Hawaii (Big Island), USA 11/23/2011
Mauna Loa, Earth's largest active volcano, is showing signs of heightened seismicity in the last few weeks. A mag. 3.0 quake struck on 11/20 followed by a 3.9, at a depth of around 5km. Smaller quakes and aftershocks also occurred. Today, mag 1.9 and 1.7 tremblors struck under the summit and NW flank of the volcano at a depth of 20.80 km (12.92 mi). These could just be purely structural or tectonic, as no heightened gas emission of fumerole temperature changes have been noted aside from the usual night/day fluctuations.
This follows on the heels of the earthquake activity at it's slightly taller neighbor, Mauna Kea, which experienced a large earthquake swarm about a month ago, with small aftershocks continuing. HVO stated in regards to this event "On the afternoon of October 19, a magnitude-4.5 earthquake occurred beneath the northwest flank of Mauna Kea at the start of a swarm more than 50 smaller quakes over the next several hours. The earthquakes were the result of crustal adjustments beneath the volcano and not to volcanic activity. Other than the swarm, typical seismicity was recorded - 6 events shallower than 20 km deep and 5 events deeper than 20 km." Although Mauna Kea did not experience volcanic tremor, as the scientists state, the same cannot be assumed for Mauna Loa without further analysis, given that, like Kiluea, it is one of the worlds most active volcanoes.
HVO's description of Mauna Loa (below):
"Re-inflation of Mauna Loa's shallow magma storage reservoirs started immediately following the most recent eruption in 1984, then turned to deflation for almost a decade. In mid-2002, inflation started again, just after a brief swarm of deep long-period (LP) earthquakes. A more intense swarm of (more than? about?) 2,000 deep LP earthquakes occurred in late 2004, immediately preceding a dramatic increase in inflation rate. Inflation slowed again in 2006, ceased altogether in late 2009, and resumed slowly in late 2010.
Rising gradually to more than 4 km above sea level, Mauna Loa is the largest volcano on our planet. Its long submarine flanks descend to the sea floor an additional 5 km, and the sea floor in turn is depressed by Mauna Loa's great mass another 8 km. This makes the volcano's summit about 17 km (56,000 ft) above its base! The enormous volcano covers half of the Island of Hawai`i and by itself amounts to about 85 percent of all the other Hawaiian Islands combined.
Mauna Loa is among Earth's most active volcanoes, having erupted 33 times since its first well-documented historical eruption in 1843. Its most recent eruption was in 1984."
It's important to note that these earthquakes could easily be crustal adjustments, and not related to any magma intrusion. However given Mauna Loa's history of destructive eruptions, it absolutely pays to keep an eye peeled on this gigantic volcano, that has caused much destruction to the environment, and property on the Big Island. Unlike Kiluea, which is sort of 'aimed away' from most populated centers on the Big Island, Mauna Loa looms over much of the Island, coincidentally making property very cheap, and insurance very expensive. Ahh, the price of paradise.