Jökull - 01.01.2010, Page 1

Earthquakes and pre-earthquake processes, special issue
Steinunn Sigríður Jakobsdóttir1, Ólafur Guðmundsson2,3 and Þóra Árnadóttir4
1Icelandic Meteorological Office, Reykjavík, Iceland
2Department of Science and Engineering, Reykjavík University, Iceland
3Department of Earth Sciences, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden
4Institute of Earth Sciences, Science Institute, University of Iceland
The year 2009 marked the centennial of earthquake
monitoring in Iceland. This year was also the 30th an-
niversary of volumetric strain measurements in bore-
holes, the 20th anniversary of the initiation of the
SIL seismic network and the 10th anniversary of the
ISGPS continuous GPS station network. To mark
these milestones, the Meteorological Office, in col-
laboration with the University of Iceland, University
of Akureyri, Reykjavík University, Iceland Geosur-
vey and the University of Uppsala hosted an interna-
tional conference on earthquakes, pre-earthquake pro-
cesses and earthquake prediction research on October
30th. The conference was dedicated to the memory of
Sigurður Thorlacius Rögnvaldsson, geophysicist, who
died in a tragic car accident in October 1999. A total
of 15 talks and 17 posters were presented at the con-
ference.
Following the conference, participants were in-
vited to submit papers to a special issue of Jökull. The
first seven papers of this issue were presented at the
meeting. The articles span a wide range of topics on
fault mapping, seismicity studies, studies of seismic
noise and GPS measurements. It is in many ways
suitable that such a wide range of topics be repre-
sented in this special issue commemorating Sigurður
Rögnvaldsson as his work during his short career was
quite broad in scope. Also, in earthquake prediction
research a multi-disciplinary approach is needed.
In the first paper of the special issue, Geirsson
et al. give an overview of results from continuous
GPS observations in Iceland, 1995 to 2010. In addi-
tion to the background, plate spreading signal and re-
bound due to melting glaciers, the CGPS network in
Iceland (ISNET) has captured deformation transients
caused by earthquakes, magma movements, and pres-
sure changes in geothermal systems, thereby provid-
ing valuable data, and complementing the SIL seis-
mic network for monitoring natural hazards in Ice-
land. Then Brandsdóttir et al. report on the May 29th,
2008, earthquake aftershock sequence which reveals
some details about the fault geometry and shows how
these two events have triggered seismicity along ad-
jacent faults. Martens et al. write about precise seis-
mic locations applying an automated detection tool
to an earthquake swarm in the rift zone in north-
ern Iceland. They compare results obtained with data
from two different networks, with 6 joint stations,
using different location software. Horálek and Fis-
cher describe intra-plate earthquake swarms in West
Bohemia/Vogtland (Central Europe) which resemble
in many ways swarms in the rift zones in Iceland.
Guðmundsson and Brandsdóttir write about geother-
mal noise clearly associated with active geothermal
areas around Ölkelduháls, SW Iceland, by study of
amplitude decay and phase correlation. Hjartardótt-
ir et al. describe a 30 km long fault on the eastern
flank of the northern volcanic zone in Iceland, possi-
bly related to the deglaciation in the early Holocene
and Einarsson describes comprehensive mapping of
Holocene surface ruptures in the South Iceland Seis-
mic zone, where the most destructive earthquakes in
Iceland occur.
JÖKULL No. 60 1