Gleefully trashy “Aftershock” applies a grindhouse sensibility — minus the faux-oldie stylings of other recent exploitation homages — to a disaster-survival thriller that acts more like a horror film. The English-language debut of Chilean director Nicolas Lopez (“Fuck My Life”) toplines “Hostel” helmer Eli Roth, no stranger to tasteless cinema, as an American caught in a major Valparaiso earthquake. This Dimension pickup is a hectic, sometimes hilarious guilty pleasure that should delight genre geeks. Still, as Tarantino’s “Grindhouse” proved, mainstream audiences can be fickle when it comes to smart, in-jokey versions of dumb movies, seemingly preferring the real dumb thing.

The pic’s first half-hour is a fast-paced and funny version of that usually blah vacation-of-horror intro in which we meet the hot young party-hearty protags, mostly foreign tourists, who’ll soon be paying for their pleasures in various grisly ways. A divorced Yank, here called only by his nickname, Gringo (Roth), is hoping to score a little love at the clubs and raves he attends with two local friends, insecure Ariel (Ariel Levy) and brash tycoon’s son Pollo (Nicolas Martinez).

They meet a multinational femme trio — boozing California wild child Kyle (Lorenza Izzo), her sober Hungarian half-sister/minder Monica (Andrea Osvart) and their Russian model pal Irina (Natasha Yarovenko) — and spend the next day sightseeing as a group. But at an exclusive dance party that night, the Big One hits, briefly trapping everyone underground and crushing plenty of revelers under falling debris.

Making their way out, with one of their number already seriously wounded, the protags find streets blocked, destruction everywhere, and looters running rampant. Then the tsunami warning alarm goes off.

The script by Roth, Lopez, and Lopez’s frequent collaborator, Guillermo Amoedo, giddily piles crisis upon crisis, with none of the customary mercy reserved for leading characters. Indeed, in several cases, the higher the billing, the more tastelessly grisly the fate. In the interests of maximum hyperbole, only one element is missing: Sensurround.

This movie does not, however, pretend to be a 1970s drive-in or ’80s direct-to-vid pic, despite the tonal and thematic nods. It’s got a contemporary look, albeit of a somewhat deliberately tacky, over-colorful stripe, with plenty of thundering club tracks in the early going. Many gags are aimed at Chilean audiences, though not the fleeting appearance of Selena Gomez, also seen at the Toronto fest laying waste to her teen-queen image in “Spring Breakers.”

The thesps are more than game; Roth, who hasn’t particularly impressed as an onscreen presence before, is clearly having great fun, and makes that feeling infectious. Production package is solid, while hanging onto a certain B-pic roughness.