Hollow Earth Radio‘s sprawling (and aptly named) annual Magma Festival returns to the Chapel with four acts: 3-year-old percussion monster Moon Joe; the duo of grown-up percussionist Dan Sasaki & Olympia multimedia artist Jean Nagai; the swampy psych improv of Knot Pine Box; and Low Yo Yo Stuff is veteran sax improviser Wally Shoup taking on a trio of bassists: Simon Henneman, PK, John Seman.