Attenuation of seismic waves in the Jan Mayen island area |
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| Authors: | J Havskov L B Kvamme H Bungum |
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| Institution: | (1) Seismological Observatory, Allśegt. 41, 5000 Bergen Norway |
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| Abstract: | An analysis of the attenuation of seismic waves as measured by the quality factorQc (for coda waves) has been performed for the volcanic Jan Mayen island in the Norwegian Sea, using earthquakes near the Jan
Mayen Fracture Zone and local seismic stations on the Jan Mayen island.Qc values of the order of 100 at a frequency of 1 Hz are found, increasing to about 300 at 10 Hz. These values are typical of
what usually is observed in tectonically influenced areas near oceanic/continental plate boundaries. It is considered likely
that these results are influenced by the fact that the Jan Mayen island, in spite of its proximity to a fracture zone, is
located in the northern end of the Jan Mayen Ridge, which now is accepted as being a micro-continent. The presence of the
active Beerenberg volcano on the Jan Mayen island does give rise to a somewhat stronger attenuation for waves traversing that
area, but this effect is weak and quite limited in spatial extent. There is also a slight increase in attenuation as a function
of depth, but less than what is observed in terms of lateral variations. This is reasonable in view of the very strong lateral
variations in lithospheric structure exhibited in this area. |
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