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Contents
Contents
Summary
Activity overview
Significant achievements as concerns short-term warnings, hazard assessments and understanding crustal processes related to earthquakes
New methods and algorithms have been developed and are applied - a basis for earthquake warnings
Changes of shear-wave splitting time to observe changes of stress
Short-term warnings based on continuous observation of the strike of horizontal compressions from fault plane solutions of microearthquakes
Slungawarning, an algorithm for alerting about time and site of impending earthquakes
SAG, spectral amplitude grouping, a method for monitoring general stress increase in an area
New observations and new understanding of earthquake related crustal processes, a basis for long-term as well as real-time interpretations
The build-up of continuous GPS measurements in Iceland and observations of active deformation preceding earthquakes
Seismic and interseismic deformation observed by interferometric analysis of Synthetic Aperture Radar (InSAR) images
The significance of paleoseismology for catching the variability of seismicity in time and space
Laboratory studies of rock samples and fluid activity in the fault zones
Modelling of processes in earth realistic heteorogenic crust
Significant warnings and other risk mitigating information during the project period
Stress forecast before the magnitude 5 earthquake on November 13, 1998
Short-term prediction and warning before the Hekla eruption starting on February 26, 2000
Short-term warning about size and location of a magnitude 6.6 earthquake in the South Iceland seismic zone (SISZ)
Continuation towards new research projects and enhanced warning service based on the results of the PRENLAB projects
A project for building an early warning system in Iceland
Developing a stress monitoring site near Húsavík, N-Iceland
Continuation of PRENLAB-2 research based on observations of the two large SISZ earthquakes in June 2000
Meetings and workshops
The role of the responsible institutions
IMOR.DG: Icelandic Meteorological Office, Department of Geophysics
UUPP.DGEO: Uppsala University, Department of Geophysics
UEDIN.DGG: University of Edinburgh, Department of Geology and Geophysics
GFZ.DR.DBL: Stiftung GeoForschungsZentrum Potsdam - Solid Earth Physics and Disaster Research - Earthquakes and Volcanism
NVI: Nordic Volcanological Institute
CNRS.TT: Centre National de la Recherche Scientifique, Delegation Paris B - Département de Géotectonique
UBLG.DF: University of Bologna, Department of Physics
CNRS.DTP: Centre National de la Recherche Scientifique, UPR 0234 - Dynamique Terrestre et Planétaire
Summary of scientific achievements by subprojects and tasks
Subproject 1: Monitoring crustal processes for reducing seismic risk
Task 1: Database development and service for other scientists
Task 1.1: Data collection
Task 1.2: Data access
Task 2: Enhancing the basis for alerts, warnings and hazard assessments
Task 3: Modelling of near-field ground motions in catastrophic earthquakes in Iceland
Task 4: Mobile stations for shear-wave splitting monitoring
Task 5: Extending the alert system functions by real-time research
Methods tested and applied for short- and medium-term warnings
An early warning system and an early warning database
Warnings for hazards in practice
Task 6: To prepare the SIL system and the alert system for use in other risk areas
References
Subproject 2: Applying new methods using microearthquakes for monitoring crustal instability
Real-time mass evaluation of relative locations
Slungawarning, an algorithm based on microearthquakes for alerting about time and site of impending earthquakes
The Spectral Amplitude Grouping method (SAG) for analyzing crustal stress conditions. A potential for intermediate-term warnings
Real-time inversion of stress tensor
References
Subproject 3: Using shear-wave splitting to monitor stress changes before earthquakes and eruptions
Task 1: Continuous monitoring of shear-wave splitting
Temporal variations in time-delays
Stress-forecasting earthquakes
Task 2: Analysis of shear-wave splitting measurements
Task 3: Establish shear-wave splitting map of Iceland
Task 4: Calibrate techniques and behaviour if and when changes are identified
Task 5: Incorporate shear-wave splitting interpretations into routine analysis
Meetings and conferences
References
Subproject 4: Borehole monitoring of fluid-rock
interaction
Geophysical logging
Task 1: Repeated logging in borehole Nefsholt
Tasks 2, 3, and 4: Cross correlation of logs of the same type from different campaigns and earlier loggings; comparison of changes in logs of different type; comparison of changes in logs with changes in seismicity, etc.
Acknowledgements
References
Subproject 5: Active deformation determined from GPS and SAR
Subpart 5A: SAR interferometry study of the South Iceland seismic zone
Subpart 5B: GPS measurements of absolute displacements
References
Subproject 6: Effects of stress fields and crustal fluids on the development and sealing of seismogenic faults
Task 1: Determination of the paleostress fields associated with the test areas from fault-slip data
Task 1.1: The South Iceland seismic zone (SISZ)
Task 1.2: The Tjörnes fracture zone (TFZ)
Task 2: Reconstruction of the current stress field associated with the test areas
Task 2.1: Inversion of large sets of focal mechanisms of earthquakes
Task 2.2: Seismotectonic analysis of individual faults
Task 3: Present-day deformation from GPS network and interferograms of ERS-SAR scenes
Task 3.1: Measuring the present-day crustal displacements in the Tjörnes fracture zone and adjacent areas
Task 3.2: 1992-1998 deformation of the Krafla volcano
Task 4: Effects of fluid pressure on faulting
Task 5: Numerical models on faults and fault populations
Task 6: Analyzing the fracture properties of Icelandic rocks in the laboratory
Task 6.1: Apparatus development
Task 6.2: Experimental results and discussion
Conclusions
References
Subproject 7: Theoretical analysis of faulting and earthquake processes
Subpart 7A: Ridge-fault interaction in Iceland employing crack models in heterogeneous media
Task 1: Magma upwelling as driving mechanism for the stress build-up in the elastic lithosphere
Task 2: Space-time evolution of the stress field following earthquakes and episodes of magma upwelling
Task 3: Secondary earthquake fractures generated by a strike-slip fault in the South Iceland seismic zone
Meetings and conferences
Subpart 7B: Modelling of the earthquake related space-time behaviour of the stress field in the fault system of southern Iceland
The model for the earthquake sequence at the SISZ
Task 1: Extrapolation of the stress field for the next years
Task 2: Pin-pointing of stress concentrations in space and time
Task 3: Search for characteristic preseismic stress level
Meetings and conferences
Acknowledgements
References
Publications
Papers directly associated with PRENLAB-2
Subproject 1
Subproject 2
Subproject 3
Subproject 4
Subproject 5
Subproject 6
Subproject 7
About this document ...
Hjorleifur Sveinbjornsson
2001-01-08
