A Tephrochronological Database

Welcome to the Tephrabase website

Tephra layers (volcanic ash layers) are now an invaluable tool in palaeoenvironmental studies. The data produced by such research can be difficult to handle and disseminate. Tephrabase is a database of tephra layers found in Iceland, north-west and northern Europe, Russia and central Mexico. Details on the location, name, age and geochemistry of tephra layers are stored in the database, as well as information about relevant volcanoes and volcanic systems. A comprehensive reference database is also included. A new Laacher See supplementary data collection has been added.

Eyjafjallajökull Eruption from the 20th March 2010

MODIS Terra satellite image of the plume heading towards Shetland, taken at 11.35 GMT 15th April 2010. (Image NASA/GSFC, MODIS Rapid Response)

Volcanic activity switched to Eyjafjallajökull's main crater just after midnight on the 14th April. After several weeks of relatively mild fissure activity in the Fimmvörduhals area, which resulted in lava flows and scoria cone creation, the main crater of Eyjafjallajökull began erupting early on the 14 April. This subglacial eruption has resulted in several jökulhlaups (large floods of melted ice) which have flowed north out of Gígjökull into the Markarfljót valley. The flood waters have flooded farmland and some properties, as well as damaging roads and bridges. In preparation holes were made in the route 1 embankments in an effort to save the main road bridge across the Markarfljót. Further flooding can be expected as long as the eruption is melting ice in Eyjafjallajökull's main crater. Although Eyjafjallajökull continues to pump ash into the atmosphere, much of Europe's airspace was reopened on 20 April. This largely reflected a change in the regulators' view on the tolerance of jet engines to low concentrations of tephra. The eruption has varied considerable over the past week, with a lava flow extending northwards beneath Gígjökull. This has contributed to continued meltwater being created. The explosivity of the eruption has also varied, with an increase in plume height to around 9 km reported by Institute of Earth Sciences/Nordic Volcanological Institute on the 6th May. Winds were carrying the tephra to the south of Iceland.

The large amounts of tephra being produced by the eruption are a result of the interaction between the lava and the glacier which overlies the volcano. The erupting magma melts the overlying ice, creating steam, and it is the rapid explosive expansion of the ice to steam which literally blows the molten lava into fine ash fragments (very similar to what happens if you pour water onto an oil fire). This type of activity (phreatomagmatic) is typical of Iceland's subglcial volcanoes and is responsible for Iceland having a fantastic record of past eruptions in its soils. This is why Iceland is probably the best place in the world to use tephrochronology (use of tephra layers for dating).

MODIS Terra satellite image of the plume heading south from Iceland, taken at 12.50 GMT 19th April 2010. (Image NASA/GSFC, MODIS Rapid Response)

MODIS Terra satellite image of the much reduced plume heading south from Iceland, taken at 11.55 GMT 20th April 2010. (Image NASA/GSFC, MODIS Rapid Response)

The MODIS Terra satellite images to the left show the clear reduction in the intensity of the plume between Monday 19th April and Tuesday 20th April. Tephra was still being produced, but in much lower quantities. This is one of the reasons for the reopening of Europes airspace, as well as the new safety threshold for tephra concentrations. On the 23 May, the Institute of Earth Sciences/Nordic Volcanological Institute reported that the volcano was dormant and just emitting steam. However, the Institute of Earth Sciences/Nordic Volcanological Institute report of the 7 June described renewed small scale activity with some local tephra production and a plume of mainly steam reaching an altitude of 4.5 km on the 4th June. The Institute of Earth Sciences/Nordic Volcanological Institute report that 100 million m3 of tephra has been erupted. Whilst this might seem like a large quantity, and it certainly has disrupted a lot of peoples' lives, it is a modest eruption.

Eyjafjallajökull burst into life after nearly 190 years of inactivity (1821-1823) on the 20th March. Fljótshlíd residents noticed an orange glow on the edge of the volcano at 23:52 GMT. The initial eruption was in the Fimmvörduhals area, the pass between Eyjafjallajökull and Mýrdalsjökull, and produced alkali-olivine basaltic lava with an SiO₂ content of around 47% according to the Institute of Earth Sciences/Nordic Volcanological Institute. Activity decreased over time until the fissure eruption stopped on the 12^th April. Analyses of the tephra from the second phase of activity show a more evolved source, with an SiO₂ content of around 58% with a high fluorine content.

With activity switching to the main crater of Eyjafjallajökull on the 14^th April, concerns will grow about neighbouring Katla (last eruption 1918), beneath Mýrdalsjökull. In the past, activity in Eyjafjallajökull has been accompanied by eruptions of Katla. For example, the last activity (1821-1823) at Eyjafjallajökull saw an eruption of Katla in 1823. An eruption of Katla, if it occurs will probably result in more intense activity and larger jökulhlaups than the current Eyjafjallajökull eruption. The Institute of Earth Sciences/Nordic Volcanological Institute at the University of Iceland are the main group who are monitoring the eruption.

Further details on the eruption can be found via these links:

• Institute of Earth Sciences/Nordic Volcanological Institute
• Details on the eruption from the Icelandic Met Office
• The Volcanic Ash Advisory Centres' (VAAC) website with aviation warnings and maps of the plume.
• Iceland Review - English language news from Iceland
• Live webcam of the eruption of Eyjafjallajökull from Hvolsvöllur
• Tephrabase entry for Eyjafjallajökull
• Tephra covers Vík in southern Iceland (BBC website)
• Icelandic Met Office predictions for ash fall in Iceland
• Eruption of the Eyjafjallajökull volcano in Iceland as seen by RADARSAT-2
• ESA animation showing the movement of the initial ash plume
• Video of the eruption by Ómar Ragnarsson, showing tephra, lava bombs and shock waves being produced from the crater (20/40/2010)
• Stunning photographs of the eruption on the Boston Globe website.
• Photographs from the Iceland's Institute of Earth Sciences of the eruption and jökulhlaup.
• Photographs of tephra (volcanic ash) fallout around the village of Kirkjubæjarklaustur, 80 km to the east of Eyjafjallajökull
• Some excellent photographs of the eruption from the Icelandic Met Office. This Icelandic version has more photographs.
• Photographs of the eruption from the Reykjavík Grapevince.
• Spectacular Icelandic film of the jökulhlaup emerging from Gígjökull and travelling down the Markarfljót
• BBC News report on the eruption at the central crater of Eyjafjallajökull and the first jökulhlaup emerging from Gígjökull and travelling down the Markarfljót
• Icelandic news report showing the impact of the jökulhlaup on the Route 1 where it crosses the Markarfljót.

The Fimmvörduhals Eruption

• Institute of Earth Sciences - Soluble fluoride on volcanic ash and scoria and analyses of lava from the Fimmvörduhals eruption
• Video and sound of the Fimmvörduhals eruption by Jón S. Erlingsson
• NASA Earth Observatory EO-1 image of the Fimmvörduhals eruption
• Photographs of the Fimmvörduhals eruption
• More photographs of the Fimmvörduhals eruption and temperature and water levels of the Krossá and Hvanná
• RUV video of initial Fimmvörduhals eruption
• New high quality video of Fimmvörduhals eruption
• Film on the BBC News website of the Fimmvörduhals eruption

Latest Updates