With so much Hawaiian volcanic activity in the news of late, now is a good time to revisit music by Alan Hovhaness and Jon Leifs. Hovhaness was inspired to write his Symphony No. 50, “Mount St. Helens,” in the wake of Helens' cataclysmic 1980 eruption, the deadliest in U.S. history. Leifs' “Hekla,” requiring 19 percussionists and a panoply of unconventional instruments, has been called the loudest piece of classical music ever written. Prepare to be blown away, this Sunday at 10 pm.