The Iceland Hotspot is a large scale feature on the earth. Its root is an active mantle plume located below the Mid-Atlantic. It can be traced by seismic tomography through the entire mantle (Figure 1). Gravity anomalies show its effects over an area of several hundreds thousands km2. Horizontal stress compressions with direction towards the plume area are indicated on both sides of the Atlantic Ocean [#!Morgan:1981!#,#!Tryggvason/etal:1983!#,#!Wolfe/etal:1997!#,#!Bijwaard/Spakman:1999!#].
Although seismic tomography work has added significant information about the Iceland plume during recent years, it has introduced new questions which can only be answered by more observations.