The Alaska Volcano Observatory raised the Shishaldin alert level to Watch and changed the aviation code to Orange on October 17th at 11:06 am AKDT.
In question, a new lava effusion, started on October 13, continues, according to the observation of continuous low level seismicity and high surface temperatures. The activity remains confined to the summit zone, without observation of ash clouds.
In Poas, the rains of the last days have allowed a build up of water in the area of Bocca A, as well as in the central sector. The activity this week was characterized by small shallow water eruptions, and bubbling in mouth A and the central area.
Steam and gas fumes continue.
The field of sulfur-rich fumaroles in the area northeast of the old lake remains active.
At the seismic level, the shallow bottom tremor is maintained (2 to 4.5 Hz), as well as earthquakes of LP type (long duration) generally of low amplitude.
Sources: Ovsicori & RSN
Currently, the Volcanological and Seismological Observatory of Costa Rica and the School of Geographical Sciences of the National University are conducting research on the Río Cuarto Lagoon. This lagoon has a depth of about 70 meters, is a crater formed by a phreatomagmatic eruption (product of the eruption of magma-water contact) about 3-4 Ma ago (Alvarado et al., 2011)
This crater has degassing with a possible accumulation of CO2 and CH4 resulting from the injection of hydrothermal gases, the microbial process and the stratification of water in three layers called epilimnion, metallimnion and hipolimnion. The first layer corresponds to surface water with higher temperature and oxygenation, the second layer is the transition between the superficial layer and the deep layer where this stratification is generated; the last layer corresponds to deeper waters with lower temperatures, lower concentrations of O2 and high concentrations of hydrothermal CO2 (Cabassi et al 2014).
There is a need for various campaigns to determine whether there is significant accumulation in the lake and at the same time to determine whether the gases being emitted are magmatic or bacterial. These accumulated gases can be very dangerous if they are suddenly released during a limnic eruption - like lake Nyos - that can be caused by a meteorological process (eg, high winds) that cause a change in the position of the lake layers, ie that is, surface water is removed, giving way to deep waters that contain gas.
This Thursday, October 17, 2019, Arcandra Tahar, member of the ESDM, inaugurated a new observation post of Bromo volcano, located in the hamlet of Cemoro Lawang.
At the event, he said: "I hope that, after the addition of the new Gunung Bromo Observation Building, the use of observation posts as a means of monitoring volcanoes and providing information on disasters in the Bromo-Tengger Caldera region will be operational, and I also hope that the community will be able to help maintain the existence of this observation post and its associated monitoring equipment. "