Norwegian Geotechnical Institute (NGI) Digital Archive
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Applied Avalanche Research in Norway: Fonnbu 50-year celebration
No full textNGI’s avalanche research station at Strynefjellet in western Norway was officially opened in October 1973, and in September 2023 NGI and the AARN project invited to a 3- day celebration in Stryn.
The aim of the celebration was networking, knowledge transfer between generations, and strengthening the collaboration both with national and international research institutes.
Forty-three Norwegian and international colleagues and contacts were gathered at Hjelle hotel. The event included a scientific seminar at the Jostedalsbreen National Park Centre, an anniversary dinner at Hjelle hotel, and a tour to Ryggfonn and Fonnbu. The event ended with a discussion on possibilities for future collaboration, research and networking, utilizing the facilities at Ryggfonn and Fonnbu.
This report summarizes the scientific contributions and discussions, as well as the discussion of future research and collaboration at Fonnbu.NVE (Norges vassdrags- og energidirektorat
An improved Chemcatcher-based method for the integrative passive sampling of 44 hydrophilic micropollutants in surface water – Part A: Calibration under four controlled hydrodynamic conditions
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Stakeholder evaluation of the co-production process of climate services. Experiences from two case studies in Larvik (Norway) and Flensburg (Germany)
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Calculation Method for Uplift Capacity of Suction Caisson in Sand Considering Different Drainage Conditions
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Tracking aftershock sequences using empirical matched field processing
Get PDFExtensive aftershock sequences present a significant problem to seismological data centres attempting to produce near real-time comprehensive seismic event bulletins. An elevated number of events to process and poorer performance of automatic phase association algorithms can lead to large delays in processing and a greatly increased human workload. Global monitoring is often performed using seismic array stations at considerable distances from the events involved. Empirical matched field processing (EMFP) is a narrow-frequency band array signal processing technique that recognizes the inter-sensor phase and amplitude relations associated with wavefronts approaching a sensor array from a given direction. We demonstrate that EMFP, using a template obtained from the first P arrival from the main shock alone, can efficiently detect and identify P arrivals on that array from subsequent events in the aftershock zone with exceptionally few false alarms (signals from other sources). The empirical wavefield template encodes all the narrow-band phase and amplitude relations observed for the main shock signal. These relations are also often robust and repeatable characteristics of signals from nearby events. The EMFP detection statistic compares the phase and amplitude relations at a given time in the incoming data stream with those for the template and is sensitive to very short-duration signals with the required characteristics. Significant deviations from the plane-wavefront model that typically degrade the performance of standard beamforming techniques can enhance signal characterization using EMFP. Waveform correlation techniques typically perform poorly for aftershocks from large earthquakes due to the distances between hypocentres and the wide range of event magnitudes and source mechanisms. EMFP on remote seismic arrays mitigates these difficulties; the narrow-band nature of the procedure makes arrival identification less sensitive to the signals’ temporal form and spectral content. The empirical steering vectors derived for the main shock P arrival can reduce the frequency dependency of the slowness vector estimates. This property helps us to automatically screen out arrivals from outside of the aftershock zone. Standard array processing pipelines could be enhanced by including both plane-wave and empirical matched field steering vectors. This would maintain present capability for the plane-wave steering vectors and provide increased sensitivity and resolution for those sources for which we have empirical calibrations.Tracking aftershock sequences using empirical matched field processingacceptedVersionpublishedVersio
The EU Center of Excellence for Exascale in Solid Earth (ChEESE): Implementation, results, and roadmap for the second phase
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Identifying mountain permafrost degradation by repeating historical electrical resistivity tomography (ERT) measurements
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A set of codes for numerical convection and geodynamo calculations
Get PDFWe present a set of codes for calculating and displaying solutions to diverse problems within thermal convection and magnetic field generation in rotating fluid-filled spheres and spherical shells. There are diverse programs for the kinematic dynamo problem, the onset of thermal convection, and boundary-locked thermal convection, and time-stepping codes for non-magnetic convection and the dynamo with either homogeneous or spatially varying thermal boundary conditions. Where possible, all programs have been benchmarked against other codes and tested by reproducing previously published results. Each program comes with the complete source code, a pdf instruction manual, and at least one example run with a sample input file and all necessary files for describing an initial condition. The only prerequisite for running most of the codes is a FORTRAN compiler. The plotting programs require in addition the PGPLOT graphics library. All source code, examples, input files, solutions, and instructions are available for download from github and Zenodo