Jökull - 01.01.2020, Page 62

The analog seismogram archives of Iceland
Figure 1. Öldugata 23, Reykjavík, the location of the first seismograph in Iceland in 1909. – Fyrsti jarðskjálfta-
mælir á Íslandi var settur upp 1909 í kjallaranum í húsi Stýrimannaskólans að Öldugötu 23 í Reykjavík.
netic sensor and recorded with a light beam on photo-
graphic paper. The old Mainka instruments were then
moved to Akureyri and Vík í Mýrdal, thus forming
the first network in Iceland. Some of the largest earth-
quakes could then be located instrumentally, even
though the accuracy was not good.
New stations were set up at Kirkjubæjarklaustur in
1958 and Eyvindará near Egilsstaðir in 1967, consist-
ing of one vertical electromagnetic Willmore sensor.
A similar sensor was added to the station in Reykjavík
in 1966.
A large step was taken in 1964 when a state-of-
the-art seismic station was established in Akureyri, in
the basement of the police station. It was a part of the
World Wide Network of Standardized Seismographs
(WWNSS) that was established and run by the US
Geological Survey. The network consisted of more
than 120 stations that were distributed throughout the
Earth, each one with three long-period sensors and
three short-period sensors (Oliver and Murphy 1971).
The main purpose of the network was to monitor nu-
clear explosions, but it also provided the first reliable
maps of global seismicity, forming one of the back-
bones of the Theory of Plate Tectonics. The data from
this network were copied and distributed to several
data centers, one of which was at the Lamont-Doherty
Earth Observatory in New York. Data from the Akur-
eyri station were used in numerous studies of world
seismicity and the internal structure of the Earth.
Data from the stations listed so far were analyzed
at the Icelandic Meteorological Office (Veðurstofa Ís-
lands). A Seismological Bulletin was issued every
year since 1926, listing earthquake epicenters and
magnitudes, and other pertinent information. The
main results for the three decades from1930 to 1960
were also published in three reports by Tryggvason
(1978a, 1978b; 1979).
Electronic revolution
A major advance in seismometry took place in the six-
ties, mainly due to the invention of the transistor and
other electronic components. Measurements using
electronic components became reliable and electronic
circuits could be designed that did not require con-
nection to the electric mains and could be run outside
under field conditions. The eruptions in Surtsey 1963-
1967 sparked new interest in earthquake monitoring.
A seismograph was operated for a while on Heimaey
(Pálmason, 1966) and a grant was obtained to buy
and build a seismic system to operate on Surtsey, con-
sisting of a 7-track tape recorder, sensors, and ampli-
fiers (Sigurgeirsson and Stefánsson, 1967; Einarsson,
1974).
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