Kilauea is one of, if not the, most active volcanoes in the world. These days, lava flows are almost constantly issuing from the lava tube system below the Pu'u O'o vent and at the summit, Halema'uma'u is aglow with the light from the lava lake that lives at the bottom of the pit crater. It is easy to forget that through all this persistent and consistent volcanism that the activity does not remain the same -- it waxes and wanes as the magmatic system fills and drains along the entire tube system that runs along the rift zones of the massive shield volcano. You can begin to get a sense of the changes in the magmatic system by watching the rising and falling of the lava lake at the Halema'uma'u crater. We have seen evidence on multiple occasions where the level of the lava lake has changed dramatically preceding new fissure vent eruptions, so watching how the level drops and then rises as the lava lake refills is a way to monitor the influx of magma into the summit around of Kilauea. The Hawaii Volcano Observatory (HVO) posted a timelapse of thermal images of the lava lake taken from webcams pointed at the lava lake, where two years (February 2011-February 2013) worth of changes are condensed into a mere minute, so the ups and downs can be seen clearly. What I find most fascinating is how dynamic the level of the lava lake is -- it starts out high and then dramatically drops (during the Kamoamoa fissure eruption), then begins to refill. However, it doesn't refill slowly and steadily. Instead, there is a pulsing of the lava level, where it might rise some, but then drop a little, then rise back up to a higher level and this is reflected in the inflation and deflation recorded by instruments measuring the shape of the summit area of Kilauea. Sometimes a darker crust can form on the lake, making it look smaller, but those crusts are usually consumed by the rising lake level or small lava flows that spill out from the lava lake. By the end of the video, we can see that the lava lake levels in the Halema'uma'u are as high as they've been anytime over the last two years. Remember, there is also a small lava lake in the Pu'u O'o crater as well, so Kilauea hosts two of these remarkable volcanic features.
A thermal image of the eastern ocean entry at Kilauea on June 27, 2013, where red/orange are hot and purple/blue are cool. The dark blue at the bottom of the image is the Pacific Ocean. A lava tube is marked with an arrow. Image: HVO/USGS. That isn't all that is up at Kilauea -- currently two lava flows from the lava tube system fed by Pu'u O'o are rolling over a forest (see above), meaning we're going to be seeing move lava tree molds/casts made. Trees can survive (well, for awhile) lava flows like the pahoehoe flows at Kilauea and they can produce molds of the trees, completely with imprints of tree bark, as the lava flow moves around the tree. Now, most of the time the tree ends up combusting as the ~1000°C basaltic lava moves by, which is why the tree molds are empty, but they preserve the evidence of the forest that once was. Below is a picture I took of a tree mold on our recent departmental trip to Hawaii where you can even tell which way the lava flow was going when it encountered the tree.
Two lava flows move into a forest on the slopes of Kilauea, seen on June 27, 2013. Image: HVO/USGS.HVO also posted this great thermal image of the slopes of Kilauea leading to the current ocean entries near Kupapa'u Point. You can clearly see on this image the active lava field along with the ocean entries, but what is remarkable is how clearly you can see the lava tubes (marked with an arrow, below) and the thermal plume in the ocean caused by the lava flows dumping into the Pacific. The image also betrays the complexity of the tube system at Kilauea (compare that with a true color image of the same area), with a dendritic web of lava channels, all insulated from the cool air at the surface by a thick crust of solidified lava. That crust is usually thick enough to walk over, which we did during out visit and you can definitely feel the heat of the lava through the roof of the tube.
A tree mold in a Kilauea lava flow. I've marked the mold itself and the inferred direction of lava flow around the (former) tree. Image taken March 2013 by Erik Klemetti. If you haven't, be sure to check out the bevy of webcams pointed at various parts of Kilauea. You can never be sure what you'll see, but it will always be something different.
Video: Hawaii Volcano Observatory / USGS.