Seismic Velocity Structure of the Irish Crust from Quarry Blasts

Travel-time tomography uses the travel times of seismic waves between pairs of sources and receivers to constrain the elastic properties of the subsurface. However, the low rate of natural seismicity in Ireland limits the application of standard local earthquake tomography. This study uses seismic wave arrival times from controlled explosions generated during quarry and mining activities to refine the constraints on the velocity structure of the Irish crust. Previous seismic studies have utilised (i) surface wave dispersion from teleseismic earthquakes, providing broad insights into the lithospheric structure, and (ii) spatially sparse seismic reflection and refraction profiles. While these studies have delineated major tectonic features, such as the late-Caledonian Leinster Granite and a crustal boundary linked to the closure of the Iapetus Ocean, the precise boundaries of these features remain unresolved. Subašić (2021) employed the FMTOMO package to compute a preliminary 3D travel-time tomography model of the Irish crust based on quarry blast data. FMTOMO (Rawlinson et al., 2006) uses a gradient-based subspace inversion scheme to derive a seismic velocity model from observed travel times. In this study, we re-evaluate and expand the input dataset used by Subašić (2021) and focus on optimising the regularisation parameters of the tomographic inversion. Event classification into natural earthquakes and quarry explosions is performed using the spectral ratio method applied to S-wave trains, a procedure developed and routinely applied by the Irish National Seismic Network (INSN). The updated dataset includes 1,411 quarry blast events with P- and S-wave travel-time measurements from 2013–2014, a period of increased station density due to temporary seismic deployments. Quarry blasts, being surface explosions, are assumed to have well-constrained surface locations. A catalogue of 234 quarry sites in Ireland was initially compiled from satellite imagery by the INSN. Hypocentre locations for each event are first calculated from phase arrival times and subsequently relocated to the nearest quarry. Given that quarry mines in Ireland typically range from hundreds of metres to a maximum of ~1.5 km in length, most events fall within the error margin of the initial locations. For events located beyond a 3 km radius of known quarries, additional searches for unrecorded sites were conducted. Satellite imagery inspections of these unclassified events identified 25 additional quarries. The operational status of these quarries during the study period was confirmed using historical imagery from Google Earth by comparing quarry areas before and after the analysed time frame

Leveraging Social Media for Geoscience Communication: Insights from the British Geological Survey's Multi-Hazard and Resilience Campaigns

Social media offers a unique avenue for scientific communication; however, it remains underutilised by many scientific organisations. This study examines the social media strategy of the British Geological Survey (BGS), the UK’s leading geoscience organisation, to assess its effectiveness in engaging the public with research on Multi-Hazard and Resilience. We investigate two key research questions; 1. how effectively does BGS engage the public through its social media efforts, and 2. what challenges does BGS face in using these social media platforms to enhance public understanding? Scientific organisations often rely on the deficit model of communication, characterised by a one-way transfer of knowledge. Yet, emerging studies suggest that a dialogue-based approach, tailored to different social media platforms and formats, may foster better public engagement. This paper provides a framework for assessing social media activity that can be applied to scientific organisations worldwide. To address research question 1, we conduct content and sentiment analysis on BGS social media posts – including X, Facebook, LinkedIn, Instagram, YouTube, and BlueSky – from May 2023 to March 2024. A systematic codebook is developed to categorise descriptive and interpretive variables for any social media output. To answer research question 2, we conduct semi-structured interviews with five BGS employees who manage departmental social media accounts to understand their attitudes towards social media engagement. Our findings suggest several actionable strategies, such as streamlining communication across platforms, maximising the reach of ‘Multi-Hazard and Resilience’ themes, increasing video content output, and better incorporating public feedback. Although focused on BGS, our mixed-methods approach and methodology offer a valuable template for other scientific organisations seeking to enhance their online presence and science communication efforts. This study highlights BGS’s successful establishment of a multi-platform online presence, showcasing a range of content formats that effectively engage audiences

The lithosphere of South America from seismic tomography: Structure, evolution, and control on tectonics and magmatism

The thickness, temperature and mechanical strength of the lithosphere vary greatly across South America and have controlled tectonic and magmatic processes during its evolution. Here, we introduce a new tomographic model of South America’s lithosphere and underlying mantle, SACI-24, and analyse this and other state-of-the-art models together with other geological and geophysical data. The new model is obtained by waveform inversion of surface, S and multiple S waveforms globally, but is optimised for South America and the surrounding oceans. SACI-24 is constrained by ∼ 970,000 seismograms from 9259 stations and maps detailed structure of cratonic lithosphere across the continent, highlighting previously unknown complexities and fragmentation. Within the Amazon Craton, the Guiana and Central Brazil blocks show high Vs exceeding 4.8 km/s in the 80–150 km depth range but are separated by lower velocities below the Amazon Basin, matching the locations of ancient rifting and the flood basalts of the Central Atlantic Magmatic Province. In the São Francisco Craton, high velocities extend north and southwest beyond the previously proposed boundaries. Warmer, thinner lithosphere underlies the Paramirim and Pirapora aulacogens, locations of magmatic and rifting cycles. A fragmented cratonic root underlies the Paraná Basin, with thinner lithosphere along its central rift. High velocities south of the Paraná Block indicate the northern Rio de la Plata Craton’s thick root. The Cenozoic intraplate basalts in the Borborema province, along the southern Atlantic coast and in Paraguay occurred in areas of thin lithosphere and near thick-thin lithospheric boundaries. Most flood basalts of the Phanerozoic large igneous provinces also map on low velocity areas. Smaller flood-basalt portions sit atop cratonic lithosphere and offer new evidence on lateral flow of flood-basalt lava and magma within the crust. About 80 % of known diamondiferous kimberlites are on thick lithosphere, with the exceptions indicating cratonic erosion and thinning since their emplacement

Waveform tomography of the Antarctic Plate

We present a new seismic shear wave velocity model of the upper mantle of the Antarctic Plate region, AP2024. It includes the lithosphere and underlying mantle down to 660 km depth beneath both the continental and oceanic portions of the plate. To augment the limited seismic station coverage of Antarctica, we assemble very large regional and global data sets, comprising all publicly available broad-band seismic data. The model is built using 785 thousand seismograms from over 27 thousand events and 8.7 thousand stations. It is constrained by both body and Rayleigh surface waves, ensuring the dense data sampling of the entire upper mantle depth range. The tomographic inversion is global but focused on the Antarctic Plate, with the data sampling maximized in the Southern Hemisphere, with elaborate automated and manual outlier analysis and removal performed on the regional data, and with the regularization tuned for the region. The upper mantle of the Antarctic continent exhibits a bimodal nature. The sharp boundary along the trans-Antarctic mountains separates the cratonic eastern from tectonic western Antarctica and shows a shear-velocity contrast of up to 17 per cent at∼100 km depth. The bimodal pattern is also seen in the oceanic part of the plate, with the older oceanic lithosphere beneath the Indian sector of the Southern Ocean showing higher shear velocities. The continental lithosphere in East Antarctica shows high velocity anomalies similar to those beneath stable cratons elsewhere around the world. It is laterally heterogeneous and exhibits significant thinning in the near-coastal parts of Dronning Maud Land and Wilkes Land. A low velocity channel is observed along the southern front of the West Antarctic Rift System and is probably related to Cenozoic rifting. High seismic velocity anomalies are detected beneath the Antarctic Peninsula and are likely to indicate fragments of the recently subducted Phoenix Plate Slab. Low velocity anomalies beneath Marie Byrd Land extend into the deep upper mantle and are consistent with a deep mantle upwelling feeding West Antarctica intraplate magmatism

Classification of Bryde’s whale individuals using high-resolution time-frequency transforms and support vector machines

Whales generate vocalizations which may, deliberately or not, encode caller identity cues. In this study, we analyze calls produced by Bryde’s whales and recorded by ocean-bottom arrays of hydrophones deployed close to the Costa Rica Rift in the Panama basin. These repetitive calls, consisting of two main frequency components at ~20 and ~36 Hz, have been shown to follow five coherent spatio-temporal tracks. Here, we use a high-resolution time-frequency transform, the 4th-order Fourier synchrosqueezing transform (FSST4), to extract time-frequency characteristics (ridges) from each call to appraise their suitability for identifying individuals from each other. Focusing on high-quality calls recorded less than 5 km from their source, we then cluster these ridges using a Support Vector Machine (SVM) model resulting in an average cross-validation error of ~11% and balanced accuracy of ~86 ±5%. Comparing these results with those obtained using the standard short-time Fourier transform, k-means clustering, and lower-quality signals, the FSST4 approach, coupled with SVM, substantially improves classification. Consequently, the Bryde’s whale calls potentially contain individual-specific information, implying that individuals can be studied using ocean-bottom data

Investigation of Depth and Dimension Effects on Ireland’s Karst Aquifers Using Synthetic Seismic Reflected Data

Karst 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

Anisotropic Seismic Structure of the Northern East African Rift System and Red Sea from Surface Waves

Continental rifting is a fundamental process of plate tectonics that has been shaping our planet for billions of years. The northern East African Rift system, including the Gulf of Aden and the Red Sea, presents an excellent opportunity to study this process in locations sub -aerially prior to continental break-up, through to full seafloor spreading. We present results from anisotropic surface wave imaging of the region’s crust and uppermost mantle. Anisotropic structures provide additional information about the form of structures at depth and deformation in the region. We find low seismic velocities within the Main Ethiopian Rift (MER), the Red Sea and Gulf of Aden that likely represent melt emplaced in the crust and uppermost mantle. Radial anisotropy, defined as a difference in wave speed of vertically versus horizontally polarized seismic waves, is observed across the region but is strongest within the rift. The strength of radial anisotropy in the MER suggests that horizontally layered melt intrusions are the dominant mode of melt storage in the mid to lower crust. Azimuthal anisotropy, defined as a variation in seismic wave speed as a function of direction, shows complex patterns that are likely related to ancient structures away from the rift, and structures related to extension and melt emplacement within the rift. Taken together, our results suggest melt has played an important role in shaping the crustal structure within the rift and may have also shaped the ancient pre-rift crustal structure

Irish National Seismic Network: An Enhanced Detection Capability

The 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

3D_DIG_Moho_and_LAB_Model_EChambers2024.nc

READ 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