Methods and resaults

In the following the methods and results of the PRENLAB-TWO project will be descibed in detail.

 

• Monitoring crustal processes for reducing seismic risk
  • Data collection
    • Data access
  • Enhancing the basis for alerts, warnings and hazard assessments
  • Modelling of near-field ground motions in catastrophic earthquakes in Iceland
• Applying new methods using microearthquakes for monitoring crustal instability
  • Investigation and monitoring of stable/unstable fault movements
    • Methods
    • The microearthquakes of the example
    • Automatic relating of the earthquakes to individual fractures
    • Discussion of picture of the seismic activity given by the automatic grouping
    • Conclusions
  • Spectral amplitude correlation
    • Composite focal mechanisms
    • Preprocessing stress tensor inversion data
• Shear-wave splitting monitoring pre-fracturing deformation
• Borehole monitoring of fluid-rock interaction
• Active deformation determined from GPS and SAR
  • SAR interferometry study of the South Iceland seismic zone
  • GPS measurements of absolute displacements
  • Digitized fault map
  • Achievements
• Effects of stress fields and crustal fluids on the development and sealing of seismogenic faults
  • Paleostress fields associated with the test areas from fault-slip data
  • Reconstruct the current stress fields associated with the test areas applying inversion of large sets of focal mechanisms of earthquakes.
  • Geodetic analysis of present day crustal displacements.
  • Investigation of the potential effects of fluid pressure on the probability of faulting
  • Detailed analysis of the Tjörnes fracture zone test site and its vicinity
  • Analysing the fracture properties of Icelandic rock in the laboratory and to make theoretical, observational and experimental studies on the sealing of seismogenic faults with application to the test areas in Iceland
    • Starting material
    • Changes and evolution of rock physical properties with temperature
    • Fracture toughness of heat-treated Icelandic basalt
    • Crack linkage and enhanced fluid permeability in heat-treated Icelandic basalt
• Theoretical analysis of faulting and earthquake processes
  • Magma upwelling as driving mechanism for the stress build-up in the elastic lithosphere
  • Space-time evolution of the stress field following earthquakes and episodes of magma upwelling
  • Secondary earthquake fractures generated by a strike-slip fault in the South Iceland seismic zone
• 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
    • The method
    • The targets
    • The tectonic setting
    • The initial stress field
    • The earthquake data
  • Changes and improvements in PRENLAB-2
    • Two problems were addressed next
  • Extrapolation of the stress field calculated within PRENLAB for the next years
  • Pin-pointing of stress concentrations in space and time
  • Search for characteristic preseismic stress level