Spectacular videos of crater rim collapse into Kilauea lava lake

The active crater within the caldera of Halemaumau on the
 summit of Kilauea. The rim is about 150 meters across,
and the lava is about 100 m below the rim. USGS.

The U.S. Geological Survey (USGS) has a permanent observatory on the summit of Kilauea volcano in Hawaii, the Hawaii Volcano Observatory (HVO).  For the past 24 years, Kilauea has been active, with 55 "episodes" of activity spread over these years.  Some of the activity has been at the summit, where there is a large crater (small caldera), "Halemaumau", and some activity has been on the flank at a growing cone named Puu Oo (I can't do the Hawaiian symbols for the proper name here).  Between 1983 and 1986, Puu Oo built a massive cone, but in 1986 the activity migrated 3 km east, and lava poured out of the east rift zone all the way to the coast.

Cover image of Krafla from Geology magazine,
March 2011

In 1992, the activity shifted back to Puu Oo, and from then until 2007 lava flows poured out of vents into the ocean, mainly inside the volcano national park. After 2007, activity continued both at Puu Oo and at the summit of Kilauea in the caldera, Halemaumau.  You can explore the USGS HVO site here for more details. Related work is described in the March issue of Geology magazine (Houghton et al., Pigeonholing pyroclasts: insights from the 19 March 2008 explosive eruption of Kilauea volcano, Geology, 39(3), 263-266, 2011.)

A few days ago, the U.S. Geological Survey reported several (?) events in which a section of rock broke off the wall and fell into the lava lake.  One of these "rocks" was about 395 feet long and 16 feet wide. It had been hanging over the pit by about 180 feet and so the USGS was able to forecast the collapse.  There is great videos of these events here and here. In this video you are looking into the throat of a crater on the floor of Halemaumau (same view as on the photo on the upper left on this post).  The walls of the crater form an arch at the top, and you are looking at a lava lake in the bottom of this crater.  The molten lava is in the bottom of the crater, about 100 meters down.  It is "red hot magma", but the surface cools by radiation to the sky and conduction to the cooler air, and so it is covered with a black crust.  Motion of the magma under the crust causes it to crack and move, a miniature version of "plate tectonics."  (The USGS made a movie exploring this analogy back in the 1960's or 1970's.)

Does anyone know if this movie still exists or is available to the public?