Main objectives of the workprogramme

PRENLAB is a two years multinational project of earthquake prediction research, starting early 1996. In this project multidisciplinary European technology and science are applied in a common action aimed at progress in earthquake prediction research and at reducing seismic risk. The questions are ``where, when and how'' large earthquake ground motions will occur. Answers are sought by studying the physical processes and conditions leading to large earthquakes. Iceland, sometimes called a Natural Geophysical Laboratory, is the test area for the project. The significance of the multidisciplinary approach of the PRENLAB project can be seen in the light of the following. The classical hazard assessment as it has been applied in Iceland and more countries is based mainly on historical documentation and limited information from instrumental earthquake catalogues of this century and a general knowledge of where the earthquake generating plate boundaries are. Although such hazard assessment is extremely useful in many aspects, it has the obvious limitations that it is only based on a few hundreds of years of history, and in fact assumes that we should only expect hazards that are comparable to those which have happened within this short history. Also it does not take into consideration the exact position of and the interaction of faults that are expected to move in earthquakes or earthquake sequences. It integrates effects over large areas in time and space while it is well known that by far the largest destruction is related to the proximity of the faults which are activated in the earthquakes each time and to the areas where the faults rupture the surface.

Hazard assessment based mainly on catalogues of earthquakes and their magnitudes has come to the state that it cannot have more progress:

• Until a better modelling of the fault processes has been achieved.
• Until we can recognize better the involved faults and monitor their movements and interaction.
• Until we can monitor better the stresses in the adjacent area and understand better the rheological properties and the role of fluids in the crust.

For a progress in earthquake hazard assessment and in general for progress in earthquake prediction research we must aim at creating dynamic models which can explain multiplicity of observations, which means that many disciplines of geosciences must be involved.

This is the basis of the PRENLAB project. It is a multidisciplinary approach in earthquake prediction research (Figure 1).

  

Figure: In the project multidisciplinary European technology and science are applied in a common action aiming at progress in earthquake prediction research and for reducing seismic risk. Scientists from 9 institutions in 6 European countries participated in the project as contractors or associated contractors, and in addition scientists from several other institutions.

The dynamic models to be created must comply with a multiplicity of observations in time scales ranging from seconds to millions of years, ranging from historical seismicity to microearthquake information, ranging from geological field observations to observations of deformation with space technology methods and borehole observations. The PRENLAB project collects information, developes methods and models to base further observations on to create a basis for a more general multidisciplinary modelling.

In the workprogramme of PRENLAB the overall objectives were summarized as follows:

• To develop methods for automatic extraction of all information available in the frequent microearthquake recordings, including fault mapping, rock stress tensor inversion, and monitoring of crustal instability.

• To make use of information from microearthquakes, geological information, historical as well as older seismological information for physical interpretation of and modelling the tectonic processes leading to earthquakes.

• To improve the understanding of the space and time relationship between earthquakes and other observable features associated with crustal deformation.

• To apply this knowledge for improved real-time evaluations and alert systems and for improved hazard assessments.