Jorge Island Research Articles

The use of a low-cost, small-aperture array as an auxiliary tool to improve infrasound monitoring in the Azores region

AbstractThe 2022’s seismo-volcanic crisis on São Jorge Island of the Azores archipelago has provided an opportunity to deploy a portable infrasound array as a collaborative work between the Research Institute for Volcanology and Risk Assessment (IVAR) of the University of the Azores (UAc) and the University of Florence (UniFI). The four-element array, SJ1, became operational on 2 April 2022. Despite being deployed in a first stage to monitor the activities related to the volcanic unrest on São Jorge Island, SJ1 worked as a supporting tool to the existing IMS infrasound station IS42, located on Graciosa Island at ~ 40 km distance, leading to an enhancement of the infrasonic monitoring network in the region. This work emphasises the importance of low-cost portable infrasound arrays to improve the coverage of infrasound observations for local and regional monitoring purposes in the Azores region. Two events recorded by both arrays are briefly exemplified: a low-magnitude earthquake on São Jorge Island and a fireball which crossed the North Atlantic Ocean. Infrasound data from both arrays are combined to obtain a fast but still accurate source localization of the analysed events.

Checklist of Basidiomycota and New Records from the Azores Archipelago

This paper presents an annotated checklist of the Basidiomycota taxa (including lichenicolous fungi and the subdivision Pucciniomycotina) from the Azores archipelago and reviews the published records to account for their taxonomic status. The number of Basidiomycota species recorded in the Azores has increased considerably during the 20th century and now stands at 544 species. This study provides distribution data and includes changes in the nomenclature of the listed taxa. Sampling campaigns contributed to 116 new records of Basidiomycota for the Azores archipelago. In addition, there were new records for eight islands: 162 species found for the first time on São Miguel Island, 55 species new to Santa Maria Island, 33 species new to Flores Island, 15 species new to Terceira Island, 9 species new to Pico Island, 17 species new to São Jorge Island, 4 species new to Graciosa Island, and 2 species new to Corvo Island. The transformation of vegetation cover in the archipelago has been very drastic, and this is reflected in the presence of many foreign fungal species on the islands. From these data, we conclude that within Macaronesia, the diversity of Basidiomycota in the Azores is more similar to that in Madeira than in the Canary Islands.

Men Who Shout at Goats

Abstract Across many world regions, the informal slaughter of livestock occupies an important place in rural day-to-day realities. This article examines killing goats on São Jorge Island to show how attention to slaughter enhances our understanding of gendered selfhood, human–animal relations, and the impacts of depopulation. Building on ethnography of smallholder farmers who see their masculinity and livelihoods endangered by demographic decline, I argue that their idea of agrarian cultivation underwrites verbal hostility against animals. Male farmers’ concept of cultivation, here conceived as productive order-making between a threatening ‘natural’ and a desirable ‘domestic’ domain, is hence an ambivalent moral idiom. In moments of slaughter, the frustration about the difficulties of cultivation is expressed as men deriding goats to salvage a desired image of manhood and competence.

Maritime Transportation Dynamics in the Azores Region: Analyzing the Period 1998–2019

The geography over which maritime transportation operates is unique, combining physical, strategic, and commercial imperatives. Physical issues are stable across time, but strategic, especially commercial, considerations continually shift with the ebb and flow of the globalization process. Contextually, the distance that isolates different locations in many cases plays a vital function in these interactions. Distance is the primary element that affects the values of interaction intensities. In fact, the issue is how the intensities were reduced with distance since this reduction is generally not linear. In this regard, this article intends to pursue the issues of the shape and parameters of the distance–decay functions based on the travel time value between islands. In this regard, almost all the Azores Islands were used as a case study. The study results show that the distance–decay functions established the unique dominance of Faial Island, Pico Island, and São Jorge Island, all in the Azores central group; in addition, there was an increase in the number of passengers in those. Moreover, the dominant position is the central islands, and their coexistence with others in the environment makes them more accessible than other islands, showing Terceira Island as a potential maritime passengers’ hub in the Azores. So, with this study, it becomes clear which are the main accessibility issues within the Azores archipelago as well as efficiency should be promoted through the design of policies in maritime passengers’ transportation.

Breeding phenology and success of the Common Snipe Gallinago gallinago in the Azores

ABSTRACTCapsule: In comparison to other regions, the Common Snipe Gallinago gallinago in the Azores starts to display earlier and for a longer part of the year, but the laying period, although it starts earlier, does not seem to differ much from that observed elsewhere. Nesting success seems similar to that observed in other populations.Aims: This study aimed to infer the breeding phenology, characterize some basic breeding parameters, and quantify nesting success in a sedentary, and data deficient population of the Common Snipe.Methods: Counts of Common Snipe in display (2014) and searches of nests and broods (2011 and 2014) were conducted during the breeding season on São Jorge Island in the Azores. Additional data collected on São Miguel Island was also considered. Nests were monitored to assess nest survival.Results: The species was seen in display between January and August, and the laying period spanned between early March and late June. The probability of survival during the nesting period was 0.55 (n = 24; 95% – confidence limits: 0.38–0.80), and desertion was the main cause of failure.Conclusions: The best period to assess the population of Common Snipe in the Azores is during April, when the displaying activity is at its maximum. The species is very sensitive to disturbance during the nesting and rearing periods, thus managers should avoid interventions in the habitat between March and July to reduce disturbance.

A multi-methodological re-evaluation of the volcanic events during the 1580 CE and 1808 eruptions at São Jorge Island (Azores Archipelago, Portugal)

Among all eruptions that took place on the Azores Archipelago since the Portuguese settlement in the XVI century, those of 1580 and 1808 in the island of São Jorge were unusual. The magma erupted in 1580 ascended from at least 23 km and ponded at a minimum depth of 16 km. Here residual magma fractionated mafic phases and plagioclase during 228 years before erupted again in 1808. Magma emission occurred from numerous fissures active at the same time and opening for several kilometres, following a local tectonic trend. Hydro-volcanic outbursts and hot rock fall over steep slopes caused casualties and injuries, and lava flows and heavy tephra fallout affected the local economy. Despite of all these dramatic consequences, the memory of these eruptions is almost vanished. Representative geosites and morphological landforms if not hindered by lush vegetation, have been reshaped by diffuse quarries and reworked to recover croplands and pastures. Aiming at a better comprehension of the multiple hazards associated with volcanic eruptions at São Jorge Island, we retraced the volcanic events of these two eruptions by matching our re-interpretation of historic reports with field data and photogrammetry, and with fluid inclusions, petrography and geochemical data of erupted products.

Evolution of a volcanic island on the shoulder of an oceanic rift and geodynamic implications: S. Jorge Island on the Terceira Rift, Azores Triple Junction

The S. Jorge Island in the Azores lies on a peculiar setting, the southern shoulder of the Terceira Rift (TR), which raises a series of questions that we address in this study. We first established the main volcanic stratigraphy by recognizing, in the field, the main unconformities/discontinuities and their meaning (major erosion surfaces and faults), then we collected critical samples, and finally dated them by K/Ar to calibrate the stratigraphy and the age of inferred large-scale flank collapses. Based on field, geochronological and marine geophysical data: (1) we found much older rocks in S. Jorge than in previous studies (ca. 1.85 Ma), and established a new volcanic stratigraphy (from bottom to top): Old Volcanic Complex (ca. 1.9–1.2 Ma), cropping out in the eastern third of the island; Intermediate Volcanic Complex (ca. 0.8–0.2 Ma), cropping out in the western two thirds of the island and separated from the underlying complex by a major fault; Young Volcanic Complex (<ca. 0.1 Ma), unconformable on both older units. (2) We discuss the most probable mode of destruction of the successive volcanic complexes, and we conclude that a major landslide occurred between ca. 1.2 and 0.8 Ma, which was responsible for the major lateral discontinuity between the Old and the Intermediate Volcanic complexes. (3) We use previous palaeomagnetic data and new seismic data to evaluate the effects of uplift of the TR's southern shoulder on S. Jorge Island, and conclude that south-westward tilting of the oldest lava flows occurred between ca. 1.2 and 0.8 Ma due to rotation of the TR's southern shoulder during uplift. (4) Finally, we used all data to constrain the age of TR initiation to be ca. 1 Ma in this sector of the TR.

Origin of the term nuées ardentes and the 1580 and 1808 eruptions on São Jorge Island, Azores

In this paper we: provide a brief account of the 1580 and 1808 eruptions on São Jorge in the Azores, which produced Pyroclastic Density Currents (PDCs); discuss the first recorded use of the term nuées ardentes to describe these PDCs; trace how this term was introduced into the scientific literature and discuss its adoption by Alfred Lacroix (1863–1948) to describe the ‘glowing clouds’ produced by Mt. Pelée (Martinique) in 1902. The 1580 and 1808 eruptions on São Jorge are important because they provide early descriptions of PDCs. Documentary evidence of the eruptions and their impacts suggest that the 1580 PDC was a hotter flow, whereas the 1808 PDCs were cooler and more moist. Contemporary accounts describe the 1580 PDC as a ‘globe of fire’, mixed with ‘caustic smoke’ and moving at speed towards the bottom of the slope. In contrast, the 1808 PDCs comprised humid ash, were not incandescent and it is likely that the flows were cooler than that produced in 1580. Since the eruption of Mt. Pelée in 1902, it has been widely accepted that the term nuées ardentes was introduced by Lacroix (1904), being based on his description of the pyroclastic flows that he witnessed. Lacroix acknowledges that the Portuguese expression, nuvem ardente was first used in contemporary accounts of the São Jorge PDCs. This was first translated as nuée ardente and introduced into the scientific by the French geologist Ferdinand Fouqué (1828–1904), who was also Lacroix's father-in-law. Indeed, Lacroix provides an account of the 1580 and 1808 eruptions of São Jorge in his 1904 work La Montagne Pelée et ses Éruptions. The seminal work of Frank Alvord Perret (1867–1943) on the 1929–32 eruptions of Mt. Pelée and his description of nuées ardentes probably helped reinforce the association between the term and Mt. Pelée.

Azorean wild rabbits as reservoirs of antimicrobial resistant Escherichia coli

Antibiotic resistance in bacteria is an increasing problem that is not only constrained to the clinical setting but also to other environments that can lodge antibiotic resistant bacteria and therefore they may serve as reservoirs of genetic determinants of antibiotic resistance. One hundred and thirty-six faecal samples from European wild rabbits (Oryctolagus cuniculus algirus) were collected on São Jorge Island in Azores Archipelago, and analysed for Escherichia coli isolates. Seventy-seven isolates (56.6%) were recovered and studied for antimicrobial resistance, one isolate per positive sample. Thirteen (16.9%), 19 (24.7%), 25 (32.4%) and 20 (26%) isolates were ascribed to A, B1, B2 and D phylogenetic groups, respectively, by specific primer polymerase chain reaction. Different E. coli isolates were found to be resistant to ampicillin (16.9%), tetracycline (1.3%), streptomycin (42.9%), sulfamethoxazole–trimethoprim (1.3%), amikacin (1.3%), tobramycin (2.6%) and nalidixic acid (1.3%). Additionally, the blaTEM, tetA, strA/strB, aadA, sul1, intI, intI2 and qacEΔ + sul1 genes were found in most resistant isolates. This study showed that E. coli from the intestinal tract of wild rabbits from Azores Archipelago are resistant to widely prescribed antibiotics in medicine and they constitute a reservoir of antimicrobial resistant genes, which may play a significant role in the spread of antimicrobial resistance. Therefore, antibiotic resistant E. coli from Azorean wild rabbits may represent an ecological and public health problem.

First report of a massive bloom of Alexandrium minutum (Dinophyceae) in middle North Atlantic: A coastal lagoon in S. Jorge Island, Azores

This is the first report of a bloom of the toxic marine dinoflagellate Alexandrium minutum in the Azores Archipelago (Northeastern Atlantic Ocean). In September 2013, high cell concentrations (1.3 × 107 cells L−1) of this species were recorded in Santo Cristo coastal lagoon causing an orange-brown water discoloration, death of small pelagic fish and toxification of shellfish resources (Ruditapes decussatus). Levels of Paralytic Shellfish Poisoning toxins in clams exceeded 30 times the regulatory limit, and were associated with the intoxication of four people.

On the endemic spider species of the genus Savigniorrhipis Wunderlich, 1992 (Araneae: Linyphiidae) in the Azores (Portugal), with description of a new species

Savigniorrhipis topographicus new species is described from the Azores. The synapomorphies of Savigniorrhipis are discussed along with the affinities of the genus within the Savignia-group. Given the extremely restricted and increasingly disturbed habitat, S. topographicus new species should be classified as Critically Endangered and its single forest habitat at Topo (São Jorge Island) should increase its current protection level to a strict nature reserve.

GPS and tectonic evidence for a diffuse plate boundary at the Azores Triple Junction

We use GPS, bathymetric/structural, and seismic data to define the pattern of present deformation along the northern half of the Azores plateau, where the Nubia–Eurasia plate boundary terminates at the axis of the Mid-Atlantic Ridge (MAR). New and existing campaign GPS velocities from the Azores islands reveal extension oblique to a series of en échelon volcanic ridges occupied by Terceira, S. Jorge, Pico, and Faial islands. In a frame of reference defined by 69 continuous GPS stations on the Eurasia plate, Terceira Island moves 2±1 mm/yr away from Eurasia, consistent with the islandʼs location within the Terceira Rift and plate boundary structure. The volcanic ridges south of the Terceira Rift move toward WSW at progressively faster rates, reaching a maximum of 3.5±0.5 mm/yr (2-σ) for the Pico/Faial volcanic ridge. The hypothesis that the Terceira Rift accommodates all Nubia–Eurasia plate motion is rejected at high confidence level based on the motions of sites on S. Jorge Island just west of Terceira Rift. All of the islands move relative to the Nubia plate, with Pico Island exhibiting the slowest motion, only 1±0.5 mm/yr (2-σ). Detailed bathymetry from the interior of the hypothesized Azores microplate reveals faults that crosscut young MAR seafloor fabric. These observations and the GPS evidence for distributed deformation described above argue against the existence of a rigid or semi-rigid Azores microplate, and instead suggest that Nubia–Eurasia plate motion is accommodated by extension across a ∼140-km-wide zone east of the MAR axis, most likely bounded to the north by the northern shoulder of the Terceira Rift. The MAR spreading rate along the western end of the Azores deformation zone (∼38.5°N–39.5°N) is intermediate between the Eurasia–North America rate measured at 39.5°N and the Nubia–North America rate measured at 38.5°N, consistent with the joint conclusions that the Nubia–Eurasia boundary is broad where it intersects the MAR, and the Azores Triple Junction is diffuse rather than discrete.

Land, Sea and Skyscape: Two Case Studies of Man-made Structures in the Azores Islands

The exploration of the Mediterranean seascape goes back to the foragers of the early Holocene period around the ninth millennium BCE. Two case studies in the Azores islands show possible integration of elements of landscape, seascape and skyscape in the way two different types of artificial structures were aligned. The major axes of the Maroiço structures from Pico Island may have been aligned on the summit of Pico Mountain and, reciprocally, on the setting sun at the summer solstice over the neighbouring Faial Island. The artificial caves near the sea excavated in Monte Brasil, Terceira Island, may have integrated solar calendrical marks, especially for the Equinox sunset over the distant S. Jorge Island.

Geodinâmica e perigosidade natural nas ilhas dos Açores

The central islands of the Azores archipelago exhibit significant volcanic and seismic activity. The most important tectonic structure responsible for this activity seems to be the leaky transform Terceira Rift, a branch of the Azores triple junction separating the Eurasia and Africa plates. In historical time (since the XV century), the most frequent volcanic eruptions were of the hawaiian and strombolian types, but the level of explosivity has occasionally reached subplinian magnitude, as it happened in the Fogo (1563) and Furnas (1630) volcanoes (hydromagmatic eruptions in the calderas). As in other volcanic regions of the world, effusive volcanism is not particularly dangerous in the Azores islands; explosive activity, however, can be catastrophic (ignimbrites formed in some islands over the last millennia). Still, throughout historical time, earthquakes have been the most dangerous natural phenomena in the Azores, sometimes bringing about tragic consequences: in 1757, an earthquake struck the São Jorge island, killing one thousand people (20% of the total population). But the most catastrophic seismic event of all occurred in the island of São Miguel in 1522: an earthquake triggered an earthflow that submerged the capital (Vila Franca do Campo) and killed nearly all of its inhabitants (several thousands). Whether or not they are triggered by earthquakes, mass movements are most common along the coast of the islands: huge falls and rotational slides are attested for by the so-called fajãs, detrital platforms on the foot of cliffs that are several hundred meters high; in death-defying fashion, some of these platforms are actually inhabitated.

Present-day deformation in São Jorge Island, Azores, from episodic GPS measurements (2001–2011)

A network of geodetic markers for high-precision Global Positioning System (GPS) surveying was established in 2001 in the island of São Jorge, at the Azores triple junction, where the North America–Eurasia–Nubia plates meet. The aim was to monitor tectonic, volcanic, and landslide-induced surface deformation in an active tectono-volcanic region. The network consisted of 17 stations, and was occupied in 2001, 2004, and 2010. GPS observations from the three episodic campaigns were analyzed using the latest geophysical models and geodetic procedures to generate a velocity field for São Jorge Island.Surface velocities estimated at 15 inland locations reveal that São Jorge is moving neither with Eurasia nor with Nubia and presents two sectors with different behavior. The NW sector of the island is moving at a rate of 2.2±0.3mm/yr to N82°±6° while the SE sector is moving at a rate of 1.4±0.3mm/yr to N109°±11°, when compared to the velocity of Nubia predicted by ITRF2008-PMM. This velocity field cannot be explained by slip along the active faults that cross the island, nor is compatible with volcanic deformation on the active volcanic rift zones. It is suggested that the velocity differences that are measured represent deformation related to local sub-surficial magmatic/volcanic processes occurring near the island. This intra-island deformation may also be related to the stress field and seafloor spreading occurring in an area situated on the western sector of the Azores Plateau, reflecting the presence of WNW–ESE volcanic structures, along which magma intrusion produces NE–SW dilatation, bounded to the East by a NE–SW trending structure, probably of tectonic nature, working as a dextral transfer zone.

Palaeomagnetic study of a subaerial volcanic ridge (São Jorge Island, Azores) for the past 1.3 Myr: evidence for the Cobb Mountain Subchron, volcano flank instability and tectonomagmatic implications

We present a palaeomagnetic study on 38 lava flows and 20 dykes encompassing the past 1.3 Myr on S. Jorge Island (Azores Archipelago-North Atlantic Ocean). The sections sampled in the southeastern and central/western parts of the island record reversed and normal polarities, respectively. They indicate a mean palaeomagnetic pole (81.3°N, 160.7°E, K= 33 and A95= 3.4°) with a latitude shallower than that expected from Geocentric Axial Dipole assumption, suggesting an effect of non-dipolar components of the Earth magnetic field. Virtual Geomagnetic Poles of eight flows and two dykes closely follow the contemporaneous records of the Cobb Mountain Subchron (ODP/DSDP programs) and constrain the age transition from reversed to normal polarity at ca. 1.207 ± 0.017 Ma. Volcano flank instabilities, probably related to dyke emplacement along an NNW-SSE direction, led to southwestward tilting of the lava pile towards the sea. Two spatially and temporally distinct dyke systems have been recognized on the island. The eastern is dominated by NNW-SSE trending dykes emplaced before the end of the Matuyama Chron, whereas in the central/western parts the eruptive fissures oriented WNW-ESE controlled the westward growth of the S. Jorge Island during the Brunhes Chron. Both directions are consistent with the present-day regional stress conditions deduced from plate kinematics and tectonomorphology and suggest the emplacement of dykes along pre-existing fractures. The distinct timing and location of each dyke system likely results from a slight shift of the magmatic source.

Land, Sea and Skyscape: Two Case Studies of Man-made Structures in the Azores Islands

Two case studies in the Azores islands show possible integration of elements of landscape, seascape and skyscape in the way two different types of artificial structures were aligned. The major axes of the Maroiço structures from Pico Island may have been aligned on the summit of Pico Mountain and, reciprocally, on the setting sun at summer solstice over the neighbouring Faial Island. The artificial caves near the sea excavated in Monte Brasil, Terceira Island, may have integrated solar calendrical marks, especially for the Equinox sunset over the distant S. Jorge Island.

Chaerophyllum azoricum Trel. grown in the Azores archipelago, Portugal: evaluation of the genetic diversity using molecular markers and comparison with volatile oils profiles

AbstractGenetic and chemical differences of nine individuals of Chaerophyllum azoricum were studied to determine whether molecular characters and volatile components could be used as taxonomical markers and to examine the correlation between them. Plant material was analysed by random amplified polymorphic DNA (RAPD) and inter simple sequence repeat (ISSR) using 21 and 19 arbitrary primers, respectively, generating 320 RAPD and 310 ISSR markers. The volatiles were isolated from each individual by distillation–extraction and analysed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS). Terpinolene (20–67%) was the main component of the volatile fraction isolated from the aerial parts of C. azoricum. Individuals harvested on São Jorge Island also had myristicin (4–23%), γ‐terpinene (5–16%), limonene (3–12%) and α‐zingiberene (2–12%) as the main components, whereas individuals collected on Flores Island had acorenone B (12–17%), myristicin (8–9%) and sabinene (4–9%) as the other dominant components. Separate cluster analyses based on molecular markers and on the chemical composition of the volatile fraction grouped, in both cases, the nine accessions in two main groups but with some subclustering differences. The correlation between the genetic diversity based on molecular marker patterns and the volatile chemical analysis of the present study was significant (Pearson's r &lt; 0.44, p ∼ 0.01). Copyright © 2009 John Wiley &amp; Sons, Ltd.

Reconsidering the origins of isotopic variations in Ocean Island Basalts: Insights from fine-scale study of São Jorge Island, Azores archipelago

New major and trace element and Sr–Nd–Pb isotope data have been determined for 21 basaltic samples from São Jorge Island, Azores archipelago. Samples can be separated into two groups best identified in a plot of 208Pb/ 204Pb versus 206Pb/ 204Pb where they form two sub-parallel mixing arrays. Lavas from the old (Topo) formation have lower 208Pb/ 204Pb for a given 206Pb/ 204Pb and more radiogenic Sr than samples from intermediate (Rosais) and young (Manadas) formations. Topo samples also tend to have higher MgO contents and lower incompatible trace element concentrations. Both Pb mixing arrays can be related to mixing of plume melts having a HIMU-like Pb isotope signature with two depleted components. One depleted component is best seen in analyses of Topo samples and is interpreted to represent upper mantle material from the nearby Mid-Atlantic ridge. The second depleted component has Sr–Nd–Pb isotopic characteristics similar to E-MORB and resides in the oceanic crust basement under São Jorge. Pb isotope analyses of lavas from São Jorge make it possible to re-define the Terceira end-member of the Azores archipelago, moving its composition to more radiogenic Pb with 206Pb/ 204Pb ~ 20.51, 207Pb/ 204Pb ~ 15.67 and 208Pb/ 204Pb ~ 39.56, at 143Nd/ 144Nd ~ 0.51295 and 87Sr/ 86Sr ~ 0.70375. Extending the interpretations made for the origins of the São Jorge isotopic mixing arrays to other islands from the Azores archipelago (Pico, Faial, Terceira and São Miguel), we show that most of the isotopic variability recorded by Azores magmas can be related to mixing of plume melts with two distinct and homogeneous signatures as well as several other components dispersed in the shallow mantle/lithosphere under the Azores. This illustrates how caution is required when interpreting ocean island basalt isotopic data as reflecting their deep mantle plume source, and subsequently for constraining mantle topology.