Chapter

Volcanic Caves of Lanzarote: A Natural Laboratory for Understanding Volcano-Speleogenetic Processesand Planetary Caves

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Abstract

The volcanic island of Lanzarote hosts an impressive variety of cavities formed by different volcanic processes. The presence of well preserved lava fields belonging to historic eruptions and more ancient and weathered quaternary and pliocene terrains and the association with an arid climate provide the unique oportunity of studying volcanic caves at different stages of evolution on the same volcanic island. The different mechanisms of lava tube emplacement can be observed in great detail, from the most recent pyroducts of different sizes formed during the Timanfaya eruption (1730-1736) to the exceptionally voluminous conduits of the Corona volcano, formed during the Last Glacial Maximum and partially submerged by the sea level upraise during the Holocene. In addition, other type of cavities, like explosive and geyser vents, “hornitos” and sinkholes in pyroclastic deposits offer the opportunity to extend the study to other important volcano-speleogenetic processes in different settings. All these cavities are easily accessible and present a variety of morphological, mineralogical, biological and microbiological significances, allowing for a wide range of multidisciplinary studies. The countless analogies with lava tube collapses and other potential volcanic cave features detected on the Moon and Mars also provide an unprecedented research ground that offers hints to solve some open issues in the interpretation of still unresolved planetary cavities. These characteristics make the Lanzarote and Chinijo Islands UNESCO Global an exceptional case where the protection and scientific outreach has been extended to the volcanic subsurface. In this chapter we offer a review of the current knowledge and existing scientific studies on the volcanic caves of Lanzarote and we discuss future researches and protection issues that need to be addressed in order to fully include this geoheritage in strategic plans of environmental protection.

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... The conduit can be drained at the end of the eruption becoming an accessible linear void following the slope of the volcanic edifice. Lava tubes can be either a single conduit with linear, sinuous, or braided paths at different superposed depths (Sauro et al., 2019(Sauro et al., , 2020Kempe, 2012;Kempe et al., 2010). Such conduits usually form during effusive eruptions in the presence of hot, fluid basaltic lava and relatively gentle slope gradients. ...
... Volcanism on Lanzarote, and the Canary Islands in general, is related to a complex volcanic hot spot, representing one of Earth's best analogues for martian volcanism (Meyzen et al., 2015). The predominance of extensive basaltic lava flows and basic pyroclastic deposits also makes it a promising analogue for lunar maria (Sauro et al., 2019). Lanzarote's pahoehoe lava flows, and wide areas covered by pyroclastic deposits, show clear similarities with the Tharsis region on Mars (Mège and Masson, 1996;Martínez-Frías and Mateo, 2019). ...
... Lanzarote also has some of the best examples of lava tubes in Europe (Sauro et al., 2019), with comparable features observed on the lunar maria or martian volcanoes such as Arsia and Olympus Montes (Hong et al., 2014;Sauro et al., 2020). The Corona lava tube system is one of the few lava tube systems extensively studied on Lanzarote. ...
Article
The paper presents new results from microseismic data analysis for the detection and delineation of near-surface lava tubes. Single-station, free-field seismic noise data were collected at the Corona Volcano area (Lanzarote, Canary Islands) as part of the PANGAEA-X 2017 European Space Agency (ESA) astronaut training campaign. The site was selected as it represents a suitable analogue for lunar maria and provided the opportunity to cross-validate and ground truth seismic and other geophysical studies. In this paper, we present our observations on the distribution of frequencies and amplitudes of standing waves generated by microtremors in the space between the ground surface and underground cavities by averaging amplitude spectra of microseismic records. This study shows that the frequency of the vertical component peaks is a relatively good indicator of presence, lateral extent and approximate dip of the cavities. However, only the vertical component peaks with a frequency either equal to or close to central to high amplitude (3.1–8.5) horizontal-to-vertical (H/V) peaks are related to lava tubes. If the P-wave velocities in the rocks overlying the lava tubes are known, then these frequencies can also be used to estimate the depth of such cavities. This study also identified some important pitfalls that may limit the use and accuracy of our approach. These include layering of rocks overlying the lava tubes, lateral changes in thickness, lateral variations of the P-wave velocity, and the presence of shallow void-rich zones. Overall, the results of this study confirmed that microseismic data are suitable for cavity detection. It is also, to our knowledge, one of the first studies dealing with microseismic data from near-surface lava tubes. With the recent increase in planetary exploration, this method can be easily adapted to support the geophysical exploration of volcanic terrains on the Moon and Mars.
... The conduit can be drained at the end of the eruption becoming an accessible linear void following the slope of the volcanic edifice. Lava tubes can be either a single conduit with rectilinear or rather sinuous path, or braided conduits presenting different superposed levels at depth (Sauro et al., 2019(Sauro et al., , 2020Kempe, 2012;Kempe et al., 2010). Such conduits usually form during effusive eruptions in presence of very hot and fluid basaltic lava and gentle slopes. ...
... Volcanism on Lanzarote, and the Canary Islands in general, is related to a complex volcanic hot spot, representing one of Earth's best analogues for Martian volcanism (Meyzen et al., 2015). The predominance of extensive basaltic lava flows and basic pyroclastic deposits also makes it a promising analogue for Lunar Maria (Sauro et al., 2019). Lanzarote's pahoehoe lava flows, and wide areas covered by pyroclastic deposits, show clear similarities to the Tharsis region on Mars (Mège and Masson, 1996;Martínez-Frías and Mateo, 2019). ...
... Lanzarote also has some of the best examples of lava tubes in Europe (Sauro et al., 2019), with comparable features observed on the Lunar Maria or on volcanoes such as Arsia and Olympus Montes on Mars (Hong et al., 2014;Sauro et al., 2020). The Corona lava tube system is one of the few extensive lava tube systems extensively studied on Lanzarote. ...
Article
This paper presents new field and synthetic modelling results of Electrical Resistivity Tomography (ERT) surveys for the identification and detection of lava tubes with the particular aim of using ERT tech-niques for stratigraphic investigations of planetary volcanic analogues. These geophysical surveys were undertaken at the Corona volcano (Lanzarote, Canary Islands), as part of the PANGAEA-X 2017 campaign, which formed part of the European Space Agency's (ESA) astronaut training program. ERT profiles were acquired at two test sites located along the main Corona lava tube system. During the campaign a variety of experimental setups were tested. This provided an ideal opportunity to cross-validate geophysical results with ground truth provided by partial surface exposure of the lava tubes and laser scanner mapping of the lava tube system in the subsurface. It also permitted an assessment of the usability of ERT in detecting lava tubes in a heterogeneous volcanic setting. Our experiments showed that a combination of different electrode arrays and their joint inversion resulted in good detectability of the lava tubes with a large size with respect to the electrode spacing. The dipole-dipole array configuration provided more accurate models for lava tubes of a size in the same order of magnitude as the electrode spacing. This study showed that the main drawbacks of ERT in heterogeneous volcanic settings are linked to lava tube-related high-resistivity anomalies which appear larger and shallower and may also be laterally shifted with respect to their true location. For lava tubes with a small size with respect to the electrode spacing our synthetic data modelling results show the difficulty in distinguishing single lava tubes from in contact lava tubes, and distinguishing lava tubes in general from void-rich zones. Overall, ERT surveys were successful in detecting lava tubes, providing a good definition of the main boundaries between different volcanic units and highlighting the presence of close, near-parallel unexplored lava tubes.
... On the other hand -on Earth -several morphological and genetical studies have been performed on lava tubes in terrestrial shield volcanoes (Kempe, 2012(Kempe, , 2019 with hundreds of kilometers of lava tubes and associated collapses and skylights mapped by speleological organizations. Detailed morphological descriptions and topographic surveys of kilometer-long tubes are available thanks to speleological explorations on Hawai'i (USA) (Bunnell, 2008;Greeley, 1971b;Kauahikaua et al., 1998;Peterson et al., 1994), the Canary Islands (Spain) (Sauro et al., 2019;Wilkens et al., 2009), Iceland (Hróarsson and Jónsson, 1991), Northern Queensland (Australia) (Atkinson et al., 1975), Sicily (Italy) (Calvari and Pinkerton, 1999), Jeju Island (South Korea) (Woo et al., 2008), the Galapagos (Ecuador) (Jorda-Bordehore et al., 2016), and many other lava fields in the world (Kempe, 2012(Kempe, , 2019. This huge amount of data can be used for comparative planetology studies in order to infer lava tube dimensions and morphologies on the different planetary bodies of the inner solar system. ...
... Lava tubes formed by shallow inflation are usually characterized by a superficial bulge (due to the inflation) along its development, and by an original horizontal elliptical cross section that can be entrenched by thermal erosion. The most remarkable examples on Earth are on Hawai'i (Kempe, 2019), on the Canary Islands (Sauro et al., 2019) and on Iceland (Hróarsson and Jónsson, 1991) but they are in any case present in all major shield volcanoes on Earth. ...
... These formed through inflation along deep inception horizons following previous lava flow boundaries where, after inflation, the conduit has been enlarged by downward thermic erosion and breakdown phenomena (Tonello, 2017;Kempe, 2019). These lava tubes are among the biggest in size on Earth, with the most famous examples being Corona Lava Tube in Lanzarote (Sauro et al., 2019) and the Undara Lava Tube in Queensland (Atkinson et al., 1975). In these cases, the flow discharge can reach values of over 50 m 3 s −1 . ...
Article
Sinuous collapse chains and skylights in lunar and Martian volcanic regions have often been interpreted as collapsed lava tubes (also known as pyroducts). This hypothesis has fostered a forty years debate among planetary geologists trying to define if analogue volcano-speleogenetic processes acting on Earth could have created similar subsurface linear voids in extra-terrestrial volcanoes. On Earth lava tubes are well known thanks to speleological exploration and mapping in several shield volcanoes, with examples showing different genetic processes (inflation and overcrusting) and morphometric characters. On the Moon subsurface cavities have been inferred from several skylights in Maria smooth plains and corroborated using gravimetry and radar sounder, while on Mars several deep skylights have been identified on lava flows with striking similarities with terrestrial cases. Nonetheless, the literature on this topic is scattered and often presents inaccuracies in terminology and interpretation. A clear understanding of the potential morphologies and dimensions of Martian and lunar lava tubes remains elusive. Although it is still impossible to gather direct information on the interior of Martian and lunar lava tube candidates, scientists have the possibility to investigate their surface expression through the analysis of collapses and skylight morphology, morphometry and their arrangement, and compare these findings with terrestrial analogues. In this review the state of the art on terrestrial lava tubes is outlined in order to perform a morphological and morphometric comparison with lava tube candidate collapse chains on Mars and the Moon. By comparing literature and speleological data from terrestrial analogues and measuring lunar and Martian collapse chains on satellite images and digital terrain models (DTMs), this review sheds light on tube size, depth from surface, eccentricity and several other morphometric parameters among the three different planetary bodies. The dataset here presented indicates that Martian and lunar tubes are 1 to 3 orders of magnitude more voluminous than on Earth, and suggests that the same processes of inflation and overcrusting were active on Mars, while deep inflation and thermal entrenchment was the predominant mechanism of emplacement on the Moon. Even with these outstanding dimensions (with total volumes exceeding 1 billion of m³), lunar tubes remain well within the roof stability threshold. The analysis shows that aside of collapses triggered by impacts/tectonics, most of the lunar tubes could be intact, making the Moon an extraordinary target for subsurface exploration and potential settlement in the wide protected and stable environments of lava tubes.
... The last ∼1.7 km of the tube are submerged below sea level, because of the marine transgression that occurred after the LGM (∼21 ka; Bard et al., 1990;Labeyrie et al., 1987). The most accessible and walkable portions of the tube are stretched over six sections (Figure 3): (a) Jameo de los Prendes-Jameo de la Gente (∼1,170 m); (b) Jameo de la Gente-Jameo de la Puerta Falsa (∼1,165 m); (c) Jameo de la Puerta Falsa-Jameo de los Verdes (∼1,290 m) and (d) Jameo de los Lagos/Perdido (∼730 m); (e) los Jameos del Agua (∼350 m); (f) Tùnel de la Atlantìda Isler, 1989;Mendo and Ortega, 1988;Montoriol-Pous and De Mier, 1969;Sauro et al., 2019;Smith, 2010, Figure 4). ...
... This suggests that, at the time of the eruption and therefore of the emplacement of the lava tube, the sea was in a phase of regression and the coastline was about 80-120 m lower than today. Thus, the eruption took place while the marine platform was a dry land Sauro et al., 2019). This emplacement framework is coherent with the paleoclimatic data collected by Labeyrie et al. (1987), that places the sea level variation between 18 and 21 ka, during the LGM event. ...
Article
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Growing interest in studying large terrestrial lava tubes is motivated in part by their analogy with their extra‐terrestrial counterparts. However, on Earth, the formation of such structures is still poorly understood. Here, the lava tube system of La Corona (Lanzarote, Canary Islands, Spain) is studied to identify how pre‐existing stratigraphy can govern a lava tube's evolution. Combining terrestrial laser scanner technology with field observations and geochemical analyses of the pre‐existing lava enabled us to reconstruct the three‐dimensional geometry of the lava tube system, the paleo‐surface trough which it developed, and the volcanic series into which it carved its path. We show that a pyroclastic layer played a key role in the development of the lava tube. The layer—Derived from late Quaternary Strombolian activity—Is traceable along almost the full length of the tube path and defines the paleo‐topography. The excavation process mostly happens because of the mechanical strength of the substrate, that controls the widening of the growing lava tube. Other influential parameters controlling erosion include slope variations of the paleo‐surface (i.e., knickpoints), and the lava physical properties. Since weak layers such as regolith are a common feature of extra‐terrestrial lava flows, the processes seen at La Corona to the may be highly relevant to the development of planetary lava tube systems.
... L'esplorazione e la mappatura di questi particolari condotti vulcanici, forniscono l'unica possibilità di studiare i condotti geyser dall'interno in modo molto dettagliato. Tutte le voragini si sono sviluppate lungo la stessa frattura, con alcuni di esse che si uniscono o si separano in diversi rami in profondità (Sauro et al., 2019). Le pareti delle cavità, le aree circostanti e le voragini in superfice sono ricoperte da crostoni di mineralizzazione, mentre i fianchi esterni del cono vulcanico sono principalmente composti da lapilli e depositi basaltici tipici delle fontane di lava. ...
Article
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Nel 2016 l’ESA – Agenzia Spaziale Europea ha avviato il programma PANGAEA (Planetary ANalogue Geological and Astrobiological Exercise for Astronauts) dedicato alla formazione degli astronauti nel campo della geologia planetaria. Il corso permette agli astronauti e ad altri attori delle future esplorazioni spaziali di studiare diversi siti europei con caratteristiche analoghe a terreni geologici lunari e marziani. L’ultima fase del corso si è svolta nell’Isola di Lanzarote, considerata un eccellente analogo della Luna e di Marte per il vulcanesimo, in particolare con esempi di idrotermalismo e attività freatomagmatiche che sono comparabili a processi osservati nelle zone vulcaniche di Marte. In questa fase del training gli astronauti svolgono dei veri e propri “traversi” con l’obbiettivo di campionare e documentare i siti e di ottenere informazioni geologiche rilevanti, in modo da fornire agli scienziati elementi importanti per comprendere i processi attivi in passato. Tali attività avvengono secondo specifiche procedure di documentazione dei siti di campionamento e dei campioni stessi e permettono di avere un quadro generale della geologia delle aree studiate. Una volta terminato il corso, i campioni raccolti sono resi disponibili a diversi enti e soggetti di ricerca che possono approfondire lo studio con analisi di laboratorio. I risultati qui presentati riguardano uno dei principali “traverse” affrontati dagli astronauti, il cono di scorie di Tinguatón nel Geoparque di Lanzarote (Isole Canarie, Spagna), formatosi durante l’ultima attività magmatica registrata nell’isola. Le testimonianze storiche riportano un’attività tardiva idrotermale con la formazione di geyser, la cui presenza passata è rintracciabile anche nelle specie mineralogiche presenti. Questo studio si è quindi focalizzato nell’identificazione dei principali minerali caratterizzanti i campioni raccolti dagli astronauti nel traverse al sito di Tinguatón svolto nella missione del novembre 2017 e presenta il ritrovamento di alcune fasi mineralogiche non ancora segnalate per la località e/o per l’Arcipelago delle Canarie. Parole chiave: ESA – Agenzia Spaziale Europea, programma PANGAEA, Tinguatón, Lanzarote, Isole Canarie, SEM-EDS, microRaman, caratterizzazione delle fasi minerali. ABSTRACT In 2016, the ESA – European Space Agency launched the PANGAEA (Planetary ANalogue Geological and Astrobiological Exercise for Astronauts) program dedicated to the training of astronauts in the field of planetary geology. The course allows astronauts and other actors of future space explorations to study different European sites with characteristics similar to Lunar and Martian geological terrains. The last phase of the course took place on the Island of Lanzarote which is considered an excellent analogue of the Moon and Mars for volcanism, in particular about hydrothermalism and phreatomagmatic activities that are comparable to processes observed in the volcanic areas of Mars. In this phase of training, the astronauts carry out real "traverses" with the aim of sampling and documenting the sites and obtaining relevant geological information, in order to provide scientists with important elements to understand the processes active in the past. These activities took place according to specific documentation procedures of the sampling sites and of the samples themselves and allow to have a general picture of the geology of the areas studied. Once the course is finished, the collected samples are made available to various research bodies and subjects who can deepen the study with laboratory analysis. The results presented here concern one of the main "traverses" faced by astronauts, the Tinguatón scoria cone in the Geoparque of Lanzarote (Canary Islands, Spain), formed during the last magmatic activity recorded on the island. Historical evidence reports a late hydrothermal activity with the formation of geysers, whose past presence can also be traced in the occurring mineralogical species. This study therefore focused on the identification of the main minerals characterizing the samples collected by the astronauts in the “traverse” at the Tinguatón site, carried out in the November 2017 mission and describes the discovery of some mineralogical phases not yet reported for the location and / or for the Canary Archipelago.
... The eventual trafficability of the tunnel and the untethered communication with the Daedalus sphere will also provide a major challenge in the entire mission scenario. Semi or complete autonomous navigation is required, and, as happens in terrestrial analogues (see [82,134] and references therein) the type of environment to expect is essentially regolith with piles of boulders of various sizes (from centimeters to tens of meters) due to the roof collapse. Therefore, navigation must be expected to be extremely challenging or impossible. ...
Book
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The DAEDALUS mission concept aims at exploring and characterising the entrance and initial part of Lunar lava tubes within a compact, tightly integrated spherical robotic device, with a complementary payload set and autonomous capabilities. The mission concept addresses specif- ically the identification and characterisation of potential resources for future ESA exploration, the local environment of the subsurface and its geologic and compositional structure. A sphere is ideally suited to protect sensors and scientific equipment in rough, uneven en- vironments. It will house laser scanners, cameras and ancillary payloads. The sphere will be lowered into the skylight and will explore the entrance shaft, associated caverns and conduits. Lidar (light detection and ranging) systems produce 3D models with high spatial accuracy inde- pendent of lighting conditions and visible features. Hence this will be the primary exploration toolset within the sphere. The additional payload that can be accommodated in the robotic sphere consists of camera systems with panoramic lenses and scanners such as multi-wavelength or single-photon scanners. A moving mass will trigger movements. The tether for lowering the sphere will be used for data communication and powering the equipment during the descending phase. Furthermore, the connector tether-sphere will host a WIFI access point, such that data of the conduit can be transferred to the surface relay station. During the exploration phase, the robot will be disconnected from the cable, and will use wireless communication. Emergency autonomy software will ensure that in case of loss of communication, the robot will continue the nominal mission.
... Lanzarote's volcanoes present beautiful pahoehoe lava flows, and wide areas covered by pyroclastic deposits, with several similarities to the Tharsis region on Mars (Martínez-Frías and Mateo, 2019). It also presents some of the most remarkable examples of lava tubes in Europe, comparable to similar features observed on the Moon or on volcanoes like Arsia and Olympus on Mars (Sauro et al., 2019). Tuff rings and scoria cones on Lanzarote are also excellent analogues to phreatomagmatic eruptions observed on Mars (Brož and Hauber, 2013). ...
Article
This paper presents new results of the application of passive seismic surveys for the stratigraphic investigation of planetary volcanic analogues. We tested HVSR (Horizontal-to-Vertical Spectral Ratio) surveys that seem particularly suitable for planetary subsurface exploration. In order to exploit the potential of these surveys in stratigraphic applications, HVSR surveys were undertaken at the Tinguatón volcanic region (Lanzarote, Canary Islands). Seismic noise measurements were collected during the PANGAEA-X 2018 testing campaign which formed part of the European Space Agency's (ESA) astronaut training program. Single-station, free-field seismic noise data were collected along two orthogonal profiles, one crossing the Tinguatón volcano, the other passing alongside the Tinguatón caldera. Seismic stratigraphic sections obtained from the shear wave constrained inversion of the main H/V peaks provided the main impedance contrasts between layers and a bulk estimate of the shear wave velocity in the layers. Contour maps of the HVSR patterns were used to recognize and identify the main volcanic units, such as scoria deposits and different basaltic lava flows, geological structures, such as a regional fault related to the volcanic vent source, and morphological characteristics, such as the Tinguatón caldera. This study also identified several pitfalls that may limit the accuracy of such investigations. These include the multilayer setting of scoria deposits and, partly, of underlying basalts, as well as the presence of very thin horizons or a very gradual increase in shear wave velocity. Our study also shows the topographic effect due to the volcano's sharp topography along crater rim is significant and results in severe artifacts in the data. From our work, it is clear that HVSR method is an effective method to support the investigation of planetary volcanic terrains on the Moon and Mars with similarly volcanic complex geological settings, even where horizontal layering and the isotropic site response are not fully verified.
... La aparición de los ejes de Tinguatón es descrita por el geólogo italiano Francesco Sauro de la Universidad de Bolonia, Departamento de Ciencias Biológicas, Geológicas y Ambientales, BIGea como (Sauro et al., 2019). ...
Article
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Chapter
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The Corona lava tube (Lanzarote, Canary Island, Spain) is one of the world's largest volcanic cave complex, with a total length of about 8km, comprising both dry and submerged sections. The 6 km long terrestrial portion of the tube is open to the surface through a series of skylights, in the local language called “jameos”, that are aligned along the cave pathway. The underground passages are mainly sinuous, partly braided and multilevel, horizontal tunnels of variable width from 2m up to over 25m (5-7m on average), laying from few meters to a maximum of 30 meters from the surface. Although the first explorations and mapping campaigns of the lava tube have started already in the seventies, until now a clear view on the development and morphometry of this subterranean conduit was elusive. With three surveying campaigns carried out between February and November 2017, about 5 km of cave passages were mapped using a Leica P40 laser scanner. A total of 28 working days and over 440 scans were necessary to map this lava tube system, which is composed by different sections connected to each other through external collapses. The main path of the entire cave system was mapped with an unprecedented resolution of few centimetres, including the most relevant upper levels as the Jameos Cumplidos, the two tourist parts of the Cueva de Los Verdes and Jameos del Agua and the partly flooded part of Cueva de los Lagos. The surveys realized inside the cave with the laser scanner were georeferenced on the surface through differential GPS, LIDAR (from the Spanish Geological Service) and photogrammetry data obtained through flights realized with unmanned aerial vehicles on the external collapses located along the cave path. The dataset gathered by the detailed 3D model of the cave system have three main purposes: 1) create a virtual and analogic model of the cave to be used for outreach and didactic purposes in the touristic centre of Casa de Los Volcanes of the Lanzarote Geopark; 2) provide a detailed map of the tube and its relative depths from the surface, identifying critical zones for potential collapses, in order to allow local institutions to develop a protection plan for this subterranean environment in relationship to the actual different land use of the overlying surface; 3) provide to scientist quantitative morphometric data (volumes, morphologies, surface roughness, etc.) to develop detailed studies on the tube genesis and peculiar morphologies. These latter studies are on-going and will allow for the first time a detailed comparison between this exceptional example of terrestrial lava tube and similar features observed on the Moon and Mars.
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The city of Naples and its neighboring is an example of urban area affected by frequent anthropogenic sinkholes. They occur where the mining of tuff at shallow depth left a wide and complex network of cavities. The collapse is usually triggered by the soaking of the overlying pyroclastic soils forwarded by the presence of leakage from aged aqueducts and sewerages. This note reports the first results of a multidisciplinary research activity aimed at enhance the knowledge of the triggering factors of these phenomena in urban contexts. The study focused on an area characterized by the presence of cavities dug in tuff, starting from the research and collection of their location and that of past collapse events. In particular, the paper presents the results of sinkhole occurrence assessment at both local and metropolitan scale. In the first case, in order to define the most likely triggering mechanisms a case study among the recent sinkholes was investigated. A detailed field survey of the phenomena permitted to define the stratigraphical and geometrical setting of the pre-existing cavity and collect soil and rock samples for the geotechnical characterization. The attained results permitted to identify the most relevant parameters that influence the susceptibility assessment in a study area at metropolitan scale. This study represents contribute to the definition of a procedure to study anthropogenic sinkhole in intensely urbanized areas and it represents a valuable support for future planning strategies of risk mitigation.
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Volcanic caves are filled with colorful microbial mats on the walls and ceilings. These volcanic caves are found worldwide, and studies are finding vast bacteria diversity within these caves. One group of bacteria that can be abundant in volcanic caves, as well as other caves, is Actinobacteria. As Actinobacteria are valued for their ability to produce a variety of secondary metabolites, rare and novel Actinobacteria are being sought in underexplored environments. The abundance of novel Actinobacteria in volcanic caves makes this environment an excellent location to study these bacteria. Scanning electron microscopy (SEM) from several volcanic caves worldwide revealed diversity in the morphologies present. Spores, coccoid, and filamentous cells, many with hair-like or knobby extensions, were some of the microbial structures observed within the microbial mat samples. In addition, the SEM study pointed out that these features figure prominently in both constructive and destructive mineral processes. To further investigate this diversity, we conducted both Sanger sequencing and 454 pyrosequencing of the Actinobacteria in volcanic caves from four locations, two islands in the Azores, Portugal, and Hawai'i and New Mexico, USA. This comparison represents one of the largest sequencing efforts of Actinobacteria in volcanic caves to date. The diversity was shown to be dominated by Actinomycetales, but also included several newly described orders, such as Euzebyales, and Gaiellales. Sixty-two percent of the clones from the four locations shared less than 97% similarity to known sequences, and nearly 71% of the clones were singletons, supporting the commonly held belief that volcanic caves are an untapped resource for novel and rare Actinobacteria. The amplicon libraries depicted a wider view of the microbial diversity in Azorean volcanic caves revealing three additional orders, Rubrobacterales, Solirubrobacterales, and Coriobacteriales. Studies of microbial ecology in volcanic caves are still very limited. To rectify this deficiency, the results from our study help fill in the gaps in our knowledge of actinobacterial diversity and their potential roles in the volcanic cave ecosystems.
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El proceso de descubrimiento, conocimiento y estudio de las cuevas volcánicas en Canarias ha sido tardío y, como en cualquier otra rama del saber humano, lento al principio y progresivamente acelerado en los últimos años. Los inicios estuvieron marcados por un espíritu de aventura, que impulsaba a los primeros espeleólogos hacia las profundidades para desvelar incógnitas fantásticas que les planteaba este medio extraño y desconocido. Con el paso del tiempo estas cavidades fueron siendo visitadas con fines cada vez más ...
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Lava caves could be useful as outposts for the human exploration of the Moon. Lava caves or lava tubes are formed when the external surface of the lava flows cools more quickly to make a hardened crust over subsurface lava flows. The lava flow eventually ceases and drains out of the tube, leaving an empty space. The frail part of the ceiling of lava tube could collapse to expose the entrance to the lava tubes which is called a pit crater. Several pit craters with the diameter of around 100 meters have been found by analyzing the data of SELENE and LRO lunar missions. It is hard to use these pit craters for outposts since these are too large in scale. In this study, small scale pit craters which are fit for outposts have been investigated using the NAC image data of LROC. Several topographic patterns which are believed to be lunar caves have been found and the similar pit craters of the Earth were compared and analyzed to identify caves. For this analysis, the image data of satellites and aerial photographs are collected and classified to construct a database. Several pit craters analogous to lunar pit craters were derived and a morphological pit crater model was generated using the 3D printer based on this database.
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Both primary and secondary caves occur in volcanic rocks. Secondary caves are either tectonic (fissure caves) or erosional (sea caves; erosional river caves). Primary caves include: tree and animal casts, hollow tumuli, drained lava tongues, pressure ridge caves, or empty vents, hundreds meter deep. The longest caves form by lateral subterraneous lava transport, termed “pyroducts” (Coan, 1844) (alias lava “tunnels” or “tubes”), integral features of pāhoehoe lava flows. They form by “inflation” at the active, downslope tip of flows or by crusting-over of channels. Internal lava falls cause their downward erosion. The longest lava cave is Kazumura Cave, Hawaii (trunk-length 41 km).
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Detailed mapping during the 1991-1993 eruption of Mount Etna has shown that there is a relationship between tumuli, ephemeral vents, lava tubes, and their parent lava flows. During this eruption, many tubes formed in stationary, inflated 'a'a lava flows. Ephemeral vents at the fronts of these stationary flows and above lava tubes fed secondary lava flows, many of which subsequently developed new tubes. The resulting complex network of tubes, ephemeral vents, and secondary flows was responsible for most of the widening, thickening, and lengthening of the 1991-1993 Etna lava flow field. The supply of relatively uncooled lava via tubes to distal parts of this flow field allowed lava to flow 3 km farther from the vent than the longest channel-fed lava flow. Our observations suggest that lava tubes play a more important role in the formation of extensive 'a'a flow fields on Etna than has previously been recognized.
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Invertebrate communities in volcanic habitats of different ages on the islands of La Palma and El Hierro were studied using standardized trapping and searching techniques. A variety of graphical and numerical approaches were used to analyse relationships among the sites. Young, barren lava flows constitute aeolian ecosystems with a fauna of generalized detritivores and predators, especially collembolans, earwigs, thysamirans and crickets. Surface samples have many individuals and low diversity; those from caves have smaller numbers but similar taxonomic composition. Vegetated surface habitats have richer communities, with diverse herbivores and predators but largely without the pioneer ‘lavicolous’ species. Caves with high humidity and stable temperature contain mainly specialized troglobitic species, but if there are both dry and humid sections lavicoles may also be present. Divergence into distinct epigean and hypogean communities results from both abiotic and biotic processes, including erosion and plant succession. While these occur mainly on the surface they also affect caves, increasing humidity and providing insulation from variations in external environmental conditions; the process is considered as a form of ‘maturation’ of the caves. Various models of succession are considered, which might help to account for the disappearance of lavicoles from mature epigean and hypogean communities.
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Some human activities threaten caves and cave life, causing disrepect for caves, habitat loss, declines in populations, or even extinction. The protection of these resources involves management of the landscape above the cave as well as the details of cave gates and security systems. Cave restoration can improve conditions for cave life but may also cause problems if not properly done. The spread of White-nose Syndrome in North American bats has changed our approach to accessing caves for all activities. "Clean caving" and decontamination are precautions against the accidental spread of wildlife diseases. Public education about cave and karst conservation is essential because many are not aware of the gradual degradation of cave resources and threats against cave life.
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The Corona lava tube on the Canarian island of Lanzarote is a unique subterranean ecosystem comprising both dry and submerged cave sections with a total length of almost 8km. Here, we present the results of a diving exploration of the lava tube that took place from 11 to 25 March 2008. Environmental characteristics are given for ecologically disparate sections of the cave, including the Cueva de los Lagos, the Jameos del Agua, and the Túnel de la Atlántida. Moreover, we compare various habitats within the lava tube, and discuss the origin of the diverse hypogean fauna, including new species of remipede crustaceans and polychaete worms discovered during the expedition.
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The island of Lanzarote, located at the eastem, oldest edge of the Canarian hotspot island-chain, has very sparse Holocene rejuvenation volcanism, possibly restricted to the 1824 and 1730 eruptions, ir1 agreement with the mature post-erosional stage of the island. The dating of the Corona Volcano, possibly the most recent eruptive event in the island before the historic eruptions, gives a mean 40Ar/.i9Ar age of 21 f 6.5 ka. This age agrees with the geological observations and the study of the Corona Volcano, particularly the large lava tube (7.6 km long, up to 25 m in diameter) formed in the initial stages of the eruption. The last 1.6 km of' this lava tube are at present submerged, ending at a depth of at least 80 m below the present sea level. Our interpretation is that the active lava tube could not have reached that depth and, therefore, the submerged part of the tube formed as the lava flowed on a coastal platform at least 1.6 km wider and at least 80 m below the present sea level, a circumstance that could only have been possible coinciding with a period of low sea-leve1 stand related to a maximum glacial, most probably the last one, at about 20 ka. The subsequent rise in sea level left the coastal platform and the end of the lava tube submerged. The age of the Corona Volcano eruption is constrained by the radioisotopic determinations in 21 + 6.5 ka and, concordantly, by the low sea-leve1 stand recorded between about 18 and 21 ka. The Corona Volcano eruption and lava tube therefore provide clear evidence of changes in sea level in the Canaries in relation to glaciations, and establish important constraints in the volcanic history of the island of Lanzarote. La isla de Lanzarote, situada en el extremo oriental de la alineación del punto caliente de las Canarias, ha tenido escasa actividad eruptiva de rejuvenecimiento en el Holoceno, posiblemente reducida a las erupciones de 1730 y 1824, hecho que concuerda con el avanzado estado post-erosivo de la isla. La datación de la erupción del Volcán Corona, aparentemente el evento volcánico anterior en Lanzarote a las erupciones históricas, ha dado una edad media ponderada 40Ar/39Ar de 21 f 6,5 ka. Esta edad concuerda con las observaciones geológicas, particularmente las circunstancias de formación del tubo volcánico de 7,6 km de longitud y hasta 25 m de diámetro que se formó en las primeras fases de la erupción. El último tramo de 1,6 km está sumergido, finalizando a una profundidad de > 80 m. Nuestra interpretación es que el tubo volcánico activo no pudo alcanzar esa profundidad circulando por un medio subacuático, sino que fluyó por una plataforma costera al menos 1,6 km más extensa y al menos 80 m más baja que la costa actual, circunstancia que sólo ha podido darse en coincidencia con un pronunciado descenso del nivel marino en un máximo glacial, con toda probabilidad el último, hace unos 20 ka. La subsiguiente transgresión inundó el tubo hasta el nivel actual. La edad de la erupción queda pues limitada por las edades radioisotópicas en 21 f 6,5 ka y, concordantemente, por el máximo descenso del nivel marino, registrado entre unos 18 y 21 ka. El estudio de la erupción del Corona establece hitos importantes en la historia volcánica de la isla de Lanzarote y aporta evidencia significativa de los cambios del nivel marino ocurridos en las Canarias en relación con las glaciaciones.
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An assemblage of endemic cavernicolous marine invertebrates, including taxa found on both sides of the Atlantic Ocean of great phylogenetic age or with affinities to deep sea organisms, inhabits the Jameos del Agua cave, a sea waterflooded Holocene lava tube cave on Lanzarote in the Canary Islands. This marine cave contains both relicts from Tethyan times, such as an apparently new crustacean family belonging to what had been the monotypic class Remipedia, and relicts of groups that are now common only in the deep sea as well as species that occur outside the cave.
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Txtbook on cave minerals and speleothems
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The flora of lichens and lichenicolous fungi of Lanzarote (Canary Islands) has been studied. The recent catalogue of the Island was composed of 170 species. In the presented annotated list, 71 taxa are additional records for the island, of which 10 are new to the Canary Islands and among them Catillaria subpraedicta and Micarea seneciae are newly described.
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Volcanic caves have been considered of little mineralogic interest until recent years. As a consequence, very few papers have been printed on this topic in the past. In reality volcanic cavities are a very favorable environment for the development of different minerogenetic processes. Cave minerals actually present in volcanic environments constitute up to 40% of secondary chemical deposits found in all the caves of the world, and 35 of them (corresponding to ~10% of the actually known cave minerals) are restricted to such a environment. In the present paper, the six minerogenetic mechanisms active in the volcanic caves (degassing, solubilization, alteration, karst process, biogenic activity, phase change) are described following the decrease of cave temperature. The genesis of some of the most important secondary chemical deposits is discussed and a tentative list of the most interesting volcanic caves for hosted speleothems is given.
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This paper presents newly discovered candidate cave entrances into Martian near-surface lava tubes, volcano-tectonic fracture systems, and pit craters and describes their characteristics and exploration possibilities. These candidates are all collapse features that occur either intermittently along laterally continuous trench-like depressions or in the floors of sheer-walled atypical pit craters. As viewed from orbit, locations of most candidates are visibly consistent with known terrestrial features such as tube-fed lava flows, volcano-tectonic fractures, and pit craters, each of which forms by mechanisms that can produce caves. Although we cannot determine subsurface extents of the Martian features discussed here, some may continue unimpeded for many kilometers if terrestrial examples are indeed analogous. The features presented here were identified in images acquired by the Mars Odyssey's Thermal Emission Imaging System visiblewavelength camera, and by the Mars Reconnaissance Orbiter's Context Camera. Select candidates have since been targeted by the High-Resolution Imaging Science Experiment. Martian caves are promising potential sites for future human habitation and astrobiology investigations; understanding their characteristics is critical for long-term mission planning and for developing the necessary exploration technologies.
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About 190 anthropogenic sinkholes occurred within the territory of the city of Naples (Southern Italy) between 1915 and 2010.In the study area, the genesis of sinkholes can be ascribed to two major factors, often strongly interacting with each other: the existence of a complex network of underground man-made cavities, and the inadequacy of the sewage disposal system.Rainfall has been identified as the main triggering factor combined with anthropogenic activity. Based on such predisposing factors, in addition to the geological setting, a susceptibility map of the territory has been realised.
Article
The Undara Volcano erupted 0.19 m.y. ago and formed lava fields covering 1,500 km2 with a volume of approximately 23 km3. One of the flows extended 160 km on a gradient that averaged only 0.3°. This great length was a result of very high effusion rates, favourable topography and lava tube efficiency. The Undara lavas are rather uniform hawaiites. Lava temperatures are estimated to have been somewhat less than 1175–1220°C and viscosities greater than 10 to 30 Pa s. Long, apparently single lava tubes are well preserved in many places. They are marked by depressions, caves and long level ridges. A system of lava tubes extends for perhaps more than 100 km. The features of the lava tubes are comparable with those described elsewhere. Aligned depressions associated with caves appear to have formed contemporaneously. Most are much wider than the caves and probably represent collapsed lava ponds. The lava tubes appear to have formed by roofing over of lava channels. Close to lava tubes, the rocks developed strongly oxidised characteristics, such as oxidised olivine phenocrysts, ferric clinopyroxene and extensively developed hematite. Differentiated lava forms drips in some caves and is also oxidised.
Article
Lava tubes and basaltic caves are common features in volcanic terrains on Earth. Lava tubes and cave-like features have also been identified on Mars based on orbital imagery and remote-sensing data. Caves are unique environments where both secondary mineral precipitation and microbial growth are enhanced by stable physico-chemical conditions. Thus, they represent excellent locations where traces of microbial life, or biosignatures, are formed and preserved in minerals. By analogy with terrestrial caves, caves on Mars may contain a record of secondary mineralization that would inform us on past aqueous activity. They may also represent the best locations to search for biosignatures. The study of caves on Earth can be used to test hypotheses and better understand biogeochemical processes, and the signatures that these processes leave in mineral deposits. Caves may also serve as test beds for the development of exploration strategies and novel technologies for future missions to Mars. Here we review recent evidence for the presence of caves or lava tubes on Mars, as well as the geomicrobiology of lava tubes and basaltic caves on Earth. We also propose future lines of investigation, including exploration strategies and relevant technologies.
Article
Samples of lichen-covered and bare lava surfaces from Lanzarote, dating from the 1730–1736 eruption, have been analysed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) to investigate the relative roles of biological and inorganic weathering processes. Lichens here grow preferentially on N and NE facing surfaces and create a range of nanomorphological features as a consequence of their weathering activities. The fruticose lichen Stereocaulon vesuvianum and a mixture of crustose lichen species are found to be particularly effective agents of weathering. Comparison of the thickness of the weathering rind on bare and lichen-covered samples (mean thickness 15.7 and 253.9 μm, respectively) shows a significant difference at the 99% confidence level. Following previous studies in Hawaii by Jackson and Keller [Am. J. Sci. 269 (1970) 466], these results are used to suggest that lichens on Lanzarote lava flows cause a 16 times increase in weathering rates over those found on bare surfaces. Comparison of these results with those from similar lava flows in Hawaii indicates that under the wetter climate of Hawaii both biological and inorganic rates are over double those found in Lanzarote.
Article
Comments and suggestions by P. Armienti, C. Newhall, R. Batiza and an anonymous reviewer led to significant improvements in the manuscript and are greatly appreciated. The eruption that took place in Lanzarote between 1 September 1730 and 16 April 1736 differs from the normal style of the historic (last 500 years) volcanism of the Canary Islands. The duration (2,056 days), extent (200 km2), volume of materials emitted (3-5 km3) and the evolution of magmas from extremely SiO2-undersaturated lavas (melanephelinites) towards olivine tholeiite compositions are quite unique in the historic trend of volcanism in the Archipelago, and, apparently, even in the Earth's historical record of basaltic fissure eruptions. However, no specific work has been undertaken until now to attempt the reconstruction of this eruption. We present here a detailed reconstruction of the eruption, based on field observations and data provided by eye-witness accounts, one of which is a hitherto unpublished manuscript. The "anomalous" nature of this eruption in relation to the historic volcanism of the Canaries--especially the continuation of the eruption after the initial phase was completed (some 3-4 months, the maximum duration of any historic eruption in the Canarian Archipelago )--might be the result of upward movement of the magma generation front to an intermediate depth along a large fracture. Financial support for this work was provided by the Spanish "Comisión Interministerial de Ciencia y Tecnología (CICYT)" and the Consejo Superior de Investigaciones Científicas (CSIC) Research Projects PR84-0136 and PB88-0024. Peer reviewed
Article
The 1730—36 Timanfaya eruption on Lanzarote, in the Canary Islands, is the second largest historical effusion on record. During its final stages, in 1736, the eruption produced the Montaña de las Nueces flow-field, consisting of sheets of pahoehoe lava that, within 4 weeks, had covered 32 km2 and reached a maximum length of almost 21 km. The tholeiitic lavas have pahoehoe surface features, but internal structures that are normally associated with massive aa flows, suggesting that their fronts advanced as single units rather than as a collection of budding pahoehoe tongues. Volume conservation and a simple model of crustal failure suggest that the main flows advanced at about 0.02 ms-1 over the prevailing slopes of ~lº. The rates of advance are (1) consistent with emplacement near the transition from pahoehoe to aa, and (2) about an order of magnitude greater than would have been expected by analogy with Hawaiian pahoehoe flow-fields of similar dimensions. Surface texture and morphology, therefore, is an insufficient guide for constraining the rate and style of pahoehoe emplacement, and a flow’s internal structure must be established before its characteristics are used to infer eruption conditions and potential hazard. This work was funded by the EU Project FLOW, Contract number ENV4-CT98-0713 Peer reviewed
De una cueva que se halla en la isla de Tenerife a distancia de una milla del ligar de Icod, hacia el norte, examinada el 14 de noviembre de 1776
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Castro JB (1779) De una cueva que se halla en la isla de Tenerife a distancia de una milla del ligar de Icod, hacia el norte, examinada el 14 de noviembre de 1776, por Don José, Don Augustín de Béthencourt de Castro y Molina, Don José de Monteverde y Molina, Cristóbal Alfonso y otros (unpublished), Depto. Zoologia, Univ. La Laguna
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The ancient inhabitants of the Canary Islands
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The Jameos del Agua cave (Lanzarote, Canary Islands): some morphological and geological features of a spectacular lava tube adapted to auditorium
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Caves of fire: inside America’s lava tubes
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Contribución al conocimiento mineralógico y mineralogénico de un nuevo tipo de yacimiento de yeso descubierto en los>> tubos de lava>> de la isla de Lanzarote (Canarias)
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Catálogo de las cavidades volcánicas de Canarias
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The ESA PANGAEA field geology training prepares astronauts for future missions to the Moon and beyond
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Sauro F, Massironi M, Pozzobon R, Hiesinger H, Mangold N, Martinez-Frías J, Cockell C, Bessone L (2018a) The ESA PANGAEA field geology training prepares astronauts for future missions to the Moon and beyond. In: EGU general assembly 2018, Vienna, pp EGU2018-4017
Gypsum speleothems in lava tubes from Lanzarote, Canary Islands. Did you say gypsum? In: 31st IAS meeting of sedimentology
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Huerta P, Martín-García R, Rodríguez-Berriguete Á, Fernández ÁLI, Martín-Pérez A, Alonso-Zarza AM (2015) Gypsum speleothems in lava tubes from Lanzarote, Canary Islands. Did you say gypsum? In: 31st IAS meeting of sedimentology, Krakow, p 240
Origin and evolution of an inflated lava tube between the Mio-Pliocene volcanic complex of Famara and the quaternary lava flows of La
  • M Tonello
Tonello M (2017) Origin and evolution of an inflated lava tube between the Mio-Pliocene volcanic complex of Famara and the quaternary lava flows of La Corona in Lanzarote. University of Padova, p 111
Geología y volcanología de las Islas Canarias
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international expedition to the Tunnel de la Atlantida
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Isler O (1986) 1986 international expedition to the Tunnel de la Atlantida. Caves Caving 45:16-21
El tubo vulcanico de Los Naturalistas
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Martín J, Díaz M (1984) El tubo vulcanico de Los Naturalistas. Lapiaz 13:51-54
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