Jökull - 01.01.2010, Page 2

Sigurður Thorlacius Rögnvaldsson
Sigurður was born in Reykjavík in January 1964.
He graduated from the Menntaskólinn við Hamrahlíð
junior college in 1982 and received his B.Sc. de-
gree in geophysics from the University of Iceland
in 1987. During his undergraduate years, Sigurður
worked summers at the Icelandic Energy Authority,
carrying out electromagnetic resistivity surveys and
other field work for geothermal prospecting.
Sigurður continued his geophysics studies in Swe-
den at the Uppsala University where he obtained a
Ph.D. degree in 1994. His supervisors while at Upp-
sala were Ragnar Slunga and Reynir Böðvarsson. His
thesis research focused on developing and testing geo-
physical algorithms implemented as part of the SIL
(South Iceland Lowland) digital seismic network for
analysis of earthquake data. In collaboration with
Ragnar Slunga, his most important contributions were
in automatic estimation of fault-plane solutions for
microearthquakes by inverting observed polarities and
spectral amplitudes of P- and S-waves, and in relative
locations of microearthquakes. Sigurður’s research
thus demonstrated that microearthquakes contain in-
formation about large-scale tectonic processes.
Upon graduation from Uppsala University, Sig-
urður first held a postdoctoral position at the Nordic
Volcanological Institute in Reykjavík, and then moved
to the Geophysical Department of the Icelandic Mete-
orological Office (IMO) in the fall of 1995. At IMO,
Sigurður participated in the deployment and day-to-
day maintenance of the SIL system as well as its de-
velopment. The map on the IMO web site showing
daily seismic activity was implemented by Sigurður
during a seismic crisis in Hengill in 1998, and it is an
example of his creativity and efforts to rapidly display
SIL data.
Sigurður Th. Rögnvaldsson. Photo: Ari Tryggvason.
Sigurður participated in a number of different Ice-
landic and international research projects after his re-
turn to Iceland but the focal point of his research
continued to be analyzing microseismicity in Iceland,
building on his doctoral work in Uppsala. These stud-
ies included mapping of faults in the Tjörnes frac-
ture zone, the South Iceland seismic zone and the
Hengill regions, using relative relocations and earth-
quake focal mechanisms. Mapping of seismically ac-
tive faults at depth using relative relocations of mi-
croearthquakes provide important information on the
seismotectonics of a region, and the method is now
also used in geothermal exploration.
Sigurður’s contributions to the field of seismology
during his short career demonstrate the enthusiasm
that he held for the subject. He was a great colleague
and a true friend - always ready to help, whether the
problem involved deciphering convoluted computer
codes, delving into the mysteries of the SIL system,
making presentable documents using LaTeX and fig-
ures using GMT, or discussing life, the universe and
everything.
2 JÖKULL No. 60