when did the largest swarm of earthquakes at long valley take place
Long Valley Caldera In May 1980, a strong earthquake swarm that included four Richter magnitude 6 earthquakes struck the southern margin of the Long Valley Caldera. It was associated with a 10 inches (250Â mm), dome-shaped uplift of the caldera floor.[14][15] These events marked the onset of the latest period of caldera unrest that is ongoing.[14] This ongoing unrest includes recurring earthquake swarms and continued dome-shaped uplift of the central section of the caldera accompanied by changes in thermal springs and gas emissions.[14] After the quake, another road was created as an escape route. Its name at first was proposed as the "Mammoth Escape Route" but was changed to the Mammoth Scenic Loop after Mammoth area businesses and land owners complained.