An earthquake early warning on the Balkan peninsula has taken many residents by surprise. Which lessons can be learned for Google's plans of a global earthquake warning system?

The Balkan Peninsula in south-eastern Europe has a long record of destructive earthquakes, the most recent examples from Croatia (2020) and Albania (2019) should still be remembered by many citizens. Since Friday evening, this record has been enriched by another element: In Bosnia-Herzegovina, an earthquake with a magnitude of 5.7 hit the southern part of the country and neighbouring parts of Croatia and Montenegro. One person died, others were injured. According to the first media reports, the extent of the damage in many villages is said to be serious, but more precise data are still being determined. But it’s not only the impact of this earthquake that will be remembered.

Earthquakes usually come as a surprise. There are no signs and no predictions. Although early warnings are possible, they have so far only been possible with enormous technical investments. Actually an unrealistic scenario for the Balkans in the near future. In fact. On Friday, residents of Sarajevo (BIH), Split (Croatia) or Podgorica (Montenegro) received an emergency notification on their Android smartphones a few seconds before the earthquake waves arrived. The approximate magnitude of the earthquake, the epicentral distance and the expected arrival of the shaking were announced relatively precisely.

In 2020, Google official announced its plans to set up a global earthquake early warning system. Instead of using expensive seismological instruments, as is the case, for example, in Japan, Mexico or China, customers here become earthquake sensors. To be more precise, smartphones: Every mobile device has an acceleration sensor that detects when and how the smartphone is moving. Users are familiar with this function, for example, from pedometers or from the angle display of the camera. But the technology can do more, for example detect earthquakes.

How does earthquake early warning work?

If the smartphone is in a stationary position, for example on the bedside table, the vibrations of the earthquake can be detected. If location sharing is activated, these registrations are processed further and compared with the data from other smartphones. If there are simultaneous shocks to devices in the same town or neighbourhood, the system knows that an earthquake is happening. The intensity of the shaking and the time of onset can be used to estimate the strength and epicentre within a few seconds and warnings can be sent to other users. Because earthquake waves travel at around four kilometers per second, it takes time to reach more distant cities. From a certain distance to the epicentre, depending on the computing time, an earthquake early warning can be made possible. This is not possible though in the immediate vicinity of the epicentre, where the worst damage usually occurs.

This function of earthquake early warning came as a surprise to Bosnia-Herzegovina and neighbouring countries. In 2020, the system first began with a test run in California, which later expanded to the other US states of Washington and Oregon. Internationally, the Philippines, Greece and New Zealand have also been involved since late 2021. There has not yet been an official announcement that other countries are now also covered. In that regard, the Bosnia earthquake came before the Google announcement. Corresponding information is also not available on the Android support page.

Warnings previously available for only four countries

The Bosnia earthquake can be seen as the first real stress test: During the earlier runs in California and later in Oregon and Washington there were no major earthquakes in these states. Although warnings for smaller earthquakes were successfully sent out, there was no real need for warnings. The situation is similar in New Zealand and Greece, where early warnings have been officially available since the end of 2021. Successful notifications, for example, prior to a (harmless) earthquake near Crete, there were also here. However, no serious damage was associated with these earthquakes.

However, whether one can speak of a successful stress test needs to be analyzed in more detail. The first impression is that there are both positive and negative aspects. It is positive that the magnitude estimated in the early warning (according to various screenshots between M5.2 and 5.5) and the epicenter are not far from the real values. Therefore, the warning would have reached the right people and also a relatively large number of people. Damage from the earthquake was relatively widespread as many houses in Bosnia are not earthquake proof. The need for early warning also in greater distance to the epicentre is given. In Mostar, where chimneys and facades collapsed, warning time was almost two seconds. In the capital Sarajevo, where cracks formed in the walls, a warning time of almost ten seconds would have allowed evacuations.

Early warning came as a surprise

For an effective and efficient use of the given warning time, however, more than a warning symbol on the display is required. Most important, people need to know how to react to such a warning. In this case, where the function was activated without any prior notice, this knowledge was completely absent. Many users on social networks shared they were mostly irritated by the warning until the earthquake actually reached them. Advice was displayed in the warning screen how the warning works and what behaviour is recommended. However, the early warning period would not have been sufficient to read it all. So this warning was of no real use.

Considered as a test run, however, one can certainly draw positive conclusions, since early warning was given for potentially endangered areas. In earthquakes with a magnitude of 5.7, damage is usually limited to a small radius around the epicenter. The fact that there were still warnings for places like Mostar speaks for a fast calculation time and would offer an enormous advantage in the case of larger earthquakes, for example with magnitude 7. If cities like Sarajevo, Podgorica or Split were also seriously endangered and had a 10-second early warning, many lives could be saved. If people knew how to react!

Earthquake early warnings for whole Europe?

With the surprising test run, Google has reached a first milestone. The goal of enabling earthquake early warnings worldwide seems to have come a big step closer. The technical requirements are obviously in place. For real benefit, however, compact information, education, practice (repeated emergencies) and above all previous notice are essential, which Google should also know. It remains unknown so far whether the warning for the Balkans was intended or perhaps a technical error. Perhaps even, by coincidence of course, the activation took place immediately before the earthquake and an official announcement was planned for the coming days.

Whatever the reason is, Google can certainly note a success in the form of a real stress test, whether intentional or not. The question remains whether and where the earthquake early warning system is now permanently active. Is it just the Balkans or maybe Italy too? Maybe even Germany and the rest of Europe?

The settings for the earthquake early warning can be found on Android devices under "Settings” – “Safety and emergency". There you have the option of turn off the function that is activated by default (provided that location has been activated). As tested by Risklayer, the earthquake early warning doesn’t seem to be available yet in Western Germany.

#zemljotres

Za one koje su pitali gde se pale obavestenja o zemljotresima na Android uredjajima. pic.twitter.com/GqPoPyUqVi — kuramochi888 (@kuramochi888) April 23, 2022

In any case, Bosnia-Herzegovina and Croatia can see the positive aspect: Prior to the next large earthquake, an early warning will probably be provided by many smartphones. It is now also up to the authorities and to the individual users to make the best of this opportunity. Disasters cannot be completely prevented by warning alone, just as the victims and injuries could not have been prevented last night, but at least the effects can be limited.