An example of this is during the 1989 earthquake in San Francisco , when sand boils brought up debris from the 1906 earthquake . This process is a result of liquefaction . By mapping the location of sand boils that erupted in the Marina District during the 1989 Loma Prieta earthquake , scientists discovered the site of a lagoon that existed in 1906 . The lagoon developed after the Fair 's Seawall was constructed , and was later filled in in 1915 in preparation for the Panama – Pacific International Exposition
1906 earthquake
1906 San Francisco earthquake
Sand boil