The 2007 seismological aftermath of the spreading episode of 1999 at Gakkel ridge, Arctic Ocean

• Main Authors: Korger, Edith I. M., Schlindwein, Vera
• Format: Conference Object
• Language: unknown
• Published: 2012
• Subjects: Arctic; Arctic Ocean; Gakkel Ridge
• Online Access: https://epic.awi.de/id/eprint/25649/; https://hdl.handle.net/10013/epic.38920

In 1999, an unusually strong, teleseismically registered earthquake swarm at the volcanic complex at 85°E/85°N gave first signs of an ongoing spreading episode at Gakkel ridge, one of the World’s slowest spreading ridges (full spreading rate about 9mm/yr). Due to the remote location of Gakkel ridge in the ice covered Arctic ocean, an immediate on-site investigation was not possible. Following a first expedition to the 85°E/85°N volcanic complex in 2001, the 2007 AGAVE expedition recorded more than 300 local earthquakes during 21 days of recording with three arrays of seismometers mounted on ice floes. We localized the microearthquakes with the least-squares routine Hyposat and a local velocity model compiled from the nearest seismic surveys, and then identified reliable good quality events. These best events were used to test a suite of velocity models for the smallest overall rms and define the velocity structure in a 1D layered model for the 85°E/85°N volcanic complex. We localized the whole suite of local earthquakes with this velocity model. Most of the events were localized directly in the rift valley, though some epicentres extended as far as 88°E and had shallow hypocentres <10 km depth.