27. Búrfellsgjá – Crater and lava channel

The lava channel Búrfellsgjá. Photo Ingibjörg Kaldal.Búrfell near Hafnarfjörður town SW-Iceland is a cinder cone that erupted 8000 years ago (~6000 BC). The crater reaches 180 m a.s.l. and is made of scoria and other pyroclastic fragments. The lava originating there is olivine tholeiitic with prominent phenocrysts of feldspar and olivine. It has the common name Búrfellshraun but parts of it have their own names such as

  • Smyrlabúðarhraun
  • Gráhelluhraun
  • Lækjarbotnahraun
  • Urriðakotshraun
  • Hafnarfjarðarhraun
  • Garðahraun
  • Gálgahraun.

The Búrfell crater is located near the eastern border of a shallow rift valley belonging to the Trölladyngja volcanic rift system. The area of the lava is estimated to be 24 km2 and 1/3 of it is covered by younger lava flows. The volume is around 0,5 km3. The age is about 8000 years BP.

Three main lava lobes have flowed from the crater towards the shore and in to the sea. The largest one reached the shore in outer Hafnarfjörður and Arnarnesvogur. The second one flowed towards Kaldárbotnar springs and from there to the shore at Hamarinn in Hafnarfjörður harbour. The third and the southernmost lava lobe is mostly covered by younger lavas. It went into the sea at Straumsvík. At this time the sea level was about 10 m lower than today. The towns Hafnarfjörður and Garðabær are partly located on the lava as well as the Straumsvík Aluminium Plant.

Árni Hjartarson, 2010

 Map of Burfellsgja - Crater and lava channel.