California's Abalone Alliance carried the Clamshell model to the Diablo Canyon plant, built beside an earthquake fault near San Luis Obispo. The September 1981 blockade — two weeks of affinity-group waves by land and sea from the Rachel Carson — produced over 1,900 arrests, the largest number in the history of American anti-nuclear action; Jackson Browne went to jail alongside grandmothers from the Mothers for Peace, the plant's original church-basement opponents.

Days after the blockade ended, PG&E admitted its seismic blueprints had been reversed between the plant's twin units — vindicating the blockaders as the licensing collapsed into years of rework. Diablo opened anyway in 1985, but the Abalone campaign's fifty-plus affinity-group culture became the organizing DNA of the decade's disarmament and Central America movements.