The unrest at Indonesia’s Agung continues and now the total evacuated has reached almost 100,000 people. Now, this volcanic crisis has been going for almost a week with no eruption … and we begin to enter the long, dark teatime of volcano monitoring: how long until people stop believing your statement’s about an impending eruption? What if Agung waits 3 months to erupt instead of 2 days? Credibility is very hard to rebuild after a false start, so I’m sure Indonesian volcanologists and officials are biting their nails as Agung keeps experiencing heightened seismicity.
Comparisons of satellite images of Agung taken in early and late September (below) show the changes in fumaroles (gas emissions) from the volcano as it became more restless.
— Simon Carn (@simoncarn) September 25, 2017
The latest BNPB (Indonesia’s disaster management agency) statement says that the earthquakes are getting more frequent and more are being felt, so they’re also getting stronger. All of this still supports the idea that magma is nearing the surface, making the likelihood of an eruption high (even though the steam plume is slightly smaller today). However, as any volcanologist would tell you, you trying to not only figure out the “when” but also the “how big“, and the latter is definitely much harder.
Indonesia officials are making plans to divert flights if/when the eruption begins and some airlines are planning to make extra fuel stops in case they have to turn back due to an eruption. Even without an eruption, the aviation alert level for Agung was raised to orange (from yellow) yesterday. Many people are making the evacuation on foot with the official exclusion zone around the volcano is currently set at 12 kilometers. Also, many countries are issuing travel warnings for people going to Bali because of the high potential of an eruption.
In Vanuatu, the evacuations near Manaro Voui (Aoba) are continuing, with the government of Vanuatu pledging $2 million to help with the preparations and evacuations. Ships have arrived with supplies for the evacuees, including water, food and essentials — however, more supplies are needed for the almost 8,000 people in 35 shelters which are rapidly becoming overcrowded. An official state of emergency has been announced for Ambae as well.
An overflight of the volcano’s summit showed vigorous explosions throwing ash and volcanic bombs. The volcano currently sits at alert level 4, which warns of the potential of volcanic bombs being thrown over 6 kilometers from the summit vent.
— Royal NZ Air Force (@NZAirForce) September 27, 2017
On the far other end of the spectrum of concern, Washington’s Mt. Rainier experienced a small earthquake swarm over the past few weeks. You can read the full USGS statement on this earthquake swarm that can be summed up as “no indication that an eruption is in the works at the volcano”. This swarm might be related to the hydrothermal system under the volcano, where water warmed by magma deep below the surface circulates. Now, I bring this up not to scare people but rather to remind that the lower 48 states have potentially active volcanoes, including Rainier, lurking near Seattle You can check out the seismicity at Rainier on the PNSN page. The last known eruption of Rainier was likely in 1894.