Diffuse H2 and He degassing survey to study of hidden potential geothermal systems in La Palma, Canary Islands

2020 ◽  
Author(s):  
Fátima Rodríguez ◽  
Antonio Polo Sánchez ◽  
Katherine Dale ◽  
Chloe Codner ◽  
Alba Martín ◽  
...  
Keyword(s):  
Rift Zone ◽  
Average Distance ◽  
Hydrothermal Systems ◽  
Soil Gas ◽  
Geothermal Systems ◽  
Soil Matrix ◽  
North West ◽  
The North ◽  
La Palma ◽  
Cumbre Vieja

<p>La Palma is one of the eastern islands of the Canary Archipelago located off the West African continental margin. Volcanic activity in the last 123 ka has taken place exclusively at the southern part of the island, where Cumbre Vieja volcano has been formed. Cumbre Vieja, one of the most active basaltic volcano in the Canaries, host seven historical eruptions being Teneguía eruption (1971) the most recent one. Cumbre Vieja volcano, characterized by a main north–south rift zone 20 km long and covering an area of 220 km<sup>2</sup>, does not show any visible degassing that show the existence of active geothermal systems. For that reason, geochemical prospecting of soil gases and volatiles in the soil matrix itself of Cumbre Vieja can provide useful information to investigate the presence of permeable areas and potential upflow areas for the degassing of geothermal systems at depth.</p><p>We report herein the results of an intensive soil gas study, focused on non-reactive and/or highly mobile gases such as helium (He) and hydrogen (H<sub>2</sub>), in Cumbre Vieja, with geothermal exploration purposes. He has unique characteristics as a geochemical tracer: it is chemically inert and radioactively stable, non-biogenic, highly mobile and relatively insoluble in water. H<sub>2</sub> 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.</p><p>Soil gas samples were collected at 1,201 sites selected from June 2019 to September 2019, with an average distance between sites of ≈ 250 m, at ≈ 40 cm depth using a metallic probe. He content was analyzed by means of a quadrupole mass spectrometer (QMS; Pfeiffer Omnistar 422) and hydrogen concentrations by a micro-gas chromatograph (microGC; VARIAN CP490). Soil He concentration showed values up to 23.9 ppm with an average of 5.73 ppm. Soil H<sub>2</sub> concentrations measured ranged from typical atmospheric values (≈ 0.5 ppm) up to 19.8 ppm. The mean value measured for H<sub>2</sub> was 0.78 ppm. Although He concentration values showed high spatial variability, the highest values can be observed in the north–south rift zone of Cumbre Vieja and around the surface contact with Cumbre Nueva ridge. Spatial distribution of H<sub>2</sub> concentration showed the highest values in the north-west area of Cumbre Vieja volcano. The results showed here are useful to identify the possible existence of permeable portions of deep-seated actively degassing geothermal reservoirs. However, a multidisciplinary approach is essential to obtain additional information about possible geothermal systems underlying at Palma island with the last goal of the selection of appropriate locations for future exploratory wells.</p>

scholarly journals La Palma island (Spain) geothermal system revealed by 3D magnetotelluric data inversion

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Federico Di Paolo ◽  
Juanjo Ledo ◽  
Katarzyna Ślęzak ◽  
David Martínez van Dorth ◽  
Iván Cabrera-Pérez ◽  
...  
Keyword(s):  
Geophysical Methods ◽  
High Resistivity ◽  
Geothermal System ◽  
Human Consumption ◽  
Geothermal Systems ◽  
Magnetotelluric Data ◽  
Volcanic System ◽  
The North ◽  
La Palma ◽  
Cumbre Vieja

Abstract The study of geothermal systems is nowadays a topic of great importance because of the huge amount of energy that could be converted in electricity for human consumption from such sources. Among the various geophysical methods employed to study geothermal reservoirs, the magnetotelluric (MT) method is capable to reveal the internal structures of the subsurface and interpret the geological structures from the electrical resistivity. We present the first 3D resistivity model of La Palma (Canary archipelago, Spain) obtained from a dataset of 44 broadband magnetotelluric soundings distributed around the island. Our results highlight the presence of resistivity anomalies, spatially coinciding with density anomalies present in literature. In the north of the island, a high resistivity anomaly can be interpreted as the signature of an old intrusive body beneath the Taburiente caldera. In the south, a complex resistivity structure around the Cumbre Vieja volcanic ridge could be indicative of presence of an active geothermal system. In particular, low-resistivity anomalies, located in a high-fractured zone, have values compatible with clay alteration caps (illite and illite–smectite). Such a result suggests the presence of hot rocks, or a dike system, heating fluids in the interior of Cumbre Vieja volcanic system.

Geothermal prospecting at Cumbre Vieja volcano (La Palma, Canary Islands) by ground radon and thoron measurements

2020 ◽  
Author(s):  
Lía Pitti-Pimienta ◽  
Anson Weidner ◽  
Rishi Shah ◽  
Rae L. McClintock ◽  
Alba Martín-Lorenzo ◽  
...  
Keyword(s):  
High Temperature ◽  
Canary Islands ◽  
Structural Control ◽  
Average Distance ◽  
Volcanic Eruptions ◽  
Soil Gas ◽  
Geothermal Resources ◽  
Geothermal Exploration ◽  
La Palma ◽  
Cumbre Vieja

<p>During geothermal exploration, the geochemical methods play a major role in both exploration and exploitation phases. Discovery of new geothermal systems requires exploration of areas where the resources are either hidden or lie at great depths. A good example of young volcanic territory with high geothermal potential where geothermal resources are either hidden or lie at great depths is La Palma island (Canary Islands). La Palma is one of the youngest and westernmost island of the Canarian archipelago, located at the West African continental margin. Cumbre Vieja volcano (220 km<sup>2</sup>) is the last stage in the geological evolution of the island and has suffered 8 volcanic eruptions in the last 500 years, the last one in 1971. Among geochemical methods for geothermal exploration, soil gas surveys are useful for delineating main upflow regions and areas of increased subsurface permeability related to high temperature hydrothermal activity at depth. Soil gas Rn surveys are particularly useful since it is a naturally occurring radioactive gas present in geofluids that may serve as a subsurface tracer of geothermal reservoirs. An intensive soil gas was carried out from June to September 2019 in order to study the potential geothermal resource in Cumbre Vieja and the presence of vertical permeability structures related to high temperature hydrothermal reservoirs. A total of 1200 samples were taken with an average distance between sites of ≈250 m. Soil gas Rn-222 activity were measured by means of a portable SARAD RTM 2010-2 radon monitor; the instrument pumped gas through a stainless steel probe inserted at 40 cm depth and measured the Rn activity by electrostatic detection of the positively charged daughter isotopes. The soil gas Rn values ranged from atmospheric levels to 8.7 kBq m-3, with an average of 1.5 kBq m-3. The spatial distribution of soil Rn displays enrichments along the three main volcanic-rift zones: N-S, N-W and N-E, and confirms a strong structural control in the degassing processes of the volcano. The three volcanic-rift areas are zones of enhanced permeability for deep gas migration and preferential routes for degassing. It is worth noting the presence of an important soil gar Rn anomaly located at the eastern part of Cumbre Vieja, out of the three volcanic-rift areas. The data presented here are important to  identify  main  upflow  regions  and  areas  of  increased  and  deep  permeability at Cumbre Vieja.</p>

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

<p>Hydrogen (H<sub>2</sub>) 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<sub>2</sub> can be produced in soils by N<sub>2</sub>-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<sub>2</sub> generated within the crust moves rapidly and escapes to the atmosphere. These characteristics make H<sub>2</sub> 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 Teneguía eruption (1971) the most recent one. Cumbre Vieja volcano is characterized by a main north–south rift zone 20 km long, up to 1950 m in elevation and covering an area of 220 km<sup>2</sup> 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.  Here we show the results of soil H<sub>2</sub> 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<sub>2</sub> content was analysed later by a VARIAN CP4900 micro-GC. A simple diffusive emission mechanism was applied to compute the emission rate of H<sub>2</sub> at each survey. Diffuse H<sub>2</sub> 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<sub>2</sub> emission rate was ∼2.5 kg·d<sup>−1</sup> and an increase of this value was observed between 2013-2017 (∼16.6 kg·d<sup>−1</sup>), reaching a value of 36 kg·d<sup>−1</sup> 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<sub>2</sub> emission related to this unrest had been observed reaching values up to ∼70 kg·d<sup>−1</sup>. Diffuse H<sub>2</sub> emission surveys have demonstrated to be sensitive and excellent precursors of magmatic processes occurring at depth in Cumbre Vieja. Periodic diffuse H<sub>2</sub> emission surveys provide valuable information to improve and optimize the detection of early warning signals of volcanic unrest at Cumbre Vieja volcano.</p>

scholarly journals Far-Field Tsunami Impact in the North Atlantic Basin from Large Scale Flank Collapses of the Cumbre Vieja Volcano, La Palma

2015 ◽  
Vol 172 (12) ◽  
pp. 3589-3616 ◽  
Author(s):  
Babak Tehranirad ◽  
Jeffrey C. Harris ◽  
Annette R. Grilli ◽  
Stephan T. Grilli ◽  
Stéphane Abadie ◽  
...  
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Far Field ◽  
Atlantic Basin ◽  
North Atlantic Basin ◽  
The North ◽  
La Palma ◽  
The North Atlantic ◽  
Cumbre Vieja

Diffuse He degassing monitoring of the Tenerife North-western Rift Zone (NWRZ) volcano, Canary Islands

2020 ◽  
Author(s):  
Guillermo Recio ◽  
Eleanor Dunn ◽  
Yasmin McInally ◽  
Nemesio M. Pérez ◽  
Cecilia Amonte ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Rift Zone ◽  
Soil Gas ◽  
Sequential Gaussian Simulation ◽  
Volcanic Complex ◽  
Concentration Data ◽  
Entire Area ◽  
North West ◽  
Geochemical Properties ◽  
Helium Emission

<p>Tenerife (2034 km<sup>2</sup>), the largest island of the Canarian archipelago, is characterized by three volcanic rifts oriented NW-SE, NE-SW and N-S with a central volcanic complex, Las Cañadas Caldera, hosting Teide-Pico Viejo volcanoes. The North West volcanic Rift Zone (NWRZ, 72 km<sup>2</sup>) of Tenerife is one of the youngest and most active volcanic systems of the island, where two historical eruptions have occurred: Arenas Negras in 1706 and Chinyero in 1909. Diffuse degassing studies has become an important volcanic surveillance tool at those volcanic areas where visible manifestations of volcanic gases are absent, as in the case of NWRZ. Mapping soil gas emission along volcanic structures can provide a better understanding of the processes occurring at depth and allows monitoring the spatial distribution, magnitude and temporal evolution of the surface gas emissions. The geochemical properties of He, minimize the interaction of this noble gas on its movement toward the earth’s surface, and make this gas an almost ideal geochemical indicator of changes occurring in the magmatic plumbing system of the volcano (Padrón et al., 2013, Geology 41(5):539–542). Since 2014, surface He emission surveys have been performed once a year as an additional geochemical tool to monitor the volcanic activity of NWRZ. At 345 sampling sites soil gas samples were collected at 40 cm depth and analyzed for He concentration within 24 hours by means of QMS, model Pfeiffer Omnistar 422. The soil helium concentration data were used to estimate the diffusive helium flux at each point, to construct spatial distribution maps by sequential Gaussian simulation and then to estimate the total helium emission in the NWRZ. Helium emission ranged between non-detected values up to 7.2 mgm<sup>-2</sup>d<sup>-1</sup>, and the emission rate of the entire area was in the range ~1 – 45 kg d<sup>-1</sup>. An increasing trend was observed in the period 2016-2018, showing a good temporal coincidence with a significant increase in seismic activity recorded in Tenerife. The promising results observed in the NWRZ and in other volcanic systems (Padrón et al., 2013) indicate that soil helium emission monitoring could be an excellent early warning geochemical precursory signal for future volcanic unrest.</p>

Monitoring diffuse CO2 emissions by means of an automatic geochemical station at Cumbre Vieja volcano, La Palma, Canary Islands.

2021 ◽  
Author(s):  
José Barrancos ◽  
Claudia Rodríguez ◽  
Eleazar Padrón ◽  
Pedro A. Hernández ◽  
Germán D. Padilla ◽  
...  
Keyword(s):  
Time Series ◽  
Monitoring Program ◽  
Soil Parameters ◽  
Monitoring Site ◽  
Maximum Magnitude ◽  
North West ◽  
La Palma ◽  
Eruptive Episode ◽  
Seismic Swarms ◽  
Cumbre Vieja

<p>La Palma Island (708.3 km<sup>2</sup>) is located at the north-west and is one of the youngest (~2.0My) of the Canarian Archipelago. Volcanic activity has taken place exclusively at the southern part of the island, where Cumbre Vieja volcano, the most active basaltic volcano in the Canaries, has been constructed in the last 123 ky. Cumbre Vieja has suffered seven eruptions in the last 500 years, being the last in 1971 (Teneguía volcano). Since the last eruptive episode, Cumbre Vieja volcano has remained in a relative seismic calm that was interrupted on October 7th and 13rd, 2017, by two remarkable seismic swarms with earthquakes located beneath Cumbre Vieja volcano at depths ranging between 14 and 28 km with a maximum magnitude of 2.7. The frequency of these seismic episodes increased in 2020 with the occurrence of five more seismic swarms</p><p>As part of the volcano monitoring program of Cumbre Vieja, diffuse degassing of CO<sub>2</sub> has been continuously monitored since 2005 at the southernmost part of Cumbre Vieja according to the accumulation chamber method. The monitoring site (LPA04) was selected because it shows anomalous diffuse CO<sub>2</sub> degassing emission values with respect to the background values that had been measured in different surveys (Padrón et al., 2015). Meteorological and soil physical variables are also measured in an hourly basis and transmitted to ITER facilities about 150 Km far away.</p><p>Since its installation, CO<sub>2</sub> emissions ranged from non-detectable (<1.5 gm<sup>-2</sup>d<sup>-1</sup>) to 1,464.0 gm<sup>-2</sup>d<sup>-1</sup>. The time series was characterized by a strong variability in the measured values that are modulated mainly by the atmospheric and soil parameters. Soil moisture is the monitored parameter that explains the highest variability of the data, being the dry season (spring y summer) the period with the highest observed diffuse emission values. This behavior in the time series has changed after 2017 as an increasing trend in being observed in a good temporal agreement with the increase of seismic activity recorded. The observed diffuse CO<sub>2</sub> emissions trend in the LPA04 geochemical station support the occurrence of an upward magma migration towards a subcrustal magma reservoir beneath La Palma island.</p><p>Padrón et al., (2015). Bull Volcanol 77:28. DOI 10.1007/s00445-015-0914-2</p>

Soil gas CO2 concentration, isotopic ratio and efflux measurements for geothermal exploration at Cumbre Vieja volcano, La Palma, Canary Islands

2020 ◽  
Author(s):  
Alba Martín Lorenzo ◽  
Banner Cole ◽  
Elizabeth Bullock ◽  
Sahlla Abassi ◽  
Lía Pitti-Pimienta ◽  
...  
Keyword(s):  
Canary Islands ◽  
Soil Co2 Efflux ◽  
Soil Gas ◽  
Geothermal System ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Geothermal Exploration ◽  
Diffuse Degassing ◽  
La Palma ◽  
Cumbre Vieja

<p>The exploration of geothermal resources on the island of La Palma, Canary Islands, was first conducted by the Spanish Geological Survey (IGME) from 1982 to 1984. These studies were focused exclusively on the southern part, where the last historical eruption, Teneguía, took place in 1971. This area still shows some geothermal features such us relatively high ground water temperatures (about 40ºC) and soil CO2 efflux values. Recent studies carried out at Cumbre Vieja volcano, the southern part of the island, on diffuse degassing, 3D gravimetry and Audio-MT probes point to promising results, although more studies are needed. We continue applying a multidisciplinary approach to obtain additional information about the geothermal system underlying at Palma island using novel techniques as well as tools which are appropriate to evaluate this system. For this reason, during summer 2019 a soil diffuse degassing research started at Cumbre Vieja volcano (220 km<sup>2</sup>) for geothermal exploration purposes. In this first phase of the diffuse degassing study about 1,200 sampling sites, with an average distance between sites of approximately 250 m were selected after taking into consideration the volcano-structural features and accessibility. In each sampling site in-situ soil CO2 efflux measurements were performed, and soil gas samples were collected at 40 cm depth for chemical and isotopic analysis. Spatial distribution of CO<sub>2</sub> efflux, statistical-graphical analysis of CO<sub>2</sub> efflux, and δ<sup>13</sup>C-CO<sub>2</sub> isotopic data to calculate and map the volcano-hydrothermal contribution of CO<sub>2</sub> were combined and used for geothermal exploration. The statistical-graphic analysis of the diffuse CO<sub>2</sub> efflux values confirms the existence of different geochemical populations showing two log-normal geochemical populations, a fact that suggests the addition of deep-seated CO<sub>2</sub>. Relatively low CO<sub>2</sub> efflux values were measured ranging from non-detected up to 72.8 g m<sup>-2 </sup>d<sup>-1</sup>, with an average value of 4.6 g m<sup>-2 </sup>d<sup>-1</sup>. The highest CO<sub>2</sub> efflux values were measured at the north end of Cumbre Vieja, around the surface contact with Cumbre Nueva ridge. The CO<sub>2</sub> isotopic composition, expressed as δ<sup>13</sup>C- CO<sub>2</sub> showed the contribution of three different end-members: biogenic, atmospheric and deep-seated CO<sub>2</sub>. The results indicate that most of the sampling sites exhibited CO<sub>2</sub> composed by different mixtures between atmospheric and biogenic CO<sub>2</sub> with slight inputs of deep-seated CO<sub>2</sub>, with a mean value of -15.3‰, being the maximum and the minimum -2.8‰ and -25.4‰ respectively. The results showed here can help to identify the existence of zones where deep-seated actively degassing from geothermal reservoirs occurs, particularly where the interpretation and application of geophysical data might be difficult.</p>

Environmental factors controlling diffuse CO2 emission rates from Cumbre Vieja Volcano, La Palma, Canary Islands

2020 ◽  
Author(s):  
Victoria Leal ◽  
Germán D. Padilla ◽  
Gladys V. Melián ◽  
Alba Martin-Lorenzo ◽  
Fátima Rodríguez ◽  
...  
Keyword(s):  
Time Series ◽  
Volcanic Activity ◽  
Sampling Site ◽  
Isotopic Analysis ◽  
Soil Gas ◽  
Sequential Gaussian Simulation ◽  
Emission Rates ◽  
La Palma ◽  
Seismic Swarms ◽  
Cumbre Vieja

<p>La Palma Island (708.3 km<sup>2</sup>) is located at the north-western end of the Canarian Archipelago and is one of the youngest island (~2.0My). During the last 123 ka, volcanic activity has taken place exclusively at the southern part of the island, where Cumbre Vieja volcano, the most active basaltic volcano in the Canaries, has been constructed. Seven historical eruptions have occurred at Cumbre Vieja, been Teneguía the last one (1971). On 7-14 of October 2017 and 10-15 November 2018, two intense seismic swarms occurred beneath Cumbre Vieja. In order to monitor the volcanic activity at Cumbre Vieja, main efforts have been focused on diffuse degassing studies since visible volcanic emissions are absent at the surface environment of this volcano. Diffuse CO<sub>2</sub> emissions have been monitored at Cumbre Vieja since 1997 in a yearly basis, with a higher frequency since the start of intense seismic swarms until August, 2019. At each survey, 600 sampling sites are selected for soil CO<sub>2</sub> efflux measurements performed in situ following the accumulation chamber method. Spatial distribution maps are constructed following the sequential Gaussian simulation (sGs) procedure and, to quantify the CO<sub>2</sub> emission from the studied area, 100 simulations are performed for each survey. At each sampling site, soil gas samples were collected at 40cm depth. Isotopic analysis of C in the CO<sub>2</sub> of selected soil gas samples (10% of the total) was performed to discriminate the origin of the CO<sub>2</sub>. Between 2001 and 2017, the estimated diffuse CO<sub>2</sub> emission rate released to the atmosphere from Cumbre Vieja volcano has ranged between 320 to 1,544 td<sup>-1</sup>. After October 2017 seismic swarms, diffuse CO<sub>2</sub> emission rates were estimated on a nearly daily basis, showing three increasing trends from 800td<sup>-1</sup> up to 3,251td<sup>-1</sup>, 2,850td<sup>-1</sup> and 1,904td<sup>-1</sup>, respectively. With the aim to filter out the effects of rainfall on the measured CO<sub>2</sub> efflux time series, a decorrelation pluviometric data analysis was performed. We found that a moving average of sixty days of the averaged rainfalls of six pluviometers on the studied area explained 49.4% of variability of diffuse CO<sub>2</sub> emission. The first peak on diffuse CO<sub>2</sub> emission remained after filtering, with a highest value of 2,020td<sup>-1</sup>, when the time series had a non linear behaviour and the two seismic swarms occurred. Highest value of the second peak was 1,495td<sup>-1</sup> whereas the third peak practically disappears after filtering, due to the high influence with rainfall. Isotopic analysis of soil C-CO<sub>2</sub> showed enrichments in volcanic-hydrothermal CO<sub>2</sub> before the two mean peaks of filtered soil CO<sub>2</sub> emission time series. We found seismological and geochemical evidences that these swarms were linked to a deep-seated magmatic intrusion. We hypothesize that the October 2017 seismic swarms were produced by an upward magma migration from an ephemeral magmatic reservoir located in the upper mantle (about 25 km depth), toward another reservoir located close to the Moho beneath Cumbre Vieja (12-15 km). The consequent depressurization of the magma batch was the source of the volatiles observed at the surface, with a delay of few weeks for CO<sub>2</sub>.</p>

scholarly journals New Data on Distribution and Population Number of Large Raptors in Northern Usturt Within Atyrau Province, Kazakhstan

2020 ◽  
pp. 82-102
Author(s):  
Ilya E. Smelansky ◽  
◽  
Andrey A. Tomilenko ◽  
Anna N. Barashkova ◽  
Alexander A. Yakovlev ◽  
...  
Keyword(s):  
Average Distance ◽  
Golden Eagle ◽  
Population Number ◽  
North West ◽  
The North ◽  
Breeding Populations ◽  
Nesting Density ◽  
Eagle Owl ◽  
Saker Falcon ◽  
Imperial Eagle

In May and June 2018 and June 2019 we surveyed breeding populations of large raptors (principally Golden Eagle Aquila chrysaetos, Eastern Imperial Eagle Aquila heliaca, Steppe Eagle Aquila nipalensis, Long-Legged Buzzard Buteo rufinus, Saker Falcon Falco cherrug and Eagle Owl Bubo bubo) in the north-west of the Ustyurt Plateau within the boundaries of the Atyrau Province, Kazakhstan. The area surveyed was ca. 1000 km2 represented the wider area of 3400 km2. Total 12 species of birds of prey were recorded and 8 of them considered as large raptors. Golden Eagle was found nesting on the Donyztau escarpment, 4 breeding territories were recorded and 3 of them successful; nesting density is estimated at about 5.0–6.7 pairs per 100 km of cliffs, the distance between neighboring pairs was ca. 6 km. Imperial Eagle: 5 breeding territories found on the Donyztau and Zheltau escarpments, 4 of them successful; average nesting density is 3.8 pairs per 100 km of cliffs. Steppe Eagle: 14 breeding territories (25 nests) revealed, among them 6 are successful (1–2 nestlings) and on other 3 breeding was failed; average nesting density is estimated at 1.3 pairs per 100 km2. Average distance between neighboring active nests is 2.5 km in Sholkara hill ridge but the distance between successful nests here is much bigger and makes about 13 km. Long-Legged Buzzard: 13 breeding territories (30 nests) found, of which 11 territories were actually occupied and 8 of them had successful breeding. Saker Falcon is found nesting on Donyztau escarpment: 4 breeding territories, including 3 successful; the average nesting density is 6.7 pairs per 100 km of cliffs. Eagle Owl recorded throughout the surveyed area; 11 breeding territories revealed, the average nesting density is 7 breeding territories per 100 km of cliffs and steep slopes. Two other species, Short-toad Eagle and Cinereous Vulture, recorded only occasionally, nesting in the area is not found. In general, our findings demonstrate the area is important for conserving several species of large raptors in the Atyrau Province.

Geochemical monitoring of Cumbre Vieja volcano (Canary Islands) by summer diffuse CO2 degassing surveys

2020 ◽  
Author(s):  
Daniel Di Nardo ◽  
Ellie-May Redfern ◽  
Filippo Zummo ◽  
Alba Martín-Lorenzo ◽  
Claudia Rodríguez-Pérez ◽  
...  
Keyword(s):  
Volcanic Activity ◽  
Sequential Gaussian Simulation ◽  
Surveillance Program ◽  
Volcanic Gas ◽  
Distribution Maps ◽  
The North ◽  
La Palma ◽  
Seismic Swarms ◽  
Gaussian Simulation ◽  
Cumbre Vieja

<p>La Palma Island is the north-westernmost and one of the youngest of the Canarian Archipelago. In the last 123ka, volcanic activity has taken place exclusively at Cumbre Vieja volcano which is located at the southern part of the island. Cumbre Vieja is characterized by a main north–south rift zone 20km long and 1950m in elevation covering an area of 220km<sup>2</sup> with volcanic vents located northwest and northeast. Cumbre Vieja is the most active basaltic volcano in the Canaries with 7 historical eruptions, being Teneguía (1971) the most recent one. The most relevant volcanic activity episodes occurred since Teneguía eruption, are two intense seismic swarms occurred beneath Cumbre Vieja on 7-9 and 13-14 of October 2017. Since visible volcanic gas emissions do not occur at the surface of Cumbre Vieja, the geochemical surveillance program has been focused mainly on diffuse degassing studies. In the last 18 years diffuse CO<sub>2</sub> emission surveys have been yearly performed in summer periods to minimize the influence of meteorological variations. Measurements have been performed following the accumulation chamber method in about 600 sites and spatial distribution maps have been constructed following the sequential Gaussian simulation (sGs) procedure to quantify the diffuse CO<sub>2</sub> emission. Herein we summarize the diffuse CO<sub>2</sub> emission time series during this period and describe the results obtained in the last 2019 survey. The soil CO<sub>2</sub> efflux values measured in 2019 survey ranged from non-detectable to 72.7gm<sup>−2</sup>d<sup>−1</sup>. Diffuse CO<sub>2</sub> output was estimated in 1,064 ± 35td<sup>-1</sup>, a value within the background +1s range (1,254 td<sup>-1</sup>) (Padrón et al., 2015, Bull. Volcanol. 77:28). In the period 2001-2017, the diffuse CO<sub>2</sub> output released to the atmosphere from Cumbre Vieja volcano ranged between 320 to 1,544td<sup>-1</sup>. Enhanced endogenous contributions of deep seated CO<sub>2</sub> might have been responsible for the higher CO<sub>2</sub> emission values measured in 2011 and 2013. After the October 2017 seismic swarms, diffuse CO<sub>2</sub> output showed an increasing trend from 788 to 3,251td<sup>-1</sup> in March 2018, to decrease gradually until 852td<sup>-1</sup> in September of that same year, and begin to gradually increase again to 2,371td<sup>-1</sup> in November 2018. These changes were possibly caused by an upward magma migration. Our results demonstrate that periodic surveys of diffuse CO<sub>2</sub> emission are extremely important for the detection of early warning signals of future volcanic unrest episodes at Cumbre Vieja.</p>

Sign in / Sign up

Export Citation Format

Share Document