In recent days, the lava lake in Halemaʻumaʻu Crater has been at a relatively high level. This view, looking roughly north-northeast, shows typical behavior, with lava rising into the lake at the distant end opposite the photographer, and sinking all along the base of the crater wall in the foreground and at right. Within this zone of subduction is a site of persistent spattering at the southeast edge of the lava lake, visible at the right edge of the photograph. On the morning of January 7 when this photo was taken, the lake was about 35 m or 114 ft below the rim. USGS Photo.

Zoomed-in view of the spattering at the southeast corner of the lava lake. The vent wall is overhung in this area. Photo taken Friday, January 7, 2016 courtesy of USGS/HVO

The January 8, 2016, rockfall and subsequent explosive event littered the rim of HalemaÊ»umaÊ»u Crater with fragments of molten lava. In this image, you can see what remains of the HalemaÊ»umaÊ»u Overlook wooden fence, which has been repeatedly been bombarded by spatter and rock fragments since 2008. The blue bucket attached to the fence is one of HVO’s tephra collectors so that lava fragments and rocky debris ejected from the summit vent can be quantified and analyzed. Photo taken Friday, January 8, 2016 courtesy of USGS/HVO

The rim of HalemaÊ»umaÊ»u Crater was covered in a nearly continuous blanket of tephra following today’s early morning rockfall and subsequent explosive event. Tephra is the general term for volcanic rock fragments exploded or carried into the air during an eruption, and can range from dust-size particles to fragments more than 1 m (3.2 ft) in diameter. Two backpacks (in background), which belong to HVO scientists who briefly entered the area to collect tephra samples for laboratory analyses, provide scale for the fragments hurled onto the crater rim this morning. Photo taken Friday, January 8, 2016 courtesy of USGS/HVO

The 10 cm (4-inch) pocket knife in this image provides scale for one of the larger fragments of molten lava that was thrown onto the rim of Halemaʻumaʻu Crater at 3:51 a.m., HST, on January 8, 2016. So much spatter was ejected to the crater rim this morning that it is hard to discern one lava fragment from another. Photo taken Friday, January 8, 2016 courtesy of USGS/HVO

This photo shows a one-of-a-kind, completely hollow Pele’s tear about 1.5 cm (1/2 inch) long. It was found on the rim of HalemaÊ»umaÊ»u and was ejected in association with this morning’s explosive event, probably during the aftermath when the lake surface was spattering vigorously. Photo taken Friday, January 8, 2016 courtesy of USGS/HVO

A rockfall on the east rim of the summit vent within KÄ«lauea Volcano’s HalemaÊ»umaÊ»u Crater triggered a small explosive event at 3:51 a.m., HST, on January 8, 2016. Explosive events like this occur more frequently when the lava lake level is relatively high, as it has been this past week—around 30-35 m (100-115 ft) below the vent rim. Rocks in the vent wall expand as they are heated by the high temperature of the lava lake and become unstable. Sections of these unstable rocks can then collapse into the lava lake. Rockfalls and subsequent explosive events occur with no warning, and the resulting fragments of hot lava and rocky debris thrown onto the crater rim pose a significant hazard in this area. Video courtesy of USGS/HVO