Seismicity in Iceland 2004

Abstract

In 2003 the SIL seismic monitoring network consisted of 41 seismic stations. The total number of earthquakes located by the SIL systemin 2003was about 10400,which is the lowest number in the last 10 years. However the number of earthquakes of magnitude greater than 1.5 was similar to 2002. Eight felt earthquakes were reported in 2003. The largest earthquake in 2003 occurred about 7 km southwest of Kleifarvatn on the Reykjanes Peninsula on August 23 at 02:00. It had a magnitudeMlw = 5 and was felt in many parts of SW– Iceland. The aftershock activity was most intense the first two days after the main shock and culminated about a week later. Seismicity beneath theMýrdalsjökull glacier was high and as in 2002 was continuous throughout the year under the western part. From mid year 2003 the seismic activity has increased at Grímsvötn volcano in the Vatnajökull ice cap. Some earthquake swarms occurred on the northern part of the Reykjanes Ridge with earthquakes greater than 4. Several earthquake swarms with earthquakes of magnitude about 3 were recorded in the Tjörnes Fracture Zone. Aftershock activity still continues on the main faults from June 2000 in the South Iceland Seismic Zone.