An eruption began in the summit caldera of Hawaiis Mauna Loa, the worlds largest active volcano, on Sunday night, the US Geological Services (USGS) volcanic activity service said. "At this time, lava flows are contained within the summit area and are not threatening downslope communities," the notification said. However, the notification warned, based on previous events, that the early eruption stages of this volcano can be very dynamic and the location and advance of lava flows can change rapidly. The volcano alert level was upgraded from an "advisory" to a "warning." The notification added that the Hawaiian Volcano Observatory (HVO) would conduct aerial reconnaissance as soon as possible to assess hazards and better describe the eruption. Over a dozen earthquakes of more than 2.5 magnitude struck the region in the last two hours, according to the USGS, with one measuring 4.2 in magnitude. Mauna Loa, which takes up more than half of the Big Island in Hawaii, and rises 13,679 feet (4,169 meters) above the Pacific Ocean, last erupted in March and April of 1984, sending a flow of lava within 5 miles (8.05 km) of the city of Hilo.