Mezue ahịrịokwu na-esonụ: N'ihi akụkọ ihe mere eme ya nke na-emepụta oké ala ọma jijiji (1857, 1906) ebe a na-elekwasị anya na nyocha nke ala ọma jijiji na California bụ San Andreas System of Faults. 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 mebiri na
1971 ma bụrụkwa nke a mataworo dị ka otu n'ime usoro mmebi isii bụ́ isi nke na-eyi ógbè ahụ ndị mmadụ jupụtara na ya egwu.