Complex sentence: Evidence suggests that the Grand Etang Lake is connected to Kick' em Jenny, an active submarine volcano to the north since when Kick Em Jenny was observed bubbling, so too were the waters in Grand Etang Lake.
Split into simpler sentences: Evidence suggests that the Grand Etang Lake is connected to Kick' em Jenny, an active submarine volcano to the north. This is because when Kick Em Jenny was observed bubbling, so too were the waters in Grand Etang Lake.