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Introduction
My research interests have been focused on the submarine morphology of ocean island volcanoes to understand how the interplay between volcanism, erosion, tectonics, sedimentation and mass-wasting processes shape the submarine landscape of these islands.
Additional affiliations
January 2013 - January 2016
Education
May 2003 - December 2007
Publications
Publications (113)
Shelves surrounding reefless volcanic islands usually host sediment that is considered to result mostly from erosion of pre‐existing volcanic rocks, with minor contributions from active volcanism and biogenic production. However, due to the scarcity of studies on volcanic islands, the way in which sediment is produced and deposited in these setting...
Esta investigación se centra en la evolución de una playa de bloques en una barrera a lo largo de un lagoon en la isla de São Jorge. Las islas Azores están expuestas a condiciones de alta energía de oleaje. La respuesta geomorfológica de este sector ha llevado al desarrollo de un programa de seguimiento para evaluar las variaciones morfológicas a c...
Motivation The objective of this study, conducted in Tavira, Portugal, is to demonstrate the capability to determine depths in shallow water regions without depending on in-situ data, particularly in areas where acquiring acoustic data is cost-prohibitive in coastal monitoring programs. A model previously trained with depth data and multispectral i...
Motivation This study was conducted in a region where the acquisition and updating of bathymetry are quite expensive through conventional methods, leading to the lack of knowledge about more than 50% of the seafloor morphology in these coastal areas. In recent decades, the scientific community has developed algorithms capable of determining depth f...
The aim of this study conducted in Tavira-Portugal, is to show the ability to determine depths without relying on in-situ data. To achieve this goal, a model previously trained with depth data and multispectral images from 2018 was used. This model enables depth determination for any period, providing multispectral images. For this study, Cube sate...
In a recent review article, Lima & Meneses (2023, Geoconservation Research, 6 (1): 114-127) reported on the Azores Geopark, introducing a new geosite for São Miguel Island. We here express our concerns regarding the data presented in this review article. In our commentary, we focus mainly on the use of out-of-date bibliographic sources and inaccura...
Este estudo foi realizado numa região onde a aquisição e atualização da batimetria é bastante dispendiosa por meio de métodos convencionais, levando ao desconhecimento de mais de 50% da morfologia do fundo marinho nas áreas costeiras. Nas últimas décadas, a comunidade científica tem desenvolvido algoritmos capazes de determinar a profundidade atrav...
Neste estudo, realizado em Tavira, pretende-se divulgar a capacidade de determinar a profundidade sem recorrer a dados in-situ. Para atingir este objetivo foi usado um modelo treinado previamente com dados de profundidade e imagens multiespectrais referentes ao ano de 2018. Este modelo permite determinar a profundidade para qualquer época, desde qu...
PETROGRAPHY AND PROVENANCE OF SANTA MARIA ISLAND SHELF SAND, AZORES
In last years, machine learning (ML) algorithms have been used in satellite derived bathymetry (SDB) with great success. However, we can use distinct parameters for building a new model, using the same ML algorithm, implying distinct results. In this study, we used the Random Forest (RF) algorithm for depth determination combining cube satellite im...
https://conf.goldschmidt.info/goldschmidt/2023/meetingapp.cgi/Paper/20264
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 r...
O turismo subaquático em Santa Maria é uma das vertentes do turismo de Natureza sustentável com maior sucesso nesta ilha do Arquipélago dos Açores. Lugares como a “Baixa do Ambrósio” e as suas jamantas (entre outros grandes pelágicos), a “Pedrinha” e os peixes e grandes “leques” bivalves da espécie Pinna rudis (Linnaeus, 1758) que aí se avistam, ou...
Knowledge of how carbonates are produced on shelves is needed for working out how these “carbonate factories” generate stratigraphy by providing particles for potential export or local deposition. Production rates can be derived straightforwardly in low-energy environments from one-dimensional analysis (age–depth variations) but rates are less easi...
Rhodoliths occur extensively around the shores of Fuerteventura Island in the Canary Archipelago, with Lithothamnion cf. corallioides being the most prominent species. A large number of rhodoliths end up washed onshore, the debris from which contributes to the formation of sediments constituting modern beaches. In a previous study by one of the co-...
Corrigendum to: Wave-influenced deposition of carbonate-rich sediment on the insular shelf of Santa Maria Island, Azores. Sedimentology, 69: 1547-1572.
ÁVILA S.P., R.S. RAMALHO, C.M. DA SILVA, M.E. JOHNSON, A. UCHMAN, B. BERNING, R. QUARTAU, P. MADEIRA, C.S. MELO, A.C. REBELO, L. BAPTISTA, S. ARRUDA, E. GONZÁLEZ, M.W. RASSER, A. HIPÓLITO, R. CORDEIRO, R. MEIRELES, V. RAPOSO, J. POMBO, R. CÂMARA, M.X. KIRBY, J. TITSCHACK, J.M. HABERMANN, R. VULLO, A. KROH, J.H. LIPPS, M. CACHÃO & J. MADEIRA, 2022....
Formulae for sediment thresholds of motion are commonly based on flume experiments on rounded quartz particles and it is unclear how well they predict thresholds in natural settings. Here, sediment threshold shear stresses were calculated from one such formula using surface grain-size data from 112 sites around Santa Maria Island. To compare with t...
This work discusses the results from the analysis of two marine cores from the Northwest (K20) and Southeast (K22) of the Faial Island shelf in the Azores. K20 is composed mostly by terrigenous sediments (fewer bioclastic particles) and a predominance of coarse to medium sands. K22 shows more bioclasts (29-49 %) than K20 (2-4 %), and the predominan...
Sediment waves are common on the submarine flanks of volcanic islands, but the processes that form them are difficult to decipher from geophysical data alone. Here, we identify downslope-trending trains of sediment waves in multibeam sonar data from five islands of the Azores. Train abundances are derived by counting the train intersections with de...
Mass-wasting events are a key process in the evolution of volcanic ocean islands. They occur at various dimensional scales and present a major source of hazard. When the collapsed material plunges into the sea, destructive tsunamis can be generated. Yet, the hazard potential of collapse-induced tsunamis is still poorly understood with different opi...
Shelves surrounding volcanic islands represent only a small portion of the entire submarine edifice that can extend to a few thousand meters below sea level. Despite their small areas, shelves show a significant morphologic imprint made by the erosional, depositional, tectonic and volcanic processes when compared to those left on slopes or the subm...
The deep-water sedimentary processes and morphological features offshore Madeira Island, located in the Central-NE Atlantic have been scantly studied. The analysis of new multibeam bathymetry, echo-sounder profiles and few multichannel seismic reflection profiles allowed us to identify the main geomorphologies, geomorphic processes and their interp...
Small landslides in the upper submarine slopes of volcanic islands present potential hazards locally because of their high frequency. We examine evidence for landsliding in high-resolution bathymetric data from Faial, Pico, São Jorge, and Terceira islands of the Azores. Because the rugged morphology of the upper slopes makes landslides difficult to...
Located on the northern coast of Santa Maria Island (Azores Archipelago, central North Atlantic), the Lagoinhas section preserves a carbonate buildup correlated with Marine Isotope Substage (MIS) 5e, the warmest interval of the Last Interglacial. The buildup is formed mainly by crustose coralline algae (CCA) identified as Spongites sp., and some su...
More than 50% of the seafloor in coastal areas is uncharted or outdated; this occurs due to the inefficiency of echo sounder systems in surveying waters shallower than 10 m, implying that, usually, only the routes of maritime traffic at these depths are surveyed in order to guarantee safety of navigation. Nevertheless, in this region occur the main...
O Programa SEDMAR (Mapeamento dos Sedimentos Marinhos), em execução no IH, sucessor do Programa SEPLAT (Cartografia dos Depósitos Sedimentares da Plataforma Continental), assenta numa abordagem multidisciplinar e tem por objetivo contribuir para o conhecimento e defesa do ambiente marinho, no continente e nas regiões autónomas da Madeira e dos Açor...
Rates of coastal erosion are needed for planning purposes and to improve understanding of how the shelves of islands develop, ultimately becoming submerged banks. Near-shore submarine platforms created by erosion of lava deltas of known age provide an opportunity to quantify erosion rates, and to investigate how those rates vary between different t...
Sedimentary rocks are rarely preserved on reefless volcanic oceanic islands, because they are mostly exported from coastal areas towards the abyssal plains and such islands typically undergo subsidence. In contrast, the exceptional geological record of the uplifted Santa Maria Island (Azores) provides a unique opportunity to gain insight on such ro...
Ongoing work shows that species richness patterns on volcanic oceanic islands are shaped by surface area changes driven by longer time scale (>1 ka) geological processes and natural sea level fluctuations. A key question is: what are the rates and magnitudes of the forces driving spatial changes on volcanic oceanic islands which in turn affect evol...
A comparative analysis of bedform fields along the submarine flanks of insular volcanoes, characterized by different morpho‐structural settings, volcanic and meteo‐marine regimes (Vanuatu, Kermadec, Bismark, Madeira and Aeolian archipelagos), is presented here to provide insights on the size distribution, morpho‐dynamic and genesis of such bedforms...
Santa Maria Island constitutes the oldest volcanic island within the Azores Archipelago, with no onshore record of eruptions younger than ≈2.8 Ma. A recent high-resolution multibeam bathymetric survey, however, revealed the presence of a seemingly young submerged wide volcanic edifice at approximately −70/−80 m, on the northeastern sector of the is...
A volcanic cone (Capelinhos) was created in western Faial island, Azores during an eruption in 1957/58. Since then, erosion by waves and rain has steadily reduced the size of this volcanic promontory. We have used successive aerial photographs to work out how rapidly it has shrunk, leaving behind a submarine platform. Erosion was fast at first, but...
Volcanic oceanic islands are the emerged portions of large volcanoes that rise abruptly from the ocean floor. Although the geological record of these islands provide some insights into the evolution of their entire volcanic edifces, for a complete picture, it is essential to study the islands' submarine pedestals and surrounding settings. In this st...
Raised marine terraces and submerged insular shelves are used through an integrated approach as markers of relative sea level changes along the flanks of the Salina volcanic Island (Aeolian Arc, southern Italy) for the purpose of evaluating its crustal vertical deformation pattern through time. Paleo sea level positions are estimated for the terrac...
A synthetic model is presented to enlarge the evolutionary framework of the General Dynamic Model (GDM) and of the Glacial Sensitive Model (GSM) of oceanic island biogeography from the terrestrial to the marine realm. The proposed “Sea-Level Sensitive” dynamic model (SLS) of marine island biogeography integrates historical and ecological biogeograp...
Supplementary Information file from:
ÁVILA, S.P., C. MELO, N. SÁ, R. QUARTAU, K. RIJSDIJK, R.S. RAMALHO, B. BERNING, R. CORDEIRO, N.C. de SÁ, A. PIMENTEL, L. BAPTISTA, A. MEDEIROS, A. GIL & M.E. JOHNSON, 2019. Towards a “Sea-Level Sensitive Marine Island Biogeography” model: the impact of glacio-eustatic oscillations in global marine island biogeog...
Giant landslides are now well known to occur in ocean islands with a frequency globally of ∼10 ky, but small landslides occurring in the steep upper submarine slopes of islands are more common and likely more frequent, making them also a potential hazard. The central and eastern Azores Islands, which are scattered about the Africa-Europe plate boun...
Since 2005, the Portuguese margin have been intensively surveyed through multibeam echo sounders (MBES) in the framework of the claim for the extension of the Portuguese Exclusive Economic Zone (EEZ). To fulfill the claim, the surveys were concentrated in the deeper ocean region nearby the EEZ limits. With a distinct objective, in 2013, a new progr...
The Working Group on the Effects of Extraction of Marine Sediments on the Marine Eco-system (WGEXT) met in Copenhagen, Denmark, 16–19 April 2018. Twelve participants from ten ICES member countries attended the meeting. Contributions were provided by correspondence from three countries whose representative were not able to attend.
The objective of W...
Based on a multibeam derived Digital Terrain Model and 165 high-resolution seismic lines covering the insular shelf of Santa Maria Island (Azores), a seismic stratigraphic interpretation was performed and a map of the sedimentary thickness was made. Results showed that the thickest depocenters were commonly associated with structural depressions on...
Available online xxxx Editor: T.A. Mather Keywords: Volcanic Ocean Islands insular shelves shelf break subsidence modeling On reefless volcanic islands, insular shelves are thought to have formed essentially by the combined effects of wave erosion and glacio-eustatic sea-level oscillations. Subsidence, however, has also been recognized as having an...
Submerged marine terraces are relict coastal erosional landforms now underwater due to rising sea level and/or land subsidence. Using as case study the shelf around Santa Maria Island (North Atlantic Ocean), we intend to advance our knowledge on the formation and preservation of these features on reefless volcanic islands. Santa Maria is an ideal p...
Volcanic islands are the emerged portions of large edifices that rise from the seafloor up to a few kilometers. Although islands provide insights into their evolution, their study only offers a small part of the history of the submarine rise, subaerial building and erosion of the entire volcanic edifices. Therefore, the study of their submarine env...
A seabed sediment-sampling survey conducted on the Pico insular shelf found abundant rhodoliths between −64 and −73 m off the south coast of the island. These were small and mainly ellipsoidal in shape with a maximum diameter of 3.75 cm. Granules and small pebbles of eroded basalt were also a typical component of these samples. Thin algal crusts we...
Supratidal talus-platforms are low-relief subaerial accumulations of debris produced by mass wasting along high coastal cliffs, being particularly abundant at reefless volcanic islands subjected to high wave energy. Known as “fajãs” across the Portuguese-speaking Atlantic archipelagos, these coastal features on rare occasions may exhibit lagoons, c...
The submarine flanks of volcanic ocean islands are shaped by a variety of physical processes. Whilst volcanic constructional processes are relatively well understood, the gravitational, erosional and depositional processes that lead to the establishment of large submarine tributary systems are still poorly comprehended. Until recently, few studies...
The Working Group on the Effects of Extraction of Marine Sediments on the Marine Eco-system (WGEXT) met in Norwich, UK, 24–27 April 2017, chaired by Ad Stolk, the Nether-lands. Eighteen participants from ten ICES member countries attended the meeting. Contributions were provided by correspondence from Portugal, Estonia and Lithuania whose represent...
The distribution and morphological characteristics of the shelves around Salina Island have been analyzed and integrated with observations from onshore geological field studies in order to improve knowledge about its evolution, and to demonstrate how shelf width/depth can be used as proxies for reconstructing the development of the volcanic edifice...
Erosion of the coasts of volcanic islands by waves creates shallow banks, but how erosion proceeds with time to create them and how it relates to wave climate is unclear. In this study, historical and recent marine geophysical data collected around the Capelinhos promontory (western Faial Island, Azores) offer an unusual opportunity to characterize...
The growth and decay of ocean-island volcanoes are intrinsically linked to vertical movements. While the causes for subsidence are better understood, uplift mechanisms remain enigmatic. Santa Maria Island in the Azores Archipelago is an ocean-island volcano resting on top of young lithosphere, barely 480 km away from the Mid-Atlantic Ridge. Like mo...
This chapter focuses on the first quantitative study of tsunami hazard in the Azores with numerical modeling, used to investigate the biggest failure known there to date. The numerical modeling is used to simulate its mass flow toward and under the sea, and the subsequent tsunami generation and propagation. The results suggest how both the present-...
Resumo: Neste trabalho são apresentados os primeiros mosaicos de alta resolução do sinal de retrodispersão acústica normalizado usados na caraterização remota do fundo marinho, no âmbito do Programa SEDMAR. Os resultados preliminares permitiram a determinação do diâmetro médio dos sedimentos nas plataformas e flancos superiores das ilhas da Madeira...
Shelves of the Azores volcanic islands were essentially formed by surf erosion of their slopes as sea level oscillated during glacial-interglacial stages. A variety of secondary processes may have changed their primary erosional morphology, and in volcanically active islands such as Pico, volcanic progradation can dominate locally. To understand th...
Large-scale gravitational flank collapses of steep volcanic islands are hypothetically capable of triggering megatsu-namis with highly catastrophic effects. Yet, evidence for the generation and impact of collapse-triggered megatsu-namis and their high run-ups remains scarce or is highly controversial. Therefore, doubts remain on whether island flan...
Shelves from volcanic ocean islands result from the competition between two main
processes, wave erosion that forms and enlarges them and volcanic progradation that reduces their
dimension. In places where erosion dominates over volcanism, shelf width can be used as a proxy for
the relative age of the subaerial volcanic edifices and reconstruction...
Shelves surrounding reefless volcanic ocean islands are formed by surf erosion of their slopes during changing sea levels. Post-erosional lava flows, if abundant, can cross the coastal cliffs and fill partially or completely the accommodation space left by erosion. In this study, multibeam bathymetry, high-resolution seismic reflection profiles and...
Massive fossil shell accumulations require particular conditions to be formed and may provide valuable insights into the sedimentary environments favouring such concentrations. Shallow-water shell beds appear to be particularly rare on reefless volcanic oceanic islands on account of narrow, steep and highly-energetic insular shelves where the poten...
Massive fossil shell accumulations require particular conditions to be formed and may provide valuable insights into the sedimentary environments favouring such concentrations. Shallow-water shell beds appear to be particularly rare on reefless volcanic oceanic islands on account of narrow, steep and highly-energetic insular shelves where the poten...