Yesterday morning at about 9:30, the vent at Halema’uma’u coughed up a dense brown cloud for several minutes. It happened at the same time as a hybrid earthquake. A hybrid earthquake?

Well, that was a new one for me, so I looked up the definition. The definition, translated to some approximate version of English, is that a hybrid earthquake is an essentially explosive event that shows up on seismometers as a mix of signals. This one started as a regular earthquake of the kind that usually produces rockslides… and we know it did, because of the brown dust in the plume… then transitions to a weirder thing, VLP (meaning Very Long Period) signals that go up and down once about every 30 seconds and lasts for several minutes. Sort of like a tuning fork with a really low frequency.

This has happened before, in March and April, when there were three small explosive events at the vent. Small by geologic standards, but still, you wouldn’t want to be standing next to one.

There were a lot more little earthquakes that did not produce anything above ground. At night, there was exceptional brightness to the plume incandescence.

Sulfur dioxide emissions are reported as average for this event cycle, 1,540,000 pounds a day. But that was from August 4, when skies here in Kona Coffee Country were definitely bluing up a little. No more. Vog is in the heavy to super-heavy range here on the southern outskirts of Kailua town. So I’m thinking their measurements simply have not caught up with reality again. Uh… wasn’t the hotshot CDC team that came to the island last month supposed to show us ignorant islanders how to make the measurements better somehow? Something about doing it in close to real time? No? I must have misunderstood.

In the East Rift Zone, the emissions are… who knows? Last measurement was July 31, when it conveniently dipped down below background values. And as I mentioned, there was a while during last week when the vog got a little less heavy. Very little if any lava is entering the ocean. No lava flows visible on the surface. USGS is calling it a ‘pause’.

Put it all together, and you get… what? Perhaps the action is shifting from the East Rift Zone more toward the summit of Kilauea where the vent at Halema’uma’u in Kilauea Caldera is the center of attention. That could explain the unusual earthquake activity. As magma moves up through the earth’s crust, that’s what it does best… produce little earthquakes all along the way. I would think that the VLP signals were very much indicative of that sort of movement. If so, we might see more unusual events or increased activity at the summit. And if so, I’ll try to let you know about it.