USGS Volcanoes: Notices released in the last day.

Strong northwesterly winds in the vicinity of Katmai and the Valley of Ten Thousand Smokes have picked up loose volcanic ash erupted during the 1912 Novarupta-Katmai eruption and are carrying it to the southeast. The National Weather Service has issued a SIGMET (https://www.weather.gov/aawu/sigmets) for this low-level event and suggests that the maximum cloud height is 6,000 ft (1.8 km) above sea level.

This phenomenon is not the result of recent volcanic activity and occurs during times of high winds and dry snow-free conditions in the Katmai area and other young volcanic areas of Alaska. No eruption is in progress. All of the volcanoes of the Katmai area (Griggs, Katmai, Novarupta, Mageik, Martin, Snowy and Trident) remain at Aviation Color Code GREEN and Alert Level NORMAL. Resuspended volcanic ash should be considered hazardous and could be damaging to aircraft and health.

For more information on volcanic ash and human health, visit the following website: http://volcanoes.usgs.gov/ash/

Official warnings about these ash resuspension events are issued by the National Weather Service: https://www.weather.gov/afc/

Forecasts of airborne ash hazard to aircraft: https://www.weather.gov/aawu/. Volcanic Ash Advisories: https://www.weather.gov/vaac/

Forecasts of ashfall: http://www.weather.gov/afc

Air quality hazards and guidance from Alaska Department of Environmental Conservation, Division of Air Quality: http://dec.alaska.gov/Applications/Air/airtoolsweb/Advisories/Index

Lava continues to erupt slowly within the summit crater of Great Sitkin Volcano. Nothing unusual was observed in clear satellite and webcam imagery. Seismicity was mostly quiet over the past day.

The current lava eruption began in July 2021 and since then has filled most of the summit crater and advanced into valleys below. There have been no explosions at Great Sitkin Volcano since an event in May 2021. The volcano is monitored using local seismic and infrasound sensors, satellite data and webcams, and regional infrasound and lightning networks.

Shishaldin Volcano continues to experience unrest with occasional small earthquakes detected throughout the day yesterday. Nothing unusual was observed in clear satellite views of the vent. Weak steaming was observed in clear webcam views.  

Local seismic and infrasound sensors, web cameras, and a geodetic network are used to monitor Shishaldin Volcano. In addition to the local monitoring network, AVO uses nearby geophysical networks, regional infrasound and lighting data, and satellite images to detect eruptions. 

Monitored CALIFORNIA VOLCANOES
Current Volcano Alert Level: all NORMAL
Current Aviation Color Code: all GREEN

Activity Update: All volcanoes monitored by CalVO show normal background earthquake activity and deformation. Monitored volcanoes include Mount Shasta, Medicine Lake Volcano, Lassen Volcanic Center, Clear Lake Volcanic Field, Long Valley Volcanic Region, Coso Volcanic Field, Ubehebe Craters, and Salton Buttes.

Past Week Observations for December 22 (0000h PST) to December 28 (2359h PST):

Typical seismicity was recorded at The Geysers geothermal field south of the Clear Lake Volcanic Field; 112 earthquakes greater than M1 were recorded, with the largest having a magnitude of M2.3.

Three earthquakes greater than M1 were recorded in the Mono-Inyo area north of Long Valley, with the largest having a magnitude of M2.1.

Three earthquakes greater than M1 were recorded in the Sierra Nevada Block, south of Mammoth Mountain and Long Valley, with the largest having a magnitude of M2.5.

Four earthquakes greater than M1 were recorded in the Coso Volcanic Field, with the largest having a magnitude of M1.9.

One earthquake greater than M1 was recorded near the Salton Buttes, with a magnitude of M1.4.