Like most armchair volcanologists on this island I have been monitoring Mauna Loa more closely lately. The deformation graphs in particular have been? Interesting. I have even gone so far as predicting that we will not get through the year without a Mauna Loa eruption.
The area of concern has been the western rift zone, exhibiting steady and shallow seismic activity for the last several years. More concerning is the rate of inflation shown in the GPS data, This seems to have doubled in rate around last October.
Then comes today.
An intense seismic swarm is currently occurring beneath the NW flank. Still fairly deep. a few kilometers below the surface, but getting shallower. Magma is definitely moving, a sizable mass moving upwards and emplacing itself higher in the volcano.
This may come to nothing in the near term. Like many seismic swarms it may stop. Just part of the process towards a future eruption some years from now, or never. Or we may be seeing the first step in a new eruption. I will hold to my prediction of an eruption sometime in 2021.
While the beaches may be closed during the pandemic, most of the trails are open. Deb and I did a little walking on the Puʻu Oʻo Trail while coming back over the hill from Hilo.
Nothing unusual to report, no rare native birds. As the ʻōhiʻa are not in bloom few birds were in evidence. Even without blooms or birds this is always a pretty trail, a rugged landscape over recent lava flows and the pioneer plants found on these flows.
Being an inveterate volcano watcher, I have not only been watching the new flow on Kilauea, but keeping a wary eye on Mauna Loa as well. The USGS has steadily been increasing the alert level on this largest of the Hawaiian volcanoes over the last year.
On this unstable rock we live, we get a fair number of earthquakes. Of course not every bump you feel is seismic, sometimes it is just a big truck on the highway. You look on the USGS Recent Earthquakes page anyway, just to see what it was. Not this time, must have been a truck. While I have the page loaded I look about… Wait? What is that cluster on the NW flank of Mauna Loa? I do not remember seeing that before!
For the last year or more there has been a steady cluster of small earthquakes just to the southwest of the main caldera. This notable cluster is usually visible when you stop by the earthquake page and indicates magma motion below the summit. It is a big part of why the USGS has upped the advisory level. The cluster on the west flank looks new to me, a lot of small quakes, some deep, some as shallow as 600m.
I am sure someone over at the USGS is looking at the same cluster and asking the same questions. Maybe they have better answers, but they have not published anything yet. Maybe, like so many times before this cluster will fade away, not to appear again. It is however a reminder that magma is moving down there, the mountain is swelling, someday she will erupt again.
Today I will be driving up and down the mountain. I know I will be looking across the saddle at the looking bulk of Mauna Loa and wondering for the thousandth time. Will I see an eruption from her during my years on island?