Information and warnings to authorities and to the public about seismic and volcanic hazards in Iceland.

Ragnar Stefansson
Icelandic Meteorological Office, Vedurstofan, Bustadavegura, IS-150, Reykyavik, Iceland.
Tel. : +354-560-0600, Fax: +354-552-8121,
E-mail: ragnar@vedur.is

The main pillar for watching of geological processes is the SIL system, which performs automatic high level analysis of data from 35 seismic stations. It analysis earthquakes down to magnitude zero to obtain hypocentres, magnitudes, fault plane solutions and other information, thus watching details of earth processes in semi-real time. It can cope with more than thousand earthquakes per day. Continuous tremor in a few frequency ranges is monitored at all stations. Information based on the monitoring of slow changes is also available in real time. Alerts based on multi station evaluations are automatically issued within a few minutes if specified features of activity in specified areas reach predefined alert levels. Alerts based on single station evaluations are issued within a couple of seconds. The alerts reach the attention of specialists who perform analysis of the real time information and issue warnings or information. Significant experience has been gained since 1992 in using the above systems for warnings and hazard information, which will be described by examples.