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Locating the Epicenter of an Irish Earthquake
Full text linkStudents will learn how to locate the epicenter of an Irish earthquake using waveform data from Raspberry Shake seismometer stations in Ireland. These are small seismometers that record ground motion and are used to detect signals such as earthquakes
Gamma-ray detection of newly discovered Ancora supernova remnant: G288.8-6.3
Full text linkContext. The supernova remnant (SNR) G288.8-6.3 was recently discovered as a faint radio shell at high Galactic latitude using observations with the Australian Square Kilometre Array Pathfinder (ASKAP) in the Evolutionary Map of the Universe (EMU) survey.
Aims: We performed the first detailed investigation of the γ-ray emission from the G288.8-6.3 region, aiming to characterise the high-energy emission in the GeV regime from the newly discovered SNR, dubbed Ancora.
Methods: Fifteen years of Fermi-Large Area Telescope (LAT) data were analysed at energies between 400 MeV and 1 TeV, and the excess seen in the region was modelled using different spatial and spectral models.
Results: We detect spatially extended γ-ray emission coinciding with the radio SNR, with detection significance up to 8.8 σ. A radial disk spatial model in combination with a power-law spectral model with an energy flux of (4.80 ± 0.91) × 10−6 MeV cm−2 s−1, with the spectrum extending up to around 5 GeV was found to be the preferred model. Morphologically, hotspots seen above 1 GeV are well correlated with the bright western part of the radio shell. The emission is more likely to be of leptonic origin, given the estimated gas density in the region and the estimated distance and age of the SNR, but a hadronic scenario cannot be ruled out.
Conclusions: Ancora is the seventh confirmed SNR detected at high Galactic latitude with Fermi-LAT. The study of this new population of remnants can provide insights into the evolutionary aspects of SNRs and their properties, and further advance efforts of constraining the physics of particle diffusion and escape from SNRs into the Galaxy
3D_DIG_Moho_and_LAB_Model_EChambers2024.nc
No full textREAD ME File For '3D_DIG_Moho_and_LAB_Model_EChambers2024_INTERPOLATED.nc'
Dataset DOI:
ReadMe Author: Emma L. Chambers, Dublin Institute for advanced Studies, ORCID: https://orcid.org/0000-0001-6969-2920
This dataset supports the publication:
AUTHORS: Emma L. Chambers*, Javier Fullea, Duygu Kiyan, Sergei Lebedev, Christopher J. Bean, Pat Meere, J. Stephen Daly, Nicola Willmot Noller, Robert Raine, Sarah Blake, Brian M. O’Reilly
TITLE: A new 3D temperature model for Ireland from joint geophysical-petrological inversion of seismic, surface heat flow and petrophysical data
JOURNAL: Geophysical Journal International
PAPER DOI IF KNOWN:
PREPRINT: EarthArXiv
PREPRINT DOI: https://doi.org/10.31223/X5RX3P
This dataset contains:
"3D_DIG_Moho_and_LAB_Model_EChambers2024_INTERPOLATED.nc" which has the final Moho and LAB depth models. Also included are latitude and longitude coordinate variables in both WGS84 and ITM coordinates. The model has been interpolated to 0.025 degree spacing laterally from an original 0.2 degree spacing.
This file is in NetCDF format. NetCDF files can be opened in most data analysis environments. For example in MATLAB use the netcdf.open command or in python xr.open_dataset(dataset.nc).
Date of data collection:
10/09/2024
Information about geographic location of data collection:
Dataset covers the Republic of Ireland and Northern Ireland in both WGS84 (latitude and longitude, EPSG:4326) and ITM coordinates (latITM and lonITM, EPSG:2157).
Licence:
CC BY-SA 4.0
Related projects and datasets:
3D_DIG_Temp_and_RMS_Model_EChambers2024.nc
3D_DIG_Temp_and_RMS_Model_EChambers2024_INTERPOLATED.nc
3D_DIG_Moho_and_LAB_Model_EChambers2024.n
The Global Heat Flow Database: Release 2024
Full text linkThe data publication contains the compilation of global heat-flow data by the International Heat Flow Commission (IHFC; www.ihfc-iugg.org) of the International Association of Seismology and Physics of the Earth's Interior (IASPEI). The presented data update release 2024 contains data generated between 1939 and 2024 and constitutes the second intermediate update benefiting from the global collaborative assessment and quality control of the Global Heat Flow Database running since May 2021 (http://assessment.ihfc-iugg.org). The data release comprises new original heat-flow data published since April 2023 (the update 2023). It contains 91,182 heat-flow data from 1,586 publications. 57% of the reported heat-flow values are from the continental domain (n ~ 54,553), while the remaining 43% are located in the oceanic domain (n ~ 36,692)
Investigation of Depth and Dimension Effects on Ireland’s Karst Aquifers Using Synthetic Seismic Reflected Data
Full text linkKarst regions are frequently classed as aquifers because they often contain sufficient groundwater to meet various needs. In Ireland approximately 16 percent of public water supply is provided by groundwater resources and karst limestones are important sources of groundwater.
There is evidence of karst features (conduits/caves) at depths >100 m below ground level in
Irish limestones that can be water bearing. The nature and extent of these types of features are poorly understood, and, to date, deep groundwater resources are largely untapped and uncharacterised. Groundwater exploration and development of these deeper features could be based on 3-D imaging using geophysics to identify potential strategic drilling targets. Karst areas are very difficult environments for any geophysical exploration due to strong lateral
and vertical heterogeneity. The main objective of the study is to develop a better understanding of deep groundwater resources in Ireland’s limestones using available seismic datasets.
We focus on direct reflection of water filled structures using characteristic seismic feature
Irish National Seismic Network: An Enhanced Detection Capability And Recent Observations
Full text linkThe Irish National Seismic Network (INSN) is operated by the Dublin Institute for Advanced
Studies (DIAS) and co-funded by the Geological Survey of Ireland (GSI). The goal of the INSN is
to monitor seismic activity in Ireland and its near-offshore. Beginning with two stations in 1980, the
INSN expanded its complement to six real-time seismic stations by 2014. From November 2018,
the INSN received funding from the GSI with the aim of doubling the number of operational
seismic stations to twelve.
We describe the methods used in planning the site locations for the new seismic stations, details on
the deployment of test stations and the subsequent data quality analysis. In particular, we make use
of power-spectral density plots, real-time seismic amplitude method (RSAM) and signal-to-noise
ratios of local events. We also describe the layout of the structures housing the new seismic stations,
which include traditional bunker-style designs, as well as shallow borehole and underground cave
installations. We present results of the fully-operational new stations highlighting the enhanced
detection capability of the network, as well as some examples of recent observations
Seismic Tomography of South America: Continental Lithosphere, Subduction-Zone Structures, and the Origins of Intraplate Magmatism
Full text linkThe lithospheric structure of South America records its long and complex tectonic evolution, during which it has influenced the distribution and composition of local magmatism, the geometry of the subduction at its western margin, and the behaviour of the Andean orogeny. Throughout the years, seismic tomography models have provided increasingly accurate images of the Earth’s structure beneath South America. However, our understanding of the upper mantle underlying the continent and its surroundings is still limited by the sparse and uneven distribution of seismic data. In this work, we present a new seismic tomography model of South America and surrounding oceans, including the crust and upper mantle. To address the heterogeneous data coverage in South America, our model SACI-24 (South America Continental Imaging 2024) is based on the inversion of more than 970,000 waveforms from ~300,000 earthquakes, recorded by more than 9000 seismic stations globally and locally. The combined regional and global dataset ensures the densest possible data sampling of the South American continent, its margins, and the surrounding oceans. We invert the waveforms using the Automated Multimode Inversion (AMI) of S-, multiple S-, and surface waves. AMI generates a set of independent linear equations with uncorrelated uncertainties for each source-receiver path. These equations describe the path-average S-wave velocity structure within approximate sensitivity kernels. We assemble these equations into a large linear system and solve it to obtain the 3D distribution of S-wave velocities in the crust, upper mantle, and transition zone. Our model is calculated globally; however, the parametrization and regularisation values are optimized for the South American region, and the data coverage is maximized only in the hemisphere centred on South America.
Within the lithosphere, our model reveals a more complex structure of the cratonic lithosphere than previously proposed. Internal heterogeneities within cratonic boundaries include regions of thinner lithosphere, which correspond to areas of proposed rifting in previous tectonic cycles. Inside the boundaries of the Amazon Craton, two distinct cratonic blocks are identified, separated by the Amazon basin. In the São Francisco Craton, newly imaged thin lithosphere underlies the Paleoproterozoic Paramirim Aulacogen area. Our work further reveals separate, high-velocity lithospheric blocks beneath the Parnaíba and Paraná basins. South of the Paraná Basin, our model maps for the first time evidence of the cratonic root of the Rio de la Plata Craton. The detailed mapping of the lithospheric structure reveals its control on several geodynamic processes. Comparison of cratonic lithosphere with the reconstructed position of hotspots reveals that lithospheric thickness is the main control on the distribution of volcanism in large igneous provinces. Under the roots of the Andean Cordillera, our model finds multiple regions of underthrusting of continental lithosphere from South America. Our high-resolution images of the active margin reveal highly heterogeneous subduction, indicating several slab segments from the Nazca and Caribbean plates. East of the Peruvian flat slab, we find areas of thick lithosphere that we attribute to the Amazon Craton, indicating the role of cratonic hydrodynamic suction in flat slab formation. Furthermore, we identify regions under the Altiplano and Puna Plateaus undergoing lithospheric root growth and delamination, indicative of varying stages of Cordillera cyclicity.
Within the mantle transition zone, we detect segments of colder mantle from the subduction of the Nazca plate. East of these subduction segments, we identify fast seismic anomalies we interpret as remnants of past lithospheric delamination events. Underlying the thick continental lithosphere, our model reveals prominent low-seismic velocity anomalies extending as deep as the transition zone, with the strongest anomaly found beneath southeast Brazil. Whole-mantle tomography shows that this anomaly extends to a depth of at least 2000 km depth, suggesting a deeply rooted mantle plume. We postulate that interaction with past slab fragments from the long-lived Nazca subduction modifies the plume ascension path, causing it to branch out and travel horizontally to areas of thin oceanic lithosphere, where we find the present-day location of the many hotspots in the Atlantic Ocean
Imaging Ireland's lithosphere by 3D joint inversion of magnetotelluric, seismic, gravity and magnetic datasets
Full text linkApplication of a seismic network to baleen whale call detection and localization in the Panama basin – a Bryde’s whale example
Full text linkBaleen whales use sounds of various characteristics for different tasks and interactions. This study focuses on recordings from the Costa Rica Rift, in the Eastern Tropical Pacific Ocean, made by 25 ocean-bottom seismographs and a vertical array of 12 hydrophones between January and February 2015. The whale calls observed are of two kinds: more commonly, repetitive 4-5 s long signals separated into two frequency bands centered at ~20 and ~36 Hz; less commonly, a series of ~0.5-1.0 s long, lower amplitude signals with frequencies between 80 and 160 Hz. These characteristics are similar to calls attributed to Bryde’s whales which are occasionally sighted in this region. In this study, the repetitive calls are detected using both the STA/LTA approach and a network empirical subspace detector. In total, 188 and 1891 calls are obtained for each method, demonstrating the value of the subspace detector for highly similar signals. These signals are first localized using a non-linear grid search algorithm and then further relocalized using the double-difference technique. The high-resolution localizations reveal the presence of at least seven whales during the recording period, often crossing the instrument network from southwest to northeast
Understanding Unrest and Dynamic Triggering Processes on Sierra Negra, Galápagos Islands
Full text linkDynamic earthquake triggering refers to the phenomenon where local seismic activity is induced by dynamic stress disturbances, originating from teleseismic earthquakes. An understanding of dynamic triggering on volcanoes offers a window into volcano stress states and seismicity initiation. Sierra Negra, a basaltic shield volcano situated on Isabela Island, Galápagos, has been the site of recurring episodes of dynamic triggering. Sierra Negra features a large elliptical summit caldera with a trap-door fault system and a magma reservoir extending 2km below the surface. Sierra Negra experienced an eruption in June 2018, characterized by a sequence of pre-eruption inflation, co-eruption deflation, and post-eruption inflation. The occurrence of dynamic earthquake triggering at Sierra Negra was observed in response to high magnitude teleseismic events from 2010 to 2018. The frequency of dynamically triggered earthquakes correlates with the increasing inflation of the magma reservoir. In this study, we aim to answer two questions: 1) How confident are we that the seismicity on Sierra Negra is dynamically triggered? And, 2) What is the location of these dynamically triggered events? Random simulations are used to calculate the likelihood that triggered events are related to teleseismic arrivals rather than being representative of local seismic activity. Results show that pre-2018 eruption, the likelihood that events are dynamic triggering is very high, compared to post-2018 eruption where events are more likely to be representative of local seismic activity. We only have access to a single station (VCH1) on Sierra Negra meaning the single-station location method must be used to locate all dynamically triggered events. To test and refine this method, 79 known seismic events are located using a full network from April 2018 – December 2018. Rotation of the 3-component VCH1 is used to calculate the back-azimuth and the P-wave to S-wave delay is used to calculate the distance between event and station. 21 unknown dynamically triggered events are located in and around the caldera using this method. Looking forward we hope to understand the relationship between the location and timing of dynamic triggering, and its potential use in understanding volcano unrest state