The 1980 Livermore earthquake occurred on January 24 at 11:00 PST in California. The epicenter of the 5.8 Mw earthquake was a hilly area 12km (7.5mi) southeast of Mount Diablo and north of Livermore Valley. The earthquake had a maximum Modified Mercalli intensity of VII (Very strong). Forty four people were injured and damage across the San Francisco Bay Area totaled $11.5 million, with the majority inflicted at the Lawrence Livermore National Laboratory.
Faulting
The mainshock was preceded by a 2.7 MLforeshock 1.5 minutes prior. In the first six days after the mainshock, 59 aftershocks were recorded measuring ≥ 2.5 ML.[3] On January 26, a Mw 5.3 aftershock occurred with an epicenter 14km (8.7mi) southeast of the mainshock. Six hundred aftershocks were recorded in the 33 days after the mainshock. An analysis of P wave indicate the fault plane solution was right-lateral strike-slip faulting.[4]
Surface faulting consisting of discontinued and small offsets occurred along the Greenville and Las Positas faults. At least 4.2km (2.6mi) of rupture occurred on the Greenville Fault, but it may have extended south to Interstate Highway 580, giving a possible total length of 6.2km (3.9mi). Surface faulting was sparse along the rupture. A maximum right-lateral offset of 25mm (0.98in) and vertical offset of 50mm (2.0in) was recorded. A 0.5km (0.31mi) rupture was located 0.12–0.25km (0.075–0.155mi) east of the main rupture, and 25m (82ft) away from another known fault. The secondary break produced 20cm (7.9in) of right-lateral offset, and 40mm (1.6in) of extension. Offset was also recorded along at least 1.1km (0.68mi) of the Las Positas Fault Zone. These consisted of small left-lateral offsets.[5]
Damage
Damage to property was nonstructural—consisting of fallen ceiling tiles, detached bricks from chimneys, ruptured gas and water lines, shattered windows, and mobile homes displaced from their foundations. At a ranch north of Livermore, along Vasco Road, two brick-and-stone fireplaces were fractured and offset from their walls. Along Interstate 580 and Greenville Road, a concrete pavement sunk 30cm (12in), and the a concrete abutment fractured and spalled. Forty four people were injured. Damage at the Lawrence Livermore National Laboratory was estimated at $10 million.[6]
The January 26 aftershock caused six additional injuries in Livermore from glass and falling debris. Fifty homes sustained minor damage in Tassajara. A fireplace was damaged, walls and concrete fractured, walls detached from ceilings, windows broke and a chimney collapsed. In Danville, a brick chimney and fireplace were damaged, stone wall was destroyed, and walls, patios, sidewalks and ceilings cracked. Several other towns reported slight damage.[6]
↑Bolt, B. A.; McEvilly, T. V.; Uhrhammer, R. A. (1981). "The Livermore Valley, California, sequence of January 1980". Bulletin of the Seismological Society of America. 71 (2): 451–463. Bibcode:1981BuSSA..71..451B. doi:10.1785/BSSA0710020451.
