Explosive volcanism on the ultraslow-spreading Gakkel ridge, Arctic Ocean

Abstract

Roughly 60% of the Earth's outer surface is comprised of oceanic crust formed by volcanic processes at mid-ocean ridges (MORs). Although only a small fraction of this vast volcanic terrain has been visually surveyed and/or sampled, the available evidence suggests that explosive eruptions are rare on MORs, particularly at depths below the critical point for

Did the 1999 earthquake swarm on Gakkel Ridge open a volcanic conduit? A detailed teleseismic data analysis

“…8). All of them occur between 5 and 9 April 1999 and HYPOSAT places them in the central rift valley of Gakkel Ridge with events 1 and 3 being located extremely close to Oden volcano (Sohn et al 2008) and to each other (see Fig. 5).…”

“…The lateral error of HYPOSAT at 95% confidence level is thus an underestimation of around 25%. All three events as laid out must reflect the same process to assume similar waveforms, all events are located between 12.6 to 16.4 km depth, all of them are located in the central rift valley, events 1 and 2 are indistinguishable up to 3,600 km offset from the source and events 1 and 3 plot nearly on the same spot close to Oden volcano (Sohn et al 2008). Thus, either this volcano or another vent aligned with Oden's chain of volcanoes and located further to the SE is the most probable source region for the repetitive events.…”

“…All events marked in red and nearly all events with more than 100 phases used in the final inversion are located in the central rift valley. A small white triangle (volcano) close to events 1 and 3 marks the position of the crater of Oden volcano which was discovered by Sohn et al (2008) unavoidable as the nearest stations to the earthquake swarm are 1,000 km away. Our geological interpretation bears this location accuracy in mind.…”

“…In 2007, the AGAVE cruise revealed thick blankets of volcaniclastic sediments in the area which contain Limu o Pele, i.e., very thin glassy crystallized rims of gas bubbles in magma and, thus, clear evidence for considerable explosive volcanism at water depths of about 4,000 m and a chain of small volcanic peaks with Oden volcano (white triangle in Fig. 1) at its easternmost location (Sohn et al 2008).…”

“…A small white triangle (volcano) marks the position of the crater of Oden volcano which was discovered by Sohn et al (2008). All figures including this one have been plotted using Generic Mapping Tools (Wessel and Smith 1998) and high b values indicated a typical volcanic character (Müller and Jokat 2000) and sonar images from the USS Hawkbill only 4 months after the main activity showed areas of high backscatter interpreted as fresh lava flows .…”