Jan Mayen - Who? Where? | Wat On Earth

By: Alan V. Morgan

There is a popular misconception by most of the general public that when the academic term ends university professors retire to the pool or cottage and sit around waiting for the next term to begin! I'm afraid that just isn't so. While Peter was labouring in the preparation of this issue of "What on Earth" I was off on a Russian icebreaker sailing around Iceland, and north to Jan Mayen and Spitsbergen. On this voyage I was trying to introduce 100 or so naturalists to the geology of the regions that we were visiting. I looked forward to this challenge. We were visiting prime areas of the world for classical interpretations of plate tectonics and particularly (at least in the case of Iceland and Jan Mayen), volcanic activity.

O.K. so I can hear most of you muttering, why Jan Mayen? Well, that story goes back 42 years when I was just 17 on an expedition in central Iceland. Our leader had been on Jan Mayen in 1959, and had commented that if we ever had the opportunity to visit the island we should. Almost half a century later the opportunity arose, and so on a crystal clear morning I first sighted Beerenberg, the northern volcano of Jan Mayen over 100 km away from the bridge of our vessel, the Professor Molchanov. Considering that the island is fog- and cloud-shrouded for about 360 days of the year our visit on June 4th and 5th must have been truly exceptional.

Jan Mayen is situated in the middle of the North Atlantic, some 500 km from Greenland 600 km from Iceland, and about 1000 km from both Norway and Spitsbergen - in other words, it's an almost unknown tourist destination! The island is located at approximately 71º N and 8º W, and it is about 54 km long by 15 km wide. It is roughly hour-glass shaped with the northern portion called Nord Jan and the southern, Sår Jan. The highest point is Beerenberg volcano on Nord Jan at 2,277 m (7468'). Tectonically the island sits on the margin of a large transform fault, the Jan Mayen Fracture Zone, just at the commencement of the northward-trending Mohns Ridge. The offset Ridge to the south, about 160 km west, is the Kolbeinsey Ridge that runs from north Iceland to the Jan Mayen transform fault. The main tectonic elements are illustrated in Figure 2.

The island was reputedly first sighted by Henry Hudson (of Hudson Bay fame) in 1607. However, this claim and perhaps those of the Icelanders hundreds of years earlier are pre-empted by the first officially recognised sighting in 1614 by a Dutch captain, Jan May, and hence the name. Unfortunately the Dutch came to hunt whales, and did so with great gusto for about three decades, until the whales (particularly the "Right" whale) became exterminated (Figs. 3 and 4). Following the demise of the whale populations the island was only intermittently visited for about 250 years. Captain Jacob J. Laad reported an eruption on Beerenberg in 1732, and W. Scoresby reported a second in the same area in 1818. Since then five eruptions have been noted.

Many hours after our initial sighting Jan Mayen gradually loomed closer, until the high cliffs along the southeast coast finally hid the northward view along the west side of Nord Jan. The cliffs of Sår Jan, usually fog shrouded, revealed a fantastic sight of complete cinder cones, buried under younger lava flows, and then transected by the sea to produce incredible cross-sections of the internal features of the small vents (Fig. 5). This one view alone was worth the trip, but there were more spectacular sights to come!

Arriving at the Norwegian weather station at Båtvika we came ashore on zodiacs, to land on a wonderful black sand beach. Here the wind had winnowed the basaltic sand and concentrated small drifts of olivine (Fig. 6). The Norwegian weather station (also acting as a LORAN C navigational station) is located beneath some steep cliffs with wonderful talus (scree) slopes and on top of some young looking (almost certainly post-glacial) lava flows (Fig. 7). A closer examination revealed that the flows had large olivine crystals (the source of the rounded olivine grains in the beach sands) as well as calcium-rich plagioclase feldspars and pyroxene crystals. These three (olivine, anorthite feldspar and pyroxene) are the first formed minerals as basaltic magmas cool.

Because the weather was so outstanding, after a short shore visit we re-embarked and the Professor Molchanov sailed northward around Nord Jan. Beerenberg was beautifully exposed in the late evening light as we went around the north side of the volcano. Huge glaciers cascaded down the flanks, and on the northeast corner we could see the location of the penultimate eruption (Fig. 8). This was a flank eruption from a 6 km-long fissure that started at an elevation of 1000m and went down to near sea level. The eruption commenced likely at 04:00 on September 18th 1970 and continued to January of 1971. Precise observations on the event were severely limited because of the poor weather conditions that prevailed in the area. There were four active craters (Figs. 2, 8) and the lava flows, like those on Heimaey in Iceland, (Wat On Earth, Fall issue, 1998; Morgan 2000) added new land on the northeast side of the island.

The most recent eruption on Beerenberg was another basaltic outpouring that commenced on January 6th 1985, but seemingly ceased on January 10th. The approximately 7 million m3 of lava that was extruded from a ~1 km fissure is about the same as the output in the first four days of the eruption from the volcano Eldfell on Heimaey, Iceland January 1973. The position of the crater that had developed by January 8th at some 200m elevation is shown in Figure 8.

The lava field that flowed from this main crater extended about 1 km to the NNE. There are reports that small (mag. ~5.0) earthquakes accompanied the eruption. A vigorous summit steam-venting episode commenced on 3rd and 4th of April, 1985, and lasted several weeks.

We continued to sail down the west coast toward Kvalrossbukta, passing several spectacular glacier tongues that cascaded from the summit of Beerenberg to sea level (Fig 9). The following day we returned to cruise along the ice margin in the zodiacs (Fig. 10). There were many interesting glacial features noted. The black basaltic ash from the eruptions on Jan Mayen has been incorporated into the glaciers and can be easily seen in the shear-planes developed within the ice and exposed at the glacier terminus. Pronounced lateral moraines can be seen in many areas. Terminal moraines are absent as the glacier front reaches the sea. Bedrock could be seen beneath the ice front and a black sand beach fringed the glacier terminus (Fig. 10).

The Professor Molchanov reached our overnight mooring at Kvalrossbukta, sheltering in a small bay on the central west side of Jan Mayen. The anchorage lies protected by a breached and almost entirely eroded crater. The high northern cliffs are stratified tuffs with hyaloclastites likely created by basaltic sub-glacial eruptions. Kvalrossbukta is the likely position of the main whaling that was conducted on from Jan Mayen from its discovery to about 1650 (Figures 3 and 4). A careful study of the woodcut (Fig. 3; - date uncertain but ca. 1620) shows three small boats in the process of harpooning a whale, probably about in the position of Fig. 8, at the extreme northern end of Nord Jan.

The second painting by Mann in 1636 shows a flensing and blubber-boiling scene and probably at Kvalrossbukta. The disturbing aspect of both of these images is the "double blow" seen depicted from the harpooned whale in Figure 3 and several whales in the sea in Figure 4. This V-shaped blowhole venting is characteristic of the Right Whale (Eubalaena glacialis). It was "right" because it was the best whale to catch, with a high oil content and abundant baleen.

The Right Whale, a 50+ tonne leviathan, is one of the more unfortunate whale species hunted by man and the North Atlantic Right Whale is now practically extirpated, with less that 1,000 to perhaps as few as 350 individuals still living.

Following our shore visit and glacier-front cruises on June 5th., we sailed south from Jan Mayen to the Tjšrnes region of north Iceland and from there down the east and south coasts of Iceland. Perhaps more on the Icelandic circumnavigation in another issue of What on Earth.

Alan V. Morgan.

References and copyright

Morgan, A.V. 2000. The Heimaey Eruption, Iceland: - A 25 Year Retrospective. Geoscience Canada 27 (1): 11-18.

Most of the background geological information is derived from the Global Volcanism Program; Volcanic Activity Reports - Jan Mayen. It can be accessed at:
http://www.volcano.si.edu/gvp/volcano/region17/atlantic/janmayen/var.htm