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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 : #Actualités volcaniques, #Eruptions historiques


The Kick'em Jenny submarine volcano saw its alert level increase on March 12, 2018;

But since his first explosive eruption observed in 1939, he remained very active.

The West Indies University (UWI) presented a list of major events.

 

Date

Activity

Observations

7/24/39

Explosive eruption

  • Strong Earthquakes

  • Eruption columns 900 ft above sea level

  • T Phase Recorded in Martinique along with several small earthquakes

10/5/43

Eruption

  • T phase detected in Martinique

  • No visual reports

  • No Tsunami reports

10/29/53

Eruption

  • Strong earthquakes in No.Grenanda

  • T Phase recorded

  • No visual reports

  • No Tsunami reports

10/24/65

Eruption

  • Earthquake felt No.Grenada, Ile de Ronde

  • T Phase recorded from Trinidad

  • Tsunami observed on Ile de Ronde and in Sauteurs

5/5/66

Eruption

  • Series of eruptions indicated by seismographs

  • No visual reports

  • No Tsunami reports

8/3/66

Eruption

  • Long sequence of earthquakes felt in No. Grenada

  • T phase recorded throughout the Caribbean

  • No visual reports

  • No Tsunami reports

5/7/72

Eruption

  • Continuous T Phase generated for 5 hr. and no other reports

6/9/74

Explosive eruption

  • Strong earthquakes in No.Grenanda

  • T Phase recorded throughout eastern Caribbean

  • Visual eruption began 6am local time-steam

  • No Tsunami reports

1/14/77

Eruption

  • T Phase recorded throughout eastern Caribbean

  • No other reports

12/29/88

Eruption

  • Earthquakes felt strongly in Grenada and other windward islands

  • T phase widely recorded

  • No Tsunami reports

3/26/89 to 1/5/90

Explosive eruption

  • Earthquakes felt strongly in Grenada and other windward islands

  • Sea boiling turbulently and throwing up small dark rocks

  • T phase widely recorded

  • First observations of strong harmonic tremor

12/2/2001

Eruption

  • Burst of T-Phase activity felt in Northern Grenanda

Multibeam bathymetry 2017 EM 710, and gas plumes recorded by RRS James Cook after Kick'em Jenny's activity in 2017 - Doc. 30 Years in the Life of an Active Submarine Volcano: A Time-Lapse Bathymetry Study of the Kick-'em-Jenny Volcano, Lesser West Indies R. W. Allen & al / 13.03.2018

Multibeam bathymetry 2017 EM 710, and gas plumes recorded by RRS James Cook after Kick'em Jenny's activity in 2017 - Doc. 30 Years in the Life of an Active Submarine Volcano: A Time-Lapse Bathymetry Study of the Kick-'em-Jenny Volcano, Lesser West Indies R. W. Allen & al / 13.03.2018

A research, published March 13 in AGU journal / "Geochemistry, Geophysics, Geosystems", opens a new vision on the world of submarine volcanoes.

Since the first eruption in 1939, Kick'em Jenny Volcano (KeJ) has been the source of 13 episodes of T-phase signals. These distinctive seismic signals, which often coincide with increased seismicity of body waves, are interpreted as extrusive eruptions. They occurred with a recurrence interval of about a decade, but direct confirmation of volcanism was rare.

By conducting new bathymetric surveys in 2016 and 2017 and reprocessing 4 sets of 30-year historical data, the study presents a clearer picture of KeJ's development over time.

Video showing two surveys of the Kick'em Jenny submarine volcano: a campaign carried out aboard the RRS James Cook in 2017 shows a close-up view of the cone and the recorded plumes of gas - the 2013 campaign was carried out on board R / V Nautilus

Currently, remote sensing of underwater eruptions relies heavily on phase T identification on regional hydrophones and seismometers. These distinctive hydro-acoustic signals can be produced by underwater earthquakes or by the interaction between water and fresh magma.

At KeJ, volcanic T-phase arrivals (which are assumed to indicate underwater eruptions) differ from signals of purely seismic origin due to their low frequency, impulsive appearance and duration (often several tens of seconds), similar signals tremor during periods of high activity (Lindsay et al., 2005). They also lack associated P and S wave arrivals, as would be expected from a signal with an earthquake source.

A correlation between the T-phase episodes was made with the morphological changes of the volcano: during the observation period, 7.09 million m³ of materials were added by constructive volcanism, but five times this amount was lost due to landslides.

Six bathymetric surveys over the period 1985-2017 revealed major morphological changes, the association of T-phase signals to both landslides and extrusive volcanism, and the importance of bathymetry over time for good monitoring of submarine volcanism.

Kick'em Jenny 3D projection using Nautilus bathymetric data in 2013: 1. Horseshoe scar surrounding the cone, resulting from a 43,000-year-old collapse of the Proto Jenny; 2. Active cone of KeJ; 3. Kick'em Jack, the largest cone in the complex; 4. Deposits of the Proto Jenny collapse, which substantially enlarged the debris flows; 5. Area spreading debris flows over more than 14 km in the deep waters of the Grenada Basin. - Doc. 30 Years in the Life of an Active Submarine Volcano: A Time-Lapse Bathymetry Study of the Kick-'em-Jenny Volcano, Lesser West Indies R. W. Allen & al / 13.03.2018

Kick'em Jenny 3D projection using Nautilus bathymetric data in 2013: 1. Horseshoe scar surrounding the cone, resulting from a 43,000-year-old collapse of the Proto Jenny; 2. Active cone of KeJ; 3. Kick'em Jack, the largest cone in the complex; 4. Deposits of the Proto Jenny collapse, which substantially enlarged the debris flows; 5. Area spreading debris flows over more than 14 km in the deep waters of the Grenada Basin. - Doc. 30 Years in the Life of an Active Submarine Volcano: A Time-Lapse Bathymetry Study of the Kick-'em-Jenny Volcano, Lesser West Indies R. W. Allen & al / 13.03.2018

The final bathymetric grids produced as a result of the reprocessing of existing bathymetric datasets (1985 - 2003 - 2013 - 2016 - 2017). The surfaces shown were smoothed using a 50 m filter for display purposes. - Doc. 30 Years in the Life of an Active Submarine Volcano: A Time-Lapse Bathymetry Study of the Kick-'em-Jenny Volcano, Lesser West Indies R. W. Allen & al / 13.03.2018

The final bathymetric grids produced as a result of the reprocessing of existing bathymetric datasets (1985 - 2003 - 2013 - 2016 - 2017). The surfaces shown were smoothed using a 50 m filter for display purposes. - Doc. 30 Years in the Life of an Active Submarine Volcano: A Time-Lapse Bathymetry Study of the Kick-'em-Jenny Volcano, Lesser West Indies R. W. Allen & al / 13.03.2018

Kick'em Jenny magma is usually a type of alkaline basalt with a mineral composition that indicates that it comes from the lower crust. Sigurdsson (1973) has shown that all the volcanoes of the West Indies arc above a subduction zone of two lithospheric plates. The activity of these volcanoes is the result of the gradual drift towards the west of a plate and its thrust under the adjacent plate.

Sampling of the crater and flanks during a multibeam survey by the NOAA research vessel, Ronald H. Brown, revealed that the dominant products of the volcano were pyroclastic deposits and pillow lavas of amphibole-rich basalts and basaltic andesites.

Rocky specimen covered with red colored bacterial material, collected in 2003 by NOAA Ocean Explorer

Rocky specimen covered with red colored bacterial material, collected in 2003 by NOAA Ocean Explorer

Sources:

- AGU - "G3" - 30 Years in the Life of an Active Submarine Volcano: A Time-Lapse Bathymetry Study of the Kick-'em-Jenny Volcano, Lesser Antilles - R. W. Allen & al / 13.03.2018

- NOAA Ocean Explorer - Geology of the Kick'em Jenny Volcano - Debby Kay, NOAA Research Web Coordinator

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