June 26 , 2016. EN. Reventador , Turrialba , Etna , Sakurajima .

Home / blog georges Vitton / June 26 , 2016. EN. Reventador , Turrialba , Etna , Sakurajima .

June 26 , 2016. EN. Reventador , Turrialba , Etna , Sakurajima .

June 26 , 2016.

 

Reventador , Ecuador :

Monday, July 25, 2016
SUMMARY OF THE ACTIVITIES OF THE VOLCANO:

The volcano is maintained with high eruptive activity.
Yesterday afternoon the volcano is uncovered for a short period and no activity was observed at the surface. Today, during the morning hours, the cameras have observed a glow in the crater with incandescent rocks rolling on the southeast flank.

 

reventador


TECHNICAL AND OBSERVATIONS APPENDIX
Seismicity:
From 11:00 (TL) yesterday until 11:00 (TL) today, 76 explosions (EXP), 50 long period (LP) events, 3 episodes of tremor emission (TRE) and 6 episodes of harmonic tremor (TRA) were recorded.
Observations of emissions and ashes:
Yesterday afternoon the volcano is uncovered for a short period and no activity was observed at the surface.
Today, during the morning hours, the cameras have observed a glow in the crater with incandescent rocks rolling on the southeast flank.

Rain and lahars:
Heavy rains are recorded, and that until the end of this report have not generated lahars.
GENERAL INFORMATION
This report on a daily basis will be published at 12:00 (TL). In the case of an increase or a change in the behavior of the volcano, it will immediately issued a special report.

Source : IGEPN.

 

Turrialba, Costa Rica :

24 and 25 July 2016, 3:40, Turrialba volcano.
During the night of July 24, there were two eruptions at 9:22 p.m. and 10:16 p.m., which projected ballistic fragments at very high temperatures to the northwest sector of the active crater. These processes have been accompanied by a phase of greater magnitude tremor with a duration of 4 and 3 minutes, respectively, which correspond to the most energetic phase of the eruptions. After these processes, there was a sustained volcanic tremor, with a variable amplitude until 3:32 am on 25 July. The periods of greatest magnitude of the tremor were accompanied by passive emissions of ashes.
The wind direction was variable to the Southwest and the Northwest, according to data from the meteorological station IMN on Turrialba volcano.

July 25, 2016, 7:40, Volcan Turrialba

At 7:22 this morning, a small eruption on the Turrialba volcano which lasted about 2 minutes, was recorded. The amplitude of the seismic signal is greater than that of the process generated overnight. Even though it was short, the energy released was important, allowing it to reach a significant height.

 

turrialba

The low speed of light winds has allowed to the eruption column to rise. The winds blow westward according to data from IMN, the weather station of the Turrialba volcano.

Source : Ovsicori

 

Etna , Sicily :

Why volcanoes change? What makes them so « unstable » at the top? A team of researchers from the Institute of Geophysics and Volcanology (INGV) and the University Roma Tre answers these questions, showing the history of the New Southeast Crater of Etna, which was recently formed.
The study (http://journal.frontiersin.org/article/10.3389/feart.2016.00067/full) was published in the journal Frontiers.
Volcanic eruptions are usually from the top, by one or more first craters. An activity typically occurs in a « persistent » crater, almost continuously over time and uses the existing vents above the volcano. Precisely for this reason, it is very rare to observe the birth of a new crater at the top, and even more exceptional, as in this case, to see a new mouth to replace the previous mouths.

« Etna is one of the few volcanoes in the world where it was possible to capture and monitor the birth of a new eruptive mouth at tha summit, which took place in the last decade, » says Marco Blacks coordinator and senior researcher at the Osservatorio Etneo INGV (INGV-oE). « in fact, the new mouths were open from the top, even in the last century, but only now, for the first time, we were able to implement a modern multidisciplinary approach to follow the birth of a new crater « .

« Inside » the New Southeast Crater (NSEC).
Interior view of the active vents (a, b) from the NSEC. Within days, the mouth « b », also called « puttusiddu » emits small amounts of ash discontinuously. The yellow arrows indicate the edge of the fracture zone involving the whole of the top of the crater area.

The New Southeast Crater was formed in the eastern base of the « oldest«  Southeast crater along a fracture oriented northwest / southeast, which has, on several occasions, « injected » magma in the last decade.
« It has grown quickly over the edge of the Valle del Bove, next to a high vertical cliff of about a thousand meters. The new eruptive cone is inherently unstable and potentially prone to collapse. For this reason also, therefore, it is necessary to carefully monitor the morpho-structural evolution of this new crater, « says Black.
From field surveys ,  aerial and satellite data and thermal deformation data soil with GPS (Global Positioning System) precision have allowed us to define the Volcanological and structural changes in the formation of this new crater .

« The causes of this important event in the recent history of Etna« , adds the researcher, « have been identified in the complex instability in that characterizes, in particular, the northern flank of the volcano. Etna, in fact, undergoes cyclically in time inflation phenomena (swelling), followed by deflation, which usually lasts from several months to several years. Recently, in periods of inflation, the northeast flank of Etna has been distorted, along trajectories of « translation » semicircular. The upper part has shifted to the Northeast, the intermediate portion to the east and finally the distal portion, near the Ionian Sea, has shifted to the south (purple arrows in Figure 2).

porzione

The movement to the northeast of the summit of the volcano has favored the opening of several eruptive fissures oriented towards North-West / South-East and the subsequent birth of the New Southeast Crater « . The volcanoes that have shown great structural changes in recent decades, such as Mount St. Helens (Washington, USA) and Bezymianny (Kamchatka, Russia) have not undergone movements of their summit craters.

« It’s on a long time (hundreds or thousands of years) that a volcano can change the configuration of its eruptive vents, as revealed by the geological data. A very important event in the history of a volcano, as the geometric variation of the ducts that transfer the magma to the surface, when it does, has always significant impact on the volcanic risk, « said Valerio Acocella, a researcher at the Roma Tre University and co-author of the work . The example of the New Southeast Crater shows how an active volcano, characterized by permanent instability of its sides, is strongly conditioned to change the position of his conduits for magma ascent, and this can be done fairly quickly. « The case of Etna, then, is an outstanding example to better understand the eruptive dynamics of volcanoes, especially if he is subject to landslides and to gravitational deformation of its sides, » says Marco Blacks.

Summary:
Usually mature volcanoes erupt from a persistent summit crater. Permanent changes in these areas should occur after major structural changes, but rarely documented. Here, we provide an example that recently took place on Etna. The eruptive activity of Mount Etna in 2007, focused on Southeast Crater (SEC), the youngest (established in 1971) and most active of the four summit craters, consisted of six paroxysmal episodes. Lava volumes that were issued, determined by field measurements and radiant heat flow curves, measured by satellite, totaled 8.67 × 106 m3.
The first four episodes occurred between endMarch and early May, from the top of the Southeast Crater and from short cracks on its sides. The last two episodes have occurred in September and November, from a new mouth (« pit crater » or « proto-NSEC« ) to the southeast base of the Southeast Crater cone.

Summit area of Etna view from Southeast. In the right foreground the Southeast Crater (SEC) and the New Southeast Crater (NSEC). Behind the SEC, the « saddle » morphological between the Central Crater (Composed by Voragine VOR and Bocca Nuova – BN). The yellow arrows show an intense beam of fumarolics fractures, organized in a nearly symmetrical graben, which slopes up towards the north and joins another graben highlighted by the black arrow, which obviously chipped the north-East crater (NEC). The black dotted line show the collapsed part of the NEC during the last eruptive period.With Francesco Ciancitto and Sonia Calvari.

This marked the final disappearance of the old Southeast Crater and the transition to the new vent. The latter, fed by dykes Northwest / Southeast, propagating from conduit from the Southeast Crater, formed since the beginning of 2011, an independent cone (the New Crater of Southeast, or «  NCSE « ) at the base of the Southeast Crater. The detailed geodetic reconstruction and structural observations in the field are used to define the deformation of the Etna area in the last decade. This suggests that the New Southeast Crater developed under the faults oriented NortheastSouthwest tensile stresses on the top of the volcano, promoted by the accelerated instability in northeastern flank of the volcano during the periods of inflation. The development of the New Southeast Crater is important not only from a structural point of view, that by its formation, which can lead to an increase in volcanic hazard. The case of the New Crater of Southeast of Etna reported here illustrates how an  instability of flank may affect the distribution and impact of volcanism, including prolonged displacement of activity from the vents on top of a volcano mature.

Source : INGV Catane  .

Photos : Marco Neri , INGV Catane , Francesco Ciancitto et Sonia Calvari .

 

Sakurajima , Japan :

Kagoshima’s Sakurajima volcano erupts, spews plume 5,000 meters up

KAGOSHIMA – The Sakurajima volcano in southwestern Japan had an explosive eruption early Tuesday, spewing volcanic ash 5,000 meters into the sky, the Meteorological Agency said.

sakurajima

It is the first eruption projecting to such an altitude since August 2013 for the volcano within kilometers of downtown Kagoshima, a city of 606,000 and major shipping port in southwestern Japan.

The agency maintains its alert level for Sakurajima at 3, which warns people not to get close to the volcano, on a scale to 5.

Source : Japantimes.

Photo : S Nakano

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