Complex sentence: Also a weak thermal eruption occurred on November 29,2012, then it stopped again, since its neighboring volcanoes are erupting more actively and continuously, taking a major load off of Klyuchevskaya Sopka.
Split into simpler sentences: Also a weak thermal eruption occurred on November 29,2012, then it stopped. Since its neighboring volcanoes are erupting more actively taking a major load off of Klyuchevskaya Sopka.