g and has an area of
145 square miles (380 square km). The island is less than 700,000 years old. The southern
part of the island is a mountainous ridge made of scoria craters, scoria mounds, and
trachytic domes.Beerenberg is a stratovolcano and it is in fact the
northern-most active volcano on Earth. The volcano is mostly covered by glaciers
and it forms the north-end of Jan Mayen Island. Jan Mayen is 54 km long and has an area of
145 square miles (380 square km). The island is less than 700,000 years old. The southern
part of the island is a mountainous ridge made of scoria craters, scoria mounds, and
trachytic domes.
Beerenberg is in a fairly unusual tectonic setting near the intersection of the Jan Mayen Fracture Zone, a transform fault and the Mohns mid-ocean ridge.
Beerenberg has erupted six times between 1732 and 1985. All of these eruptions were on flank vents and produced lava flows and scoria cones. The most recent eruptions were in 1970, 1973, and 1985.
The 1970 eruption began on September 18 and continued to January, 1971. Intense storms hid the onset of the eruption. A commercial pilot spotted the eruption cloud on September 20 and I have been told that he reported a forest fire. The island was evacuated immediately, but having decided that the situation was not as dramatic as feared, key personnel and geologists were transported to the island later the same day. The rest of the personnel returned within short time.
This was the only historic eruption witnessed in modern times at the area. The eruption was large, erupting at least 0.5 cubic km of basalt from a 3.7 mile (6 km) long fissure that ran from sea-level to an elevation of 3,000 feet (1,000 m). The capacity of the eruption was 100 square meter lava/sec. There were at least five active craters and the lava that ran out into the sea produced 4 square km new land.
The 1985 eruption began on January 6, 1985 and lasted only 35-40 hours. In that brief time about 7 million cubic meters of lava was erupted (roughly enough to bury a football field in 1400 yards of lava!). Earthquakes, with magnitudes up to 5, occurred during the eruption. The eruption was thought to be from a leaky fracture zone, not the Jan Mayen magma system proper. The vent was 22 miles (35 km) from the settlement called Olonkin City.