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Earth of fire

Actualité volcanique, Articles de fond sur étude de volcan, tectonique, récits et photos de voyage

Publié le par Bernard Duyck
Publié dans : #volcanic activity

In the SAR intensity image of July 3, changes in the topography, which would be caused by lava, etc., are observed on the southwest and west sides of the pyroclastic cone, and the coastline changes on the south-west side of Nishinoshima.

In addition, the diameter of the pyroclastic cone increased approximately 1.5 times from June 19, and topographic changes on the southern slope are visible.

From the north side to the east side of the pyroclastic cone, there is a decrease in the intensity of reflection, which would be due to the fall of the ashes.

The image becomes dark in the area where the reflection intensity is low.

Nishinoshima - SAR intensity images of July 3, 2020 and June 19, 2020, for comparison - Doc. GSI
Nishinoshima - SAR intensity images of July 3, 2020 and June 19, 2020, for comparison - Doc. GSI

Nishinoshima - SAR intensity images of July 3, 2020 and June 19, 2020, for comparison - Doc. GSI

On SAR intensity images from July 3, 2020 (left) and June 19, 2020, we can see the topographic changes. The light blue line indicates the area where topographic changes were observed from June 5, 2020 to June 19, 2020, and the red line indicates the area where topographic changes were subsequently observed.

Nishinoshima - topographic changes - The light blue line indicates the area where topographic changes were observed from June 5, 2020 to June 19, 2020, and the red line indicates the area where topographic changes were subsequently observed. - DoC. GSI 03.07.2020

Nishinoshima - topographic changes - The light blue line indicates the area where topographic changes were observed from June 5, 2020 to June 19, 2020, and the red line indicates the area where topographic changes were subsequently observed. - DoC. GSI 03.07.2020

NASA images show that SO2 swirls from the Nishinoshima volcano eruption still cover much of the North Pacific on July 3. Part of the SO2 has dispersed through the Aleutian Islands and Alaska to the Chukchi and the seas of eastern Siberia, above 70 ° North.
 

Nishinoshima - 03.07.2020 / 01h00-23h27 UT - sulfur dioxide swirls over the North Pacific - Doc. Suomi NPP / OMPS (via S. Carn)

Nishinoshima - 03.07.2020 / 01h00-23h27 UT - sulfur dioxide swirls over the North Pacific - Doc. Suomi NPP / OMPS (via S. Carn)

Nishinoshima - 03.07.2020 / 01h00-23h27 UT - sulfur dioxide eddies over the North Pacific - Doc. Suomi NPP / OMPS (via S. Carn)

Nishinoshima - 03.07.2020 / 01h00-23h27 UT - sulfur dioxide eddies over the North Pacific - Doc. Suomi NPP / OMPS (via S. Carn)

The thermal anomalies noted by Mirova have remained intense in recent days. The JMA announces this July 4 a volcanic plume of 8,300 meters high in Nishinoshima, against the more than 3,400 meters observed by the Japan Coast guards on June 29.

 

Sources:

GSI - JMA - Mainichi - VAAC Tokyo - Mirova

Nishinoshima - thermal anomalies and radiative power at 04.07.2020 / 03.45 am - Doc. Mirova Modis - one click to enlargeNishinoshima - thermal anomalies and radiative power at 04.07.2020 / 03.45 am - Doc. Mirova Modis - one click to enlarge

Nishinoshima - thermal anomalies and radiative power at 04.07.2020 / 03.45 am - Doc. Mirova Modis - one click to enlarge

No surface eruption is reported by Ovsicori in Poas.

The seismic activity of July 3 is more important than that of yesterday.

At the time of this report, the winds were blowing southwest.

The gas ratios and concentrations remain relatively stable: H2S / SO2 = 0.06 - 0.08; SO2 = 1.0 - 1.7 ppm. The CO2 / SO2 ratio could not be determined. In addition, at the watchtower, maximum concentrations of sulfur dioxide remain below 4 ppm. In the past few days, a discontinuous tremor has appeared (3-4 Hz). On the other hand, the low frequency (1 - 2 Hz) is continuous.

 

 Source: Ovsicori

Poas - 03.07.2020 / 07:39 - the acid lake is agitated and topped with fumaroles - Ovsicori webcam

Poas - 03.07.2020 / 07:39 - the acid lake is agitated and topped with fumaroles - Ovsicori webcam

In 2018, using a Landsat 8 nocturnal thermal infrared image, the emergence of a new thermal zone near Tern Lake on the northeast margin of the Sour Creek dome in the Yellowstone caldera, been highlighted.

A high spatial resolution airborne visible image from August 2017 revealed a large area (~ 33,300 m²) of recently fallen trees, mostly devoid of vegetation, with bright soil, similar to other nearby thermal areas.

Field observations in August 2019 confirmed that it was an acid-sulfate thermal zone heated by steam, with an arc-shaped zone of hydrothermally modified and heated soil, with temperatures surface 60 to 80 °C, several smoking fumaroles and boiling temperatures (93 °C) were measured just below the surface.

Yellowstone national Park - location and simplified geological map of the new spa area (modified from Christiansen, 2001) - Doc. USGS - one click to enlarge

Yellowstone national Park - location and simplified geological map of the new spa area (modified from Christiansen, 2001) - Doc. USGS - one click to enlarge

Yellowstone national Park - new thermal area of ​​Tern lake - photo M.Poland / YVO

Yellowstone national Park - new thermal area of ​​Tern lake - photo M.Poland / YVO

This area was surrounded by cooler soil also strewn with recently fallen trees. In the hottest area, there were vapor emissions from several points, and sulfur crystals bordered some of the smoking areas. The soil temperature in these fumaroles was 92 °C (198 °F) - the boiling temperature at this altitude (about 8000 feet or 2500 meters). Throughout this area, just 5-10 cm below the surface, temperatures were constantly boiling.

The ground was so hot that parts of some fallen trees became charcoal. The sides of the trees fallen against the hot ground are cooked and blackened, while the sides facing the sky are not burnt. In the cooler area, parts of the soil were at ambient temperatures.

Yellowstone national Park - new thermal area of ​​Tern lake - FLIR image (IR) of the framed red area - Doc. M.Poland / YVO

Yellowstone national Park - new thermal area of ​​Tern lake - FLIR image (IR) of the framed red area - Doc. M.Poland / YVO

The initial formation of this new thermal zone is not clearly linked to separate seismic or geodesic events, although the period of rapid growth partly coincides with a period of rapid local uplift, possibly suggesting a causal relationship.

The identification of this emerging thermal zone illustrates the importance of thermal infrared satellite imagery combined with high spatial resolution remote sensing data and field observations to map, measure and monitor the thermal zones of Yellowstone.

It is also an example of the dynamics that we expect to see in large caldera systems like Yellowstone.

 

Sources:

From USGS articles, and from Michael Poland / YVO

- Frontiers in health science - A Newly Emerging Thermal Area in Yellowstone - R. Greg Vaughan & al.

- Discovering new thermal areas in Yellowstone's dynamic landscape! Release Date: APRIL 1, 2019

- Yellowstone's newest thermal area: An up-close and personal visit! Release Date: AUGUST 26, 2019

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