HONOLULU (AP) - The Hawaiian Volcano Observatory has been busy with lava flow from Kilauea Volcano but also is paying close attention to Mauna Loa.
Mauna Loa last month had its largest swarm of earthquakes in nearly a decade and continues to swell.
University of Hawaii volcanologist Michael Garcia says the earthquakes suggest that Mauna Loa is waking up but that it could be months before it does anything.
The volcano also may do nothing, as happened in 2004 and 2005.
Garcia says when one volcano is very active, the other tends to be quiet and swelling at one volcano puts pressure on the other, inhibiting the rise of magma in the second volcano.
The Honolulu Star-Advertiser reports both volcanoes erupted at the same time in 1919 and 1984.