ ranged from 532 up to 2823 t d-1 between 2001 and 2020, with the highest value measured in 2020. In the case of NWRZ, the diffuse CO2 emission rate ranged from 52 up to 867 t d-1 between 2000 and 2020, with the highest value measured in one of the surveys of 2005. Finally, and for NSRZ, the diffuse CO2 emission rate ranged from 78 up to 819 t d-1 between 2002 and 2020, with the highest value measured in 2019. The temporal evolution of diffuse CO2 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 CO2 emission rates at NERZ, NWRZ and NSRZ is also coincident with the observed increase of diffuse CO2 emission rate at the summit crater of Teide. This work demonstrates the importance of performing soil CO2 efflux surveys at active rift systems in volcanic oceanic islands as an effective geochemical monitoring tool.

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

10.5194/egusphere-egu21-15403 ◽

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

Hydrogen (H2) 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 H2 can be produced in soils by N2-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, H2 generated within the crust moves rapidly and escapes to the atmosphere. These characteristics make H2 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&#237;a eruption (1971) the most recent one. Cumbre Vieja volcano is characterized by a main north&#8211;south rift zone 20 km long, up to 1950 m in elevation and covering an area of 220 km2 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. &#160;Here we show the results of soil H2 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. H2 content was analysed later by a VARIAN CP4900 micro-GC. A simple diffusive emission mechanism was applied to compute the emission rate of H2 at each survey. Diffuse H2 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 H2 emission rate was &#8764;2.5 kg&#183;d&#8722;1 and an increase of this value was observed between 2013-2017 (&#8764;16.6 kg&#183;d&#8722;1), reaching a value of 36 kg&#183;d&#8722;1 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 H2 emission related to this unrest had been observed reaching values up to &#8764;70 kg&#183;d&#8722;1. Diffuse H2 emission surveys have demonstrated to be sensitive and excellent precursors of magmatic processes occurring at depth in Cumbre Vieja. Periodic diffuse H2 emission surveys provide valuable information to improve and optimize the detection of early warning signals of volcanic unrest at Cumbre Vieja volcano.

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Methane emission to the atmosphere from landfills in the Canary Islands

10.5194/egusphere-egu2020-5651 ◽

2020 ◽

Author(s):

Eleazar Padrón ◽

María Asensio-Ramos ◽

Nemesio M. Pérez ◽

Daniel Di Nardo ◽

Violeta T. Albertos-Blanchard ◽

...

Keyword(s):

Canary Islands ◽

Interpolation Method ◽

Sampling Site ◽

Landfill Gas ◽

Mean Value ◽

Sequential Gaussian Simulation ◽

Fugitive Emission ◽

Contour Maps ◽

Direct Measurements ◽

Gaussian Simulation

Methane (CH4) is an important greenhouse gas, and is increasing in the atmosphere by 0.6% (10 ppb) each year. Important sources of this gas are landfills; in fact more than 10% of the total anthropogenic emissions of CH4 are originated in them by anaerobic degradation of organic matter. Even after years of being closed, a significant amount of landfill gas can be released to the atmosphere through its surface as diffuse or fugitive degassing.Many landfills currently report their CH4 emissions to the atmosphere using model-based methods, which are based on the rate of production of CH4, the oxidation rate of CH4 and the amount of CH4 recovered (Bingemer and Crutzen, 1987). This approach often involves large uncertainties due to inaccuracies of input data and many assumptions in the estimation. In fact, the estimated CH4 emissions from landfills in the Canary Islands published by the Spanish National Emission and Pollutant Sources Registration (PRTR-Spain) seem to be overestimated due to the use of protocols and analytical methodologies based on mathematical models. For this reason, direct measurements to estimate CH4 emissions in landfills are essential to reduce this uncertainty.In order to estimate the CH4 emissions to the atmosphere from landfills in the Canary Islands, 34 surveys have been performed since 1999 to the present. Each survey implies hundreds of CO2 and CH4 efflux measurements covering the landfill surface area. Surface landfill CO2 efflux measurements were carried out at each sampling site by means of a portable non-dispersive infrared spectrophotometer (NDIR) model LICOR Li800 following the accumulation chamber method. Samples of landfill gases were taken in the gas accumulated in the chamber and CO2 and CH4 were analyzed using a double channel VARIAN 4900 micro-GC. The CH4 efflux measurement was computed combining CO2 efflux and CH4/CO2 ratio. To quantify the diffuse or fugitive CO2 and CH4 emission, gas efflux contour maps were constructed using sequential Gaussian simulation (sGs) as interpolation method. Considering that (a) there are 6 controlled landfills in the Canary Islands, (b) the average area of the 34 studied cells is 0.15 km2 and (c) the mean value of the CH4 emission estimated for the studied cells range between 6.2 and 7.2 kt km-2 y-1, the estimated CH4 emission to the atmosphere from landfills in the Canary Islands showed a range of 5.7-6.7 kt y-1 (mean value of 6.2 kt y-1). On the contrary, and for the same period of time, the PRTR-Spain estimates the CH4 emission in the order of 6.4-16.4 kt y-1 (mean value of 9.2 kt y-1), nearly 46% more than our estimated value. This result demonstrates the need to perform direct measurements to estimate the surface fugitive emission of CH4 from landfills.Bingemer, H. G., and P. J. Crutzen (1987), J. Geophys. Res. 92, 2182-2187.

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Crustal versus source processes recorded in dykes from the Northeast volcanic rift zone of Tenerife, Canary Islands

Chemical Geology ◽

10.1016/j.chemgeo.2012.10.013 ◽

2012 ◽

Vol 334 ◽

pp. 324-344 ◽

Cited By ~ 15

Author(s):

F.M. Deegan ◽

V.R. Troll ◽

A.K. Barker ◽

C. Harris ◽

J.P. Chadwick ◽

...

Keyword(s):

Canary Islands ◽

Rift Zone

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The E-Learning on Analysis of the Experimental Results by Using Graphs

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.804.355 ◽

2015 ◽

Vol 804 ◽

pp. 355-358 ◽

Cited By ~ 1

Author(s):

Sirin Sirathanakul ◽

Tanatta Amnuywattanakul

Keyword(s):

Conventional Technique ◽

Graphical Analysis ◽

Learning System ◽

Control Group ◽

Average Value ◽

Multi Stage ◽

E Learning ◽

Power Point ◽

Experimental Group ◽

Research Tools

E-learning is a popular technique that can solve learning problems of student. In this study, the learning package of data analysis by using graphing paper to attain linear relationship between independent and dependent variables was invented and utilized. The learning package, consisting of contents and answer key video made from Power Point was converted to video format. The samples were 58 students of Bachelor of Science program who were selected by multi-stage sampling and divided into experimental and control groups. The experimental group composed of 29 students, learnt by using e-learning via LMS Moodle at RMUTP website. The control group, 29 students, was performed by a conventional technique through multimedia teaching with PowerPoint. The research tools consisted of the lesson of graphical analysis, the questionnaire for quality evaluation of the lesson and the achievement evaluation. The results were found that the quality of research tools was very good and the average value of learning achievement of the experimental group was higher than the control group, no significant statistic at level of 0.05 by comparing with statistical method of t-test (n=29). It indicated that e-learning system can be used as a practical tool for increasing skill of the samples as well as correspondence between them in classroom.

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Geochemical evidences of seismo-volcanic unrests at the NW rift zone of Tenerife, Canary Islands, inferred from diffuse CO2 emission

Bulletin of Volcanology ◽

10.1007/s00445-017-1109-9 ◽

2017 ◽

Vol 79 (4) ◽

Cited By ~ 4

Author(s):

Pedro A. Hernández ◽

Germán Padilla ◽

José Barrancos ◽

Gladys Melián ◽

Eleazar Padrón ◽

...

Keyword(s):

Canary Islands ◽

Co2 Emission ◽

Rift Zone ◽

Diffuse Co2 Emission

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High resolution 3D P wave velocity structure beneath Tenerife Island (Canary Islands, Spain) based on tomographic inversion of active-source data

Journal of Geophysical Research Atmospheres ◽

10.1029/2011jb008970 ◽

2012 ◽

Vol 117 (B9) ◽

Cited By ~ 24

Author(s):

Araceli García-Yeguas ◽

Ivan Koulakov ◽

Jesús M. Ibáñez ◽

A. Rietbrock

Keyword(s):

High Resolution ◽

Wave Velocity ◽

Canary Islands ◽

Velocity Structure ◽

P Wave ◽

Tomographic Inversion ◽

P Wave Velocity ◽

Source Data ◽

Tenerife Island ◽

P Wave Velocity Structure

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Tendencias poblacionales recientes de la avutarda hubara en las Islas Canarias: análisis metodológico y estado de conservación

Animal Biodiversity and Conservation ◽

10.32800/abc.2012.35.0125 ◽

2012 ◽

Vol 35 (1) ◽

pp. 125-139

Author(s):

C. Schuster ◽

◽

J. J. Iglesias-Lebrija ◽

L. M. Carrascal ◽

◽

...

Keyword(s):

Canary Islands ◽

Conservation Status ◽

Distance Sampling ◽

Small Variation ◽

Population Trends ◽

Line Transect ◽

Sampling Area ◽

Average Value ◽

Houbara Bustard ◽

Population Sizes

Recent population trends of the houbara bustard in the Canary Islands. Methods and conservation status Determining conservation status requires rigorous and reliable data about population sizes and trends, especially if they have to be applied to islands where the species have small populations. The Canary bustard houbara (Chlamydotis undulata fuertaventurae) is catalogued as ‘in danger’ by the Red Book of the Birds of Spain. This work analyzes the value of previously published information on the species using the method of adjacent linear transects separated by 200 m, as a baseline for establishing robust population trends in 30 important areas (ranging from 1.3 to 12.8 km2) for the houbara in the islands of Lanzarote and Fuerteventura (Canary Islands). Censuses were repeated on the same dates (from November to December) and localities as those carried out in 1994, 2004 and 2006. The detection probability of the houbara was estimated by means of distance sampling, being 0.42 up to 250 m from the observer, and 0.82 in the main census belt of 100 m on either side of the line transect. The method of adjacent linear transects —counting the maximum number of hubaras detected— provides accurate figures of population densities (detection of 95.2% of the birds). The previous estimations of houbara densities can therefore be considered highly trustworthy, with a probable average underestimation of only 5 %. Nevertheless, the confidence intervals of density estimations using only one census were very large. Therefore, with only one census per sampling area and year it is not possible to obtain precise estimates of houbara densities with small variation around the average value. This raises concern when trying to obtain solid evidence about the increases–decreases of houbara populations comparing different dates or study areas. The density of the Canary Island hubara bustard decreased significantly from 2004/2006 to 2011 in eight areas of Fuerteventura (Vega Vieja, Los Alares–Pocetas, Matas Blancas, Lorenzo– Diviso, Corralejo, Lajares and Fimapaire) and in two areas of Lanzarote (Argana and La Santa). Conversely, the density of the houbara significantly increased in three areas of Lanzarote (Zonzamas, Guatiza and Llano de las Maretas). As a whole, average population density did not differ significantly between 2004/2006 and 2011 in Fuerteventura (slight decrease of 29% in 2011), but there was a significant increase in Lanzarote (increase of 60% from 2004/2006 to 2011). The change in density from 2004/2006 to 2011 tended to be an increase in areas further from paved roads, and a decrease in locations predominantly covered by loose sandy soils.

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Petrofabric and geochemical features of ultramafic rocks on the example of restite metamorphites of the Kuznetsk Alatau (Western Siberia), olivine cumulates of the Yoko-Dovyren layered massif (Northern Cisbaikalia) and their analogues from ultrabasic xenoliths of the Canary Islands (Spain)

Vestnik of Saint Petersburg University Earth Sciences ◽

10.21638/spbu07.2021.404 ◽

2021 ◽

Vol 66 (4) ◽

Author(s):

Vera A. Krylova ◽

◽

Gabriel Gutierrez-Alonso ◽

Igor F. Gertner ◽

Tatiyana S. Krasnova ◽

...

Keyword(s):

Canary Islands ◽

Layered Intrusions ◽

Plastic Deformations ◽

Geochemical Parameters ◽

Ultramafic Xenoliths ◽

Tenerife Island ◽

Olivine Cumulates ◽

Basic Rocks ◽

The Relationship ◽

Primary Crystals

The article presents the results of petrostructural and mineralogical studies of olivine grains from ultrabasic and basic rocks of different genesis. In particular, they correspond to cumulative dunites of the Yoko-Dovyren layered massif (Northern Cisbaikalia), restite hyperbasites of the Velvet massif (Kuznetskiy Alatau), and xenoliths of peridotites from basalts of the Canary Islands (Spain). The relationship between the petrostructural and mineralogical features of ultrabasic rocks is shown, which makes it possible to identify their cumulative and restite varieties. An important element of the petrostructure of ultrabasites is the orientation of olivine, which reflects either the conditions for the formation of primary crystals in the magmatic melt, or the conditions for its recrystallization as a result of plastic deformations during exhumation to the Earth's surface. The mineral composition of rocks is an additional feature that reflects the real conditions of formation. In the presence of basic plagioclase, it is already quite difficult to speak about the restitic nature of these ultrabasic rocks. On the other hand, plastic deformations of olivine are characteristic of restitic hyperbasites, in which plagioclase is absent. The results of mineralogical studies in ultrabasic xenoliths of the Canary Islands showed the presence of basic plagioclase (labradorite), as well as chrysolite-type olivine (12-16 Fa), which corresponds to the attributes of ultrabasic layered intrusions such as the Yoko-Dovyren dunite-troctolite-gabbro pluton. For restite hyperbasites (by the example of the Kuznetsk Alatau), the iron content of olivine does not exceed 9-10% of the fayalite end, while plagioclase and clinopyroxene are absent. A characteristic feature of the xenoliths of the Canary Islands is the presence of endiopside, which is present in layered intrusions, but is absent in the restrained fragments of the upper and lower mantle. It is assumed that the xenoliths in the basalts of the Canary Islands are not of a mantle nature, but are fragments of a deep magma chamber. The studies of the optical orientation of olivine in xenoliths of the rocks of Lanzarote Island confirm these conclusions. The geochemical parameters of ultramafic xenoliths on Tenerife Island may well correspond to deeper formations.

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