Seismologists call it proof California is "earthquake country." About 300 quakes shook Southern California throughout the day Sunday. This video captures one families reaction. Most of the earthquakes were small to moderate sized tremors, but the strongest registered in at a magnitude of 5.5 They struck in and around the city of Brawley near California's border with Mexico.Only minor damage has been reported. There were no reports of injuries. Seismologists say even more tremors are expected in the coming days.