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Earth of fire

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

Articles avec #sismologia catégorie

Publié le par Bernard Duyck
Publié dans : #volcanic activity, #Sismologia
 Popocatépetl - explosion of March 21, 2020 / 10:41 p.m. - WebcamsdeMexico

Popocatépetl - explosion of March 21, 2020 / 10:41 p.m. - WebcamsdeMexico

In Popocatépetl, in the past 24 hours, 74 exhalations have been identified thanks to the surveillance system, accompanied by volcanic gas emissions, small quantities of ash and sometimes incandescent fragments. Night glow is observed.

During the day, we see the constant emission of volcanic gases and sometimes slight amounts of ash, which are dispersed to the northwest.

The activity was a little more intense in the evening, with an explosion at 10:40 pm, and the ejection of incandescent materials on the upper slopes.

This activity remains under the Amarillo Fase 2 alert.

 

Source: Cenapred & WebcamsdeMexico.

Mayotte - Earthquake between Mayotte and Anjouan on 21..03.2020 / 9h46 loc. M 5.8 (red dot epicenter) - Doc. REVOSIMA

Mayotte - Earthquake between Mayotte and Anjouan on 21..03.2020 / 9h46 loc. M 5.8 (red dot epicenter) - Doc. REVOSIMA

A strongly felt earthquake in Mayotte in the order of M5.8 was recorded on March 21, 2020 at 06:42 UT (09:46 local time Mayotte) by the Mayotte volcanological and seismological monitoring network (REVOSIMA). The epicenter was located this time between the islands of Mayotte and Anjouan, 50 km NW of Mayotte and 30 km deep.

To illustrate the order of magnitude, it had the same intensity as the strongest earthquake felt in May 2018. It was less felt, due to the distance and its depth.

Up to now, the epicenters of earthquakes have been located east of Mayotte, and originate from two areas of magmatic flux emission.

We can notice the alignment between Comoros, the new earthquake zone, Mayotte and the earthquake zone since 2018 at the SSE of the island.

It remains to determine the exact nature of the earthquake

 

Sources: REVOSIMA, OVPF and Journal de Mayotte

Reykjanes - location and magnitude of the earthquakes at 21.03.2020 / 11:00 am - Doc. IMO
Reykjanes - location and magnitude of the earthquakes at 21.03.2020 / 11:00 am - Doc. IMO
Reykjanes - location and magnitude of the earthquakes at 21.03.2020 / 11:00 am - Doc. IMO

Reykjanes - location and magnitude of the earthquakes at 21.03.2020 / 11:00 am - Doc. IMO

In the Reykjanes Peninsula, on March 20, at 8:30 p.m., an earthquake swarm started with Krysuvik. By midnight, 60 earthquakes had been detected in the region. The biggest M3 happened at 9:21 p.m. No reports were received. Then the activity decreased.

The uncertainty phase due to the uprising in Reykjanes is still valid according to the Ministry of Civil Protection.

The latest deformation results around Mt. Thorbjorn indicate that inflation causing an uprising in the region has resumed. The uprising is slower than when it was measured in January, but seems to be in the same place. The most likely explanation for the signal is that the influx of magma has started again.

 

Source: IMO / March 21 00:18 GMT

Uplift at Yellowstone and how it does NOT mean an eruption is coming - Dr. Janine Krippner and Mike Poland.

To fill this period of confinement, and for those who master English, you can follow on YouTube a series by Dr. Janine Krippner entitled "Volcano moments", including an example above.

Interviews with volcanologists on different volcanic or seismic subjects, by following this link: https://www.youtube.com/playlist?list=PLjrF2J-wVC2OreS8nFgTgVZ5fnxymyQi3

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Publié le par Bernard Duyck
Publié dans : #volcanic activity, #Sismologia
 Yasur - emission of gas and ash on 15.03.2020 / 10.45 am - Doc. VGO

Yasur - emission of gas and ash on 15.03.2020 / 10.45 am - Doc. VGO

In Vanuatu, Yasur activity is on the rise, with explosions in progress and emission of gases and / or volcanic ash observed. Villages near the volcano are likely to be impacted by ash falls and volcanic gases in an area NNW, current direction of the winds.

The volcanic alert remains at 2; the danger to life zone remains within the limits of danger zone A, approximately within 600 meters around the cone.

 

Source: VGO

Popocatépetl - activity of the last 24 hours - Doc. Cenapred / CNPC / Seguridad

Popocatépetl - activity of the last 24 hours - Doc. Cenapred / CNPC / Seguridad

Over the past 24 hours at Popocatépetl, Cenapred has identified 125 exhalations, accompanied by gas, water vapor and little ash, as well as explosions, including two minor around 11:07 p.m. and 4:05 a.m., and a moderate, the 14.03 at 8.45 p.m. All the explosions were responsible for a plume of about 1,500 meters, dispersing to the northeast, and for ejecting incandescent materials at a medium distance from the crater.

Between these episodes, gas emissions, and slight amounts of ash are reported.

Tremor was recorded for 189 minutes.

The volcanic alert remains at Amarillo Fase 2.

 

Source: Cenapred

Shishaldin - RSAM between 14.03 and 15.03.2020 at 7:30 a.m. - Doc. AVO / UTCSSBA_BHX

Shishaldin - RSAM between 14.03 and 15.03.2020 at 7:30 a.m. - Doc. AVO / UTCSSBA_BHX

AVO raised the alert level of the Shishaldin to Watch and the aviation code to orange this March 14 at 10:31 pm, following the observation on a high resolution satellite image of lava, and of what appears to be a new cone in the summit crater.

A weak tremor is also detected.

This increase is justified by a possible continuation of the activity, with little or no warning signs, resulting in lava flows outside the crater, lahars and ash clouds at low altitude.

 

Source: AVO

Klyuchevskoy - 15.03.2020 / 7:19 am - webcam IVS FEB RAS, KVERT

Klyuchevskoy - 15.03.2020 / 7:19 am - webcam IVS FEB RAS, KVERT

Strombolian activity continues at Klyuchevskoy on March 15, with an ash explosion reaching 5,500 meters asl. The ash and gas cloud drifted 170 km towards the ENE.

The aviation code remains orange, due to possible ash explosion between 5,000 and 7,000 meters asl. anytime

 

Sources: KVERT & VAAC Tokyo

 Reykjanes peninsula - location and magnitude of earthquakes at 15.03.2020 / 08h55 - Doc. IMO
 Reykjanes peninsula - location and magnitude of earthquakes at 15.03.2020 / 08h55 - Doc. IMO
 Reykjanes peninsula - location and magnitude of earthquakes at 15.03.2020 / 08h55 - Doc. IMO

 Reykjanes peninsula - location and magnitude of earthquakes at 15.03.2020 / 08h55 - Doc. IMO

The seismic swarm that started on March 12 northeast of Grindavík on the Reykjanes Peninsula is still in progress, but the intensity of the swarm has decreased since the start.

Many minor earthquakes are still detected in the region. At the start of the swarm, an M5.2 earthquake occurred approximately 5 km NE of Grindavík. During the first day of the swarm, eight more earthquakes above M3.0 were detected. Uplift is no longer observed in the area, which is likely due to the cessation of the influx of magma. The phase of uncertainty declared by the Civil Protection is still in force.

 

At 05:55, an M3.2 earthquake was detected just north of Herðubreið. More than 100 earthquakes have been located there since yesterday. About a week ago, a hundred earthquakes were also located there. Seismic swarms are common in this area, the last time an earthquake above M3.0 was detected in a similar area in November 2019.

 

Source: IMO / Icelandic Met Office

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Publié le par Bernard Duyck
Publié dans : #volcanic activity, #Sismologia
Popocatépetl - 07.03.2020 / 07h26 - WebcamsdeMexico

Popocatépetl - 07.03.2020 / 07h26 - WebcamsdeMexico

The Cenapred informs during the last 24 hours to Popocatépetl 189 exhalations, some of these events were accompanied by gas emissions and slight amounts of ash. and three minor explosions recorded yesterday at 7:30 p.m., 9:20 p.m. and March 7 at 7:23 a.m. At the seismicity level, 215 minutes of tremor were also recorded

Since this morning and until the time of this report at 11:15 a.m., volcanic gas emissions and slight amounts of ash have been presented which are scattered towards the northeast.

Cenapred requests not to access the volcano.

The Popocatépetl volcanic alert remains at Amarillo Fase 2.

 

Source: Cenapred

Popocatépetl - summary of activity over the past 24 hours - Doc. Cenapred / CNPC / Seguridad

Popocatépetl - summary of activity over the past 24 hours - Doc. Cenapred / CNPC / Seguridad

The news of volcanic areas is rather summarized at this time by news of the developed seismicity.

In the Reykjanes Peninsula, seismic activity continues at the southwestern tip of Reykjanestá since February 15. We distinguish on March 6 at 4:55 pm an earthquake of M 3.1.
Earthquakes have greatly decreased near Thorbjorn, but the status unquestionably promulgated by the Civil Protection remains current.
IMO always advises against excursions to the Eldvörp region.

 

Source: IMO

Reykjanes peninsula - location and magnitude of earthquakes - Doc. IMO 07.03.2020 / 19h20
Reykjanes peninsula - location and magnitude of earthquakes - Doc. IMO 07.03.2020 / 19h20

Reykjanes peninsula - location and magnitude of earthquakes - Doc. IMO 07.03.2020 / 19h20

On March 7, 2020 at 8:58 p.m. (Canary time), the seismic stations of the Canaria seismic network (C7) of the Canary Volcanological Institute (INVOLCAN) recorded an earthquake of magnitude 5.5 according to the Spanish Geographic Institute and M 5.2 according to EMSC (Euro-Mediterranean seismological center) and NEIC (National Earthquake Information Center).

The epicenter of this earthquake is located in the Madeira archipelago, about 50 kilometers south of Funchal, and was very clearly felt on the islands of Madeira and Porto Santo Santo. This seismic event was felt with less intensity also in Lisbon, as well as in the islands of Tenerife and La Palma, located approximately 1,000 and 380 kilometers from the epicenter respectively.
Another shake of Ml4.3 is reported at 9:22 p.m. by the IGN.

 

Sources: InVolcan, IGN and EMSC

Madère - epicenter of the earthquake of 07.03.2020 / 20.58 Can - M5.2 (review) depth 10 km - Doc.EMSC

Madère - epicenter of the earthquake of 07.03.2020 / 20.58 Can - M5.2 (review) depth 10 km - Doc.EMSC

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Publié le par Bernard Duyck
Publié dans : #Sismologia, #Tectonics

If I tell you about the Michoacán-Guanajuato volcanic field, that doesn't mean much to you ... but if I say that it shelters the Parícutin, you can see better.

This extensive volcanic field in central Mexico, 250 km by 200 km, contains more than 400 vents. The predominant volcanic form is cinder cone, but small shield volcanoes, lava domes, maars and tuff rings, lava flows without cones are also present.

The two best representatives known are the Jorullo, which was built in the 18th century and the Parícutin, which formed in a grain field between 1943 and 1952.

Seismic swarm at Michoacán - Doc. SSN / UNAM 04.02.2020 - one click to enlarge

Seismic swarm at Michoacán - Doc. SSN / UNAM 04.02.2020 - one click to enlarge

 Seismic swarm at Michoacán - Doc. SSN / UNAM on 27.01.2020

Seismic swarm at Michoacán - Doc. SSN / UNAM on 27.01.2020

Why come back today ... because from January 5 to February 3, 2020 (in progress), the National Seismology Service (SSN) reported a seismic sequence with 1,824 earthquakes located near Uruapan, in the State of Michoacán, and more generally in the Mexican Neovolcanic Axis.

The largest earthquakes in the sequence were magnitude 4.1, one of them occurred at 2:49 a.m. on January 23, 2020, two others on February 2 at 7:47 p.m. and 10:58 p.m. respectively.

Uruapan / Michoacan - epicenter of the M3.9 earthquake / depth 12 km from 02.02.2020 / 22:48 - Doc. EMSC - EMSC

Uruapan / Michoacan - epicenter of the M3.9 earthquake / depth 12 km from 02.02.2020 / 22:48 - Doc. EMSC - EMSC

This region is characterized by intense seismic activity, related to the subduction of the Cocos plate under the North American plate. Under this part of the North American plate, the Cocos plate plunges with a very small angle almost horizontally, then after about 250 km, almost under Mexico, the diving is done abruptly.

Regional tectonics  &  Diving of the Cocos plate in 2 stages / © Perez-Campos et al., GRL 2008 - one click to enlargeRegional tectonics  &  Diving of the Cocos plate in 2 stages / © Perez-Campos et al., GRL 2008 - one click to enlarge

Regional tectonics & Diving of the Cocos plate in 2 stages / © Perez-Campos et al., GRL 2008 - one click to enlarge

For the moment, and pending the results of sampling, there is no indication of a link between earthquakes and magmatic intrusion activity.

More news is expected from Cenapred and the SSN / National Seismology Service.

 

Sources:

- National seismology service / UNAM - Special report / seismic sequence from January 5 to February 3, 2020.-  http://www.ssn.unam.mx/sismicidad/reportes-especiales/2020/SSNMX_rep_esp_20200113_secuenciaMichoacan_M39.pdf

- Global Volcanism Program - Michoacán-Guanajuato - http://volcano.si.edu/volcano.cfm?vn=341060

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Publié le par Bernard Duyck
Publié dans : #Underwater volcanism, #Sismologia

A joint study by the German Center for Geoscience Research / GFZ and the Institute for Research in Astrophysics and Planetology, entitled "Drainage of a deep magma reservoir near Mayotte inferred from seismicity and deformation", examines the seismicity associated with the seismic crisis that started in June 2018.

It highlighted magmatic movements under the seabed, before and during the eruption of this new volcano off the island of Mayotte.

More than 7,000 volcano-tectonic earthquakes and 407 earthquakes of very long period were studied with new techniques adapted to compensate the lack of instrumentalization (before the MAYOBS 1 campaign with the Marion Dufresne).

For the record : Mayotte - seismic swarms 2018-2019 - Doc. archived / BRGM

For the record : Mayotte - seismic swarms 2018-2019 - Doc. archived / BRGM

 "An earthquake goes around the world" - Doc. infogram archived on 11/11/2018

"An earthquake goes around the world" - Doc. infogram archived on 11/11/2018

For the record : MAYOBS campaign - CNRS / IPGP / IFREMER / BRGM / Univ Paris 02 to 18.05.2019

For the record : MAYOBS campaign - CNRS / IPGP / IFREMER / BRGM / Univ Paris 02 to 18.05.2019

The first earthquakes responded to the propagation of a magmatic dyke from the depths of the Moho to the surface.

From June, VLP signals, lasting 20-30 minutes and so powerful that they could be recorded a thousand kilometers away, appeared ... while the subsidence of the soil at Mayotte was measured by GNSS.

The study authors interpret this as a sign of the collapse of the large deep magma chamber, more than 3.4 km³ at about 30 km deep, following its emptying.

The eruption could not be noticed at the start, the seabed being 3 km below the surface.

Seismicity highlights the stages of the formation of the underwater volcano off Mayotte.
Sketch of the deep magma reservoir and the ascending path of magma to form a new underwater volcano. Different types of seismic and surface deformation accompany the four identified phases of agitation. Doc. CESCA ET AL. 2019, NATURE GEOSCIENCE

Sketch of the deep magma reservoir and the ascending path of magma to form a new underwater volcano. Different types of seismic and surface deformation accompany the four identified phases of agitation. Doc. CESCA ET AL. 2019, NATURE GEOSCIENCE

The earthquakes continue, even if we speak less: according to data from the RéNass / National Network for seismic monitoring, January 1 was marked by 7 earthquakes, including one of M 4.8. This January 8, an earthquake of MLv 1.8 was noted.

 

Sources:

- CNRS - Espace Presse 07.01.2020 - Volcano off Mayotte: seismicity sheds light on the stages of its formation - link

- "Drainage of a deep magma reservoir near Mayotte inferred from seismicity and deformation"
Simone Cesca, Jean Letort, Hoby N. T. Razafindrakoto, Sebastian Heimann, Eleonora Rivalta, Marius P. Isken, Mehdi Nikkhoo, Luigi Passarelli, Gesa M. Petersen, Fabrice Cotton & Torsten Dahm
Nature Geoscience, January 6, 2020

- BRGM - Volcano and earthquakes in Mayotte: monitoring of earthquake-volcanic activity - REVOSIMA - link

- RéNass / National seismic monitoring network - link

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