Tuesday, April 14, 2015

Mauna Loa Quake Activity Increases

During the past couple weeks, Mauna Loa, Hawaii's largest and historically most active volcano, has been exhibiting more quake activity at its summit, and SW rift zone. HVO is monitoring the situation. Inflation restarted in the volcano in 2010, and a slow but gradual inflation is taking place. This is a bit unusual, as Kilauea is still pumping plenty of lava out and consistently creating new land. Typically, Mauna Loa only inflates when Kilauea is not active. It would be highly unusual, however not unprecedented, for both volcanoes to be erupting at the same time.

Many shallow quakes exceeding magnitude 2.0-3.5 have occurred near the summit. Fumerole temperatures remain slightly elevated.

The latest report from HVO states:

"MAUNA LOA VOLCANO (VNUM #332020) 19°28'30" N 155°36'29" W, Summit Elevation 13681 ft (4170 m) Current Volcano Alert Level: NORMAL Current Aviation Color Code: GREEN

Monitoring data through the month of March 2015:

Seismicity: Seismicity at Mauna Loa remains elevated in several parts of the volcano. Earthquake rates on the Upper Southwest Rift Zone (Sulfur Cone) and Mokuʻāweoweo Crater remain elevated, with over 100 earthquakes occurring in March. Though there were no swarms on the west flank of Mauna Loa, earthquake rates remained above background with approximately 25 earthquakes occurring in March. All earthquakes in the past month have been small relative to earthquake sequences observed before eruptions in 1975 and 1984.

Deformation: The pattern of motion of continuously recording GPS stations in March indicate that inflation continues. Average velocities since the start of the current inflationary period in mid-2014 are not quite as fast, but very similar to those observed in 2005 which, along with a short period in 2002, had been the time of highest observed velocities since GPS monitoring started in the mid-1990's.

Background: 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 several thousand deep Long Period (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."

It is unclear how April's upcoming report will look, however there have been much larger quakes at the summit compared to March. They are still below the magnitudes preceding the earthquakes in the above report.

It is likely Mauna Loa is entering into a heightened phase of activity, but it is impossible to know when it will erupt, however HVO will certainly have more advanced notice since it's last time, as monitoring techniques and technology are by far more advanced than they were in the 1970's and 80's.

For now, I am keeping my eye on this volcano.

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