alter table is taking a long time

Hi
i have main table where and that table i have inherited 64 times, but
today i needed some extra space to a column so i have run an alter
table to one of my columns

the query is running for over 4 hours and i don't have a clue when it
will stop, the storage of this 64 table has around 30 and milions of
records,

Any advices on what i should need to do next,

Regards