Article
Geochemistry & Geophysics
Steve Lund, Gary Acton, Brad Clement, Makoto Okada, Lloyd Keigwin
Summary: The study presents important information on the paleomagnetic field variations during two specific periods based on PSV and excursion data obtained from ODP sites in the western North Atlantic. By correcting age estimates and comparing records, it reveals significant variability of the geomagnetic field at different timescales and characteristics of excursions, providing insights into the behavior of the magnetic field between reversals.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Steve P. Lund, Martha Schwartz, Lloyd Keigwin
Summary: New paleomagnetic records recovered from deep-sea sediment cores of the Bahama Outer Ridge reveal the occurrence of the Blake Event around 119-126,000 years BP within Marine Isotope Stage 5. The Blake Event is characterized by a local magnetic field reversal and our detailed analysis confirms deviations from long-term averages on various timescales.
PHYSICS OF THE EARTH AND PLANETARY INTERIORS
(2021)
Article
Geography, Physical
Venera Dobrica, Cristiana Stefan, Crisan Demetrescu
Summary: This study examined the Earth's surface magnetic field and its secular variation, focusing on the internal constituents and dynamics of the SV foci. By analyzing long time-span geomagnetic models and applying filtering techniques, the study revealed new features of the Earth's surface field evolution, such as the westward drift of the inter-centennial constituent and the westward drift of higher frequency constituents in the equatorial band.
GLOBAL AND PLANETARY CHANGE
(2021)
Article
Geology
Ruth M. Corkill, Gillian M. Turner
Summary: The paleomagnetic records of three lake sediment cores in northern New Zealand have been merged to produce a new Holocene geomagnetic secular variation record. These records were correlated using tephra and magnetic susceptibility variations, showing well-defined swings in magnetic direction at different time periods. The regional nature of geomagnetic secular variation is indicated by its agreement with records from Mavora Lakes, 1000 km further south.
NEW ZEALAND JOURNAL OF GEOLOGY AND GEOPHYSICS
(2022)
Article
Geochemistry & Geophysics
Gabriel West, Andreas Nilsson, Alexis Geels, Martin Jakobsson, Matthias Moros, Francesco Muschitiello, Christof Pearce, Ian Snowball, Matt O'Regan
Summary: This study investigates the behavior of the geomagnetic field in polar regions during the late Holocene period. By analyzing well-dated sediment cores from the Chukchi Sea, Arctic Ocean, the authors provide valuable insights into the changes in the geomagnetic field in the Arctic over the past few thousand years.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2022)
Article
Geochemistry & Geophysics
Gillian M. Turner, Ruth M. Corkill
Summary: The southwest Pacific region is under-represented in palaeomagnetic secular variation databases, but reliable data from this region are crucial for constructing global models and master records for dating purposes. The NZPSV11k and NZPSV1k records provide valuable insights into the palaeomagnetic and archaeomagnetic variations in the region. The records show significant differences from global models, highlighting the importance of incorporating data from the region.
PHYSICS OF THE EARTH AND PLANETARY INTERIORS
(2023)
Article
Meteorology & Atmospheric Sciences
Weimin Jiang, Guillaume Gastineau, Francis Codran
Summary: The climate responses to fluctuations in the Atlantic meridional overturning circulation (AMOC) were investigated using sensitivity experiments. Modifications were made to the baroclinic component of the North Atlantic Ocean currents in an atmosphere-ocean general circulation model, which reproduced the typical AMOC multidecadal variability. Results showed that a strong AMOC led to widespread warming in the Northern Hemisphere and a northward shift of the intertropical convergence zone over the Atlantic Ocean. The driving mechanism for these climate responses was found to be an anomalous cross-equatorial Hadley circulation transporting energy and moisture.
JOURNAL OF CLIMATE
(2023)
Article
Oceanography
Nicola Jane Brown, Cecilie Mauritzen, Camille Li, Erica Madonna, Pal Erik Isachsen, J. H. LaCasce
Summary: In this study, we investigated the drivers of variability in the Norwegian Atlantic Slope Current using satellite altimetry and ocean reanalysis data. We found that the highest and lowest extremes in ocean transport occur over two days as atmospheric pressure systems approach, resulting in water piling up or extracting at the coast of Norway. Other sources of short-term variability are unlikely to have covariability over large separations. Monthly variability can be explained by passing weather systems.
JOURNAL OF PHYSICAL OCEANOGRAPHY
(2023)
Article
Geochemistry & Geophysics
Mao Ning, Chen Shi, Yang YongYou, Wu Xu, Li YongBo
Summary: The purpose of this research is to compare the observed secular variations of the geomagnetic field with those calculated by IGRF and WMM, and to evaluate the accuracy of IGRF-12 and WMM2015 in mainland China. Using hourly mean data from 10 geomagnetic reference stations in mainland China from 2009 to 2022, the external interference field and crustal magnetic field were eliminated, and the secular variation of the core field was extracted. The results show that the prediction accuracy of the seven geomagnetic elements in the WMM2015 model is better than that of IGRF-12, but the error increases with time. The maximum 1-year error of the total field intensity of the two models is 13 nT, and the 5-year error reaches 153.65 nT, which does not meet the requirements of high-precision geomagnetic navigation. It is suggested to develop a rapid secular variation model (1 year) by supplementing multi-source magnetic survey data in China to improve prediction accuracy.
CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION
(2023)
Article
Environmental Sciences
Partha Sarathi Jena, Ravi Bhushan, Shivam Ajay, Nisha Bharti, A. K. Sudheer
Summary: The study using marine sediment core and AMS technology shows that the estimation of Be-10 depositional flux is significantly affected by local processes, leading to a notable discrepancy between model-derived deposition rates and measured values. Moreover, variations in Be-10 depositional flux and the Be-10/Be-9 ratio over the past 43 ka demonstrate the impact of changes in Earth's magnetic field.
SCIENCE OF THE TOTAL ENVIRONMENT
(2022)
Article
Geochemistry & Geophysics
Alexander A. Harker, Michael Schindelegger, Rui M. Ponte, David A. Salstein
Summary: This study reexamines the ocean's contribution to rapid, non-tidal Earth rotation variations and identifies issues in oceanic angular momentum estimates. Accounting for OAM from other models significantly reduces the variance of atmosphere-corrected geodetic excitation, and higher model resolution is suggested as a target for improving the oceanic component in Earth system modeling.
JOURNAL OF GEODESY
(2021)
Article
Geochemistry & Geophysics
B. Eid, F. Lhuillier, V. P. Shcherbakov, V. V. Shcherbakova
Summary: This study provides new absolute and relative paleointensity data from a basaltic sequence in Ethiopia, finding no robust correlation between changes in dipole moment and reversal frequency over the past 155 million years. However, the results are consistent with the predicted paleosecular-variation proxy trend from numerical dynamo simulations.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Brendan T. Reilly, Joseph S. Stoner, Saedis Olafsdottir, Anne Jennings, Robert Hatfield, Greta Bjork Kristjansdottir, Aslaug Geirsdottir
Summary: We investigated the amplitude and frequency of geomagnetic change in the Northern North Atlantic region over the past 15 thousand years. Using high-resolution sediment cores, we validated prior results and provided stronger geochronological constraints on the paleomagnetic secular variation signal. Our study also revealed greater variability and higher amplitudes on centennial timescales, which is important for understanding the geodynamo.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geosciences, Multidisciplinary
Alexandre Fournier, Julien Aubert, Vincent Lesur, Erwan Thebault
Summary: Each IGRF model includes a secular variation component describing the evolution of the main magnetic field for the next 5 years, with each Gauss coefficient assumed to undergo independent linear evolution. Physics-based forecasts for candidate SV models have increased, driven by satellite data spanning over two decades and progress in numerical modeling of Earth's core dynamics. Rapid geomagnetic variations identified in satellite data can impact the quality of IGRF predictions, necessitating frameworks that incorporate short-term geomagnetic processes.
EARTH PLANETS AND SPACE
(2021)
Article
Geochemistry & Geophysics
Yuhji Yamamoto, Hiroto Fukami, Peter C. Lippert
Summary: This study provides new insights into relative paleointensity (RPI) variations by conducting rock magnetic and paleomagnetic measurements on Eocene marine sediments. The results show that RPI fluctuates within each chron and is influenced by inhomogeneous rock magnetic properties. The study also establishes a stacked RPI curve for Chron 18 and compares it with records from the equatorial Pacific, revealing similar characteristics.
EARTH AND PLANETARY SCIENCE LETTERS
(2022)
Article
Geochemistry & Geophysics
Annemarieke Beguin, Adriano Pimentel, Lennart de Groot
Summary: By analyzing and integrating new paleomagnetic data from Pico Island in the Azores Archipelago, this study successfully constructed a curve of the direction and intensity changes of the Earth's magnetic field over the past two thousand years. The research revealed a period of low inclination between AD 900 and 1560, with minimum values of 32 degrees.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Engineering, Environmental
Diana Linhares, Adriano Pimentel, Patricia Garcia, Armindo Rodrigues
Summary: This study evaluated the concentrations of essential nutrients in topsoils and pasture grass from Sao Miguel Island, finding that the highest concentrations were observed in areas with basaltic soils, while the lowest values were found in areas with trachytic soils. The uneven distribution and deficiency of essential nutrients in topsoil and pasture grass could lead to harmful health effects on grazing cattle.
ENVIRONMENTAL GEOCHEMISTRY AND HEALTH
(2021)
Article
Geochemistry & Geophysics
A. Di Chiara, L. Tauxe, H. Staudigel, F. Florindo, M. Protti, Y. Yu, J. -A. Wartho, P. van den Bogaard, K. Hoernle
Summary: This study focused on the Cretaceous Normal Superchron (CNS) and found that the geomagnetic field strength was higher than the long-term average during this period, remaining consistent before and after the onset of CNS. This suggests that there is not a strict correlation between the length of polarity intervals and the strength of the magnetic field.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2021)
Article
Geosciences, Multidisciplinary
Adriano Pimentel, Stephen Self, Jose M. Pacheco, Adam J. Jeffery, Ralf Gertisser
Summary: Ignimbrites are relatively rare on ocean island volcanoes, but make up a significant part of the stratigraphy of Terceira Island. A study on the Lajes-Angra Ignimbrite Formation reveals insights into the composition and petrogenetic processes of the ignimbrites, showing variability in trace element and groundmass glass compositions. The architecture of these ignimbrites suggests complex depositional conditions and challenges common assumptions about the relationship between aspect ratio and PDC dynamics.
FRONTIERS IN EARTH SCIENCE
(2021)
Article
Geosciences, Multidisciplinary
Mariana Andrade, Ricardo S. Ramalho, Adriano Pimentel, Armand Hernandez, Steffen Kutterolf, Alberto Saez, Mario Benavente, Pedro M. Raposeiro, Santiago Giralt
Summary: The study explores the lacustrine sedimentary record of Lagoa da Lomba on Flores Island to gain insight into the island's recent eruptive history, revealing a longer duration of volcanic activity in the Holocene than previously thought and highlighting the potential risk of future eruptions. It emphasizes the importance of tephrostratigraphy in reconstructing past volcanic activity, especially on small volcanic islands with limited exposure due to erosion and dense vegetation.
FRONTIERS IN EARTH SCIENCE
(2021)
Article
Geochemistry & Geophysics
Anita Di Chiara, F. Javier Pavon-Carrasco
Summary: Understanding the variations of the Earth's magnetic field over time in Africa is crucial for various reasons, including the study of the South Atlantic Anomaly (SAA) and the development of a regional geomagnetic model. The new model reveals the westward migration of the SAA from the Indian Ocean over Africa since 1100 CE and can be used for paleomagnetic dating of archaeological sites and volcanic units.
PHYSICS OF THE EARTH AND PLANETARY INTERIORS
(2022)
Article
Environmental Sciences
Francisco Valente, Jose Virgilio Cruz, Adriano Pimentel, Rui Coutinho, Cesar Andrade, Jorge Nemesio, Selma Cordeiro
Summary: This paper characterizes the potential impacts of tephra fall on the groundwater-fed water supply system of Ponta Delgada by comparing two scenarios of explosive eruptions. The results highlight the need for preparedness measures to mitigate the consequences of a volcanic crisis on water supply.
Article
Geosciences, Multidisciplinary
B. S. Ellis, A. Pimentel, J. A. Wolff, A. Etter, E. A. Cortes-Calderon, C. Harris, D. F. Mark, J. Neukampf, O. Bachmann
Summary: This study focuses on the Sete Cidades volcano on the island of Sa similar to o Miguel in the Azores archipelago, examining the magma storage conditions and eruptive activities. The findings reveal that magmas were stored at high temperatures under volatile-rich conditions, leading to multiple trachytic pumice eruptions.
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
(2022)
Article
Geosciences, Multidisciplinary
Mariana Andrade, Adriano Pimentel, Ricardo Ramalho, Steffen Kutterolf, Armand Hernandez
Summary: Monogenetic volcanoes are small and short-lived, and can experience various eruptive styles. Volcanism in monogenetic volcanic fields may migrate to different locations over time, making volcanic hazard assessment challenging. This study reconstructs the eruptive history of the Funda Volcanic System (FVS) in Flores Island based on tephrostratigraphic work, geochemical analysis, and radiocarbon dating. The results reveal multiple volcanic events at FVS with different eruptive styles, emphasizing the diversity and recurrence of volcanic activity. These findings are important for future volcanic hazard assessment studies.
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
(2022)
Article
Geosciences, Multidisciplinary
Mariana Andrade, Ricardo Ramalho, Adriano Pimentel, Steffen Kutterolf, Armand Hernandez
Summary: The volcanic island of Flores in the Azores Archipelago has no recorded eruptions since its settlement in the 15th century, but at least six eruptions occurred during the Holocene, indicating its potential activity. This study reconstructs the eruptive history of the Comprida Volcanic System (CVS) in Flores, revealing that it was formed in a single volcanic eruption around 3180 cal yr BP. The eruption started with Hawaiian-style lava fountaining followed by Strombolian activity and phreatomagmatic explosions, highlighting the role of groundwater in transforming the eruption into a highly explosive event.
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
(2023)
Article
Geochemistry & Geophysics
Anita Di Chiara, Adrian R. Muxworthy, Ricrdo I. F. Trindade, Franklin Bispo-Santos, Evelyn B. Baker
Summary: Palaeointensity data from the Precambrian are crucial for understanding the timing of Inner Core Nucleation (ICN), but limited data has made it difficult to determine its timing. Numerical dynamo simulation models predict an increase in entropy, affecting the field strength and showing an anomaly in the palaeointensity record at ICN. New estimates of geomagnetic field intensity from the Mid-Mesoproterozoic Nova Guarita dyke swarm provide valuable constraints for assessing numerical simulations of the Mesoproterozoic geodynamo.
STUDIA GEOPHYSICA ET GEODAETICA
(2023)
Article
Geosciences, Multidisciplinary
Cesar Andrade, Vittorio Zanon, Fatima Viveiros, J. Virgilio Cruz, Adriano Pimentel, Rui Coutinho
Summary: A pioneer study was conducted in the crater lagoon of Vila Franca do Campo Islet to identify potential CO2 degassing zones in the marine environment using a floating accumulation chamber. The study included CO2 flux measurements, water parameter determinations, and stable isotopic composition analysis. The results indicated the presence of biogenic CO2 and the estimated emission of 0.05 t d(-1) from the water surface. The study suggests the application of this methodology to other coastal marine areas with reported anomalous gas emissions.
BULLETIN OF VOLCANOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Stephen P. Hicks, Sandro B. Matos, Adriano Pimentel, Giacomo Belli, Duccio Gheri, Maria Tsekhmistrenko, Kasra Hosseini, Wolfram H. Geissler, Rita Silva, Nicolau Wallenstein, Ana M. G. Ferreira
Summary: Small meteoroids entering Earth's atmosphere often go unnoticed due to observational biases. However, by utilizing seismoacoustic methods and satellite data, a previously unreported fireball in the Azores in 2022 was detected and characterized. The findings provide insights into the size and frequency of meteoroid entries, advancing our understanding of their sources and entry processes.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Multidisciplinary Sciences
Anita Di Chiara, Lisa Tauxe, Thomas E. Levy, Mohammad Najjar, Fabio Florindo, Erez Ben-Yosef
Summary: This study presents 11 robust archaeointensity results from the Pre-Pottery to Pottery Neolithic era in Jordan, with two of them being the oldest data for the Levant, ancient Egypt, Turkey, and Mesopotamia. Virtual Axial Dipole Moments suggest a weak Earth's magnetic field in the Southern Levant around 7600 BCE, strengthening to greater than present levels around 7000 BCE, and gradually weakening again around 5200 BCE. Successful results from burnt flint highlight its potential for archaeomagnetic research in prehistoric periods.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Geosciences, Multidisciplinary
Joana Medeiros, Rita Carmo, Adriano Pimentel, Jose Cabral Vieira, Gabriela Queiroz
Summary: This study introduces a new method to assess the economic impact of volcanic eruptions on the tourism sector, demonstrating the economic risks under different eruption scenarios through numerical simulations and estimating potential losses. This approach has the potential to be applied to other volcanic regions, geological hazards, and economic sectors.
NATURAL HAZARDS AND EARTH SYSTEM SCIENCES
(2021)