Tue. Oct 22nd, 2019

They register 500 "important" sesms in the Teide in a single day – The Province

The immediate question would be: will there be an eruption in Tenerife? The response of the researchers, just as quickly and bluntly: yes. When? Maybe soon, maybe in 100 years, maybe in a little while … It's totally unpredictable. For now there is no reason for concern but the Teide, which concentrates hundreds of tremors in the last three years, is active, as are other volcanoes on the Islands. This is explained by Ithaiza Domínguez, an expert from the National Geographic Institute (IGN), who was consulted about the seismic movements regularly detected in Tenerife since 2016 and, especially, in the area of ​​the Teide National Park. As stressed, and in line with what was reiterated by the IGN and other specialists last Tuesday, on the occasion of the last swarm of small earthquakes in Tenerife, it is a usual situation in these three and a half years, although anomalous with respect to previous stages because , since the normal breaks of the bark, the mixture of this phenomenon has been joined since then with the detection of fluids, which suggests that there may be magma.

Although the movements detected by the instruments of the IGN during the past Tuesday in the surroundings of the Teide were exactly 25, a usual cap for the last three and a half years, the last day with some more than striking figures occurred on June 14. So much that the IGN itself prepared an express report on what happened. That day, 500 "important" earthquakes were registered, according to the rating given by Dominguez, a figure that is only comparable to what happened on October 2, 2016, all detected in the west of Las Cañadas. Yes, Domínguez clarifies that the instrumentation and controls have been improving a lot in recent years, each time with more measuring stations and more advanced technology.

For this reason, Dominguez and other experts, such as Luca D'Auria (Canarian Volcanological Institute, Involcan), stress that, had these advances been made before, many other earthquakes of very low magnitude would have been detected. In fact, in the last week, the strongest was 2.2, not enough for the population to perceive it, although it was insufficient for the seismographs.

Since the events of October 2, 2016, the IGN, the Institute that directs volcanic monitoring in the Canary Islands, has been developing various reports in which it is noted that, annually, more than one thousand seismic movements are recorded. The great difference is that, since then, a considerable number of "hybrid events" have been added to the habitual volcanotectonic type, which are composed of those ruptures of the crust and, at the same time, by fluid elements, such as water or, in this case and according to Domínguez, magma.

The swarm of June 14 was detected about 7 kilometers deep. Domínguez says they believe there is a link between those who are registering in Vilaflor (and nearby areas of Adeje) with those of the Teide National Park. "This phenomenon is going to continue and surely there will be an eruption, the problem is to know when, because it is completely unpredictable." The truth is that the last one that occurred in Tenerife was 110 years ago (Chinyero, 1909). in 1798 (Chahorra) and in 1706 (Garachico). You never know or exist techniques that can foresee it ".

As noted, the eruptions monotorizadas in the Islands begin with the Sea of ​​Calms, in El Hierro, last 2011. Of course, for the sake of general tranquility, it is clear that if there is a volcanic eruption, the previous earthquakes would be detectable by the population and, therefore, could prepare the event and preventive measures. These previous strong upswings would be the usual, although, within the unpredictability of these phenomena, Dominguez also clarifies that scientific guarantees can never be full of that assertion.

If there is magma, will there be an eruption? "Not necessarily, that magma may have been there for years, and yet we did not detect it because the instruments we had were not adequate, El Hierro's was accumulating for years, but that's how volcanic islands like the Canary Islands work The activity, in fact, has not changed much since 2016, but it is true that they generate the logical uncertainty ", explains Ithaiza Domínguez. According to the locations, swarms of up to 800 movements on October 2, 2016 are concentrated in an area of ​​Las Cañadas between Pico Viejo and Bocatauce, as well as at a depth of 10 kilometers.

This diagnosis coincides in large part with that of Luca D'Auria, who emphasizes that what is taking place is "usual" with respect to the last three years but "anomalous" with respect to what was recorded in the Islands before 2016, precisely on the part of the fluids that has been detected in many of the seismic events recorded in the area of ​​Las Cañadas and Vilaflor. "About 20 years ago, we would not have detected this, it could be a dynamic of the volcano, due to fluid pressure, but it is not to worry about," he stresses.

Be that as it may, the fact is that the improvement in detection certifies that something moves under Las Cañadas, only that, now, it can be registered and measured. Of course, it is not very new to say that there are small earthquakes and magma under such volcanic islands. The problem is knowing when and where the new Teneguía will arise or which volcano will awaken completely.

500 earthquakes in just two hours on June 14

The last report of the IGN on the activity in Tenerife, issued by what happened on June 14, notes that, after an earthquake of magnitude 1.9, "located in the interior of the Teide National Park, northeast of the Isora and southwest of Pico Viejo ", from 16:20 (UTC) and in just two hours were counted about 500 earthquakes. "The spectral content of the recorded signals indicated that the events had a high energy content at low frequency, the series ends with an earthquake of the same characteristics at 17:58 (UTC) of magnitude 1.6 (mbLg)", points out the text at its beginning.

Gradual increase until the great swarm of 2016

The analysis reviews what happened in Tenerife since, in the years 2004 and 2005, there is a "seismic crisis with more than 200 earthquakes located between Icod de los Vinos and the north of Vilaflor, of which 4 were felt by the population" . In this case, the tremors had magnitudes between 0.7 and 2.6, as well as depths from 0 to 15 km. In these cases, they were located northwest of Teide and southwest of Las Cañadas, "with clearly differentiated seismicity." In addition, "during 2004 were detected about 3,000 earthquakes in this island and surroundings, of which more than 1,000 were directly related to this activity." This is how it arrives on October 2, 2016, when there is a swarm of more than 800 earthquakes. In this case, they stood at 0.2 and 0.9 and all occurred "in an interval of just five hours". Its location occurred with dispersion and in direction NE-SW, "between Guía de Isora and Pico Viejo".

Seismicity in Vilaflor between 5 and 9 kilometers

The study also refers to what happened in Vilaflor from October 2017 to the present. As indicated, about 500 earthquakes have been recorded with magnitudes between 0.0 to 2.3 and depths of 5 to 9 kilometers, although it is stressed that they are of "purely volcano-tectonic" origin.

A total of 52 stations throughout the Archipelago

Currently, and this report also reflects, the Seismic Network of the Canary Islands, under the IGN, is composed of 52 stations "that transmit the data in real time to an automatic analysis and location system. two seismic antennas (Arrays), reaching a total of 71 seismic sensors distributed throughout the Canary Islands. " These data are studied by analysts for 24 hours and 365 days a year.

Activity in the fault between Tenerife and Gran Canaria, and in El Hierro in the last 3 months

As can be seen in the image above of the National Geographic Institute that accompanies these lines, and as stressed by the various experts consulted, the seismic activity has not stopped in the Canary Islands, in reality, never, only now much more is detected. The graph reflects the movements accumulated in the last three months, in which, although little earthquakes are observed, curiously, in or near the Island of the Volcanoes (Lanzarote), La Gomera or Fuerteventura, many are the points that appear in the rest of the map. Above all, on the island of El Hierro, where there is the highest concentration and movements of the highest magnitude, as well as in Tenerife (especially around Teide, the rest of Las Cañadas and the southern region), as well as in the valley of Güímar and in the wide Atlantic strip between Tenerife and Gran Canaria. It is in this part where the famous fault is located that, for example, derived in the famous earthquake of May 1, 1989, which reached 5.3 on the Richter scale, with its epicenter 15 kilometers from the coast of Güímar. A tremor that was felt by the population, surprised around 2:30 in the morning, which caused many to go out to the street quite alarmed. The second most intense occurred on February 5, 2010, with 4.1 degrees.

Last Tuesday, there were 25 around Vilaflor and Adeje, with a top of 2.2 degrees, while in front of the Puertito de Güímar and the Candelariero littoral, five were registered. The IGN has also registered them in Guía de Isora, Fasnia or La Guancha, while in El Hierro they are located, above all, in La Frontera and El Pinar. Especially, in the western part of the Island and in the Mar de las Calmas, which was little in 2011.

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