High Quality Content by WIKIPEDIA articles! The 1979 Imperial Valley earthquake occurred at 16:16 Pacific Standard Time (23:16 UTC) on October 15 and impacted the Imperial Valley in southeastern Southern California with the epicenter just south of the international border of the United States and Mexico. It had a magnitude of 6.4 on the moment magnitude scale and a maximum perceived intensity of IX (Violent) on the Mercalli intensity scale. With a relatively shallow hypocenter, it caused property damage estimated at $30 million, and badly affected the irrigation systems in the Imperial Valley, but was not responsible for any deaths.