OK this article is pretty old but still worth the read: "Hasta La Muerte," at the Village Voice, on the rise of thrash metal in Southern California, a rise led by mostly Mexican Americans:
For some reason, '80s-style thrash is making a major comeback in the metal underground, led by a wave of Latino-dominated bands from Southern California, Mexico, and South America. These new disciples are hardcore, sporting the Metallica-circa-'83 look—denim vests, bullet belts, tight jeans—and generally paying heartfelt tribute to the old school in their band photos, logos, and demo titles.
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The movement's flagship act, if there is one, is Fueled by Fire, from Norwalk, California. They're signed to Metal Blade (the label that first presented Metallica and Slayer to the world), and their sound is pure '80s mayhem: "Thrash Is Back" could be a lost Exodus track, as vocalist Giovanni Herrera barks out a tribute to moshpit mayhem.
"For some reason" opens lots of questions, doesn't it? Of course, Mexico has been hard-rock-friendly for ages. And Mexican Americans have a long history with thrash, death-metal and punk rock, which has been the most chronicled of all the outsider subgenres. See "Teenage Alcoholics," a history of the punk movement in East L.A by Jimmy Alvarado. Also, the images from the scene by Diane Gamboa, at KCET. Village Voice link.
* Photo of Fueled by Fire from their MySpace.