HAWAII NATIONAL PARK, Hawaii (AP) - Scientists at the Hawaiian Volcano Observatory have recorded increased seismic activity on the flanks and summit of Mauna Loa over the past 13 months.
The observatory said in a weekly activity update Thursday there is no sign of an impending eruption.
Earthquake swarms were detected prior to previous eruptions of the volcano.
Seismic activity was elevated for at least 3 years before the mountain's 1984 eruption. Scientists recorded 28 earthquakes greater than magnitude 3 and 2 earthquakes greater than magnitude 4.
Over the past year, four distinct earthquake swarms have occurred.
Each swarm began with earthquakes northwest of the summit, followed by shallow earthquakes at the summit several days to one month later.
These earthquakes have all been less than magnitude 2.2, except for a magnitude-3.5 quake on May 9.
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