I would guess you've got Roll Forward Recovery Log mode on.  Is this the
desired state?

What processes are running?  Is there an expiration process running?
Reclamation?  Something is doing lots of database thingies so they are
being logged and saved (if you're using Roll Forward Recovery log mode).
 Do you have a database backup trigger set?  If so, when the log reaches
this amount, a db backup will be done and the log flushed.  If you don't
have a trigger, keep an eye on the log and do a manual backup before it
fills.

I'll assume you know all of this.  Either something is running that should
be running, or something is running that shouldn't.  You may need to halt
ADSM and restart it.  Somewhat disconcerting but the goal is to stop the
behavior first and understand it later.

Kelly