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Two subglacial lakes in the western part of Vatnajökull ice cap, southeastern Iceland, 10 and 15 km WNW of Grímsvötn volcano, are the source of regular jökulhlaups in the Skaftá river. The eastern cauldron featured a jökulhlaup that started on 30 September 2015. The seismic signals generated by the flood were recorded using two seismic arrays (clusters of seismometers) operated by the Dublin Institute for Advanced Studies (DIAS) and the Icelandic Meteorological Office’s national seismic network, SIL. The arrays were maintained outside Vatnajökull ice cap. In the Vatnajökull region, the SIL network consists of stations that are partly installed on nunataks and within the ice. We performed array-processing in the frequency domain (FK-analysis) on data filtered 1.2 to 2.6 Hz using the array-processing code as implemented in Obspy to derive back azimuth and slownesses of a tremor source propagating with the flood front. We perform beam stacking in the time domain on data filtered from 5 to 20 Hz to derive the back-azimuth of high-frequency transients moving with the flood front. We used the SIL network for location and magnitude determination of 45 events near the cauldron and the flood path. These are possibly 22 icequakes and 23 earthquakes. We used the array data to apply an STA/LTA filter and template matching approach on data filtered from 1 to 15 Hz to detect 669 events associated with the flood. 30% of these could be clustered into families and are likely due to the ice-shelf collapse once the subglacial lake drained. These catalogs are further discussed and evaluated in Eibl et al. 2020 and Eibl et al. 2023. This data publications releases the catalogs of (i) tremor, (ii) located events and (iii) STA/LTA detected and clustered events.
The eleven islands of the South Sandwich volcanic arc are amongst the least explored places on Earth. The mostly glacier covered volcanoes are home to the largest penguin colonies worldwide, and nine of them have reported (historic) eruptive activity. Any attempt of systematically mapping volcanic activity, or landscape- and glacier dynamics at the South Sandwich Islands is challenging due to their remoteness and inaccessibility.The data presented here were acquired in the framework of the volcano-related project “SSIVOLC” during cruise PS119 on board the German icebreaker research vessel RV Polarstern that headed to the South Sandwich Islands on 15 April 2019 from Punta Arenas and retuned on 31 May 2019 to the Falkland Islands. A major aim of SSIVOLC was to collect photogrammetric data of the glacier-covered Mount Michael Volcano on Saunders Island, which is highly active and holds an active lava lake within its summit crater, which seems to be persistent since the 1990s (Grey et al. 2019).Here, we are providing full access to optical DSLR camera footage and to a selection of still images acquired by unmanned aerial vehicles (UAVs) that we were able to collect on May 17 and May 22, 2019. Because of the remoteness, inaccessibility, and difficult climatic conditions, footage like this is extremely rare, but of great value to various scientific communities, including volcanologists, biologists, and glaciologists. The data were acquired using handheld DSLR cameras and two different UAV models. The former were taken by scientists aboard RV Polarstern using consumer cameras of type Panasonic DMC-G6, Canon EOS 7D Mark II, or SONY DSC-RX10M3 that carried the DMC-G6 (integrated), EF28-300mm (f/3.5-5.6L IS USM), and DSC-RX10M3 (integrated) lenses, respectively (cf. Table 1). The UAV images were acquired in 2-second time-lapse mode using the DJI Mavic 2 Pro, and the DJI Phantom 4 Pro quadcopters. The performance of the UAVs under very cold (-15°C to 0°C) and windy (8 to 25 knots) conditions, and during low light or dark hours exceeded our expectations.Our UAVs were operated under special permission that was designed by the Govenor under Article 6 of the Air Navigation (Overseas Territories) Order 2013, and issued by the Government of South Georgia and the South Sandwich Islands (GSGSSI) and the Air Safety Support International Ltd. This special permission allowed for the operation of the small unmanned aircraft Beyond Visual Line of Sight (BVLOS) and up to an altitude of 5,000 ft, in the United Kingdom Overseas Territory of South Georgia and the South Sandwich Islands. We were launching the UAVs from the RV Polarstern (located just offshore the island), and reached a maximum UAV altitude of 1,370 m above sea level, which allowed for the collection of the unprecedented UAV based photo archive of Saunders Island.The associated data descriptinon summarizes the basic parameters of the UAV flights, the weather conditions, and the major issues that we were facing while operating the drones under the given circumstances. We are summarizing important metadata of our footage in Table 1, and the footprints and viewing geometries are given in Figure 1. The data are provided in .JPG format. Each drone acquisition carries the GPS coordinates (GCS Lat/Long WGS84) of the UAV position in their properties. Panorama pictures (named PA-xx-xx-xx) are not provided in full resolution (for storage reasons), but can be shared in full resolution upon request (please contact the corresponding author, N. Richter). We also discuss some details and give interpretations for selected acquisitions below, referring to an additional labelled version (provided in .PDF format). Please note that the scales on labelled pictures are rough estimates only as in fact scales vary significantly throughout the depth of each picture.
Seismological experiment at Strokkur from 2020" is a seismological experiment realized at the most active geyser on Iceland by Eva Eibl (University of Potsdam) in collaboration with Gylfi P. Hersir formerly at ISOR Iceland. The geyser is part of the Haukadalur geothermal area in south Iceland, which contains numerous geothermal anomalies, hot springs, and basins (Walter et al., 2018). Strokkur is a pool geyser and has a silica sinter edifice with a water basin on top, which is about 12m in diameter with a central tube of more than 20m depth. The aim of the seismic experiment is to monitor eruptions of Strokkur geyser from March 2020 using three broadband seismic stations (Nanometrics Trillium Compact 120s). Sensors were buried at distances of 38.8m (GE4, SE), 47.3m (GE3, SW), and 42.5m (GE2, N) from Strokkur center. Within this time period about 1 month of data is missing due to power outages. At any other times at least one station recorded the eruptions. From this dataset, converted to MSEED using Pyrocko, currently a catalogue of 506,131 water fountains was determined and further investigated in Eibl et al. (2025). In addition, Eibl et al. (2025) assessed the effect of the weather on the system including the bubble trap suspected at around 24 m depth by Eibl et al. (2021). Waveform data are available from the GEOFON data centre, under network code 2Z.
The interactive web page contains supplementary information for a publication by Hensch et al. 2019: "Deep low-frequency earthquakes reveal ongoing magmatic recharge beneath Laacher See Volcano (Eifel, Germany)". Details on the analysis of three tectonic and nine deep low-frequency earthquakes are given, including parameter results, error estimates, and figures. The analysis has been performed using the Grond software package (Heimann et. al 2018).The open source software for seismic source parameter optimization (Grond, Heimann et al., 2018) implements a bootstrap-based method to retrieve solution sub-spaces, parameter trade-offs and uncertainties of earthquake source parameters. Synthetic and observed P and S phase waveforms are restituted to displacement and filtered between 0.5 and 5 Hz in variable frequency ranges, depending on the signal-to-noise ratio (SNR) and the character of the signals. Station amplification factors and transfer functions have been evaluated before the restitution using an empirical calibration method (see Dahm et al., 2018). From waveforms, different types of body wave attributes were calculated, as amplitude spectra, envelopes, and amplitude spectral ratios.The Green's functions (GF) were calculated with the orthonormal propagator method (QSEIS, Wang, 1999; see https://github.com/pyrocko/fomosto-qseis/), for a 1 km grid spacing in a volume of 150 km source-receiver distances and 1 - 50 km source depths. The sampling rate was 40 Hz and the GF include near field terms. All GF are stored in a Pyrocko GF store (Pyrocko toolbox, see Heimann et al., 2017). We use a nearest neighbor interpolation in between the grid points of the pre-computed GF.Restituted observed and synthetic ground displacement time series are filtered and windowed between [-2 s; +3 s] from the expected phase arrival, given the tested candidate source model at each forward modeling step in the optimization. Additional to full waveforms, amplitude spectra, envelopes and spectral ratios between P-SV and SH-SV waves are compared. For spectral ratios, a water level approach was implemented to avoid bias from high noise. All components of the mixed inversion received a proper linear weighting with factors between 0.5 and 3, which was selected after running tests with some master events. Weighting and frequency range were defined different for earthquakes with magnitudes above or below ML 2. P and S phase arrivals have been picked to ensure correct selection of time windows during the centroid inversion, and station blacklists were considered event-wise, depending on the SNR.The plots show for every event the data fits and different types of solution plots. The naming of pages is self-explanatory, but more information can be found in the Grond documentation (https://pyrocko.org/grond/). In order to evaluate the ensembles of solutions for interpretation, we extended the standard statistical analysis of Grond to consider a cluster analysis of source mechanism distributions before statistical analysis. This is introduced because the best ensemble solutions of many of the DLF events show higher variability and groups of different mechanisms. A simple mean or median does not always represent the families of best performing solutions. We therefore declustered the ensemble of best solutions using the method of Cesca et al. (2013), applying the Kagan angle norm, and performed the statistical analysis for each individual cluster.
In May 2018 a volcano-seismic sequence accompanied the upward migration of a magmatic intrusion from Moho depth to the seafloor led to the drainage of the deep magmatic reservoir and to the birth of a submarine volcano offshore the island of Mayotte, Comoro Islands. This process of magma transport was accompanied by an intense seismic swarm and peculiar long-duration very long period signals. Between 1 January 2018 and 1 May 2019 we detected 407 sources of very long period signals and 6990 volcano-tectonic earthquakes. This report collects detection, location and source parameters catalogs for these two sets of earthquake sources.This data publication provides the catalogues of very long period (VLP) signals and volcano-tectonic (VT) earthquakes, as discussed in Cesca et al. (2019). Here, methods and data used to create the different catalogues are only briefly discussed; a more accurate description is given in Cesca et al. (2019), which furthermore discusses the different processes of dike migration, undersea eruption, deep reservoir drainage and overburden sagging which are responsible for the seismic activity.
In October 2021, GFZ installed together with INGV Catania, Iraci and ASIR Ltd (Advances Seismic Instrumentation & Research) the very first seismic borehole broadband seismometers at two selected sites at Mt. Etna, Sicily (see Fig. 1). The installation was completed under the EU-funded project ‘SiC nano for PicoGeo’ (http://www.picogeo.eu/). Site one is located next to the Astrophysical Observatory at Serra La Nave (SLN) and site two is located in the city of Mascalucia (MAS). At each site one borehole broadband seismometer was permanently installed (cemented) at approximately 70 m depth. In approx. 1-2m distance, a second ground-level borehole 4.5 Hz Geophone was temporarily installed (sanded) at 1 m depth until July 2022 (see Fig. 2). The ground-level geophones served as a local surface reference sensor to better evaluate the increase of signal quality from surface to depth. Test data were evaluated between October 2021 and July 2022. Sensor settings were adjusted during this time period to obtain the best possible data resolution at both test sites. This data publication compiles a segment of waveform recordings utilized for the assessment of data quality from the two installed broadband borehole seismometers, along with noise plots (Fig. 3-5) illustrating the enhancements in the data quality of frequency ranges compared to surface sensors at Mt. Etna.
Cliffs line many erosional coastlines. Localized failures can cause land loss and hazard, and impact ecosystems and sediment routing. Links between cliff erosion and forcing mechanisms are poorly constrained, due to limitations of classic approaches. Combining multi-seasonal seismic and drone surveys, wave, precipitation and groundwater data we study drivers and triggers of seismically detected failures along the chalk cliffs on Germany's largest island, Rügen. The network consists of four (later five) seismic stations along the 8.6 km long chalk cliff coast. Waveform data are available from the GEOFON data centre, under network code 4K.
Strokkur_1yr is a one year seismological experiment realized at the most active geyser on Iceland by Eva Eibl (University of Potsdam) in collaboration with Thomas R. Walter, Phillippe Jousset, Torsten Dahm, Masoud Allahbakhshi, Daniel Müller from GFZ Potsdam and Gylfi P. Hersir from ISOR Iceland. The geyser is part of the Haukadalur geothermal area in south Iceland, which contains numerous geothermal anomalies, hot springs, and basins (Walter et al., 2018). Strokkur is a pool geyser and has a silica sinter edifice with a water basin on top, which is about 12 m in diameter with a central tube of more than 20 m depth. The aim of the seismic experiment is to monitor eruptions of Strokkur geyser from June 2017 to June 2018 using four broadband seismic stations (Nanometrics Trillium Compact Posthole 20 s). Sensors were buried 30–40 cm deep in the ground at distances of 38.8 m (G4, SE), 47.3 m (G3, SW), 42.5 m (G2, N), and 95.5 m (G1, NE) from Strokkur center. Data gaps represent 15–44 % of the records as during the winter period maintenance intervals were longer and battery drainage was high. However, at any given time, at least one station recorded the eruptions. From this dataset, converted to MSEED using Pyrocko, a catalogue of 70,000 eruptions was determined and further investigated in Eibl et al. (2020) Waveform data are available from the GEOFON data centre, under network code 7L.
Geysers are accessible sites of hot pots, springs and pools that regularly erupt. To investigate the frequency and dynamics of water eruptions we setup a local broadband seismic network at Strokkur geyser, Iceland. The experiment was running for 1 year, from June 2017 to June 2018. Four broadband seismic stations (Nanometrics Trillium Compact Posthole 20s) were buried 30-40 cm deep in the ground at a distance of 39 m (G4, SE), 47 m (G3, SW), 43m (G2, N) and 96 m (G1, NE) from the center of the Strokkur pool geyser. Regular visits and 2-month interval battery replacement allowed to power the stations without solar panels, therewith limiting visibility and site impact. From this data we picked a catalog of 73,466 eruptions, that are statistically further evaluated in Eibl et al. (2020), allowing to distinguish 50,135 single eruptions, and over 20,000 multiplet eruptions (i.e. several eruptions in close succession). The mean waiting time after an eruption at Strokkur linearly increased from 3.7 to 16.4 min for single and multiplets, respectively. This data publications releases the catalog of 73,466 eruptions.
This dataset documents surface deformation and fracture evolution on Mount Thorbjörn during the 2023 - 2024 volcano-tectonic unrest in the Svartsengi volcanic system on the Reykjanes Peninsula (SW Iceland). The data consist of four cm-resolution orthophotos and digital elevation models (DEMs) derived from four drone photogrammetric surveys conducted on 23 July 2022, 18 November 2023, 25 April 2024 and 20 August 2024. The drone images were processed using Agisoft Metashape software to generate products for structural mapping and temporal comparison. The drone data evidences fracture reactivation processes and associated new surface fractures and sinkholes. The dataset includes maps of these structures, carried out using QGIS, and describes their temporal evolution. A full description of the data can be found in the file description.
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