Will Ethereum die in 2020

Earthquake in Switzerland in 2020

(Zurich) (PPS) 2020 was both an eventful and a calm year for the seismic network in Switzerland. Last year, the Swiss Seismological Service at ETH Zurich recorded 1,400 earthquakes in Switzerland and other countries near the border. That is a little more than would have been expected in the long-term average. Sensory reports from the population were received for 106 of these earthquakes, and more than 100 people reported their observations for seven of them. The background noise also recorded by the seismic network was exceptionally quiet last year. The recorded data show that this has decreased sharply in many places, especially during the lockdown.

The largest earthquake and most of the felt earthquakes occurred in connection with an earthquake sequence near Elm (GL), which was particularly active in both spring and autumn. On May 26, 2020, the first strong earthquake with magnitude 3.1 shook the Glarus region. Dozens of minor aftershocks followed. On October 25, the largest earthquake of the year occurred in the same fracture system with a magnitude of 4.3, which was felt as far as Ticino and Lake Constance. No damage worth mentioning was recorded. This was followed by more than 250 aftershocks, some of which were also perceptible over a wide area, with magnitudes of up to 3.9. In total, more than 350 earthquakes occurred as part of this sequence. It contributes significantly to the fact that an above-average number of earthquakes occurred in 2020.

While the Elm sequence mainly affected German-speaking Switzerland, on June 23, an earthquake with a magnitude of 3.8 near Vallorcine (F) caused a lot of sensations from western Switzerland. The population of Ticino felt a quake above all near Milano (I) with a magnitude of 3.9 and one near Bellinzona (TI) with a magnitude of 2.9. Another stronger earthquake with a magnitude of 3.5 occurred on November 9th south of Arolla (VS) in the Swiss-Italian border area. The earthquake in Croatia with a magnitude of 6.3, which caused severe damage in the epicentral region, shows that larger earthquakes can be felt by people over long distances. In Switzerland, about 600 kilometers from the epicenter, over thirty people noticed and reported the tremors. Most of them were on the top floors of taller buildings at the time of the quake. From such a distant earthquake, it is mainly the long-period waves that hit Switzerland that can cause high buildings in particular to sway.

When the more than 200 seismic stations in Switzerland are not recording the waves of an earthquake, they measure what is known as background noise. In addition to natural vibrations, triggered by storms or the movements of the sea, this noise is primarily influenced by human activities such as traffic. Seismometers can only detect general movement patterns and not how individual people or vehicles move, for example. The lockdown in March and other measures to contain the coronavirus led to a marked decrease in this background noise. This rest period is the longest ever recorded. Otherwise, similar periods of rest can only be observed on the weekends or over the festive season.

If you look at the development (see figure in the appendix) of the daily background noise at four different locations, you can see a clear decrease in all of them as a result of the lockdown on March 16, 2020. With the end of the extraordinary situation in mid-June, the background noise increases again. The background noise recorded by the seismometers is unique at each station and depends, for example, on how far away certain noise sources are. If you take the example of the small ski jump in Bern or the barracks area in Zurich, you can also see the decline as a result of the lockdown, but it is less pronounced than at other locations. This is due to the fact that both locations are further away from busy roads compared to others. The smaller, recurring fluctuations that can be seen at all locations reflect the days of the week and weekends. So even during the lockdown, the background noise on the weekend was again lower than from Monday to Friday.

75 years ago today - the last major Swiss quake

It was already dark when a violent earthquake with a magnitude of 5.8 struck the Valais on January 25, 1946. Four people were killed, numerous were injured and 3,500 buildings, some seriously damaged. It took a while for the full extent to become clear. That had to do not only with the time of the quake, but also with the extent of the damage and the evaluation options of the seismic data at the time. The quake not only caused building damage, which in many cases only became apparent in daylight, it also triggered avalanches and rock falls. In addition, the data from the few seismographs in Switzerland first had to be read and evaluated by hand. It was just as time-consuming to collect reports of sensations and damage, which were more important due to the small number of instrumental records. It is the largest Swiss earthquake in the past 150 years and the last one so far to claim fatalities. Could such a quake happen again and what would be the consequences today?

Find out more: www.seismo.ethz.ch/home/#news