Jökull - 01.06.2000, Page 46

Foulger and Field
Km
Figure 10. Density variations required by the observed Bouguer anomaly field in a slab of thickness 1 km with
its top surface at sea level. Contour interval is 50 kg/m3. Light grey areas: high densities; dark grey areas: low
densities. - Þyngdarfrávik, mceld í 50 kg/m3 einingum, innan spildu sem nœr frá sjávarmáli og niður á 1 km
dýpi undir Kröfluöskjunni.
DISCUSSION
Hengill-Grensdalur
The observed and simulated Bouguer anomaly fields
correspond broadly. The main area of misfit is a zo-
ne of unmodelled relatively low gravity trending NE
across the area (Figure 5c) with residuals larger th-
an the estimated eiror (Figure 6d) south of Heng-
ill and over Hrómundartindur. These two areas are
each constrained by several gravity stations and the
anomalies are thus reliable. No seismic station was
deployed in the area of the residual south of Hengill,
but two seismic stations were sited on Hrómundart-
indur (Figure 2). It is thus unlikely that poor resoluti-
on in the LET at intermediate depths can explain the
residual over Hrómundartindur, though this is a more
tenable explanation for the residual south of Hengill.
Explanation for the misfit is most likely to be
found either in underestimate of the error sources 1-3,
44 JÖKULL No. 48