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News Archive 2018

2018-05-16

[Available in DE /FR] Zwei Beben in der Nähe von Châtel-St-Denis

[Available in DE /FR] Zwei Beben in der Nähe von Châtel-St-Denis

Am Dienstag, dem 15. Mai 2018, hat sich um 17:30 Uhr (Lokalzeit) in der Nähe von Châtel-St-Denis (FR) in einer Tiefe von ungefähr 5 km ein erstes Erdbeben der Magnitude 3.1 ereignet.

Die Erschütterungen waren vorwiegend in der Umgebung von Châtel-St-Denis bis hin nach Vevey gut zu spüren. Da sich das Beben relativ nahe der Erdoberfläche ereignet hat, wurde es vor allem im Gebiet des Epizentrums relativ deutlich verspürt. Die Anzahl der Erdbebenmeldungen nahm entsprechend mit der Distanz ab. In den vergangenen Jahren haben sich in der Umgebung von Châtel-St-Denis keine grösseren Beben oder Erdbebenschwärme ereignet. Dies im Unterschied zum weiter östlich gelegenen Château-d’Oex, wo in den vergangenen Monaten zahlreiche Beben aufgetreten sind. Einen Zusammenhang zwischen dem Beben von Châtel-St-Denis und denjenigen von Château-d’Oex besteht aber nicht. Bei einem Beben dieser Stärke sind keine Schäden zu erwarten.

Am Mittwoch, dem 16. Mai 2018, hat sich um 11:32 Uhr ein zweites Beben ereignet. Die Magnitude war mit 2.9 leicht schwächer. Das Epizentrum dieses Bebens liegt am selben Ort wie jenes des ersten (etwas 2 km südwestlich von Châtel-St-Denis). Das zweite Beben ereignete sich aber vermutlich noch ein bisschen näher an der Erdoberfläche.

2018-05-05

Successful start to the InSight Mars mission

Successful start to the InSight Mars mission

On 5 May 2018, the NASA rocket carrying the InSight lander lifted off successfully. After initially heading south from Vandenberg Air Force Base in California, after around 90 minutes the InSight separated from the launch vehicle and headed off on its trajectory to Mars. After a voyage lasting a good six months and covering 485 million kilometres, the lander is scheduled to touch down on the Red Planet on 26 November 2018. InSight will be the first mission to take a look deep below the surface of Mars to study the planet's interior by measuring the planet's heat loss and recording marsquakes.

The InSight Lander will place a seismometer, dubbed SEIS (standing for Seismic Experiment for Interior Structure), on the surface of Mars. As soon as data gathered by SEIS arrive at ETH Zurich, seismologists from the Swiss Seismological Service (SED) and the Seismology and Geodynamics Group (SEG) will analyse them as part of their routine work. However, with just one seismometer in place, this will be no easy task. Unlike on Earth, where seismologists can rely on very many recording stations to precisely determine the origin of a tremor, on Mars there will be no addtional reference points. For this reason, special care will be taken to extract as much information as possible from even the weakest signals indicating possible marsquakes, meteorite impacts or even minor tornadoes. For this purpose, staff at the Marsquake Service will combine methods taken from the early days of seismology, when there were only a few seismometers on Earth, with modern analytic methods for locating seismic events.

It is hoped that the results of the InSight mission will provide insights into one of the fundamental questions of planetary and solar system research, giving us a better understanding of the processes that created the Earth-like planets of the inner solar system (including Earth) more than 4 billion years ago. 

Learn more about the InSight mission and related acitivites at ETH www.insight.ethz.ch

See what our Mars scientists are telling about the @NASAInSight mission

Watch the launch

2018-04-26

Anthropogenic or not? Investigating the magnitude 5.5 Pohang earthquake in South Korea

Anthropogenic or not? Investigating the magnitude 5.5 Pohang earthquake in South Korea

A recently published paper in Science, written by a team of the Swiss Seismological Service at ETH Zurich and collaborators from the Engineering Geology group at ETH, GFZ Potsdam and the Glasgow University, explores the potential link between a magnitude 5.5 earthquake in South Korea and a nearby geothermal project. The earthquake, which occurred on 15 November 2017, injured about 80 people and caused damage to numerous buildings in the city of Pohang. If proven to be anthropogenic, it would be the largest earthquake known to have been associated with the exploitation of deep geothermal energy.

Seismograms of induced earthquakes are generally indistinguishable from those of natural earthquakes. Therefore, investigations focus on a range of indicators, taking into account the location of earthquakes, their depths, and the history of stimulation activities conducted underground. By analyzing publically available continuous waveform and geodetic data from satellites, the paper contributes to the understanding of the nature of the event.

The study shows that the mainshock and its largest aftershocks occurred within 2 km distance or less of the geothermal site. Furthermore, they are located within 1.5 km distance of an induced event, which occurred in April 2017 during one of the underground stimulation operations. These locations are confirmed by a Korean study, which has been simultaneously published in Science. In general, the closer an earthquake sequence is located to a geothermal site and to previous related seismic activity, as well as the sooner it happens after underground operations, the greater the chance of being related to it. The mainshock and the 46 aftershocks detected between 15 and 30 November 2017 all occurred at depths of 3 to 7 kilometres. Such depths are unusually shallow when compared to previously registered natural events in the area. The analysis of satellite data illustrates that the mainshock displaced the surface of the earth permanently by up to 4 cm, indicating that the activated, and previously unknown fault, is a steeply dipping and very shallow thrust fault that passes directly beneath the bottom hole section.

These indications combined lead to the conclusion that a connection between the magnitude 5.5 earthquake in South Korea and the nearby geothermal project is plausible. However, the mainshock occurred about two months after the last stimulation activities. So far, there is no quantitative model available that relates the injection activities conducted to the occurrence of this event. The Korean government has appointed an independent expert commission to examine all pieces of evidence and to evaluate if the event was triggered or induced by the nearby stimulation activities. To our understanding, the commission will (re-)analyze all available data and models, including microseismicity data, injection volumes, reservoir pressures, and detailed hydrological and geological data, which are essential to understand the relation between the injection operations and the earthquake sequence.

The Swiss Seismological Service (SED) at ETH Zurich has first informed the public (see SED news) in November 2017 about the Pohang earthquake in the context of the release of a good practice report on induced seismicity. At the same time, Geo-Energie Suisse AG had notified the canton of Jura, where currently the only EGS-style deep geothermal project in Switzerland has applied for a construction permit. In consequence, the canton instructed Geo-Energie Suisse AG to evaluate potential implications for the planned Haute-Sorne geothermal project. An immerged understanding of the link between the magnitude 5.5 Pohang earthquake and the nearby geothermal project is crucial for a safe and sustainable future exploitation of geothermal energy.

2018-04-19

Bundesrat bewilligt neues Massnahmenpaket zum Schutz vor Naturgefahren

Bundesrat bewilligt neues Massnahmenpaket zum Schutz vor Naturgefahren

Im Rahmen des Projekts «Optimierung von Warnung und Alarmierung bei Naturgefahren» (OWARNA) verbessern Bund und Kantone seit 2010 laufend ihre Zusammenarbeit sowie Vorhersagen, Warnungen und Informationen bei Naturereignissen wie Hochwasser, Sturm, Lawinen oder Erdbeben. Die zuständigen Fachstellen des Bundes koordinieren ihre Anstrengungen im Lenkungsausschuss «Intervention Naturgefahren» (LAINAT). Der Bundesrat hat an seiner Sitzung vom 18. April 2018 den neuesten OWARNA-Bericht zur Kenntnis genommen und für die Periode von 2019 bis 2023 entsprechende Ressourcen bewilligt. Neben der Fortführung der bisherigen Massnahmen steht in den nächsten Jahren vor allem die Anpassung und Weiterentwicklung von Produkten und Warnungen zu klimatischen Gefahren im Vordergrund.

2018-04-18

Alpine orogeny: Did the mountains form after ballast was jettisoned, rather than after being squeezed up in a collision between tectonic plates?

Alpine orogeny: Did the mountains form after ballast was jettisoned, rather than after being squeezed up in a collision between tectonic plates?

A recently published new model of the Alpine orogeny suggests that the rocks comprising the Alps rose to form a mountain range because they broke free of the heavier lower layer of the subducting European plate. This is the theory proposed by Edi Kissling from the Institute of Geophysics at ETH Zurich and Fritz Schlunegger from the Institute of Geological Sciences at the University of Bern. Previous assumptions were based on the hypothesis that the Alps were pushed up when two tectonic plates, the Adriatic in the south and the European in the north, collided. However, various recent geophysical and geological findings contradict the old bulldozer model.

The rigid rocky shell of the Earth - the lithosphere - is divided into plates that float, like rafts, on the viscous mantle beneath. These plates consist of two layers, the crust on top and the so-called mantle lithosphere underneath. The crust provides uplift and prevents the heavier mantle lithosphere from sinking into the mantle. The oceanic parts of lithospheric plates have a far thinner crust than the plates' continental parts. This makes them far less buoyant, so in so-called subduction zones the oceanic lithosphere can sink as a whole in the mantle and thereby help to push the continental part of the plate across the Earth's surface.

When the Alpine orogeny began, such a subduction occurred, when the former oceanic part of Europe was pushed underneath the Adria/African continent further south. After the whole ocean was subducted, the two continental lithospheric plates collided, much like two rafts might do. According to the previous orogenic model for the Swiss Central Alps, the collision between the two continental plates pushed together the rock material between them, causing it to surge upwards.

But recent geophysical data on the deep structure of the Alps and geological findings about how the Swiss Mittelland (or Swiss Plateau) arose indicate that this coming together, if anything, only played a very minor role in the formation of the mountain range. Instead, the Alps were pushed up to form mountains because the continental crust had freed itself from the heavy lower layer of the subducting European plate. This gave the crust, which is up to 60 km thick, tremendous additional uplift, and it has easily borne the weight of the mountains ever since, similarly to the way in which icebergs float on water. The greater uplift of the continental crust is constantly compensating for the height of the mountain range, which would otherwise decrease through erosion processes. Rivers and glaciers shape the mountains by carrying away soil and depositing sedimentation in the foreland basin, previously on the Swiss Plateau and today in the Po Valley.

So the concepts looming largest in the new model on the formation of the Alps are the floating tectonic plate's gravitational (and thus vertical) forces. This differentiates the model posited by the two authors from the previous bulldozer model, in which horizontal forces predominate.

Publication: "Rollback orogeny model for the evolution of the Swiss Alps", Tectonics, 2018

Further information: Edi Kissling, Fritz Schlunegger

2018-04-08

[Available in DE/FR] Neues Beben in der Nähe von Château-d’Oex

[Available in DE/FR] Neues Beben in der Nähe von Château-d’Oex

Am Sonntag, dem 8. April 2018 hat sich um 23:50 Uhr (Lokalzeit) in der Nähe von Château-d’Oex (VD) in einer Tiefe von ungefähr 6 km ein Erdbeben der Magnitude 2.9 ereignet.

Die Erschütterungen waren vorwiegend im Gebiet um Château-d’Oex gut zu spüren. Zudem haben auch im unteren Rhonetal viele Personen das Beben wahrgenommen. Dies aufgrund seiner Bodenbeschaffenheit (weiche Sedimente) und der damit verbundenen Verstärkung der Erdbebenwellen. Bei einem Erdbeben dieser Stärke sind in der Regel keine Schäden zu erwarten.

Die Region um Château-d’Oex wurde bereits 2016 und 2017 von zahlreichen Erdbeben erschüttert. Das stärkste Beben mit einer Magnitude von 4.3, gefolgt von zahlreichen Nachbeben, ereignete sich am 1. Juli 2017. Das Beben vom Sonntag wurde etwa 3 km südöstlich der Erdbebenschwärme im Jahr 2016 und 2017 lokalisiert.

2018-03-12

[Available in DE] Erdbeben an der deutsch-schweizerischen Grenze nahe Laufenburg

[Available in DE] Erdbeben an der deutsch-schweizerischen Grenze nahe Laufenburg

Am Montag, 12. März 2018 hat sich kurz nach Mitternacht um 00:29 Uhr (Lokalzeit) ein Erdbeben der Magnitude 3.1 in Deutschland ereignet, ungefähr 13 km nördlich von Laufenburg. Das Erdbeben ereignete sich in 17 km Tiefe und wurde in der Nähe des Epizentrums und auch auf der schweizerischen Seite der Grenze deutlich verspürt. Schäden sind bei einem Erdbeben dieser Stärke in der Regel nicht zu erwarten.

2018-02-08

Using seismic measuring devices to record avalanches

Using seismic measuring devices to record avalanches

Avalanches pose a danger to mountain villages and snow sports enthusiasts. Some recent avalanches have provided important information for reliably assessing avalanche danger. However, since many avalanches fall at night or in uninhabited areas, there is often uncertainty about when they occurred and how many actually swept down into the valleys below. A joint project by the Swiss Seismological Service (SED) at the ETH Zurich and the WSL Institute for Snow and Avalanche Research (SLF) showed that seismic measurements could help determine such facts.

However, there were a number of difficulties to overcome. Unlike earthquakes, the signals associated with avalanches have neither a clear beginning nor distinct wave phases. This makes avalanche falls hard to detect using conventional seismic methods. Furthermore, signal quality suffers from the continuous motion of descending avalanches. So researchers at the SED developed a computer model that uses special methods to process these signals. The model was tested on more than 350 real avalanches recorded by the SLF above Davos in 2012.

The results are promising: the computer model automatically recorded over 90% of all avalanche falls. Fine-tuning their detection would necessitate deploying a higher number of sensors in a more sophisticated configuration. The SED, in collaboration with the SLF, now intends to further investigate this and thereby make an important contribution towards forecasting avalanche danger.

Publication: Heck, M., Hammer, C., van Herwijnen, A., Schweizer, J., and Fäh, D.: Automatic detection of snow avalanches in continuous seismic data using hidden Markov models, Nat. Hazards Earth Syst. Sci., 18, 383-396, https://doi.org/10.5194/nhess-18-383-2018, 2018.

2018-02-01

[Available in DE / FR] Erneutes Erdbeben bei Bludenz (A)

Am Donnerstag, den 1. Februar 2018, hat sich um 02:47 Uhr (Lokalzeit) ein Erdbeben der Magnitude 4.1 ca. 10 km östlich von Bludenz ereignet. Bludenz liegt am nördlichen Ende des Montafon-Tals im Bundesland Vorarlberg in Österreich. Das Erdbeben wurde nach ersten Analysen ziemlich nahe an der Oberfläche lokalisiert, die Tiefe ist aber aufgrund der Entfernung zu den nächsten Messstationen nur sehr unsicher zu bestimmen. Bei einem Erdbeben dieser Stärke sind kleinere Schäden in der Nähe des Epizentrums nicht auszuschliessen.

 

Gemäss den Berichten, welche auf unserer Webseite in der ersten Stunde nach dem Erdbeben eingegangen sind, war das Erdbeben auch in Liechtenstein und in weiten Teilen der (Ost-)Schweiz, insbesondere in den Kantonen St. Gallen und Graubünden deutlich spürbar. Schäden sind in der Schweiz keine zu erwarten.

Dies ist das zweite deutlich verspürte Beben im Silvretta-Gebirge innerhalb der letzten zwei Wochen. Schon am 17. Januar 2018 hatte sich 13 km östlich von Bludenz ein Erdbeben mit einer Magnitude von 4.1 ereignet, das in der Schweiz (vor allem in der Ostschweiz) deutlich verspürt wurde.

2018-01-25

Earthquakes in Switzerland in 2017: an overview

Seismic events in 2017 once again showed that Switzerland is an earthquake country. There were two widely felt earthquakes with magnitudes above 4 and hundreds of aftershocks. Furthermore, the Swiss Seismological Service (SED) at ETH Zurich recorded more small quakes than ever before. In all, some 1'230 earthquakes were registered in Switzerland and its neighbouring countries in 2017.

On 3 March 2017, Switzerland was shaken by the strongest earthquake in more than 10 years. The earthquake with a magnitude of 4.6 occurred near Urnerboden in the border area between Uri, Schwyz and Glarus. It was felt in many parts of Switzerland and caused some minor damage to buildings near the epicentre and 100 aftershocks. The last earthquake larger than this, with a magnitude of 4.9, occurred on 8 September 2005 near Vallorcine (France) just across the Swiss border close to Martigny (VS). A second widely felt earthquake in 2017 took place on 1 July near Château-d'Oex (VD). This earthquake had a magnitude of 4.3 and triggered approximately 240 aftershocks, some of which were also felt.

Overall, in 2017 the SED registered and located more events than ever before: around 1'230 earthquakes in Switzerland and its neighbouring countries. More than 700 of these were microearthquakes, with magnitudes of less than 1.0 to -0.4. Such earthquakes are becoming increasingly “visible” in some parts of the country thanks to the improvement of Switzerland's seismic measuring system, which is making an important contribution towards gaining a deeper understanding of the structures and processes in the country's subsurface. In 2017, 23 earthquakes occurred with magnitudes of 2.5 or higher, in line with the average for the past 42 years. The earthquake activity was concentrated mainly in the Valais, Grisons and the area along the Alpine front.

Furthermore, earthquakes were clearly felt last year by sections of the Swiss population near Vallorcine (France) on 20 March (magnitude 3.0), near Sion (VS) on 2 June and 5 August (with magnitudes of 3.3 and 2.4 respectively), as well as near Zug (ZG) on 21 November (magnitude 3.3).

Year-by-year fluctuations in earthquake frequency are normal and do not permit conclusive forecasts of future seismicity. As a rule, damaging earthquakes with a magnitude of 6 occur in Switzerland once in every 50 to 150 years. The probability of this occurring in 2018 is therefore about 1 percent.

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Past Annual Reports

2018-01-17

[Available in DE / FR] Erdbeben bei Bludenz (A) auch in der Schweiz deutlich verspürt

[Available in DE / FR] Erdbeben bei Bludenz (A) auch in der Schweiz deutlich verspürt

Am Mittwoch, 17. Januar 2018 hat sich um 20:07 Uhr (Lokalzeit) ein Erdbeben der Magnitude 4.1 13 km östlich von Bludenz (Vorarlberg, Österreich) ereignet. Bludenz ist das nördliche Ende des 39 km langen Montafon-Tals. Das Erdbeben war nach ersten Analysen ziemlich oberflächennah, die Tiefe ist aber aufgrund der Entfernung zu den nächsten Messstationen nur sehr unsicher zu bestimmen. Kleinere Schäden sind bei einem Erdbeben dieser Stärke in der Nähe des Epizentrums vereinzelt möglich.

Das Beben war auch in weiten Teilen der (Ost-)Schweiz, insbesondere im Raum St.Gallen (56 km Entfernung zum Epizentrum) deutlich spürbar.

Erdbeben sind im Silvretta-Gebirge keine Seltenheit. Bereits am 8. Januar 2018 hatte sich an der Grenze zwischen Vorarlberg und Tirol ein leichtes Erdbeben mit einer Magnitude von 2.9 ereignet, das in der Region schwach verspürt wurde.