Yellow Alert issued due to unusual rapid inflation beneath Mt. Thorbjorn on Reykjanes peninsula, Iceland #YellowAlert #MountThorbjorn #reykjanes #iceland
The map shows recent earthquake activity in the area. Mt. Thorbjorn is situated just above the black triangle which indicates one of IMO’s seismographs.
Inflation has been detected in the last few days. An earthquake swarm has been ongoing during the same period. A state of uncertainty has been declared. The aviation color code has been raised to yellow for Reykjanes.
An inflation has been detected since January 21st and is centred just west of Mt. Thorbjorn on Reykjanes peninsula. The inflation is unusually rapid, around 3-4 mm per day and has accumulated to 2 cm to date. It has been detected both on continuous GPS stations and in InSAR images. The inflation is most likely a sign of magma accumulation at a depth of just a few km. If magma accumulation is causing the inflation, the accumulation is very small, with the first volume estimate is around 1 million cubic meters (0,001 km3). This is the conclusion of a meeting held with the Scientific council of the Civil Protection at the IMO this morning.
Accurate measurements of crustal deformation on Reykjanes peninsula span approx. three decades. During this period no comparable signal has been measured. This is unusual for this period. An earthquake swarm has been ongoing, since January 21st, alongside the deformation signal just east of the inflation centre (northeast of Grindavík). The largest earthquakes occurred on January 22nd and were of M3,7 and 3,6. They were felt widely on the Reykjanes peninsula and all the way to Borgarnes region. The earthquake swarm is currently in decline. Swarms like this are common and not unusual by itself in the area. The fact that an inflation is occurring alongside the earthquake swarm is a cause for concern and closer monitoring.
The inflation is centred within an active volcanic zone
The inflation is occurring on plate boundaries and within the volcanic system of Svartsengi which is either considered a separate system or part of the Reykjanes volcanic system. The last known eruption was during Reykjanes fires, which occurred between 1210-1240 AD. Within that period a several eruptions occurred within that system, thereof there were three eruptions in Svartsengi system. The eruptions were effusive (non-explosive) fissure eruptions erupting on 1-10 km long fissures. No explosive eruptions are known from this system. The largest eruption in the swarm, from 13th century, formed Arnarseturshraun lava (estimated 0,3 km3 and 20 km2). Historically, the duration of these eruptions spans from a few days up to several weeks. Seismic activity is very common in this area and is linked to the plate boundaries, geothermal activity and possible magma intrusions. The largest earthquakes measured in this area are about M5.5.
Courtesy of en.vedur.is
Courtesy Aaron Merculieff
The National Weather Service issued a SIGMET aircraft safety alert as the ash plume from Shishaldin reached as high as 20,000 feet in elevation and extended up to 90 miles eastward from the volcano.
A lava flow is visible from the northeast flank of the volcano, with a large steam plume moving to the south-southeast visible in webcam imagery on Saturday.
A volcanic cloud is reported to extend up to 90 miles east from Shishaldin, located on Unimak Island in the eastern Aleutian Islands.
According to the U.S. Geological Survey, Shishaldin is one of the most actives volcanoes in the Aleutian volcanic arc — with 24 confirmed eruptions since 1775.
In April and May of 1999, an eruption at Shishaldin generated an ash column reaching 45,000 ft. about sea level.
Courtesy of ktuu.com
Sernageomin has raised the alert level to Orange for the first time since 2015 due to escalating seismic tremor and a more turbulent lava lake (present in some form since late 2014). Although fairly unlikely, it is possible that a repeat of the March 2015 paroxysmal event could soon occur if there is a similar trend in activity. An exclusion zone of 2km is in force.
Courtesy of volcanodiscovery.com