As of: February 16, 2024, 5:16 a.m
By: Johannes Welte
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A previously harmless series of earthquakes has been shaking the northern Alps since the beginning of January.
A researcher warns: Catastrophic earthquakes are also possible at any time.
St. Johann – The ground seems to be boiling: The Austrian Institute for Weather and Earthquake Research
GeoSphere Austria
in Vienna registered 500 tremors this January.
For comparison: In the whole of last year (2023), 1,300 earthquakes were counted in Austria; based on the month, this means an almost fivefold increase in the number of events.
The swarms of earthquakes around St. Johann are primarily responsible for this enormous accumulation.
The ground between Watzmann and Kitzbühel is shaking
Here alone, over 350 tremors were recorded by the measuring sensors, 41 of which were noticed by the population.
On January 23rd, at 4:50 a.m., the strongest earthquake to date with a magnitude of 3.9 on the Richter scale woke people from their sleep in the border triangle.
The last light earthquake occurred at 2:11 a.m. on Ash Wednesday.
The earth also shook in the Inn Valley in Hall, Innsbruck, Telfs and Imst, and the tremors extended all the way to the Zugspitze near Ehrwald.
The map from GeoSphere Austria shows the earthquakes in the Eastern Alps in the first half of February.
The red quake was on Thursday, the orange quake occurred from Monday to Wednesday, and the yellow quake occurred in the eleven days before.
An earthquake in Gloggnitz (large district) on February 1st even had a magnitude of 4.5.
© GeoSphere Austria
Even in Oberstdorf im Allgäu the ground was shaking at the beginning of January.
The strength of the tremors is not yet cause for concern, but their frequency is unusual.
“Everything is within the normal range,” explains Christine Freudenthaler, seismologist from
GeoSphere Austria
.
“These are dislocations in the subsurface, tensions in the earth's crust, which are released in many small shocks instead of in one larger earthquake.” The cause is the folding of the Alps, which is still ongoing.
However, large earthquakes are not expected in the northern Alps.
4,100 years ago, the Eibsee witnessed a gigantic landslide that triggered an earthquake.
Such strong earthquakes are possible again at any time in the northern Alps.
© IMAGO/Martin Rügner
In the 1930s, chimneys collapsed during an earthquake in Tyrol - there was a catastrophe in northern Italy in 1976
The most severe earthquake since systematic earthquake monitoring began in this zone occurred on October 7, 1930 near Namlos in the Reutte district (Tyrol).
It measured 5.3 on the Richter scale.
31 of the 47 chimneys in town collapsed at that time.
According to Dr.
According to Joachim Wassermann, head of the seismology department at the Bavarian Geophysical Observatory in Fürstenfeldbruck, such shocks (up to 5.5) on the Richter scale can be expected north of the Inn.
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The earthquake in Friuli on May 6, 1976 had a magnitude of 6.5.
It cost 989 people their lives.
© imago stock&people
The northern Alps are too far away from the zone in northern Italy in which the Adriatic plate pushes under the European continental plate and thus further folds the Alps.
Severe earthquakes occur there again and again.
On May 6, 1976, an earthquake with a magnitude of 6.5 caused a catastrophe in Friuli in northern Italy near the border with Slovenia and Austria: 989 people died and 45,000 were left homeless.
Expert reports ten severe earthquakes - violence from 220 Hiroshima bombs on Eibsee
Jasper Moernaut, professor at the Institute of Geology at the University of Innsbruck, believes that earthquakes of this magnitude are possible again at any time in the northern Alps.
While researching mud layers in several lakes in Bavaria and Tyrol, the institute discovered that earthquakes in prehistoric times caused huge landslides between Zugspitze and Ötztal.
Chronological list of Alpine earthquakes with magnitude on the Richter scale:
6200 B.C.
BC: Earthquake at Lake Achensee, one to two meter high jump in the terrain, 6.3
2100 BC: Earthquake triggers landslide at Fernpass and Eibsee, 6.1-6.5
1000 BC
BC: Earthquake triggers landslide on Tschirgant, 240 million cubic meters of rock fall into the valley.
18 square kilometers buried.
5.8-6.3
250 AD earthquake destroys Roman city Augusta Raurica (Kaiseraugst) near Basel, 5.5-6
January 3, 1117: In Verona, the city walls collapse, churches and monasteries collapsed in an earthquake.
Even St. Michael's Church in Bamberg is damaged, 7
January 25, 1348: Friuli and Carinthia, earthquake triggers Dobratsch landslide and a tidal wave.
Damage to Passau, 5000 dead, August 6th
Oct. 18, 1356: Great earthquake in Basel, collapse of the cathedral, 2,000 dead, largest natural disaster in Switzerland, 6.0-7.1
July 17, 1670: Quake in Hall/Tyrol, collapse of the church tower, severe damage.
Many aftershocks until 1671, several deaths, 5.2
Dec. 22, 1689: Quake in Innsbruck, several people die in collapsing inns.
Serious damage in Innsbruck and other places.
Aftershocks lasting several months, 4.8
Oct. 7, 1930: Quake in Namlos/Tyrol.
Damage to buildings.
Daily aftershocks until mid-year 1931, 5.3
May 6, 1976 Major earthquake in Friuli, 989 people die, 45,000 become homeless, 6.5
January-February 2024: Series of earthquakes scares the residents of St. Johann out of their sleep, up to 3.9
Around 4,100 years ago, 350 million tons of rock broke out of the Zugspitze and the Riffelseewand above the Eibsee near Garmisch-Partenkirchen, fell 1,400 meters into the depths and pushed themselves over the Eibsee to the opposite valley wall, where the sediments are up to a height of 1,260 meters still detectable.
An indescribable catastrophe, the landslide had the force of 220 Hiroshima bombs, every life was crushed in the disaster area.
At the same time there was a landslide at the Fernpass, in whose rubble the Blindsee, Weißensee and Mittersee were formed.
The landslide at Tschirgant in Tyrol buried the Inn Valley and the lower Ötz Valley after an earthquake.
A second landslide occurred further east near Haiming.
© Institute of Geology at the University of Innsbruck
Around 1,100 years later, another landslide caused 240 million cubic meters of rock to fall at Tschirgant and Haiming, the rubble dammed the Inn, and the gigantic stone avalanche rolled into the Ötztal.
18 square kilometers of land were buried.
A second, smaller landslide crashed into the Inn Valley near Haiming.
When researching the causes of these gigantic rockslides, the geologists found what they were looking for by examining sediments in Lake Plansee near Reutte and at Lake Piburgersee in the Ötztal: “There were two serious earthquakes that triggered these rockslides,” says Moernaut.
Researchers on severe earthquakes: “We have to expect this in the future too.”
In total, the geologists found traces of ten prehistoric earthquakes between Ötztal and Zugspitze - with magnitudes between 5.5 and 6.5.
The earthquake at Eibsee and Fernpass had a magnitude between 6.1 and 6.5, the one at Tschirgant and Haiming between 5.8 and 6.3.
It can be assumed that these prehistoric catastrophes also claimed human lives.
At that time, members of the Urnfield and early Hallstatt cultures settled in Austria, northern Italy and Bavaria.
The researchers also discovered traces of an earthquake around 8,300 years ago at Lake Achensee.
Moernaut: “Here we discovered a jump in terrain of one to two meters in the sediments.” The researchers assume a magnitude of 6.3.
Geologist Jasper Moernaut taking samples of sediments at Lake Achensee.
© Institute of Geology at the University of Innsbruck.
Is the time of these big earthquakes in the northern Alps over?
Moernaut: “We have to expect this in the future too.” A severe earthquake like the one in Friuli in 1976 is also possible at any time in Tyrol and the Bavarian Alps.
Even in Munich, a strong earthquake would cause damage to buildings
A new strong earthquake could cause serious damage.
“If the Achensee quake were to repeat, Munich would be affected by an earthquake intensity of seven,” explains the scientist.
According to Mercalliskala, this means: “Even in moving cars, standing becomes difficult.
Damage to furniture, loose bricks falling down.
Buildings with inadequate construction or faulty structural design will be severely damaged, with light to moderate damage to normal buildings.”
The Blindsee at the Fern Pass was created as a result of an earthquake that triggered a huge landslide.
© CHROMORANGE / Martina Raedlein
According to Moernaut, predicting such earthquakes is very difficult in the Alps: “Earthquake events are difficult to predict in the very rugged mountains - in contrast to Anatolia or California, where there are cycles.” But Moernaut knows: “In 10,000 years there are approximately four severe earthquakes between Ötztal and Zugspitze.” According to the Innsbruck researchers, a severe earthquake with a magnitude of over 6 occurs every 1,000 to 2,000 years. The last one was 3,000 years ago.
A new severe earthquake would therefore be overdue.