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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
Piton de la Fournaise - vigilance level - photo OVPF

Piton de la Fournaise - vigilance level - photo OVPF

The Piton de La Fournaise Volcanological Observatory announces this June 22 the return of the volcano to alert level "Vigilance".

Since June 16, a recovery in seismicity and inflation has been observed under the Piton de la Fournaise.

Thus 18 superficial volcano-tectonic earthquakes (<2 km below the summit) were recorded under the summit zone between June 16 and 22.

This seismicity is accompanied by a resumption of inflation (swelling) at the base and at the top of the Piton de la Fournaise building. This inflation of the building is synonymous with a pressurization of the superficial magmatic reservoir located around 1.5-2.5 km below the summit.

In parallel, the CO2 fluxes in the far field soil (Plaine des Cafres and Plaine des Palmistes sectors) which had reached maximum values ​​at the end of the eruption of 2-6 April 2020, continue to decrease, in agreement with deep ascent of magma to more superficial areas of the feeding system. Even if the trend is downward, the absolute values ​​of the CO2 flux through the soil remain very high.

Note that this process of recharging the surface reservoir can last several days to several weeks before the reservoir roof becomes fragile and ruptures, thus giving rise to an injection of magma towards the surface and an eruption, but can also stop without giving rise to an eruption in the short term.

 

Source: OVPF

Piton de la Fournaise - Histogram representing the number of surface volcano-tectonic earthquakes recorded between June 1 and June 21, 2020 (© OVPF-IPGP).

Piton de la Fournaise - Histogram representing the number of surface volcano-tectonic earthquakes recorded between June 1 and June 21, 2020 (© OVPF-IPGP).

Piton de la Fournaise - Illustration of the deformation over the past two months. Here are represented baselines (variation in distance between two GPS receivers) crossing the Piton de la Fournaise building, at the top (top), at the base of the terminal cone (in the middle) and in the far field (bottom ). An increase is synonymous with elongation and therefore swelling of the volcano; conversely, a decrease is synonymous with contraction and therefore deflation of the volcano. (© OVPF-IPGP).

Piton de la Fournaise - Illustration of the deformation over the past two months. Here are represented baselines (variation in distance between two GPS receivers) crossing the Piton de la Fournaise building, at the top (top), at the base of the terminal cone (in the middle) and in the far field (bottom ). An increase is synonymous with elongation and therefore swelling of the volcano; conversely, a decrease is synonymous with contraction and therefore deflation of the volcano. (© OVPF-IPGP).

Two interesting articles to read:

- New results on the activity of the Campi Flegrei caldera thanks to radon monitoring for seven years. - INGV 22.06.2020

Map of the Campi Flegrei caldera (Naples-Italy). The map, modified after 16 (10.1016 / j.apradiso.2020.109140) using PAINT (Microsoft Corporation, version: 6.1907.18017.0), shows the structural framework of the caldera characterized by tectonics and volcano-tectonic activity . The two radon monitoring sites of Monte Olibano and Monte Sant’Angelo, and the other monitoring sites for geochemical and geophysical parameters are reported. The squares represent the Campi Flegrei seismic network in green and the NeVoCGPS network in orange

Map of the Campi Flegrei caldera (Naples-Italy). The map, modified after 16 (10.1016 / j.apradiso.2020.109140) using PAINT (Microsoft Corporation, version: 6.1907.18017.0), shows the structural framework of the caldera characterized by tectonics and volcano-tectonic activity . The two radon monitoring sites of Monte Olibano and Monte Sant’Angelo, and the other monitoring sites for geochemical and geophysical parameters are reported. The squares represent the Campi Flegrei seismic network in green and the NeVoCGPS network in orange

Since 2004-2005, the Campi Flegrei caldera is experiencing a new period of troubles characterized by an uplift of the soil, seismicity, changes in the composition of fumarolic fluids and a general increase in emissions of volcano-hydrothermal fluids. The long series of data, acquired since 2011, highlights how this crisis is also affecting the activity of 222Rn in soils.

The data suggest two main considerations:

- the first concerns the extension of the zone affected by the current troubles which results much larger than the zone of seismicity and the zone of intense hydrothermal activity of Pisciarelli and Solfatara.

- the second consideration considers 222Rn and its potential as an indicator of the evolution of a volcanic crisis: the radon signals show, in fact, a pattern very similar to that of the more conventional geophysical and geochemical parameters regularly monitored for monitoring volcanic systems (the tremor caused by the major fumarolic vent recorded by a seismic station; the accumulation of background seismicity; the maximum vertical deformation acquired by GPS networks during the current phase of uplift; temperature- hydrothermal system pressure estimated from gas geo-indicators)

These results represent an absolute novelty in the study of such a calderic zone and mark a significant advance in the use and interpretation of the radon signal, and also indicate that the long-term observation of the radon signal on several sites in a seismic-volcanic area could help improve the characterization of the region.

 

Original article:

Sabbarese, C., Ambrosino, F., Chiodini, G. et al. Continuous radon monitoring during seven years of volcanic unrest at Campi Flegrei caldera (Italy). Sci Rep 10, 9551 (2020).https://doi.org/10.1038/s41598-020-66590-w - link

http://creativecommons.org/licenses/by/4.0/.

Simplified map of the 8th continent - Doc. GNS Science

Simplified map of the 8th continent - Doc. GNS Science

- Zealandia, the Lost Continent, as you have never seen

Two maps and a website published by GNS Science this week provide insight into the incredible forces that shaped Aotearoa in New Zealand and the mainly submerged continent that lies beneath the New Zealand Islands.

The maps cover the bathymetry (shape of the ocean floor) and the tectonic origins of the eighth continent on Earth - the 5 million square kilometers of Te Riu-a-Māui / Zealandia on which New Zealand is located.

The documents are also available through a new interactive website called E Tūhura - Explore Zealandia (TEZ) - http://data.gns.cri.nz/tez.

TEZ is designed to explore terrestrial and offshore geoscience data in and around Te Riu-a-Māui / Zealandia.

 

Sources:

- GNS Science - New maps and website give fresh insights into NZ continent - 06/22/2020 - link

- E Tuhura- Explore Zealandia - link

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