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Multiparametric measurements of the 2021 Tajogaite eruption on La Palma, Canary Islands, Spain

This data repository contains electrical and seismic tremor measurements, thermal infrared imagery, atmospheric conditions and information on plume heights that were recorded and collected during the 2021 Tajogaite eruption on La Palma, Canary Islands, Spain. The 2021 Tajogaite eruption lasted from 19 September until 13 December 2021. The "data description" file provides more detailed information on each dataset and the way the data is formatted. The electrical data was recorded using a Biral Thunderstorm Detector BTD-200. This sensor was installed at two consecutive locations: BTD1 (28.635°N, 17.876389°W) recorded from 11-26 October 2021 and BTD2 (28.602365°N, 17.880475°W) recorded from 27 October 2021 until the end of the eruption. The volcanic tremor measurements were recorded at seismic station PLPI (28.5722°N, 17.8654°W), which was operated by the Instituto Volcanológico de Canarias. Here we provide the seismic tremor amplitudes within the Very Long Period (0.4-0.6 Hz) and the Long Period (1-5 Hz) frequency bands between 10 September and 20 December 2021. Thermal infrared videography of the explosive volcanic activity was done using an InfraTec HD thermal infrared (TIR) video camera. This camera was installed in El Paso (28.649361°N, 17.882279°W) and recorded almost continuously between 3-8 November 2021. Here we provide individual thermal infrared frames. Atmospheric conditions were obtained from weather balloon measurements at Güímar (station nr. 60018) on Tenerife, which were provided by the University of Wyoming, Department of Atmospheric Science (http://weather.uwyo.edu/). In addition, atmospheric data was collected from ground-based weather stations at El Paso and Roque de los Muchachos, which were operated by the State Meteorological Agency (AEMET) of Spain on La Palma. Information on the volcanic plume heights was obtained from both the Toulouse Volcanic Ash Advisory Center (https://vaac.meteo.fr/volcanoes/la-palma/) as well as the Plan de Emergencias Volcánicas de Canarias.

sdaas - a Python tool computing an amplitude anomaly score of seismic data and metadata using simple machine learning algorithm

The increasingly high number of big data applications in seismology has made quality control tools to filter, discard, or rank data of extreme importance. In this framework, machine learning algorithms, already established in several seismic applications, are good candidates to perform the task flexibility and efficiently. sdaas (seismic data/metadata amplitude anomaly score) is a Python library and command line tool for detecting a wide range of amplitude anomalies on any seismic waveform segment such as recording artifacts (e.g., anomalous noise, peaks, gaps, spikes), sensor problems (e.g., digitizer noise), metadata field errors (e.g., wrong stage gain in StationXML). The underlying machine learning model, based on the isolation forest algorithm, has been trained and tested on a broad variety of seismic waveforms of different length, from local to teleseismic earthquakes to noise recordings from both broadband and accelerometers. For this reason, the software assures a high degree of flexibility and ease of use: from any given input (waveform in miniSEED format and its metadata as StationXML, either given as file path or FDSN URLs), the computed anomaly score is a probability-like numeric value in [0, 1] indicating the degree of belief that the analyzed waveform represents an anomaly (or outlier), where scores ≤0.5 indicate no distinct anomaly. sdaas can be employed for filtering malformed data in a pre-process routine, assign robustness weights, or be used as metadata checker by computing randomly selected segments from a given station/channel: in this case, a persistent sequence of high scores clearly indicates problems in the metadata

Long-period transients (tilt signals) on continuous broadband seismograms recorded during meter-scale hydraulic fracturing experiments at Äspö Hard Rock Laboratory

This dataset contains processed (downsampled, rotated to local Äspö96 coordinate system, cut) broadband seismograms from two seismometers (Trillium Compact 120s), showing long-period transients on the horizontal components recorded during multiple hydraulic fracturing experiments in the Äspö Hard Rock Laboratory (HRL). Furthermore, the dataset contains extracted tilt time series and the injection parameters of the experiment to allow reproducing the results of Niemz et al. (2021). The seismic waveforms were recorded during meter-scale hydraulic fracturing experiments in the Äspö Hard Rock Laboratory (HRL) in Sweden (Zang et al., 2017). This dataset only contains a subset of the data recorded during the experiments, monitored by a complementary monitoring system. The two seismometers contained in this dataset (A89 and A8B) were located in galleries adjacent/close to the injection borehole (see Fig. 2 in Niemz et al., 2021). The experiments were conducted at the 410m-depth level of the Äspö HRL. Each of the six experiments (HF1 to HF6) consisted of multiple stages with an initial fracturing and three to five refracturing stages (see injection parameters contained in this dataset). The six injection intervals were located along a 28m-long injection borehole. The borehole was drilled sub-parallel to the minimum horizontal compressive stress direction. The distance of the two seismometers to the injection intervals in the injection borehole is between 17 m and 29 m for sensor A89 and 52 m to 72 m for sensor A8B. A89 and A8B correspond to BB1 and BB2 in Niemz et al., 2021. For more details regarding the experimental setup, see Zang et al., 2017; Niemz et al., 2020; and Niemz et al., 2021. The records of the two seismometers show long-period transients that correlate with the injection parameters. These transients are the response of the seismometers to a tilting of the gallery floor. The extracted tilt time series provide independent insight into the fracturing process during the hydraulic stimulations (Niemz et al., 2021).

Source parameters of Acoustic Emissions from triaxial experiments on Westerly granite, Aue Granite and Flechtigen Sandstone

This dataset is supplementary material to "What controls the presence and characteristics of aftershocks in rock fracture in the lab?" by Joern Davidsen, Thomas H. W. Goebel, Grzegorz Kwiatek, Sergei Stanchits, Jordi Baro and Georg Dresen (Davidsen et al., 2021). The dataset contains source parameters of acoustic emission events recorded during triaxial fracture and friction (stick-slip) experiments performed on two Westerly Granite samples, Aue Granite and Flechtigen Sandstone. Basic seismic catalog associated with each experiment contains origin time, hypocentral location in local Cartesian coordinate system of the sample, acoustic-emission derived magnitude and polarity coefficient (a simplified measure of mechanism type: shear, pore opening or collapse). Extended catalog information is available for selected experiments including information whether event is background seismicity, trigger of following events or triggered by preceding events. In addition, we provide information on focal mechanisms calculated in each experiment using full moment tensor inversion. Focal mechanism catalogs include information on strike, dip and rake of two nodal planes, and percentage of isotropic, clvd and double-couple components of the full moment tensor. The detailed description of catalog is provided in the data description file which is also included in the zip folder of the data.

Black Forest Observatory Data

The Black Forest Observatory Data collection compiles digital data recorded at Black Forest Observatory (BFO) in Germany and provided through several international data centers. BFO aims to observe the entire geodynamic spectrum. It strives to ensure continuous, uninterrupted operation and is internationally recognized for high signal quality and sensitivity. Observed quantities cover three components of acceleration (including ground motion, gravity and tilt), strain, magnetic field, and others (see description of instruments below). The set of instruments and data recorders in operation provides a significant level of redundancy, which allows to distinguish natural phenomena from possible instrumental artefacts. The Black Forest Observatory (BFO) is a joint research facility of the Karlsruhe Institute of Technology (KIT) and the University of Stuttgart (Duffner et al., 2018; Gottschämmer et al. 2014). Since 1971 it is operated in cooperation of the geophysical and geodetic institutes of both universities (Zürn, 2014). BFO is staffed with two scientists and one technician. Main activities of the observatory fall into four categories, which are (1) observation and publication of a continuously recorded multi-parameter geodynamic data set, (2) research, (3) hosting of guest-experiments, and (4) teaching. The location of the observatory (48.3301 °N, 8.3296 °E) in the middle of the Black Forest was carefully selected at large distances to potential anthropogenic sources of noise. The instruments are deployed in a former silver mine in competent granite rock at a depth of up to 170 m below the surface and at up to 700 m distance from the entrance of the mine. This provides a thermally very stable environment. Two air-locks provide additional protection against air-pressure variations and ensure thermal stability. Because of these favorable conditions and the excellent high precision instruments operated at BFO the observatory is internationally well known as one of the most sensitive sites for long period observations, providing international standards for the scientific community, e.g. for recordings of Earth's free oscillations. The Black Forest Observatory operates broad-band seismometers (STS-1 and STS-2), gravimeters (superconducting gravimeter SG056, LaCoste Romberg earth-tide gravimeter ET-19), tiltmeters (Askania borehole tiltmeter, Horsfall fluid tiltmeter), an array of three invar-wire strainmeters, magnetometers (a scalar GSM-90 Overhauser magnetometer and a three component Rasmussen fluxgate magnetometers) and a permanent GPS-station. These are supplemented by regularly repeated magnetic base-line measurements and observations of absolute gravity as well as the recording of several environmental parameters (air-pressure, infrasound, humidity, wind speed, precipitation and temperature). Some of the latter are used to correct geodynamic recordings for remaining disturbances. The data are published in near-real-time through international data centers (IRIS DMC at Seattle, SZO at the BGR in Hannover, INTERMAGNET, GNSS Data Center at the BKG in Frankfurt, IGETS Database at GFZ Potsdam). Data are made available free of charge to scientific projects as well as to the general public with attribution as defined in the Creative Commons Attribution 4.0 International Licence (CC BY 4.0). An extended review of research at BFO is given by Zürn (2014) and Duffner et al. (2018, in German). Both provide references to published BFO research.

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