100 years of seismic observations

100 years of seismic observations

The first seismograph in Iceland was installed in Reykjavík in 1909. The seismograph was a Mainka instrument and it was sent from Germany under the auspices of the International Seismological Association (ISA). The seismograph measured the horizontal north-south component of the ground motion and the records were sent to Strasbourg for analyzing. In 1913 another seismograph of the same type was installed in Reykjavík that measured east-west movement. The operation of the seismographs was ceased in 1914 due to funding restrictions during World War I.

The operation of the seismographs was recommenced in 1925 and 1927 at the Icelandic Meteorological Office (IMO), where data processing was also conducted. Amplification of ground motion was low and even several felt earthquakes were not recorded. In 1951-1952, three Sprengnether short-period seismographs, measuring all three components, were installed. The old seismographs were moved to Akureyri, in the north of the country, in 1954, and to Vík, south of the Mýrdalsjökull ice cap, in 1955. It then became possible to locate earthquakes of magnitude three and larger, and the number of earthquakes recorded increased considerably.

In 1958, a new recording station, equipped with a horizontal short period Willmore seismograph, was installed southwest of the Vatnajökull ice cap. The same type of seismograph was installed in Reykjavík in 1966 and in the east of the country in 1967. In 1968, a new station was installed southeast of Mýrdalsjökull. With these six stations mapping of the main seismically active areas in Iceland was possible.

In 1960, IMO was invited to participate in a project sponsored by the U.S. Coast and Geodetic Survey. The aim of this project was to set up an international seismic network, and in 1964 a station was installed in Akureyri as part of the World Wide Standardized Seismograph Network.

From 1925 to 1964, IMO was the only institute in Iceland monitoring seismicity. In 1964, the Science Institute of the University of Iceland installed a seismograph on Heimaey to monitor seismicity in the area during the Surtsey eruption. Two years later the institute set up a station on Surtsey. After 1970, the Science Institute, in collaboration with other Icelandic institutes, monitored seismic activity in several regions around the country with portable instruments. From 1972 - 1985, the Science Institute and the Lamont-Doherty Earth Observatory in New York collaborated in installing a seismograph network throughout Iceland, including a network of five seismographs in the interior of the country. During the same period the number of stations in the IMO network increased markedly.

A new era of seismic monitoring began in Iceland in 1991, when a digital seismic system, the SIL system, was upgraded to fully automatic operation. It was designed and initiated within the Nordic SIL project in 1988 - 1994. The number of stations in the network increased gradually to the present day total of 55. The operation of the old IMO network was discontinued over a twenty-year period, 1974 - 1994. The operation of the Science Institute network was completely discontinued in 1990, except the highland network which is at this time being dismantled.




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