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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
 Geldingadalur - new crack close to a previously formed cone - Photo Civil Defense 17.04.2021

Geldingadalur - new crack close to a previously formed cone - Photo Civil Defense 17.04.2021

Geldingadalur - new crack close to a previously formed cone (in the box on the left) - webcam Geldingadalur / RUV 17.04.2021

Geldingadalur - new crack close to a previously formed cone (in the box on the left) - webcam Geldingadalur / RUV 17.04.2021

Lava begins to flow from Geldingadalur in the east towards Meradalur. At around 7 a.m. on April 17, it was 235 meters east of the pass.

As of 3 a.m. on April 17, it was confirmed that a new crack opening had formed at the eruption sites. It is a small opening located on a lava field and near another crater in the region. This new opening is unlikely to change much as the rash progresses.

Volcanologist Þorvaldur Þórðarson says it is possible that outgassing cracks are a sign that a new eruptive fissure is forming. The other possibility is that in some cases the molten lava could come in contact with the water-soaked substrate. If this happens, the water in the mud boils underneath, expands very quickly and causes what is called an artificial eruption.

 

Sources: IMO, RUV, mbls, Jarðsöguvinir - Friends of Historical Geology

Geldingadalur - the lava flow passes the pass to Meradalur - photo 04.16.2021 / Reynir Freyr Péta - RÚV

Geldingadalur - the lava flow passes the pass to Meradalur - photo 04.16.2021 / Reynir Freyr Péta - RÚV

According to UWI, the long period seismic (LP) swarm accompanied by hybrid events continues at La Soufrière in St. Vincent. The frequency of these earthquakes dropped significantly around 8 p.m. on April 16 and has remained almost constant since then.

An image of the new crater has been established on the basis of photo analysis: it measures 900 meters north-south and 750 m. east-west, for a depth of a hundred meters. The new crater appears to contain several vents, but one seil has been clearly identified. To the east of the new crater, a vast tephra rampart would reach 75 m. thick. (Interpretation: Adam Stinton, UWI-SRC / MVO. Image: provided to UWI-SRC by Raphael Grandin of IPGP.)

 

The eruption continues, without an explosion at this time. The red alert remains in effect.

Source: UWI-SRC

Soufriere of St. Vincent - new crater on 15.04.2021 - Doc. UWI / Planet Labs - one click to enlarge

Soufriere of St. Vincent - new crater on 15.04.2021 - Doc. UWI / Planet Labs - one click to enlarge

Soufrière de St. Vincent - 15.04.2021 / 14:41 - Interpretation Adam Stinton, UWI-SRCMVO. - Image provided by Raphael Grandin / IPGP.

Soufrière de St. Vincent - 15.04.2021 / 14:41 - Interpretation Adam Stinton, UWI-SRCMVO. - Image provided by Raphael Grandin / IPGP.

At Piton de La Fournaise, the eruption continues, with a relatively stable tremor.

Lava fountain activity continues, mainly at the main cone upstream.

The lava is focused on the plateau downstream of the eruptive site, with the establishment of tunnels showing numerous resurgences.

During the last 24 hours, 10 VT earthquakes under the summit craters have been recorded.

Average lava flows, estimated from sulfur dioxide flows on April 16, are of the order of 8.3 m³ / s, down from the peak on April 13.

Piton de La Fournaise - the flow stagnates, with activity in lava tunnels - photo OVPF 04.16.2021

Piton de La Fournaise - the flow stagnates, with activity in lava tunnels - photo OVPF 04.16.2021

The lava samples taken from the eruptive site on April 11 by teams from the OVPFIPGP could be analyzed at the IPGP in Paris and at the Observatoire de Physique du Globe de Clermont Ferrand (OPGC-LMV). Pyroclastic samples emitted by the lava fountains had been sampled near the main cone, and the lava had been sampled downstream of the eruptive fracture.

The pyroclastic deposits of the lava fountains consist entirely of "golden" type pumice. This variety of pumice is characterized by millimetric vesicles organized around large central centimetric vesicles. Their vesicularity reaches very high values ​​up to 86% vol% with 10 to 20% of isolated vesicles (not connected to each other).

Piton de La Fournaise - Lapilli of "golden" type pumice emitted by lava fountains on April 11, 2021 with few fine particles formed by slightly elongated grains and rare Pelé hair - Doc. OVPF.

Piton de La Fournaise - Lapilli of "golden" type pumice emitted by lava fountains on April 11, 2021 with few fine particles formed by slightly elongated grains and rare Pelé hair - Doc. OVPF.

Mineralogical analysis indicates the presence, in decreasing order of plagioclase, pyroxene and olivine. The proportion of olivine is lower in the flows and greater in the projections. The abundance of plagioclase and pyroxene reflects relatively low temperatures overall and an overall evolved nature of the magmas emitted. Lavas are rich in microcrystals (44%) while pyroclastic products are much more vitreous (a few percent of microcrystals).

A more detailed report on these analyzes will be attached to the monthly OVPF-IPGP bulletin.

 

Source: OVPF

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