Mezue ahịrịokwu na-esonụ: N'ihi akụkọ ihe mere eme ya nke ịmepụta nnukwu ala ọma jijiji (1857,
1906) ebe a na-elekwasị anya n'ịtụle ihe ize ndụ nke ala ọma jijiji na California bụ usoro mmebi nke San Andreas. Agbanyeghị, usoro mmebi, gụnyere Sierra Madre<unk>Cucamonga Fault System nke na-agafe n'ókè nke San Gabriel na San Fernando Valleys, mekwara ka ọtụtụ ihe dị nro na nnukwu ihe na Greater Los Angeles Area. Akụkụ ebe ọdịda anyanwụ nke usoro mmebi a gbawara na 1971, a chọpụtawokwa ya dị ka otu n'ime usoro mmebi isii bụ́ isi bụ́ ndị na-eyi ógbè a ndị mmadụ jupụtara na ya egwu.