Hello,
There are a few things in your steering file that I do not understand -- for instance you set your initial conditions to:
INITIAL ELEVATION = 1.0
and then you set your boundary to:
PRESCRIBED ELEVATIONS = 1000.0
as if you had a 1000 m tsunami wave coming annihilate the "british isles"
The friction also seem wrong ...
However, I do not thing this is the problem of your simulation -- rather, it may have to do with your mesh -- could you share you geo file with us so we can have a look and advise ?
Hope this help,
Sébastien.