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Volcanic hazard assessment is generally based on past eruptive behavior, assuming that previous activity is representative of future activity. Hazard assessment can be supported by Artificial Intelligence (AI) techniques, such as machine learning, which are used for data exploration to identify features of interest in the data. Here, we applied a machine learning technique to automate the analysis of these datasets, handling intricate patterns that are not easily captured by explicit commands. Using the k-means clustering algorithm, we classified effusive eruptions of Mount Etna over the past 400 years based on key parameters, including lava volume, Mean Output Rate (MOR), and eruption duration. Our analysis identified six distinct eruption clusters, each characterized by unique eruption dynamics. Furthermore, spatial analysis revealed significant sectoral variations in eruption activity across Etna's flanks. These findings, derived through unsupervised learning, offer new insights into Etna's eruptive behavior and contribute to the development of hazard maps that are essential for long-term spatial planning and risk mitigation. [ABSTRACT FROM AUTHOR]

Volcanic hazard assessment is generally based on past eruptive behavior, assuming that previous activity is representative of future activity. Hazard assessment can be supported by Artificial Intelligence (AI) techniques, such as machine learning, which are used for data exploration to identify features of interest in the data. Here, we applied a machine learning technique to automate the analysis of these datasets, handling intricate patterns that are not easily captured by explicit commands. Using the k-means clustering algorithm, we classified effusive eruptions of Mount Etna over the past 400 years based on key parameters, including lava volume, Mean Output Rate (MOR), and eruption duration. Our analysis identified six distinct eruption clusters, each characterized by unique eruption dynamics. Furthermore, spatial analysis revealed significant sectoral variations in eruption activity across Etna’s flanks. These findings, derived through unsupervised learning, offer new insights into Etna’s eruptive behavior and contribute to the development of hazard maps that are essential for long-term spatial planning and risk mitigation.

Stromboli is an open-conduit active volcano located in the southern Tyrrhenian Sea and is the easternmost island of the Aeolian Archipelago. It is known as "the lighthouse of the Mediterranean" for its continuous and mild Strombolian-type explosive activity, occurring at the summit craters. Sometimes the volcano undergoes more intense explosions, called "major explosions" if they affect just the summit above 500 m a.s.l. or "paroxysms" if the whole island is threatened. Effusive eruptions are less frequent, normally occurring every 3–5 years, and may be accompanied or preceded by landslides, crater collapses and tsunamis. Given the small size of the island (maximum diameter of 5 km, NE–SW) and the consequent proximity of the inhabited areas to the active craters (maximum distance 2.5 km), it is of paramount importance to use all available information to forecast the volcano's eruptive activity. The availability of a detailed record of the volcano's eruptive activity spanning some centuries has prompted evaluations on its possible short-term evolution. The aim of this paper is to present some statistical insights on the eruptive activity at Stromboli using a catalogue dating back to 1879 and reviewed for the events during the last two decades. Our results confirm the recent trend of a significant increase in major explosions, small lava flows and summit crater collapses at the volcano, and might help monitoring research institutions and stakeholders to evaluate volcanic hazards from eruptive activity at this and possibly other open-vent active basaltic volcanoes. [ABSTRACT FROM AUTHOR]

Stromboli is an open-conduit active volcano located in the southern Tyrrhenian Sea and is the easternmost island of the Aeolian Archipelago. It is known as “the lighthouse of the Mediterranean” for its continuous and mild Strombolian-type explosive activity, occurring at the summit craters. Sometimes the volcano undergoes more intense explosions, called “major explosions” if they affect just the summit above 500 m a.s.l. or “paroxysms” if the whole island is threatened. Effusive eruptions are less frequent, normally occurring every 3–5 years, and may be accompanied or preceded by landslides, crater collapses and tsunamis. Given the small size of the island (maximum diameter of 5 km, NE–SW) and the consequent proximity of the inhabited areas to the active craters (maximum distance 2.5 km), it is of paramount importance to use all available information to forecast the volcano’s eruptive activity. The availability of a detailed record of the volcano’s eruptive activity spanning some centuries has prompted evaluations on its possible short-term evolution. The aim of this paper is to present some statistical insights on the eruptive activity at Stromboli using a catalogue dating back to 1879 and reviewed for the events during the last two decades. Our results confirm the recent trend of a significant increase in major explosions, small lava flows and summit crater collapses at the volcano, and might help monitoring research institutions and stakeholders to evaluate volcanic hazards from eruptive activity at this and possibly other open-vent active basaltic volcanoes.

Volcanism has played a major role in modifying the Martian surface. The Tharsis volcanic province dominates the western hemisphere of the planet with numerous effusive volcanic constructs and deposits. Here, we present the results of an in‐depth study aimed at characterizing and modeling the emplacement conditions of 40 lava flows in the Tharsis volcanic province. These lava flows display a range of lengths (∼15–310 km), widths (∼0.5–29 km), and thicknesses (∼11–91 m). The volumes and flow masses range from ∼1 to 440 km3 and ∼1011 to 1014 kg, respectively. Using three different models, we calculated a range of eruption rates (0.3–3.5 × 104 m3/s), viscosities (104–107 Pa s), yield strengths (800–104 Pa), and emplacement times (8 h–11 years). While the flow lengths and volumes are typically larger than terrestrial lava flows by an order of magnitude, rheologies and eruption rates are similar based on our findings. Emplacement times suggest that eruptions were active for long periods of time, which implies the presence and persistence of open subsurface pathways. Differences in flow morphology and emplacement conditions across localities within Tharsis highlight different pathways and volumes of available material between the central volcanoes and the plains. The scale of the eruptions suggests there could have been eruption‐driven local, regional, and perhaps, global impacts on the Martian climate. The relatively recent age of the eruptions implies that Mars has retained the capability of producing significant localized volcanism. Plain Language Summary: Volcanoes have resurfaced a majority of the Martian surface. Understanding the volcanic history of Mars is critical to understanding the evolution of the planet. Lava flows are one of the most common volcanic features on Mars, and numerous examples are present in the Tharsis volcanic province on shield volcanoes and in vast volcanic plains. Using three different approaches, we characterized the eruption conditions of 40 lava flows. In addition, we measured their dimensions and calculated volumes and masses. We observed flow dimensions (e.g., lengths and volumes) larger than typical terrestrial lava flows. Viscosities and yield strengths were similar to terrestrial values; however, effusion rates were generally at the higher end of terrestrial rates. These results indicate that lava flows erupted on Mars did not require exotic compositions or exceptionally high eruption rates to be emplaced. However, this does imply longer eruption times, which requires the existence of long‐lived subsurface conduits capable of transporting magma to the surface. Key Points: The large thick lava flows in Tharsis are explained by basaltic and basaltic‐andesite compositions without resorting to exotic compositionsThe observed lava flows likely required longer‐lived eruptive conditions and larger active conduits than their terrestrial counterpartsSeemingly high eruption rates for some solitary flows are reasonable extrapolations of terrestrial conditions with higher supply dimensions [ABSTRACT FROM AUTHOR]

The temporal evolution of effusion rate is the main controlling factor of lava spreading and emplacement conditions. Therefore, it represents the most relevant parameter for characterizing the dynamics of effusive eruptions and thus for assessing the volcanic hazard associated with this type of volcanism. Since the effusion rate curves can provide important insights into the properties of the magma feeding system, several efforts have been performed for their classification and interpretation. Here, a recently published numerical model is employed for studying the effects of magma source and feeding dike properties on the main characteristics (e.g., duration, erupted mass, and effusion rate trend) of small‐volume effusive eruptions, in the absence of syn‐eruptive magma injection from deeper storages. We show that the total erupted mass is mainly controlled by magma reservoir conditions (i.e., dimensions and overpressure) prior to the eruption, whereas conduit processes along with reservoir properties can significantly affect mean effusion rate, and thus, they dramatically influence eruption duration. Simulations reproduce a wide variety of effusion rate trends, whose occurrence is controlled by the complex competition between conduit enlargement and overpressure decrease due to magma withdrawal. These effusion rate curves were classified in four groups, which were associated with the different types described in the literature. Results agree with the traditional explanation of effusion rate curves and provide new insights for interpreting them, highlighting the importance of magma reservoir size, initial overpressure, and initial width of the feeding dike in controlling the nature of the resulting effusion rate curve. Key Points: The effects of magma source and feeding dike properties on the evolution of small‐volume effusive eruptions are studied numericallyTotal erupted mass is mainly controlled by magma reservoir conditions (in particular, dimensions and overpressure) prior to the eruptionDifferent types of effusion rate curves were modeled, classified, and compared with the effusion rate trends defined in the literature [ABSTRACT FROM AUTHOR]

Although most of the large volcanic landforms on Mars have been extensively studied, this is not the case for kilometer-sized landforms whose origin remains uncertain and which might provide important insights into the evolution of Martian volcanism. Previously, different populations of small-scale putative scoria cone volcanoes have been described in Tharsis, specifically in areas where the heavily fractured crust of the Noachian- and Hesperian-age escaped Amazonian resurfacing by younger lava flows. Therefore, we decided to explore a region of old fractured crust in Tharsis, Claritas Fossae, to search for signs of local-scale volcanic activity. Here, we present the results of a mapping campaign focused on the morphological and spectral properties of small-scale constructional mounds in the Noachian-age Claritas Fossae region that was affected by Hesperian- to early Amazonian-aged fracturing. By using data from Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE), we mapped 39 mounds superimposed on the ancient crust and determined their morphological and morphometrical properties. The majority of the mounds are elongated (WNW- trending) with steep flanks and without associated flow units. The general appearance of studied edifices is consistent with a volcanic origin and their shapes suggest that they have been emplaced by effusion of viscous, volatile poor lavas incapable of significant flow. In addition, a spectral investigation utilizing the data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) reveal that some of the mounds showed evidence for high concentrations of low-calcium pyroxenes (LCP). Based on the relative stratigraphy, we demonstrate that volcanic activity is responsible for their formation and postdates the main N-S-trending fracturing of the Claritas Fossae, suggesting the formation of a volcanic field in the period spanning through the Late Hesperian and the Early Amazonian. However, morphological evidence such as well-preserved volcanic fissures and fresh-appearing slopes of some of the edifices might suggest even younger age. Among the mapped edifices, we found a well-preserved circular-shaped cone with a short-distance flow-like unit spreading from a caldera-like structure that challenges a scenario in which all the edifices are old. Such relatively young ages of volcanic activity combined with LCP-rich compositions might have critical implications for understanding the temporal evolution of magma compositions on Mars. Moreover, the observed shapes and spectral characteristics of the studied edifices appear to be quite different from other volcanic fields of similar geological settings observed so far on Mars. Therefore, we underline the importance of studying old and heavily fractured terrains that escaped later resurfacing by widespread younger lava flows, in order to search for evidence of small-scale volcanism and better understand local Martian magmatic systems. • Noachian-aged fractured crust of Claritas Fossae hosts 39 volcanic edifices • Volcanoes are superimposed on the N-S fractures and postdate their formation • Volcanoes are spatially associated with low-calcium pyroxenes • They were formed by the low-voluminous effusive eruptions of viscous magma • Volcanism might be associated with Amazonian-age partial melting beneath Claritas Fossae [ABSTRACT FROM AUTHOR]

Kīlauea is a frequently active, open-system volcano on the Island of Hawaiʻi known for erupting olivine-dominated tholeiitic basalt compositions. On rare occasions it erupts more differentiated magmas (<1% of erupted volume), such as basaltic andesites and andesites, from its rift zones. These differentiated magmas offer an opportunity to understand better the petrology, magma storage, magma mixing, and eruptive triggers that occur in Kīlauea's rift zone reservoirs. This study focuses on an eruption from the Southwest Rift Zone of Kīlauea, which is dominantly basaltic andesite with subordinate basalt. This eruption originated at the Kamakaiʻa Hills during the early 19th century and has two eruptive phases: 1) an early 'a'ā phase that is primarily exposed in the eastern part of the flow field, with minor western lobes, and 2) a late pāhoehoe phase that makes up most of the western part of the flow field. The early 'a'ā phase covers at least 5.8 km2 with an erupted volume of ∼150 × 106 m3 and consists of uniform composition basaltic andesites with 3.72–4.15 wt% MgO over its ∼7 km flow length. The late pāhoehoe phase reached >10 km from its vent, covers an area of ∼7.1 km2, has a volume of ∼100 × 106 m3, and initially erupted basaltic andesite near its vent (4.50–5.64 wt% MgO extending to 3.8 km from vent) with channel and tube-fed basalt (6.21–12.38 wt% MgO sampled at >3.8 km from vent) emplaced during its waning stages. Most Kamakaiʻa Hills lavas are crystal-poor, containing ≤1.5% glomerocrysts and individual phenocrysts of plagioclase + clinopyroxene + Fe Ti oxides ± orthopyroxene, as well as olivine in lavas with >6 wt% MgO. Major-oxide and trace-element concentrations throughout the Kamakaiʻa Hills lavas demonstrate the involvement of three distinct magmatic processes. First, the basaltic andesites of the early 'a'ā phase are the products of fractionation of plagioclase + clinopyroxene + Fe Ti oxides ± orthopyroxene, indicative of magmas that have been stored in rift zone reservoirs for decades or longer. Second, the near-vent (within ∼400 m of vent) basaltic andesites of the late pāhoehoe phase yield chemical concentrations that indicate magma mixing with a more differentiated magma (of a similar evolved composition to basaltic andesites at ∼55–56 wt% SiO 2 and ∼3.4–4.1 wt% MgO that erupted in the lower East Rift Zone in 2018). Third, the progressively more mafic magma (containing olivine + plagioclase + clinopyroxene) that continued to erupt throughout the waning stages of activity suggests an eruptive triggering process whereby an intruding summit or uprift reservoir basalt overpressurized and forced out the stored, differentiated magma of the Kamakaiʻa Hills rift zone reservoir. • The Kamakaiʻa Hills erupted a large volume of differentiated magma from Kīlauea. • This magma evolved over decades to centuries in a rift zone storage reservoir. • Dike intrusion resulted in a hydraulic plunger-type eruption trigger. • Magma mixing indicates multiple magma pods associated with the rift zone reservoir. • A similar reservoir is presumed to still be within the Southwest Rift Zone. [ABSTRACT FROM AUTHOR]

Abstract: The dynamics of effusive events is controlled by the interplay between conduit geometry and source conditions. Dyke‐like geometries have been traditionally assumed for describing conduits during effusive eruptions, but their depth‐dependent and temporal modifications are largely unknown. We present a novel model which describes the evolution of conduit geometry during effusive eruptions by using a quasi steady state approach based on a 1‐D conduit model and appropriate criteria for describing fluid shear stress and elastic deformation. This approach provides time‐dependent trends for effusion rate, conduit geometry, exit velocity, and gas flow. Fluid shear stress leads to upward widening conduits, whereas elastic deformation becomes relevant only during final phases of effusive eruptions. Simulations can reproduce different trends of effusion rate, showing the effect of magma source conditions and country rock properties on the eruptive dynamics. This model can be potentially applied for data inversion in order to study specific case studies. [ABSTRACT FROM AUTHOR]

The volcanic activity that built up the Monte dei Porri stratocone (Salina Island) was reconstructed using new stratigraphic data, which allowed seven eruption units to be distinguished. Alternating Strombolian/Vulcanian to sub-Plinian/Plinian explosive and effusive activity emplaced fall and pyroclastic density current deposits and lava flows that formed the volcanic cone. The minimum erupted bulk volumes were assessed at 100 × 10 6 m 3 each for EU1, EU2, EU3 and EU6, while that of EU4 is ca. 200 × 10 6 m 3 . Rough estimation of EU7 volume yields values around 150 × 10 6 m 3 . The calculation of volume was not possible for the EU5 deposits. The magmas that fed the different eruption units of the Monte dei Porri succession range in composition from basalt to andesite, with the exception of dacites erupted in the initial phase of activity. SEM image analyses on coarse ash from the different pyroclastic units suggest that hydromagmatic fragmentation cannot be the cause of the large variations in explosivity observed throughout the stratigraphic succession. Based on the lithic component of pyroclastic deposits and xenolith contents of lava flows, the plumbing system that fed the different eruption units of Monte dei Porri was split into a deep magma storage level (15–20 km) and shallower magma batches (3–5 km). Our calculations indicate that the volumes of erupted material can account for magmatic triggering (injection of new magma) of eruptive units from the shallower feeding system, but they are not sufficient for suggesting magmatic initiation of the eruption units from the deeper feeding system. It is therefore assumed that the eruptions from the deep magma reservoir necessitate a favourable lithostatic stress, likely calling for a reduction of the local tectonic forces. A qualitative model explaining the eruptive style transitions among and within the different eruption units is presented, taking into account the relation between magmatic overpressure and lithostatic stress. [ABSTRACT FROM AUTHOR]

Ulleung Island is the top of a 3000 m (from sea floor) intraplate alkalic volcanic edifice in the East Sea/Sea of Japan. The emergent 950 m consist of a basaltic lava and agglomerate succession (Stage 1, 1·37–0·97 Ma), intruded and overlain by a sequence of trachytic lavas and domes, which erupted in two episodes (Stage 2, 0·83–0·77 Ma; Stage 3, 0·73–0·24 Ma). The youngest eruptions, post 20 ka bp, were explosive, generating thick tephra sequences of phonolitic composition (Stage 4), which also entrained phaneritic, porphyritic and cumulate accidental lithics. Major element chemistry of the evolved products shows a continuous spectrum of trachyte to phonolite compositions, but these have discordant trace element trends and distinct isotopic characteristics, excluding a direct genetic relationship between the two end-members. Despite this, the Stage 3 trachytes and some porphyritic accidental lithics have chemical characteristics transitional between Stage 2 trachytes and Stage 4 phonolites. Within the phonolitic Stage 4 tephras three subgroups can be distinguished. The oldest, Tephra 5, is considerably enriched in incompatible elements and chondrite-normalized rare earth element (REE) patterns display negative Eu anomalies. The later tephras, Tephras 4–2, have compositions intermediate between the early units and the trachyte samples, and their REE patterns do not have significant Eu anomalies. The last erupted, Tephra 1, from a small intra-caldera structure, has a distinct tephriphonolite composition. Trace element and isotopic chemistry as well as textural characteristics suggest a genetic relationship between the phaneritic lithics and their host phonolitic pumices. The Stage 4 tephras are not related to earlier phases of basaltic to trachytic magmatism (Stages 1–3). They have distinct isotopic compositions and cannot be reliably modelled by fractional crystallization processes. The differences between the explosive phonolitic (Stage 4) and effusive trachytic (Stage 2–3) eruptions are mainly due to different pre-eruptive pressures and temperatures, causing closed- versus open-system degassing. Based on thermodynamic and thermobarometric modelling, the phonolites were derived from deeper (subcrustal) magma storage and rose quickly, with volatiles trapped until eruption. By contrast, the trachytes were stored at shallower crustal levels for longer periods, allowing open-system volatile exsolution and degassing before eruption. [ABSTRACT FROM PUBLISHER]

Historic and recent (last 2,000 years) eruptions on the active volcanic island of Tenerife have been predominantly effusive, indicating that this is the most probable type of activity to be expected in the near future. In the past, lava flow invasion caused major damage on the island, and as the population and infrastructure have increased dramatically since the last eruption, lava flows are the most important short-term volcanic risk on Tenerife. Hence, an understanding of lava flow behaviour is vital to manage risks from lava flows and minimise future losses on the island. This paper focuses on the lava flows from the historic eruptions in Tenerife, providing new data on the volumes emitted, advance rates and the timing of the emplacement of flows. The studies show three main stages in the development of unconfined flow fields: the first stage, corresponding to the fast advance of the initial fronts during the first 24-36 h of eruption (reaching calculated velocities of up to 1.1 m/s); the second stage, in which fronts stagnate; and a third stage, in which secondary lava flows develop from breakouts 4-7 days after the initial eruption and farther extend the flow field (velocities of up to 0.02 m/s have been calculated for this stage). The breakouts identified originated at sites both proximal and distal to the vent and, in both cases, caused damage through lengthening and widening the original flow field. Hence, the probability of damage from lavas to land and property is highest during stages 1 and 3, and this should be accounted for when planning the response to a future effusive eruption. Tenerife's lava flows display a similar behaviour to that of lava flows on volcanoes characterised by basaltic effusive activity (such as Etna or Kilauea), indicating the possibility of applying forecasting models developed at those frequently active volcanoes to Tenerife. [ABSTRACT FROM AUTHOR]

Abstract: Using Etna as a case study location, we examine the balance between the volume of magma supplied to the shallow volcanic system (using ground-based SO2 data) and the volume erupted (using satellite thermal data). We do this for three eruptions of Mt. Etna (Italy) during 2002 to 2006. We find that, during the three eruptions, 2.3×107 m3 or 24% of the degassed volume remained unerupted. However, variations in the degree of partitioning between supplied (Vsupply) and erupted (Verupt) magma occur within individual eruptions over the time scales of days. Consequently, we define and quantify three types of partitioning. In the first case, Vsupply Verupt, i.e. less lava is erupted than is supplied. In such a case, magma can erupt in an explosive manner, as occurred during Phase II of the 2002–2003 eruption, or remain within or below the edifice. In the third case, Vsupply =Verupt, i.e. all supplied magma is erupted. During 2002–2006, over a total of 280days of eruptive activity, this balancing case applied to 50% of the time. [Copyright &y& Elsevier]

Abstract: The 2007 effusive eruption of Stromboli followed a similar pattern to the previous 2002–2003 episode. In both cases, magma ascent led to breaching of the uppermost part of the conduit forming an eruptive fissure that discharged lava down the Sciara del Fuoco depression. Both eruptions also displayed a ‘paroxysmal’ explosive event during lava flow output. From daily effusion rate measurements retrieved from helicopter- and satellite-based infrared imaging, we deduce that the cumulative volume of lava erupted before each of the two paroxysms was similar. Based on this finding, we propose a conceptual model to explain why both paroxysms occurred after this ‘threshold’ cumulative volume of magma was erupted. The gradual decompression of the deep plumbing system induced by magma withdrawal and eruption, drew deeper volatile-rich magma into the conduit, leading to the paroxysms. The proposed model might provide a basis for forecasting paroxysmal explosions during future effusive eruptions of Stromboli. [Copyright &y& Elsevier]

The Ilopango caldera in central El Salvador is the source of at least 13 voluminous rhyolitic eruptions over the last two million years, including the 431 CE Tierra Blanca Joven (TBJ) which blanketed areas inhabited by the Mayan civilization, and the 1.707 ± 0.022 Ma Olocuilta ignimbrite, one of the largest Quaternary eruptions in Central America. These rhyolitic deposits have been the subject of numerous detailed studies. In contrast, the abundant effusive and monogenetic eruptions at Ilopango have not been studied. These small-volume eruptions range from basalt to rhyolite (49.7–72.8 wt% SiO 2) and occur both within the caldera margin and on the south flank of the Antiguo Ilopango stratovolcano. Here we present 28 new 40Ar/39Ar ages and geochemical data from domes, lavas, dikes, and ignimbrites from the Ilopango caldera and the Antiguo Ilopango stratovolcano as well as from adjacent volcanic systems. Collectively, these new data are used to construct a revised eruptive sequence for the Ilopango caldera that spans almost three million years. The new chronostratigraphy for Ilopango is highlighted by two volcanic cycles. Each cycle starts with rhyolite dome effusions, and then a prolonged period of explosive rhyolitic volcanism followed by a ~120–175 kyr period of less evolved eruptions. The spatio- and chemo-temporal patterns in the Ilopango eruptive sequence are similar in many ways to those observed in other well-studied Quaternary silicic centers. • We have new ages and geochemical data from 28 units from the Ilopango caldera system. • The new chronostratigraphy for Ilopango suggests there have been at least two volcanic cycles. • Evolution of the Ilopango magma system is similar to other Quaternary silicic systems. [ABSTRACT FROM AUTHOR]

El País is a monogenetic lava flow field located 16 km southeast of Peine town in the Altiplano-Puna area, Antofagasta region, Chile. El País is a monogenetic lava flow field located 16 km southeast of Peine town in the Altiplano-Puna area, Antofagasta region, Chile. El País is composed by lava flows of small-to-moderate volumes, which are fed from individual point sources unassociated with a central volcano of large-volume (stratovolcano) typical of the Andean arc. This lava flow field was emplaced in an area dominated by thin-skinned deformation under a compressive tectonic regime, where multiple volcanic centers (monogenetic and polygenetic volcanoes) have been developed. The volumetric and chemical evolutions were determined by fieldwork, stratigraphic, morphometric, textural (density and vesicularity), petrographic, and geochemical analyses. El País can be divided into three principal mafic lava flows such as Northern-, Main-, and Western-lava flows, which display an E-W orientation. Besides, at least eight ephemeral vents were identified as small erosion remnants of lava emitting point-sources. The identified vents are principally aligned in an ENE-WSW direction, east of the Main lava flow. It is inferred that El País was emplaced near-simultaneously above two ignimbrite sheets: Tucúcaro Ignimbrite (3.2 Ma) and Patao Ignimbrite (3.1 Ma). Stratigraphically, the Main lava flow has a surface texture with strong similarities to an ʻaʻā lava flow, composed of three unique layers well distinguishable in the field such as i) Basal, ii) Top auto-breccia, composed of sub-angular scoriaceous and dense clasts in an oxidized matrix, and iii) A single core between both auto-breccias, composed of dense lavas, exhibiting multiple cooling jointing, such as vertical to platy jointing. The advanced stage of erosion since the formation of El País is evidenced by the poorly preserved lava flows (flat morphology), upper auto-breccia layer, and the presence of large sub-angular blocks of lava (vesicular and dense) along the axis of the lava flows. The eruptive products are geochemically basaltic andesite (Main lava flow and ephemeral vents) and andesite (specifically in the Northern lava flow), making the lava flow field one of the most mafic in the broader region. The lava presents a glomeroporphyric texture, showing at least three different glomerocrysts: i) Plagioclase + clinopyroxene having reabsorption boundaries, ii) Clinopyroxene with reabsorption boundaries, and iii) Plagioclase with sieve-texture. The groundmass is principally composed of glass, plagioclase microlites with a low orientation preference, and opaque minerals (magnetite). This study helps understand the development of dispersed-monogenetic-volcanism (e.g., Tilocálar complex and Cerro Tujle maar), and its relationship with neighboring polygenetic volcanism (e.g., Toloncha stratovolcano) in the Central Volcanic Zone of the Andes, northern Chile. • Different vent location during effusive eruption in lava flow field context. • Ascent rate of basic and intermediate volcanism related with deep source and low magma supply. • Erosion process in dessert climate. [ABSTRACT FROM AUTHOR]