Earthquakes: Maps and Lists

The maps and lists available for the regions of Austria, Europe, and the World show all earthquakes recorded by the Earthquake Service in the last 14 days. If the population felt an earthquake, the symbol on the map is highlighted with a thick coloured border, and the corresponding row in the list is displayed in bold.

The lists include the key information about the earthquakes, with the start of the quake (origin time) provided in both Coordinated Universal Time (UTC) and local time (for Austria, for example, Central European Time – CET or Central European Summer Time – CEST). The date always refers to Universal Time. The coordinates are given in decimal degrees and refer to the WGS-84 ellipsoid. The 'Region' column lists the largest towns nearest to the epicentre.

Please note that the list for the Austria region only displays earthquakes with an epicentre in Austria. If an event you felt does not appear in the selected map or list view, the following reasons may apply:

  • The event is currently being analysed.
  • The event was not identified as an earthquake (e.g., a sonic boom caused by an aircraft or an explosion).
  • The epicentre of the earthquake is located outside of Austria.

Significant tremors that have been recorded and localized but do not originate from tectonic earthquakes (e.g., detonation of an aerial bomb, landslide) are also occasionally displayed in the map and list view.

By clicking on the epicentres (circles) on the map or on the entries in the list, you will be directed to the detailed view of the selected earthquake. The detailed view opens below the map or the list.

Earthquake Detailed View

In the detailed view, you will find additional information about the selected earthquake, as well as the recording of the quake (seismogram) from up to five nearest stations of the GeoSphere Austria seismic network. If there is a press release from the Earthquake Service regarding the event, it will also be displayed.

For all listed earthquakes, the quake has been recorded at least at one station of the GeoSphere Austria seismic network. The Austrian Earthquake Service (including magnitude determination) localizes earthquakes in Austria and neighbouring areas. For more distant earthquakes, the localization results from international organizations are provided. Under 'Source', you can see which organization the information about the selected earthquake comes from.

In-depth Information: Interpretation of the Seismogram

When an earthquake is recorded, the ground motion over time is captured and displayed as a seismogram. The symbol Δ indicates the distance between the respective station and the epicentre. The seismogram shows the arrival times of the first and subsequent wave types (e.g., P, S). Once an earthquake has been manually processed, a red vertical bar marks the arrivals at the stations. Depending on the travel path of the wave from the epicentre to the station, the following important wave types can be distinguished:

  • P, S: General terms for body waves: compressional or primary wave (P) and shear or secondary wave (S). In P-waves, the particle motion occurs in the direction of propagation, while in S-waves it occurs perpendicular to the direction of propagation. The time difference between the two body waves allows for a rough estimation of the distance to the hypocentre.
  • Pg, Sg: The direct P- or S-wave that propagates through the earth´s crust. Pg, Sg are typical for local earthquakes.
  • Pn, Sn: The P- or S-wave that travels along the Mohorovičić discontinuity. Pn, Sn are observed at distances of about 120 km and beyond.

In-depth Information: Magnitude

Magnitude is a measure of the energy of an earthquake and is calculated from the instrumental recordings. From the magnitude, and taking into account the depth of the source and other factors such as soil conditions, the effects of the earthquake can be estimated.

For different distances and frequency ranges, various types of magnitude can be calculated. These are also listed, allowing you to infer how the magnitude was determined. The most important types of magnitude are:

  • ml – The local magnitude (ml) is generally used for nearby distances (< 600 km). The formula originally used for the “Richter Magnitude” in California has been adapted for use in the Austria region.
  • mb – The body wave magnitude (mb) is determined from the amplitude of compressional waves. It is typically used for distant earthquakes (> 2,000 km) and provides a quick estimate of an earthquake´s strength.
  • ms – The surface wave magnitude (ms) is determined from the amplitude of surface waves. The surface wave magnitude is an important measure for estimating earthquake damage. Compared to body waves, however, surface waves arrive much later at distant stations (about one hour at a distance of 12,000 km).
  • mw – The moment magnitude (mw) is calculated from the spectral content of the waves and is independent of frequency.