Kammala jumla mai zuwa: Saboda tarihinsa na haifar da manyan girgizar ƙasa (1857,
1906) babban abin da ke tattare da kimanta haɗarin girgizar ƙasa a California shine San Andreas System of Faults. Koyaya, tsarin kuskure, gami da Sierra Madre<unk>Cucamonga Fault System wanda ke gudana a kan iyakar San Gabriel da San Fernando Valleys, ya kuma haifar da jerin matsakaici zuwa manyan abubuwan da suka faru a Greater Los Angeles Area. A shekara ta 1971 ne ɓangaren yamma na wannan wurin ya fashe kuma an gano cewa yana ɗaya daga cikin manyan wuraren da ke da haɗari ga wannan yankin da ke da yawan jama'a.