Volcanic Material Research Articles

Inverse Modeling of the Initial Stage of the 1991 Pinatubo Volcanic Cloud Accounting for Radiative Feedback of Volcanic Ash

AbstractThe way volcanic clouds evolve is very sensitive to the initial spatial 3D distributions of volcanic materials, which are often unknown. In this study, we conducted inverse modeling of the Mt. Pinatubo cloud using total ozone mapping spectrometer 2D mapping of Aerosol Index and SO2 loading during the first three post‐eruption days to estimate the time‐dependent emissions profiles and initial 3D spatial distributions of volcanic ash and SO2. We account for aerosol radiative feedback and dynamic lofting of volcanic ash in the inversion calculations for the first time. This resulted in a lower ash injection height (by 1.5 km for ash) than without ash radiative feedback. The Pinatubo eruption ejected ≈77% of fine ash at 12–23 km, ≈65% of SO2 at 18–25 km. In contrast with previous studies, which suggested that all volcanic materials were emitted above the tropopause, a significant fraction of SO2 (5.1 of 15.5 Mt) and fine ash (37.2 of 66.5 Mt) were ejected in the troposphere, where SO2 quickly oxidized into sulfate aerosol that is short‐lived in the troposphere. This explains the early presence of sulfate aerosols in the plume and why the models can reproduce the observed volcanic aerosols' optical depth (AOD), assuming lower‐than‐observed SO2 emission in the stratosphere. Despite the quicker than in observations build‐up of sulfate AOD, in a month after the eruption, the evolution of the Pinatubo AOD simulated using the obtained ash and SO2 initial distributions converges with the available stratospheric aerosol and gas experiment observations.

Dating volcanic materials through biochronostratigraphic methods applied to hosting strata (example from the Iberian Chain, eastern Spain)

Volcaniclastic accumulations in shallow marine environments are prone to be eroded and transported by sedimentary agents and then resedimented either on contemporaneous or younger substrates. Therefore, dating of the volcanic events through the sediments containing interbedded volcanic layers can lead to errors. A case study of volcanism in the southeastern Iberian Range during the Early and Middle Jurassic is presented. Precise dating of hosting carbonate sediments based on ammonite and brachiopod biochronostratigraphic method has allowed distinguishing 13 volcanic levels of different ages ranging from the early Pliensbachian to the early Bajocian. A set of petrological, geomorphological, sedimentological, and paleontological criteria are applied in order to discriminate primary from secondary (epiclastic) volcaniclastic deposits and thus make it possible to match the ages of primary volcaniclastic deposits with volcanic eruptions. Implementation of such criteria has confirmed that the early Pliensbachian–early Bajocian interval (ca. 20 Ma) corresponds with the actual period of volcanic activity.

Gyttja as a Soil Conditioner: Changes in Some Properties of Agricultural Soils Formed on Different Parent Materials

Organic matter is essential in improving the physical, chemical and biological properties of soils. Thus, the organic matter is widely considered a crucial indicator of environmental quality and biodiversity. In this study, the effect of gyttja addition as a soil conditioner on some physical and chemical properties of soils formed on volcanic and serpentine parent materials was investigated. The layout of the incubation study was randomized plots with 3 replications and the study lasted for 8 months to determine the value of gyttja in improving soil quality in two different parent materials. The results showed that pH, EC, total CaCO3, soil organic matter (SOM), wet aggregate stability (WSA), structural stability index (SSI), Ca-ex, Mg-ex, Fe-ex and P-av values of volcanic soils were significantly increased with increasing gyttja addition rates, while dispersion ratio (DR), Cu-ex and Cd-ex values were decreased. Likewise, pH, total CaCO3, SOM, WSA, SSI, Ca-ex and P-av values of serpentine soils were increased with increasing gyttja rates, while DR, Mg-ex, Fe-ex, Cd-ex, Ni-ex, Mn-ex, Cu-ex and Zn-ex values were decreased. The changes in the values of soil properties were statistically significant. The results demonstrated that gyttja addition overall decreased the erosion susceptibility and heavy metal contents of serpentine and volcanic soils. Moreover, the gyttja addition ameliorated some of the chemical soil properties. Therefore, gyttja could be suggested as a soil conditioner in the remediation of problematic soils.

Changes of Soil Chemistry Characteristics of Tephra Mount Anak Krakatau-Indonesia, Through Leaching Experiment

Studying the weathering process in pristine volcanic materials is crucial as this process will determine further soil characteristics. Mount Anak Krakatau is reported as one of the fastest-growing volcanoes. This volcano erupted powerfully in December 2018, ejecting tons of volcanic materials. These materials are considered pristine and unweathered tephra. Hence, a leaching experiment can be one of the crucial methods to predict further soil characteristics formed as climatic factors. Tephra sampling was conducted on 13 Augustus 2019 or eight months after the massive eruption of Mount Anak Krakatau in December 2018. Tephra samples were leached by deionized water (H2O), oxalic acid (H2C2O4) 0.02 M, and citric acid (C6H8O7) 0.02 M (solvents) for 90 days. pH of tephra increased approximately from (3.95– 4.99 ) to (5.12–8.11). Organic-C rose about 0.2 to 1 point higher than organic-C of tephra before the leaching experiment. The increasing value of organic-C was predicted to increase CEC (Cation Exchange Capacity) (2.13–5.36 cmolc kg-1). After the leaching experiment, the tephra’s surface was weathered clearly as an impact of solvents and the growing of algae.

Testing the volcanic material burying Pompeii as pozzolanic component for compatible conservation mortars

The aim of this work is to evaluate the potential use of ashes and lapilli that buried Pompeii as pozzolanic material for the formulation of conservation mortars. XRD analyses proved that the mineralogical composition of these volcanic products is consistent with the original pozzolanic mortars preserved at the archaeological site. A first set of pozzolanic mortars were prepared by using silica sand as aggregate. After curing the lapilli-based mortars, the measured compressive and flexural strengths proved to be higher than those of the control samples made of commercial pozzolan. A second set of samples, prepared by replacing silica sand with similar size coarse ash and lapilli, proved that volcanic aggregates further enhanced the mechanical properties by the formation of interfacial transition zones. The result of this research demonstrates that the volcanic material burying the archaeological site of Pompeii could be used as raw material in the formulation of compatible conservation mortars. As volcanic pozzolan is increasingly investigated as potential Supplementary Cementitious Material (SCM) for the production of sustainable concretes, preliminary considerations about the impact of the present work to this field of research are also provided.

Geotechnical aspects of drilling and excavation of volcanic terrain for groundwater exploitation

Heterogeneity of volcanic materials that constitute the Canary Islands (Spain) means that mining work in water galleries excavated on these islands, drilling into the terrain for many kilometres, is very challenging. They are composed of materials that vary significantly in terms of cohesion, ranging from very consolidated to loose and highly unstable. Water galleries have been key in the development of the Canary Islands, in order to obtain drinking water from the aquifer. Generally, aquifers are located in mountainous areas with difficult access, which complicates the drilling work. This article analyses the main geotechnical problems encountered in the construction of subterranean water galleries in the Canary Islands, as well as possible solutions to these problems, so that these can be applied to similar territories. As a general conclusion, the instabilities inherent in volcanic materials affect this type of work, and it is necessary to take specific measures for each type of geotechnical risk, as proposed in this article.

Dual use of pumice in lime mortars

The use of natural pumice as pozzolanic materials in lime mortars has been known since ancient times. Current professional works are more concerned with the effects of coarse natural pumice used as an aggregate in cement mortars or self-compacting concrete, than with replacing the binder with ground pumice. The use of a combination of finely ground natural pumice as a binder substitute and at the same time the lightening of lime or cement mortars with coarse natural pumice has not yet been the subject of any research. For this reason, the aim of this paper is to describe the effects of the partial replacement of lime with finely ground natural pumice on the mechanical, microstructural and durability properties of air-lime mortars lightweight with coarse natural pumice, which meet the functional and technical criteria imposed on repair mortars. Pumice is lightweight amorphous volcanic material with porous structure created by entrapment of gasses during the rapid cooling of lava. It shows similar pozzolanic activity to trass or natural zeolite predicting an improvement in mechanical properties and durability of lime-pumice mortars. The fine pumice addition to lime mortars led to decrease in amount of kneading water required for the preparation of the mortars with the same workability. The use of lightweight pumice aggregate in the composition of mortars led to their higher porosity, lower density, improved capillary transmission capability and water absorption, and increased salt crystallization resistance, while the replacement of lime with fine pumice resulted in an increase in the strengths and frost resistance of the prepared mortars. The resistance of the mortars to the salt crystallization of NH4NO3, Na2SO4, and NaCl was improved, although the mortars had relatively low resistance to the reaction of NH4NO3 and Na2SO4, where nitrocalcite, cesanite, and calcium sulfoaluminates were formed, breaking the structure of the mortars. Considering the compatibility, functional and technical criteria, lime-pumice lightweight mortars could be classified as repair mortars.

Early Evolution of the Stratospheric Aerosol Plume Following the 2022 Hunga Tonga‐Hunga Ha'apai Eruption: Lidar Observations From Reunion (21°S, 55°E)

AbstractThe exceptionally violent eruption of the Hunga Tonga‐Hunga Ha'apai volcano (HTHH) of 15 January 2022, in the South Pacific, was associated with a powerful blast that injected gases, steam and aerosol to unprecedentedly high altitudes. This article details unique observations of the young volcanic plume from ground‐based lidars at Reunion (21°S, 55°E). Two lidars, operating at wavelengths of 355 and 532 nm, recorded the plume overhead from 19 January until 28 January providing the vertical structure and the optical properties of the plume. A series of thick stratospheric plumes between 36 and 18 km altitude have been characterized along time, with aerosol optical depth as high as 0.84 at 532 nm and negative Angström exponents for the main layers down to −0.8 ± 0.8. The diversity of plumes properties is explained by the injection heights of the volcanic material as well as stratospheric dynamics and chemistry.

High variability of interaction energy between volcanic particles: implications for deposit stability

Landslides on the flanks of stratovolcanoes can significantly modify the structure of the volcano. Macroscopic factors that determine the stability of volcanic deposits are well understood, but the microscopic interactions between particles and their impact on deposit cohesion remain poorly understood. Deposit cohesion is related to the energy of interaction between particles, and its calculation depends on the surficial properties of the eruptive materials. The purpose of this study was to perform a preliminary comparative analysis of the surficial properties of volcanic materials from various tectonic settings, including electrical (zeta potential) and thermodynamic (surface free energy) components and to calculate the total interaction energy between particles under different environmental conditions. We analyzed samples of eruptive materials obtained from volcanic flows characteristic of six active volcanoes (El Hierro, Pico Do Fogo, Vulcano, Stromboli, Mt. Etna, and Deception Island). The results show that deposit cohesion varies among volcanoes and changes drastically with the pH of the medium. Among the volcanic systems investigated, El Hierro (pH = 3) has the most cohesive materials, while Mt. Etna (pH = 8) has the least cohesive materials. Our results suggest that microscopic electrical and thermodynamic properties play a role in the stability of volcanic deposits, and confirm the need for a greater research focus in this area.

Characterization of Volcano-Sedimentary Rocks and Related Scraps for Design of Sustainable Materials.

This work started as a joint academia and company research project with the aim of finding new applications for domestically sourced volcanic products and related waste (pumice, lapillus, zeolitic tuff and volcanic debris from Tessennano and Arlena quarry) by creating a database of secondary volcanic raw materials and their intrinsic characteristics to help industry replace virgin materials and enhance circularity. In this context, accurate chemical, mineralogical, morphological, granulometric and thermal characterizations were performed. Based on the results presented, it can be concluded that due to their lightness, these materials can be used in the design and preparation of lightweight aggregates for agronomic purposes or in the construction field. Furthermore, due to their aluminosilicate nature and amorphous fraction, pumice and lapillus can play the role of precursor or activator for geopolymer preparation. With its porous nature, zeolitic tuff can be exploited for flue gas treatment. Due to the presence of feldspathic phase (sanidine), these materials can be used in tile production as a fluxing component, and with their pozzolanic activity and calcium content, they have application in the binder field as supplementary cementitious material or as aggregates.

Volcanic Soils: Their Characteristics, Management Practices, and Potential Sollution for Water Pollution

Volcanic soils are formed from materials originating from volcanic eruptions, and with various pedogenic processes occurring, volcanic soils have unique physical, chemical, and biological characteristics. This paper aims to review the characteristics of volcanic soils, constraints, management practices, and their potential as adsorbents for contaminants. The paper was based on secondary information using a systematic review. The studies carried out include identifying manuscripts, analyzing report data, critically assessing the topic, and combining the results of relevant published manuscripts. The issues raised include data on volcanic soils, management practices, water pollution, and using volcanic soils as an environmentally friendly adsorbent. Colloidal compounds in the clay fraction of volcanic soils generally contain active Al and Fe compounds, allophane, imogolite, ferrihydrite, or Al/Fe-humus complex, and together with opaline silica. The volcanic soil material produces a pool of Al and Fe solid phases with high reactivity, which contributes to the unique physicochemical properties of Andisol. The main problem chemically is the high adsorption of phosphate and nitrate ions which causes the fertilization process to be inefficient. The main problem affects the adsorption of phosphate and nitrate on agricultural lands, so fertilization becomes inefficient. However, the high reactivity of volcanic soils can be used as a basic pollutant adsorbent. This is quite a promising opportunity, given the wide distribution of volcanic soils, so this resource is a very prospective candidate as an adsorbent material in water purification.

Differential response of chlorophyll-a concentrations to explosive volcanism in the western South Pacific

When it is deposited in the ocean, volcanic ash has the potential to release iron and other nutrients into surface water to stimulate ocean productivity. In the western South Pacific Ocean (SPO), one of the most important volcanic ash deposition regions, occasional widespread transport of volcanic ash may supply the nutrients not only locally around source islands but also within the wider the western SPO, accompanied by phytoplankton response. Through a comparative analysis of satellite and reanalysis data for the past 19 years (2004–2022), this study reveals that four explosive volcanic eruptions, Rabaul volcano, Papua New Guinea (October, 2006), Ambae volcano, Vanuatu (July, 2018), Ulawun volcano, Papua New Guinea (June, 2019), and Hunga volcano, Tonga (January, 2022), had the most strong stratospheric injection (>15 km) and mass loading of volcanic materials over the wider the western SPO (covering an area of >765,000 km2). The transport of 2006, 2018, 2019 volcanic emissions, was not likely associated with significant ash deposition over the western SPO. However, the Hunga eruption led to the deposition of ash-laden volcanic plumes over a wide area (~2,000 km from source), and was followed by the increase in chlorophyll-a concentrations (Chl-a) in the region (~70% increase). Minor changes related to other nutrient sources (e.g., hydrothermal input) suggest a link between the increase in Chl-a and 2022 Hunga ash falls over the western SPO. Our results indicate that volcanic ash deposition has implications for phytoplankton productivity in the western SPO, and highlights the need for further research into understanding how nutrient supply alleviated limitations of phytoplankton at the community level.

The ephemeral fumarolic mineralization of the 2021 Tajogaite volcanic eruption (La Palma, Canary Islands, Spain)

The present work aims to characterize the ephemeral mineral assemblage related to the fumarolic fields of the Tajogaite volcano, formed in 2021 in La Palma Island (Canary Islands, Spain). A set of 73 samples was obtained after two sampling campaigns in different fumarole sectors of the studied area. Mineralization related to these fumaroles formed efflorescent patches located at variable distance from the main volcanic craters. Distal patches are predominantly whitish, while in the vicinities they typically show yellowish to orange colours. Field observations also revealed that fumaroles usually occur in elevated topographic areas as well as over fractured and porous volcanic pyroclastic materials. The mineralogical and textural characterisation of the Tajogaite fumaroles unfolds a complex mineral assemblage, comprising cryptocrystalline phases related to low (< 200 °C) and medium temperature (200–400 °C) conditions. In Tajogaite, we propose a classification of three different fumarolic mineralization types: (1) fluorides and chlorides located in proximal fumarolic areas (~ 300–180 °C); (2) native sulphur associated with gypsum, mascagnite and salammoniac (~ 120–100 °C) and (3) sulphates and alkaline carbonates typically occurred in distal fumarolic areas (< 100 °C). Finally, we present a schematic model of the formation of Tajogaite fumarolic mineralization and their compositional evolution developed during the cooling of the volcanic system.

Potential Use of Scoria as a Cementitious Material for Green Concrete Production

The demand for cement, which is one of the key components of concrete, is high in Ethiopia, but it is the most expensive and environmentally unfriendly construction material. Due to the increasing concerns about the environment worldwide, researchers have started looking for other resources that can be used to reduce the pollution caused by the cement industry. One of the most effective ways to reduce the pollution caused by the cement industry is by using volcanic scoria powder as a partial replacement for cement in concrete production. Scoria is a locally available natural volcanic material in Ethiopia, especially around the rift valley regions. This natural resource can also be used to reduce energy consumption and the cost of production of cement. To investigate this study, nonprobability sampling techniques were adopted to collect samples from the study area. A differing proportion of scoria powder was considered as a partial replacement of cement after analyzing its characteristics, and its effect on the fresh and mechanical properties of hardened concrete was examined. The test results on the characteristics of scoria revealed that the material is suitable to be used as a supplementary cementitious material in concrete production; hence, its main constituents SiO2 + Al2O3 + Fe2O3 are higher than 70% as per ASTM C618. As the content of scoria powder replacement in cement is increased, it reduces the slump of freshly mixed concrete properties. The hardened concrete specimens made with 10%, 20%, and 30% partial replacement of cement with scoria achieved the specified minimum strength after 28 days of curing time. But concrete specimens made with 40% scoria content do not satisfy the minimum specified concrete strength even after 90 days. The significant strength achievement in scoria blended concrete specimens occurred when moving from 56 to 90 days of curing with 10% replacements. However, in reference specimens, this was observed during 28 days of curing times. The findings of this investigation revealed that scoria powder could replace cement by 30% for the production of normal concrete and it also has the potential to protect the environment from carbon dioxide emissions. These findings satisfy the basic strategy of green concrete production in worldwide.

Control of micro-wettability of pore-throat on shale oil occurrence: A case study of laminated shale of Permian Lucaogou Formation in Jimusar Sag, Junggar Basin, NW China

The control of micro-wettability of pore-throat on shale oil occurrence in different types of reservoir spaces remains unclear. Take the shale oil reservoir of the Permian Lucaogou Formation in the Jimusar Sag, Junggar Basin as an example, the reservoir space in laminated shale and the control of micro-wettability of pore-throat on shale oil occurrence were studied by using scanning electron microscope (SEM), multi-stage pyrolysis, quantitative fluorescence, nuclear magnetic resonance (NMR) and other techniques. The results show that there are mainly two types of laminated shale in the Lucaogou Formation, namely laminated shale rich in volcanic materials + terrigenous felsic, and laminated shale rich in volcanic materials + carbonate. The former type contains feldspar dissolution pores and intergranular pores, mainly with felsic mineral components around the pore-throats, which are water-wet and control the free shale oil. The latter type contains carbonate intercrystalline pores and organic pores, mainly with oil-wet mineral components around the pore-throats, which control the adsorbed shale oil. The oil-wet mineral components around the pore-throats are conducive to oil accumulation, but reduce the proportion of free oil. In the Lucaogou Formation, free oil, with high maturity and light quality, mainly occurs in the laminated shale rich in volcanic materials + terrigenous felsic.

Quaternary Magnetic Stratigraphy of Deep‐Sea Sediments in the Western North Pacific: Influences of Paleomagnetic Recording Efficiency and Lock‐In Delay

AbstractUnderstanding past environmental changes in the western North Pacific is rather limited due to the general paucity of robust chronology for carbonate‐lacking pelagic clay sediments. Here, we present a new magnetostratigraphy of Quaternary deep‐sea sediments in the northern Mariana Basin. A comprehensive set of paleomagnetic, rock magnetic, and microscopic results reveal that paleomagnetic signals are mainly carried by detrital magnetic minerals of Asian eolian dust and volcanic origins. The volcanic materials, most likely from the Mariana Arc, are characterized by low coercivity (∼30 mT) interacting single domain (SD) and pseudo‐SD grains, associated with abundant dendritic magnetic crystals/inclusions. This volcanic component is a suitable remanence carrier but is less efficient in recording geomagnetic intensity than the higher coercivity eolian component. The relative paleointensity record derived with minimum rock magnetic artifacts shows comparable patterns with global templates. At the Matuyama‐Brunhes transition, a ∼2‐cm remanence lock‐in depth offset is identified from beryllium isotope records, and the estimated magnetostratigraphic age delay is small (∼8 kyr). Our results provide an improved understanding of remanence recording processes in carbonate‐poor deep‐sea clays and demonstrate magnetic stratigraphy as a valuable chronology in the western North Pacific region.

Physical Properties of the Canary Islands’ Volcanic Pyroclastic Materials as Horticultural Substrates

In the Canary Islands and in other parts of the world where it can be found in its natural state, basaltic tephra, or “Picón” as it is known locally, is commonly used as a soilless substrate for crops. The aim of this study is to learn more about the physical properties of the Canary Islands’ tuff, and to find a simple method to predict the hydraulic behaviour of these substrates due to their heterogeneity. To accomplish this, 32 tuff samples were collected from all the quarries on the island of Tenerife (Canary Islands) that were authorised for the study. The tuffs had hydraulic properties that were highly influenced by the particle size. Coarse tuffs had an aeration capacity greater than 35% v/v and easily available water of less than 5% (v/v), while fine tuffs had aeration capacities below 20% v/v and elevated water retention (20 to 26% v/v). The intermediate tuffs had characteristics that varied between those of the two previous groups. Particle size fractions of less than 1 mm demonstrated the best correlation to common air:water ratios and present the best predictive capacity to relations involving air. By focusing on air:water ratios and the previous assumption, an attempt was made to predict the suitability of new pyroclastic material samples emitted by the La Palma Volcano as growing substrates for vegetables.

Mozahem stratovolcano and its structural controlling factors in the Cenozoic magmatic arc of Iran

The location of volcanoes in magmatic arcs associated with subduction zones often follows the structures present at the time of magma formation in these zones. The Mozahem stratovolcano, which has been caused by the subduction of the oceanic crust of Neotethys under Central Iran, is one of the Neogene volcanoes located in the southeast of the Urumieh-Dokhtar magmatic arc. The magmatic nature of the rocks forming the volcano is potassium-rich calc-alkaline. In this research, we used petrology, satellite images, and aeromagnetic data to understand the relationship between tectonics and magmatism. Mozahem stratovolcano area is limited to the NW-SE-trending Rafsanjan and Shahr-e-Babak fault zones and cut by the N–S-trending Anar fault. During the Neogene, the activity of the dextral Anar fault, especially in its southern termination areas, has caused changes in the local stress field and created deformations in different parts of this region. The displacement of blocks on both sides of the Anar fault has led to the development of compressive structures (folds and thrusts) at the eastern and tensile structures (dikes and subvolcanic masses) at its western half. The location of minor faults in the southern tip of the Anar fault and different mechanisms on both the eastern and western sides of the fault are comparable with the model of synthetic and antithetic splay faults at the tip. At the confluence of the Anar fault, NE-SW-trending Madvar-Riseh fault, and the NW-SE-trending Mozahem fault, lava, and pyroclastic volcanic materials erupted and the stratovolcano was formed. A tectonic evolution model was prepared to show how the area and the stratovolcano were formed and evolved.

Chemolithotrophic biosynthesis of organic carbon associated with volcanic ash in the Mariana Trough, Pacific Ocean

Volcanic ash is a major component of marine sediment, but its effect on the deep-sea carbon cycle remains enigmatic. Here, we analyzed mineralogical compositions and glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in submarine tuffs from the Mariana Trough, demonstrating a fraction of organic carbon associated with volcanic ash is produced in situ. This likely derives from chemolithotrophic communities supported by alteration of volcanic material. Tuff GDGTs are characterized by enrichment of branched GDGTs, as in chemolithotrophic communities. Scanning electron microscope, Raman spectrum and nano secondary ion mass spectrometry analysis demonstrates organic carbon exists around secondary heamatite veins in the altered mafic minerals, linking mineral alteration to chemolithotrophic biosynthesis. We estimate organic carbon production of between 0.7 − 3.7 × 1011 g if all the chemical energy produced by ash alteration was fully utilized by microorganisms. Therefore, the chemolithotrophic ecosystem maintained by ash alteration likely contributes considerably to organic carbon production in the seafloor.

Emplacement history of volcaniclastic turbidites around the central Azores volcanic islands: Frequencies of slope landslides and eruptions

Volcanic islands export clastic material to their surrounding oceans by explosive eruptions, lava emissions, biogenic production on their shelves, and failure of their slopes, amongst other processes. This raises the question of whether geological events (in particular, eruptions and landslides) can be detected offshore and dated, and whether any relationships (for example, with climate changes) can be revealed using sediment cores. The volcanically active central Azorean islands (Faial, Pico, São Jorge, and Terceira), with their neighboring submarine basins, are potentially good candidates for such an analysis. Here, chronostratigraphies of four gravity cores collected amongst the islands are constructed based on twelve radiocarbon dates and two dates derived by geochemically correlating primary volcaniclastic turbidites with ignimbrites on Faial and Terceira Islands. Age-depth models are built from the hemipelagic intervals to estimate individual turbidite dates. Volumes of turbidites are modeled by multiplying basin areas with bed thickness, allowing for various turbidite thinning rates and directions. The volumes of landslide-generated turbidites are only comparable with the largest volumes of their adjacent upper-slope submarine landslide valleys; therefore, such turbidites in the cores likely derive from these largest landslides. Emplacement intervals between turbidites originating from both landslides and pyroclastic density currents are found to be mostly a few thousand years. Frequencies of landslide-generated turbidites and hemipelagic sedimentation rates were both highest in the past 8 k.y. compared to preceding periods up to 50 k.y. High hemipelagic sedimentation rates are interpreted to be related to sea-level rise, allowing more shelf bioproduction and release of particles by coastal erosion. The coincident increased frequencies of submarine landslides may also be associated with the increased sediment supply from the islands, resulting in a more rapid build-up of unstable sediments on submarine slopes. Notably, the emplacement frequencies of turbidites of pyroclastic density current origins do not suggest the decreased eruption frequency toward the Holocene that has been found elsewhere.