Surtsey - Geology
The outline of Surtsey in 1967, 1977 and 2004. In 2004, the island had an area of 1.41 km. Surtsey's palagonite tuff core, shown here in light brown, is around 0.39 km above sea level.
Geologists closely observed the Surtsey eruption, which lasted from 1963 until 1967, carrying out a broad programme of research on and around the island even before the eruption was over. Sigurður Þórarinsson (1912-1983), a geologist then working at the IINH, took significant part in these first research excursions. After the eruption ended, three long-term monitoring projects were established on Surtsey, examining erosion, hydrothermal activity and the formation of palagonite tuff. The basic data for these geological monitoring projects are the 54 stereo aerial photograph series that have been taken of the island to date, the first of which were made in February 1964. Not only do these aerial photographs give us unique insight into the island's overall growth and erosion, they also reveal microscopic morphological changes to its surface. Nine bathymetric maps of the ocean floor surrounding Surtsey were produced between 1964 and 2000 that show changes to the sea bottom over this time period. It has been stated that data comparable to that which we have on Surtsey's development can be obtained nowhere else on Earth.
Erosion on Surtsey
This project has focused mainly on coastal erosion and changes to Surtsey's area. Sigurður Þórarinsson at the IINH and J. O. Norrman at the University of Uppsala in Sweden were initially in charge of the project. Sveinn P. Jakobsson assumed responsibility for the monitoring project in 1990. Surtsey was at its largest in the spring of 1967, when it measured 2.65 km2, but erosion was initially rapid. Surtsey shrunk by 0.23 km2 over the course of the year following the end of the eruption. Coastal erosion on the island has gradually slowed since then. In August 2004, Surtsey's area was measured at 1.41 km2.
The development of Surtsey's hydrothermal area
Following the eruption, a hydrothermal system developed in Surtsey's tephra pile. The hydrothermal area on Surtsey is clearly connected to the feeder dikes of its lava craters and other intrusions at various depths. Above sea level, temperatures of around 100°C – steam temperatures – have prevailed in the tephra, except where there are intrusions. Temperature measurements made at the surface have shown that surface temperatures have decreased from 1967. Measurements in a drillhole made in 1979 on the eastern side of the island, show a mean annual temperature decrease of close to 1°C. Hydrothermal activity has sped up the palagonitisation of the tephra considerably, a decisive factor for Surtsey's survival in decades and centuries to come. Sveinn P. Jakobsson has been in charge of this project from the outset.
The formation of palagonite tuff
The first traces of palagonite tuff on the surface were found in November of 1969 in the hydrothermal area of the eastern tephra pile, at which point a good part of the subsurface tephra had likely already consolidated into tuff. Research on the drilling core from the 1979 drillhole indicates that at temperatures of 100°C, tephra had consolidated into palagonite tuff within the space of around a year. The palagonite tuff area, as visible on the surface, was quick to expand at first. The rate of consolidation has since slowed. By 2004, an estimated 85% of the volume of tephra above sea level had been converted into tuff. This tuff has an estimated area of 0.39 km2 above sea level and now forms the island's core. Palagonite tuff is hard and extremely resistant to coastal erosion. Comparison with other outer islands in the archipelago indicates that this core will continue to withstand the ocean waves for many years to come. Monitoring of palagonite tuff formation on Surtsey has taken place continuously since 1969. Sveinn P. Jakobsson has been in charge of this project from the outset.
- Palagonitisation in Surtsey (see bottom of page)
- Surtsey, the Surtsey Research Society homepage
- The Nomination of Surtsey for the UNESCO World Heritage List (10.5 MB)
- Surtsey fact sheet (129 K)
- Sveinn P. Jakobsson and Guðmundur Guðmundsson 2003: Rof Surtseyjar. Mælingar 1967-2002 og framtíðarspá. Náttúrufræðingurinn 71, 138-144.
- Jakobsson, S. P., G. Gudmundsson and J. G. Moore 2000: Geological monitoring of Surtsey, Iceland, 1967-1998. Surtsey Research 11, 99-108.
- Sveinn P. Jakobsson 2000: Geological map of Surtsey, scale 1:5.000. The Icelandic Institute of Natural History and the Surtsey Research Society.