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Earth of fire

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

tectonics

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

May is "Volcano Awareness Month" in Washington State, where 5 active volcanoes dominate the skyline. The peaks are often snow-capped and appear serene, but recent eruptions, steaming vents and occasional earthquakes remind us of their volcanic origins and potential for future eruptions.

"Volcano Awareness Month" in Washington state, where 5 active volcanoes dominate the skyline. - Doctor. USGS - one click to enlarge

"Volcano Awareness Month" in Washington state, where 5 active volcanoes dominate the skyline. - Doctor. USGS - one click to enlarge

Today, stratovolcanoes dominate the horizon (triangles) but they are only the most recent example of volcanism. Scientists used maps and a DEMS to find 2,999 vent locations in the US portion of the Cascades (pink areas). There are probably more vents that have been buried or eroded.

Tectonic context of the Cascades - Doc. USGS - one click to enlarge

Tectonic context of the Cascades - Doc. USGS - one click to enlarge

The tectonics of the northeast Pacific give a varied volcanic history. The Pacific Northwest has an active volcanic arc (Cascades Range), a nearby oceanic ridge (Pacific Plate-Juan de Fuca Plate Spreading Ridge), the world's youngest floodplain basalt province (Columbia River Basalt), a range hotspots of young volcanoes to the east (Yellowstone Trend), volcanism linked to continental extension, etc.

It is a volcanological paradise. The western margin of North America has long been dominated by dextral subduction and transtension. This animation attempts to simplify a complex tectonic interaction through cross-sections.

Volcanic evolution of the northwest of the North American continent: 55 million years of history. - IRIS earthquake sciences/animation accompanying a talk during IAVCEI 2017 in Portland, OR. Written and directed by Anita Grunder, Oregon State University Graphics, animation and narration by Jenda Johnson, Earth Sciences Animated - Reviewed by Ray Wells, U.S. Geological Survey

Halema'uma'u's summit crater also underwent major changes, and its lava lake disappeared during the 2018 eruption of Kïlauea. While lava flows in lower Puna drained the summit magma reservoir, Halemaʻumaʻu suffered 62 collapses (some with explosive eruptions). Each gradual collapse was marked by earthquakes that were felt throughout the summit. When the dust settled (and there was a lot of dust), the collapses had lowered the crater floor by more than 500 m.

The end of the 2018 eruption and caldera collapse events resulted in a period of quiescence not seen in Kīlauea for over 35 years. It also brought a new and interesting change to the volcano.

For the first time since written records began, a lake of water formed in the deep pit of Halemaʻumaʻu. First noticed in July 2019, water continued to slowly fill the crater over the next year and a half until it was about 50m deep.

On the night of December 20, 2020, the lake of water evaporated within an hour or two when Halema'uma'u erupted again. Within a day, the new lava lake was deeper than the water lake, and it continued to grow and fill the crater until May 2021. Again, Kīlauea did not stay silent for a long time. Halemaʻumaʻu began a new eruption in September 2021; an eruption that continues to this day. These two eruptions filled Halemaʻumaʻu with over 320 m of lava.

Volcano Awareness Month in Washington State, Kilauea Evolution and New Earthquake Swarm in Reykjanes.

Kilauea - A) Top left, photo of Halema'uma'u before the start of the 2018 collapse events with the decade-old active lava lake that formed in 2008. B) Top right , pictured after the 2018 collapse events caused the floor of Halema'uma'u crater to drop more than 1,600 feet (500 m) in just 4 months. C) Bottom left, in July 2019, a lake of water began to form in the newly deepened Halemaʻumaʻu, and this lake continued to grow over the next year and a half. D) Bottom right, the December 2020 eruption boiled the lake water overnight and continued through May 2021 before another eruption began in September 2021, continuing until 'now. All photos courtesy of the U.S. Geological Survey's Hawaiian Volcano Observatory. - one click to enlarge

Summary of activity as of 05.05.2022 : The eruption at the summit of Kīlauea Volcano in Halema'uma'u Crater has continued for the past 24 hours. All recent lava activity has been confined to the crater, and current data indicates that this scenario is likely to continue.

Eruption of lava from the western Halema'uma'u vent into the active lava lake and crater floor has continued over the past 24 hours. The active lava lake has experienced continuous surface activity and its surface level has been relatively stable during this period. Relatively slow lava seeps continued along the northeastern and southern margins of the crater floor yesterday, and this morning a particularly vigorous and expansive seep began along the northwestern margin just after 2 a.m. morning. Flyby measurements on April 6, 2022 indicated that the crater floor had experienced a total elevation of approximately 99 meters and 66 million cubic meters of lava had been shed since this eruption began on September 29, 2021.

Current volcanic alert level: Watch
Current Aviation Color Code: Orange.
No significant changes were noted at the summit or in the East Rift Zone.

 

Sources: HVO-USGS Daily update & Volcano Watch / Kïlauea's dynamic landscape: reflections on the past four years.

Kïlauea / Halema'uma'u - HVO therm webcam 05.05.2022 / 7:44 PM HST

Kïlauea / Halema'uma'u - HVO therm webcam 05.05.2022 / 7:44 PM HST

IMO has detected 173 tremors in the past 48 hours in the Reykjanes Peninsula. Most of the tremors occurred northeast of the Krýsuvík volcanic system, specifically beneath Kleifarvatn. In addition to the current M 3.4 earthquake, there was an M 2.9 earthquake before. Both tremors were felt in the greater Reykjavik area Lake Kleifarvatn is associated with a fault system and has been the site of several earthquakes over the past week.

More than 1,000 earthquakes have been detected under Reykjanes in the past 3 weeks. Most occur in the regions of Thorbjörn, Eldvörp and Kleifarvatn.

 

Source: IMO

Reykjanes Peninsula - Seismic swarm as of 05.05.2022 / 5:15 p.m. - Doc. IMO
Reykjanes Peninsula - Seismic swarm as of 05.05.2022 / 5:15 p.m. - Doc. IMO
Reykjanes Peninsula - Seismic swarm as of 05.05.2022 / 5:15 p.m. - Doc. IMO

Reykjanes Peninsula - Seismic swarm as of 05.05.2022 / 5:15 p.m. - Doc. IMO

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Publié le par Bernard Duyck
Publié dans : #volcanic activity, #Tectonics, #Tsunami
Hunga tonga- Hunga Ha'apai eruption- photo Taaniela Kula 14.01.2022 / 5:14 p.m. - TGS / via Matongitonga

Hunga tonga- Hunga Ha'apai eruption- photo Taaniela Kula 14.01.2022 / 5:14 p.m. - TGS / via Matongitonga

Some interesting info on the ongoing eruption at Hunga Tonga-Hunga Ha'apai.(HTHH)

The latest satellite images show the Tongan ash cloud approaching east of Kadavu at 11 p.m. FT. Much of southern Lau is also covered currently. (Fiji Earthquakes & Weather)

HTHH 15.01.2022 / 8:20 p.m. - Doc. WeatherWatch.co.nz

HTHH 15.01.2022 / 8:20 p.m. - Doc. WeatherWatch.co.nz

HTHH - 15.01.2022 - Fiji is currently sandwiched between a developing weather system to the west and a massive ash cloud from the Tonga eruption to the east. - Doctor. Fiji Earthquakes & Weather - one click to enlarge

HTHH - 15.01.2022 - Fiji is currently sandwiched between a developing weather system to the west and a massive ash cloud from the Tonga eruption to the east. - Doctor. Fiji Earthquakes & Weather - one click to enlarge

The massive shock wave from the eruption of the Hunga Tonga volcano today, January 15 (04 UTC) circled the globe at 1100 km/h and crossed Europe 15 hours later. Many weather stations record astonishing pressure changes of 2 to 3 mbar during the passage of several waves.

( Severe weather EU).

HTHH- shock wave velocity calculation - Doc. WeatherWatch.co.nz 15.01.2022 / 8:20 p.m.

HTHH- shock wave velocity calculation - Doc. WeatherWatch.co.nz 15.01.2022 / 8:20 p.m.

HTHH - the shock wave recorded in Slovenia (Europe) at 17,000 km as the crow flies from the eruptive site - Doc. Severe weather EU 15.01.2022 - one click to enlarge

HTHH - the shock wave recorded in Slovenia (Europe) at 17,000 km as the crow flies from the eruptive site - Doc. Severe weather EU 15.01.2022 - one click to enlarge

Evolution of HTHH according to satellite data

The new lands created by the eruption of December 2014-January 2015, and which connected the 2 small islands, are no longer visible on the SkySat / Planet satellite image of 01.15.2022. according to the radar images, the piontes of the islands were partly washed away.

These new lands were added on the edge of the islands and a major depression / intractrateric cliff. The mass collapsed, presumably generating the tsunami.

Hunga Tonga-Hunga Ha'apai - image archive sat. CNES Pleïade 19.01.2015 - one click to enlarge

Hunga Tonga-Hunga Ha'apai - image archive sat. CNES Pleïade 19.01.2015 - one click to enlarge

HTHH- image Sentinel-2 bands 4,3,2 from 02.01.2022 - one click to enlarge

HTHH- image Sentinel-2 bands 4,3,2 from 02.01.2022 - one click to enlarge

HTHH - SkySat/Planet image 15.01.2022 / 2:25 UTC

HTHH - SkySat/Planet image 15.01.2022 / 2:25 UTC

HTHH - Sentinel radar images between 11.12.2021 and 16.01.2022 at 6 a.m. - via Dr. Janine Krippner - one click to enlarge

HTHH - Sentinel radar images between 11.12.2021 and 16.01.2022 at 6 a.m. - via Dr. Janine Krippner - one click to enlarge

A map, created with April 2016 data from the R/V Falkor, by the Global Volcanism Program, showed details of the entire volcanic edifice. Measured on this quick Google Earth overlay, the diameter of the caldera rim is about 6 km. Recent eruptions have occurred on the N and NE sides. The red asterisk corresponds to the 2009 vent.

A map, created with April 2016 data from the R/V Falkor, by the Global Volcanism Program, showed details of the entire volcanic edifice. Measured on this quick Google Earth overlay, the diameter of the caldera rim is about 6 km. Recent eruptions have occurred on the N and NE sides. The red asterisk corresponds to the 2009 vent.

A map, created with April 2016 data from the R/V Falkor, by the Global Volcanism Program, showed details of the entire volcanic edifice. Measured on this quick Google Earth overlay, the diameter of the caldera rim is about 6 km. Recent eruptions have occurred on the N and NE sides. The red asterisk corresponds to the 2009 vent.

Tectonic context of the eruption:

Tonga sits above the Tonga-Kermadec subduction zone, where the Pacific plate is sinking beneath the Australian plate.
In this case, the melting is due to the addition of water, much like how adding salt can melt ice. (Dr. Judith Hubbard)

How does water enter subduction? Well, the subduction plate (the Pacific plate in this case) has been under the sea for tens of millions of years and is therefore soaked like a sponge.
During subduction, the plate gradually heats up, eventually releasing water molecules into the corner of the dominant mantle, which is hot but essentially dry and practically solid. With the addition of H2O (and/or CO2) this changes, and thus a water-rich magma is formed, which is typical of subduction zone volcanoes. (comment by Boris Behncke, INGV volcanologist)

Tectonics Tonga-Kermadec - Dr. Judith Hubbard 15.01.2022

Tectonics Tonga-Kermadec - Dr. Judith Hubbard 15.01.2022

Arc Tonga-Kermadec - Doc. NSF - one click to enlarge

Arc Tonga-Kermadec - Doc. NSF - one click to enlarge

Sources:

- Dr. Judith Hubbard, Dr. Janine Krippner, Boris Behncke

- Berrocoso, M., Torrecillas, C., Jigena, B., & Fernandez-Ros, A. (2012). Determination of geomorphological and volumetric variations in the 1970 land volcanic craters area (Deception Island, Antarctica) from 1968 using historical and current maps, remote sensing and GNSS. Antarctic Science, 24(04), 367–376. https://doi.org/10.1017/S0954102012000193

- Bulletin of the Global Volcanism Network (2015). BVGN, vol. 40, no. 1 (January 2015). http://volcano.si.edu/showreport.cfm?doi=10.5479/si.GVP.BGVN201501-243040

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

According to visual feedback from the OVPF-IPGP webcams, and thanks to short gaps in the cloud mass very present on the relief of Piton de la Fournaise, at least four eruptive cracks could be observed. These cracks are located on the southern flank at the base of the terminal cone, to the southeast of the Piton Kala Pélé and to the southwest of the Château Fort crater. The lowest point of emission is around 2000 m above sea level. At 8:30 am on December 22, all four cracks were still active but the most activity was on the lower crack in altitude.

On the evening of December 22, activity focused on only one of the eruptive fissures, the one further downstream, where a cone began to form under the activity of a lava fountain of about 60 m. height.

Piton de La Fournaise - webcam Piton de Bert 22.12.2021 / 13h55 TU - OVPF

Piton de La Fournaise - webcam Piton de Bert 22.12.2021 / 13h55 TU - OVPF

Piton de La Fournaise - webcam Piton de Bert 22.12.2021 / 15:06 UT - OVPF

Piton de La Fournaise - webcam Piton de Bert 22.12.2021 / 15:06 UT - OVPF

Piton de La Fournaise - only the downstream fountain is active on the evening of December 22, with the start of the formation of a cone - OVPF

Piton de La Fournaise - only the downstream fountain is active on the evening of December 22, with the start of the formation of a cone - OVPF

Piton de La Fournaise - trémor at 23.12.2021 / 07h - Doc .OVPF

Piton de La Fournaise - trémor at 23.12.2021 / 07h - Doc .OVPF

Over the last 24 hours:

- The surface deformations do not show any particular displacement.

- Thanks to a milder weather forecast, estimates of lava flow could be established by satellite method with the HOTVOLC platform (OPGC - Clermont Auvergne university), with an average of 4-7 m3 / sec and peaks at 22 m3 / sec.

Since last night, activity has only focused on one of the eruptive cracks, the one further downstream (around 2030 m altitude), where a cone began to form.

 

A field reconnaissance was made on the morning of December 23 thanks to the assistance of the Air Section of the Gendarmerie and the PGHM. This mission made it possible to precisely locate the vent which is still active and the flow front around 9:30 am (local time):

- the lava flow, in graton, had traveled 2.2 km from its point of emission (and was located at approximately 2000 m altitude)

- the flow front was located 550 m from the southern rampart, 3.2 km from the top of the major slopes, 8.1 km from the road and 9 km from the ocean.

This mission also made it possible to recover samples of lava (slag projected by lava fountains and lava flows) which will be very useful, once analyzed, to better understand the path taken by the in-depth magma and the dynamism of the rash. At 9:30 a.m. local time, the lava fountain regime was still very active but with heights only intermittently exceeding the height of the cone, estimated at 10 m.

 

Alert level: Alert 2-1 (eruption in the enclosure)

 

Source: OVPF

Piton de La Fournaise - 12.23.2021 / 9:30 am - location of the emission center and the casting front - Doc. OVPF

Piton de La Fournaise - 12.23.2021 / 9:30 am - location of the emission center and the casting front - Doc. OVPF

Piton de La Fournaise - the eruptive cone on 12/23/2021 / 9 a.m. loc.- photoOVPF

Piton de La Fournaise - the eruptive cone on 12/23/2021 / 9 a.m. loc.- photoOVPF

Lava dome growth continues at Sheveluch, strong fumarole activity, and incandescence of the lava dome and hot avalanches accompany this process. Satellite data from KVERT showed that explosions sent ash on December 23, 2021 up to 5.7-6.0 km altitude, and the ash plume extended 31 km northeast of volcano.

The extrusive eruption of the volcano continues. Ash explosions up to 10-15 km altitude. could arise at any time. Current activity could affect international and low-flying aircraft.

 

The aviation code remains orange.

 

Source: KVERT

Sheveluch - The Growing Dome - photo archives 09.2021 / Andrew Matseevsky

Sheveluch - The Growing Dome - photo archives 09.2021 / Andrew Matseevsky

The summit eruption of the Kīlauea volcano has stopped. Depending on the size and length of recent breaks, the current break should last for several days. All recent lava activity remains confined to Halema'uma'u Crater in Hawai'i Volcanoes National Park, and there is no sign of migrating activity elsewhere on Kīlauea.
The rapid deflationary trend began yesterday, December 20, 2021 around 11 a.m. and subsided early on December 21. The volcanic tremor associated with the eruption has practically ceased and the seismic activity remains below the background noise.

The surface of the lake became crusted after a sequence of partial overturns last night. The lake has experienced a total elevation of around 69 meters since lava emerged on September 29. The total erupting volume since the start of the eruption was estimated to be around 30 million cubic meters on November 16.

 

Source: HVO Daily Report

Kilauea - Halema'uma'u - active vent on 12.20.2021 - photo S. Carr - HVO

Kilauea - Halema'uma'u - active vent on 12.20.2021 - photo S. Carr - HVO

Kilauea - Halema'uma'u - crust over the lava lake on 12.21.2021 - HVO webcam

Kilauea - Halema'uma'u - crust over the lava lake on 12.21.2021 - HVO webcam

In the Reykjanes Peninsula, the earthquakes are aligned with the SW-NE direction, directly above the intrusion that caused the eruption earlier this year. The activity has recently moved south. The main activity last night was in Litla Hrút, but now appears to be south of the Geldingadalur eruption sites.

These earthquakes all appear to be at a relatively great depth, they are all at a depth of around 6-7 kilometers, according to volcanologist Þorvaldur Þórðarson.

The most important earthquake of M4.9 took place on December 22 at 10 a.m.

 

General seismic cracks on the Reykjanes Peninsula align with the N-S direction and are connected to the boundaries of the plates that cross the peninsula. The rows of craters and intrusions on the Reykjanes Peninsula, on the other hand, are almost always laid out in this diagonal fashion.

There is some uncertainty as to what scenarios can occur, but one of the scenarios is that magma can rise to the surface quite quickly.

 

Source: IMO

Reykjanes Peninsula - seismic swarm - location and magnitude of earthquakes as of 23.12.2021 / 07:10 - Doc. IMO
Reykjanes Peninsula - seismic swarm - location and magnitude of earthquakes as of 23.12.2021 / 07:10 - Doc. IMO
Reykjanes Peninsula - seismic swarm - location and magnitude of earthquakes as of 23.12.2021 / 07:10 - Doc. IMO

Reykjanes Peninsula - seismic swarm - location and magnitude of earthquakes as of 23.12.2021 / 07:10 - Doc. IMO

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Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques, #Tectonics
Okmok volcano - photo archives Mees, Burke / AVO - 04.2021

Okmok volcano - photo archives Mees, Burke / AVO - 04.2021

Between September and November 2021, the Alaska Volcano Observatory observed a change from the long-term deformation pattern of the Okmok volcano, measured by two continuous Global Navigation Satellite System (GNSS) stations in the caldera. The deformation pattern at Okmok generally consists of almost continuous inflation, with episodes in which this movement accelerates, and is generally believed to be related to the injection of magma somewhere between 2 and 4 km (1 , 2 to 2.5 miles) below the caldera floor.

In contrast, the changes we have observed recently are consistent with an increase in pressure at a shallower depth, less than 1 km (0.6 miles) below the caldera floor. The location on the map of this new source of deformation is near cone D, just south of the young cone of tephra Ahmanilix, created in the 2008 eruption. The deformation has since returned to background levels. There was no noticeable change in seismic activity during this period, and satellite images showed no change in surface.
The recently observed deformation is consistent with a small intrusion of shallow magma, but other non-magmatic processes such as hydrothermal activity cannot be excluded. If the deformation was caused by a shallow magma intrusion, it can increase the likelihood of an eruption. Previous eruptions at Okmok have occurred with little precursor seismic activity, and AVO continues to closely monitor the volcano.

The volcanic alert is: normal, with an aviation code: green.

 

Source: AVO

Voui lake (foreground) & Manaro-Lakwa lake (background) on Ambae - photo archives Karoly Nemeth / GVP-11911

Voui lake (foreground) & Manaro-Lakwa lake (background) on Ambae - photo archives Karoly Nemeth / GVP-11911

The Vanuatu Department of Meteorology and Geohazards (VMGD) reported that vapor emissions were visible up 250m on average from Lake Voui in Ambae from December 5-7. A still image from a video taken from an airplane showed brown water surrounding an active and growing cone that ejected wet tephra less than 10m above the surface of the lake.

The alert level remained at 1 (on a scale of 0 to 5) and the public was warned to stay outside the danger zone defined as a radius of 2 km around the 2017-2018 active vents in the lake Yes and far from drainages during heavy rains.

Ambae, is a basalt massif of 2500 km³ and the largest active shield volcano in the arc of Vanuatu. Its summit area has two concentric calderas, the largest of which is 6 km in diameter and the smallest comprising three lakes (Manaro-Ngoru, Manaro-Lakwa and Manaro-Voui). A large central building is also called Manaro Voui or Lombenben volcano. Post-caldera explosive eruptions formed the summit craters about 360 years ago. A tuff cone was built in Lake Voui (or Vui) about 60 years later. The last known flank eruption, around 300 years ago, destroyed the population of the Nduindui region near the west coast.

 

Source: VMGD / via GVP

La Palma / Cumbre Vieja - photo Rubén López 08.12.2021

La Palma / Cumbre Vieja - photo Rubén López 08.12.2021

La Palma - seismicity and RSAM at 08.12.2021 - Doc. IGN - one click to enlargeLa Palma - seismicity and RSAM at 08.12.2021 - Doc. IGN - one click to enlarge

La Palma - seismicity and RSAM at 08.12.2021 - Doc. IGN - one click to enlarge

La Palma / cumbre Vieja - Evolution of an announced collapse in the eastern cone - 08.12.2021 / IGME

La Palma / cumbre Vieja - Evolution of an announced collapse in the eastern cone - 08.12.2021 / IGME

Communication from Pevolca concerning the eruption of Cumbre Vieja in La Palma:

The cracks and fractures observed in the previous days in the upper part of the secondary cone remain without significant changes or modifications. Lava flows mainly through the central sector of the flows, through pre-existing lava tubes, gaining ground in south and west directions. The affected area is estimated at 1,184 hectares.

Regarding seismicity, the values ​​remain low in the intermediate range, while the number of earthquakes at depths greater than 20 kilometers remains at very low values ​​and the tremor level is at low values ​​with little variability.

Air quality levels due to sulfur dioxide yesterday exceeded the recommended daily value at the El Paso station and the alert threshold at Los Llanos de Aridane, then fell to good levels and reasonably good.

 

Source: DSN, IGN, IGME

Grimstvötn - Relative vertical displacement GPS as of 07.12.2021 - IMO

Grimstvötn - Relative vertical displacement GPS as of 07.12.2021 - IMO

The Grimsvötn ice cap has dropped 80m! The jökulhlaup decreases rapidly, as does the seismic tremor. Seismic activity has been low since Monday's M3.6 and the aviation color code for this volcano was turned volcano back to yellow on December 7, in line with the decreased likelihood of an eruption.

Scientists will continue to monitor the area closely although there is currently no indication of an impending eruption in Grísmvötn.

 

Source: IMO

Oregon - seismic swarm location and magnitudes as of 12/08/2021 - USGS earthquake hazards program

Oregon - seismic swarm location and magnitudes as of 12/08/2021 - USGS earthquake hazards program

A swarm of earthquakes began on December 7, 2021 about 400 km off the Oregon coast. The swarm occurred along the Blanco Fracture Zone, a right lateral transform fault zone marking the boundary between the Pacific Plate to the southwest and the Juan de Fuca Plate to the northeast. During the first 12 hours of the swarm, the USGS recorded 37 earthquakes of M3.4 or greater, including nine earthquakes of M5 or greater. In this time range, the two largest earthquakes in the swarm were M5.8. There have been sparse reports of light tremors associated with these earthquakes along the Pacific Northwest coast.

Considering the moment tensors and the orientation of the fracture zone, these events probably occurred on a steeply dipping fault, right lateral and oriented southeast. At this location, the Juan de Fuca Plate slides past the Pacific Plate at a speed of 49 mm / year along an azimuth of 110 degrees from the north. The Juan de Fuca Plate eventually sinks beneath North America along the Cascadia Subduction Zone about 360 km (220 miles) east of this swarm; therefore, this earthquake did not occur over the subduction zone, but rather is the result of interactions between the Pacific-Juan de Fuca plates further west.


 

Source: USGS earthquake hazards program

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Publié le par Bernard Duyck
Publié dans : #volcanic activity, #Tectonics

In Chile, four volcanoes have their volcanic alert in Amarilla level today: the Nevados de Chillan complex, the Villarica, the Copahue and the Laguna del Maule complex.

All are monitored 24/7 by professionals from the South Andes Volcanic Observatory, OVDAS.

Activity of the Copahue, the Laguna del Maule complex, the Veniaminof and earthquakes off Raoul island.

Over the past few days, Copahue's volcanic activity has evolved to show visible signs on the surface. It is important to mention that very low frequency (very long period VLP) seismicity has been recorded in the previous months, generally linked to the rise of the magmatic material to more superficial levels. Likewise, on May 20, a series of volcanic seismological events located south-southwest near the volcanic building were recorded.

On June 16, there was an increase in energy from the seismic tremor with subsequent stabilization and decrease in the following hours. At the same time as this decrease, the incandescence and the emission of particles were detected from cameras installed by OVDAS. The latest sulfur dioxide recordings obtained by the equipment installed for its detection indicate average flows of 592 tonnes / day for June 15, considered as usual values ​​for this activity.

On the other hand, the monitoring stations which measure the deformation in the volcanic sectors do not show changes related to this activity. In addition, the images available on the Planet satellite platform indicate a decrease in the volume of the lake housed in the active crater.

In summary, the changes in seismological behavior, the anomalies in the surface assessments and the decrease in the volume of the crater lake suggest the presence of a volume of magma at superficial levels.

 

Sources: Sernageomin & Onemi

Copahue - photo Valentina Sepulveda @Valecaviahue 14.06.2020 in the evening - un clic pour agrandir

Copahue - photo Valentina Sepulveda @Valecaviahue 14.06.2020 in the evening - un clic pour agrandir

The Sernageomin through a special report of volcanic activity (REAV) reported the change of alert from GREEN to YELLOW in the volcanic complex of Laguna del Maule

The above responds to the increase in volcano-tectonic (VT) type seismic activity, associated with rock fracturing, through seismic swarms on June 11, 13 and 15-16. These events were characterized by their small scale and by their location in the southwest of the lagoon (Las Nieblas sector)

In addition, in this same area during the previous months, diffuse carbon dioxide (CO2) anomalies were detected through the ground.

Therefore, due to the persistent presence of seismic swarms in the same area, added to the gas anomaly and the constant deformation that has characterized the volcanic complex over the past decade, it is considered to be at above its basic level.

A potential allocation area is set at a radius of 2,000 meters around the passive carbon dioxide degassing center

 

Source: Sernageomin

The Laguna del Maule volcanic complex - photo Sernageomin / Rayen Gho

The Laguna del Maule volcanic complex - photo Sernageomin / Rayen Gho

In the past few days, there have been periods of earthquakes and occasional earthquakes in Veniaminof. This represents a deviation from the background activity. Thus, the aviation color code and the alert level of the volcano are increased to YELLOW / ADVISORY.

This type of seismic activity generally precedes the eruptive activity with Veniaminof, but does not mean that an eruption will occur. Eruptive activity generally consists of emissions of minor ash, lava fountains and lava flows from the small cone of the summit caldera. Ash emissions are generally confined to the summit crater, but larger events can cause ash to fall in nearby communities and drift of airborne ash.

 

The Veniaminof volcano is an andesitic stratovolcano with a summit caldera 10 km in diameter located on the Alaskan Peninsula, 775 km (480 mi) southwest of Anchorage and 35 km (22 mi) north of Perryville . It is monitored by local seismic sensors, satellite data, web cameras, and infrared and lightning networks remotely.

 

Source: AVO

Veniaminof - the summit cone and the lava flows 2018 - photo Matt Loewen / AVO taken during the field visit in June 2019

Veniaminof - the summit cone and the lava flows 2018 - photo Matt Loewen / AVO taken during the field visit in June 2019

An earthquake of M7.4, 470 km south of Raoul island, in the north of New Zealand, on 19.06.2020 at 12:49 local time occurred in the Tonga-Kermadec subduction zone, where the Pacific plate plunges towards west under the Australian plate, causing tension events at shallower depths and compression tremor at greater depths.

This earthquake was felt widely along the east coast of New Zealand.

 

Source: GeoNet

 Location of Raoul Island in the Kermadec Islands and earthquakes over M5.0 in the last month (20 May – 20 June 2019). The subduction zone north of New Zealand is visible in red. - Doc. GNS

Location of Raoul Island in the Kermadec Islands and earthquakes over M5.0 in the last month (20 May – 20 June 2019). The subduction zone north of New Zealand is visible in red. - Doc. GNS

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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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