2 strong earthquakes in the South Sandwich Islands

Two strong earthquakes have recently struck the South Sandwich Islands a month apart.

The first strong earthquake with a magnitude of 6.4 occurred on the 15th November 2018 at 20:02 UTC. The epicenter of the quake was reported to be about 101km east of Visokoi Island with a depth of 15km.

6.4 magnitude earthquake on 15th November 2018. SOURCE: USGS.

The second strong earthquake with a magnitude of 7.1 occurred on the 11th December 2018 at 02:26 UTC. The epicenter of the quake was reported to be about 48km north of Bristol Island with a depth of 164.7km.

7.1 magnitude earthquake on 11th December 2018. SOURCE: USGS.

Eruption occurred on Saunders Island

A fresh ash fallout is present on the northwest flank of Mount Michael on Saunders Island in a Landsat 8 satellite image from 28th September 2018. This is a sign that an eruption had recently occurred on this volcano sometime between the days of 23rd September and 28th September.

EDIT: After studying satellite images on the EOSDIS Worldview website, it is most likely that the eruption occurred on the 27th September 2018 based on the wind direction going northwest.

Ash deposits on the northwest flank of Michael Volcano on 28th September. SOURCE: Landsat 8/Sentinel Hub.

Thermal anomaly present again on Saunders

While studying recent satellite images of Saunders Island on Sentinel Hub, I observed that a thermal anomaly had returned inside the summit crater of Mount Michael on the 23rd September 2018. This indicates that volcanic activity has resumed.

Judging by the size of the double anomaly I am under the opinion that it could either be a lava pond or some mild strombolian activity at the most, or simply some intensive fumarolic activity at the least.

Hotspot is present inside the crater of Michael Volcano on 23rd September. SOURCE: Sentinel-2/Sentinel Hub.

6.1 Magnitude earthquake in South Sandwich Islands

A strong magnitude 6.1 earthquake hit the South Sandwich Islands on the 14th August 2018 at 03:29 UTC. The epicenter of the quake was reported to be about 126km northeast of Bristol Island with a depth of 35km.

6.1 magnitude earthquake on 14th August 2018. SOURCE: USGS.

Eruptive activity on Michael Volcano possibly ended in April

While studying recent satellite images of Saunders Island on Sentinel Hub, I discovered that the last time a thermal anomaly was present inside the crater of Mount Michael was on the 3rd April 2018. White plumes continued to be present in images until the 18th April 2018.

The thermal anomaly on Mount Michael started appearing in satellite images on the 31st January 2018 but was last seen on the 3rd April 2018. In my opinion this suggests that some kind of eruptive activity was going on in that period either at the most, a temporary lava lake or at the least, some intensive strombolian activity.

Hotspot inside the crater of Michael Volcano while emitting a steam plume on 3rd April. SOURCE: Sentinel-2/Sentinel Hub.

Possibly a lava lake on Mount Michael?

The latest Sentinel-2 images of Saunders Island as viewed on the EOSDA website show that the activity on Mount Michael pretty much remains the same. An infrared false colour image shows that a thermal anomaly still appears inside the summit crater of Mount Michael indicating possible lava lake activity.

Shortwave Infrared image shows that a thermal anomaly still persists inside the summit crater of Mount Michael. SOURCE: Sentinel-2/EOS Data Analytics.

Natural colour image of Saunders Island. Could that be ash deposits on the NNE flank? SOURCE: Sentinel-2/EOS Data Analytics.

Possible eruption on Zavodovski plus activity persists on Saunders Island

Satellite image from 23rd March 2018 shows what appears to be a dirty grey colour on Zavodovski Island with a hazy plume extending southeast of the island for a short distance. This suggests that it's likely to have been an eruption which occurred on Mount Curry.

What appears to be a likely ash plume on Zavodovski Island during 23rd March. SOURCE: Terra/MODIS/NASA.

Meanwhile, down at Saunders Island a satellite image from 29th March 2018 shows a hazy plume extending east-southeast then east. Then again in an image from 3rd April 2018 a hazy plume is seen extending southwest of the island along with an additional white plume which is seen drifting towards the southeast before changing direction to the southwest.

This indicates that the activity on Mount Michael more or less remains unchanged.

Hazy plume originating from Saunders Island extending ESE then east on 29th March. SOURCE: Terra/MODIS/NASA.

A hazy plume and a white plume originating from Saunders Island on 3rd April. SOURCE: Aqua/MODIS/NASA.

Thermal anomaly persists on Mount Michael

The thermal anomaly is still present inside the summit crater of Mount Michael on Saunders Island as seen in the recent satellite images from 10th February 2018. As the images were viewed on the EOSDA website, I was able to zoom in on to the summit area of Mount Michael Volcano where I had a more clearer view of the summit crater area.

A degassing plume was present but an infrared image revealed that a thermal anomaly was present in the northern part of the crater interior indicating volcanic activity. It could either be low level strombolian activity, or it could be lava flows covering a small part of the crater interior, or it could be a lava lake.

Shortwave Infrared image showing a hotspot inside the crater of Michael Volcano. SOURCE: Sentinel-2/EOS Data Analytics.

Natural colour image of the summit area of Michael Volcano. SOURCE: Sentinel-2/EOS Data Analytics.

Thermal anomaly detected on Mount Michael

In a satellite image by Landsat 8 taken on the 31st January 2018, a thermal anomaly is present inside the summit crater of Mount Michael on Saunders Island. It is clearly an indicator that some elevated activity has been taking place inside the crater of Mount Michael.

In my opinion, I believe some low level strombolian activity has been occurring or at least a lava pool is present on the crater floor.

Activity inside the crater of Mount Michael Volcano. SOURCE: Landsat 8/USGS/NASA.