Tonight after normal work hours I was trained how to monitor the vent at Halema`uma`u. Ever since the caldera explosions earlier this year, HVO has had staff members watching the vent around the clock. The explosions have been at night, so it’s critical to have someone monitoring it constantly. However, monitoring an active vent isn’t as simple as sitting and staring at it.
There are several measurements geologists, seismologists, and geophysicists use to forecast eruptive activity and study an active volcano. Some of these measurable factors include earthquakes/seismicity, vent temperature, and tilt (deformation).
Seismicity and earthquakes help us see the frequency and characteristics of movement inside the earth. Some earthquakes are very shallow and originate within the volcano, oftentimes near the magma chamber. Other earthquakes are deep and come from the earth’s mantle, more than 70 kilometers (43.5 miles) below the surface. We’re concerned with the shallow ones, since they often occur in “swarms” before a volcanic eruption. Tonight I learned how to examine a seismograph and earthquake data to determine if significant eruption activity is happening.
We constantly monitor the temperature of the sulfur dioxide (SO2) gas that Halema`uma`u emits. Temperature spikes can indicate changes in vent activity, or just changes in the weather. You have to pay attention to see what is significant.
Another of the things that we monitor closely is called deformation. We use electronic tiltmeters that are semi-permanently or permanently located all around the island to measure changes in the slope of various locations. If the slope of an area increases steadily, it can indicate that the magma chamber is filling up. This can mean that an eruption is in the near future. It doesn’t always, however, so we have to make sure that we see a definite trend or we’ll be caught crying wolf. Here’s a really cool example of how volcanologists used tilt to track Kilauea’s past eruptions.
There’s more than this to monitoring, but it’s late and I have a field excursion tomorrow! It’s going to be very low-impact, since I’m still 2 days away from medical clearance to resume hardcore field work. I’m housesitting for another volcanologist now, and this one has eight cats. It’s quite a bit different than watching the two dogs at the other house! Word has gone around the office that I used to be a vet tech, so my pet-sitting skills are proving helpful to members of the staff who want their vacations.
Just so you don’t feel deprived, here’s a picture of the ocean entry plume from last week. Tomorrow will bring new and exciting pictures of Mauna Loa, Mauna Kea, Hualalai, and the Kona coast, provided the weather decides to cooperate. We’re catching the rain from a passing tropical storm, and it’s quite wet right now. Anyway, the plume awaits!