While things are presently paused this morning at the Leilani eruption site, the summit of Kilauea is causing concern. Over the past several days, the lava lake has been dropping out of sight, and as of yesterday, is no longer visible on the observation cameras.
This is what the cameras saw on May 4th when the lava lake started its withdrawal (you're looking down the throat of the volcano)........
This morning the scientists were able to visualize the lava level (oh my, brave people to get that close!!!!) when they went up to investigate a rockfall within the volcano's throat. They could still see lava way down there.
So what's the big deal? Possible explosion. Yikes! Here's a USGS diagram of what might happen if the lava keeps withdrawing......
I saw that this morning HVO issued their first warning about Kilauea summit..........
HVO/USGS Volcanic Activity Notice
Volcano: Kilauea (VNUM #332010)
Current Volcano Alert Level: WARNING
Current Aviation Color Code: ORANGE
Issued: Wednesday, May 9, 2018, 8:02 AM HST
Source: Hawaiian Volcano Observatory
Location: N 19 deg 25 min W 155 deg 17 min
Elevation: 4091 ft (1247 m)
Volcanic Activity Summary:
Primary hazards of concern should this activity occur are ballistic projectiles and ashfall.
During steam-driven explosions, ballistic blocks up to 2 m (yards) across could be thrown in all directions to a distance of 1 km (0.6 miles) or more. These blocks could weigh a few kilograms (pounds) to several tons.
Smaller (pebble-size) rocks could be sent several kilometers (miles) from Halemaʻumaʻu, mostly in a downwind direction.
Presently, during the drawdown of the lava column, rockfalls from the steep enclosing walls of the Overlook crater vent impact the lake and produce small ash clouds. These clouds are very dilute and result in dustings of ash (particles smaller than 2 mm) downwind.
Should steam-driven explosions begin, ash clouds will rise to greater elevations above ground. Minor ashfall could occur over much wider areas, even up to several tens of miles from Halemaʻumaʻu. In 1924, ash may have reached as high as 20,000 feet above sea level. Small amounts of fine ash from these explosions fell over a wide area as far north as North Hilo (Hakalau), in lower Puna, and as far south as Waiohinu.
Gas emitted during steam-drive explosions will be mainly steam, but will include some sulfur dioxide (SO2) as well. Currently, SO2 emissions remain elevated.
Steam-driven explosions at volcanoes typically provide very little warning. Once the lava level reaches the groundwater elevation, onset of continuous ashy plumes or a sequence of violent steam-driven explosions may be the first sign that activity of concern has commenced.
Kīlauea's lava lake began to drop on May 2, 2018. From its peak on May 2 to the most recent measurement at 9 pm on May 6, the lava lake surface dropped a total of more than 200 m (656 ft). The subsidence was at a relatively constant rate of about 2 meters (yards) per hour.
Measurements of subsidence have not been possible since May 6 because of thick fume and the increasing depth to the lava surface. However, thermal images indicate continued lowering of the lake surface since that time, consistent with deflationary tilt recorded at Kīlauea's summit. Therefore, we infer that the lake surface continues to drop at roughly the same rate. So, while HVO cannot report exact depths of the receding lava lake, we can monitor the overall trend.
USGS and HVO scientists are monitoring changes at the summit 24/7 and watching for signs that hazardous conditions have increased, or may increase. HVO is working closely with Hawai'i Volcanoes National Park and Hawai'i County Civil Defense to respond to this situation.