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Earth of fire

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

sismologia

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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