Volcanic activity in Canary Islands 2021

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Am I missing something here is the Richter scale not used all over the world so why do IGN have to make their own assumptions on the Canary Islands ??



The IGN elaborates a specific local magnitude scale for earthquakes in the Canary Islands
The reason is that the one used, Richter's, was calibrated in peninsular territory, so it should be adapted to the reality of the islands to give more accurate results.
- Almost 70 earthquakes shake La Palma in the early hours of this Monday

Efe

November 1, 2021 11:07 a.m.
0

The National Geographic Institute (IGN) has developed a scale of magnitude of seismic movements specific for the Canary Islands, which will lead to transform the previous records to adapt them to the new formula, but the differences will be a few tenths, the seismologist told Efe of the IGN Juan Rueda.

La Palma trembles with the second magnitude 5 Earthquake

KNOW MORE
At the moment, the work is being submitted for publication prior to its integration into the calculation process and, when it occurs, the magnitudes of the Canary Islands earthquakes determined by the IGN will have a lower degree of uncertainty.

The reason for making a specific scale is that the one currently used by the IGN was made in peninsular territory, explained Juan Rueda, who pointed out that the measurement of the magnitude in seismic movements was the idea of physicist and seismologist Charles Francis Richter .

Before 1935, which was the year that Ritcher defined the magnitude, earthquakes were measured only by their intensity, by the damage they caused, has indicated the seismologist of the National Geographic Institute. Ritcher wanted to have a number so that he could define the energy released by earthquakes, and take that number out of the seismogram registry.

The American physicist had a Wood-Anderson seismograph with analog recording in California and said that if he measured the maximum amplitude of the wave in the record and made its logarithm, the result would be a measure of energy. And in addition, he said that a parameter had to be removed depending on the place where the Earthquake occurs and the place where the station is located, and therein lies the problem because "the rest of us are not in California, so the The attenuation parameter that must be removed from the logarithm of the amplitude is different depending on the place, "pointed out Juan Rueda.

What is usually done is to calibrate the Ritcher scale to each place, and this was carried out in peninsular territory and therefore the National Geographic Institute uses the magnitude mbLg. These letters correspond to m (magnitude), b (body -body-, because internal waves are measured), and Lg (because of the multiple waves that are registered in an Earthquake, the Lg wave is used in the peninsula).

In this way, in the Canary Islands a formula made for a different territory is used, and in view of this situation in the National Geographic Institute a new formula has been developed for the Canary Islands, where before the magnitude of earthquakes was calculated based on the duration of the record of the Earthquake, something that was carried out from analog records.

In this way, how long an Earthquake lasted was measured, a formula was applied and that gave a value of magnitude duration.

Juan Rueda has stressed that "all" the magnitudes are intended to give values similar to those of Ritcher in California, which leads to different agencies giving magnitudes that present differences, but these are small.

The change that will be made for the Canary Islands will lead to homogenizing the previous magnitudes with the new ones, as happened when the mbLg magnitude began to be applied in the islands, and it is done to avoid bias when comparing the magnitude of earthquakes in different periods.

Juan Rueda has specified that when he says that the magnitude is determined by the amplitude of the seismic waves, it must be taken into account that an Earthquake is registered in multiple seismic stations, so that an average of the magnitude values is made for each station.

And since there is a coefficient that depends on each station, since it is different in each one, and there is "always" an uncertainty in the value of the magnitude, something that is due to the calculation method since the energy is not measured in the focus. but in the distance, with which a correction must be made to extrapolate what the energy would be at the focus of the Earthquake, he added.

In this context, he has emphasized that it is a hoax to say that the IGN reduces the magnitude of earthquakes, and has said that what happens is that the first calculation is automatic, it is carried out by a computer that is continuously analyzing the waveform.

When the computer detects an Earthquake it measures the maximum amplitude, which is "peak to peak", and then the analyst person carries out a review and most of the time that peak is something "isolated", so you have to go at the maximum but sustained amplitude of the seismogram, which lowers the amplitude, and therefore the magnitude.

Juan Rueda recalled that the magnitude scale has no limit, but a seismic movement has never been recorded above 9.

[jand]

Am I missing something here is the Richter scale not used all over the world so why do IGN have to make their own assumptions on the Canary Islands ??

Jan
Carlos Seisdedos Garcia ¿Me estoy perdiendo algo aquí en todo el mundo? La escala de Richter se usa para medir terremotos. ¿Por qué el IGN tiene que crear sus propias reglas?
· Reply · 3m
Carlos Seisdedos Garcia
Jan exactamente, por eso mi duda, vale q esto son islas pero digo yo que un terremoto afecta lo mismo en península q en una isla q en otro continente, y no entiendo esa nueva escala


Carlos Seisdedos Garcia
Jan exactly, that's why my doubt, it's worth q these are islands but I say that an Earthquake affects the same in q peninsula on an island q on another continent, and I do not understand that new scale

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"The worst that can happen is that the volcano generates terrible explosions and the lava needs more mouths to exit"
Miguel Ángel Morcuende, technical director of Pevolca, and who 'stands up' to the volcano, says that the eruption will last at least two more months

A Miguel Angel Morcuende stop him constantly in the street. Someone always approaches him, and not so much because he is the visible face of the La Palma volcano , but to thank him. They shake their hands, they leave the table paid for and some of them even throw themselves into their arms.

Morcuende, except for his very strong Madrid accent, is from La Palma to La Palma. This forestry engineer, who has lived in the Canary Islands for 36 years, accepted the difficult task of 'standing up' to the volcano by accepting the technical direction of the Special Plan for Civil Protection and Emergency Attention for Volcanic Risk, better known as Pevolca.


Volcanologists will become concerned when the depth of the Earthquake approaches the surface
They do not rule out that earthquakes of greater intensity will occur in the area affected by the volcano on the island of La Palma


More than six weeks have passed since the La Palma volcano erupted and seismic activity has not stopped . The residents have felt in the last 24 hours a total of 21 earthquakes, reaching the maximum intensity in the epicentral zone IV-V (on a scale over XII) in one registered at 6.19 hours, which reached a magnitude of 4.6 and a depth of 38 kilometers. The total sum of earthquakes located in the area affected by the volcano in the last 24 hours amounts to 138, according to data from the National Geographic Institute (IGN).

At the moment, the average depth at which these tremors are registered continue to be in the transit between the crust and the earth's mantle , between 10 and 14 kilometers, according to the volcanologist of the Illustrious Official College of Geologists José Luis Barrera Morate. Despite this, the volcanologist explains to this newspaper that some "have escaped" and have been registered at a lesser depth. Although, he confesses that earthquakes are always a "problem" and must be "aware" of them, the concern would begin at the moment in which the depth at which they occur rises towards the most superficial layers. "We will have to monitor that area where the hypocenter of the Earthquake is rising," says Barrera.

In addition, Juan Rueda, head of the IGN Seismographic Detection service, recalls that earthquakes are the result of the rupture of the crust due to the force of magma . “One should be concerned when a seismicity appears at a shallower depth in another area of ​​the island. For it to occur, a new eruptive mouth does not have to be opened, ”confesses Rueda.

Higher intensity earthquakes
In accordance with what has historically occurred with seismic activity on La Palma, Rueda does not rule out the occurrence of some of greater intensity .

Likewise, Barrera insists on the importance of differentiating intensity and magnitude. “ The intensity of an Earthquake refers to the effects that seismic waves had on the earth's surface . As an example, a magnitude six Earthquake in the middle of the ocean has zero intensity because no one feels it, "he says. However, the magnitude , also known as the Richter seismological scale, is a measure of the energy that is released during the Earthquake

In the depth range between 30 and 36 kilometers earthquakes of magnitudes between 4.2 and 4.9 occur," he acknowledges.

https://www.abc.es/sociedad/abci-peor-pu...ticia.html

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La Palma volcano update: Intense ash emissions continue, bad air quality in the Ariadne Valley
Mon, 1 Nov 2021, 08:46
08:46 AM | BY: T

Not much has changed at the ongoing eruption. The main vent at the crater emits near-continuous jets of ash-rich fountains while modest amounts of lava flow from lower vents into a channeled surface flow on the western flank of it.
Volcanic tremor as an indicator of magma flow rate has decreased a bit, but remains high. No significant changes in Earthquake activity or ground deformations can be reported either, all pointing to that the eruption is in a more or less stable phase and shows no clear trend, certainly no signs of possibly ending very soon, unfortunately.
Meteorological conditions remain adverse for the western part of the island, in particular the Ariadne valley, where thick vog (volcanic fog) prevails, an unhealthy mixture of gasses and fine ash particles trapped in the air.
In Los Llanos de Ariadne, concentration values of up to 499 grams of fine dust or ash particles per cubic meter in the air have been detected recently. This is 10 times the standard threshold of 50 micrograms/m3 still considered as healthy to breathe. It is strongly advised to avoid going outside, close windows, and wear dust masks (preferably FFP2 type).


https://volcanodiscovery.de/uploads/pics...ov21-2.jpg

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Earthquakes really picking up a M4.2 13:03

http://www.ign.es/web/resources/volcanol..._KxSOqQ0A8