The 1732 Surtseyan eruption of Eggoya, Jan Mayen, North Atlantic: deposits, distribution, chemistry and chronology

The island of Jan Mayen in the North Atlantic Ocean is home to the world's northernmost active subaerial volcano, Beerenberg. Of the five known historical eruptions on the island, the locations of two eruptions (1732 and 1818) have not been accurately located. It is known that the 1732 and 1818 eruptions occurred on the south flank of Beerenberg, and several eruption sites have been proposed for these events. Here we show that the tuff cone of Eggoya on the SW flank of Beerenberg was the site of the 1732 eruption, based on interpretation of the deposits, field relations and historical sources. We further describe the deposits from the eruption and show that Eggoya is the largest explosive eruption described from Jan Mayen, emplacing at least at least 0.3-0.4 km(3) (VEI 4) of basanitic tephra up to distances of at least 111 km from Jan Mayen and covering a minimum area of around 500 km(2) within the 2-cm isopach. We also present our eruption scenario and show that this was an emergent Surtseyan eruption with activity shifting between tephra jetting, continuous uprush and more magmatic phases.