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From The Atlantic Wire: The Case of the Volcano That Set Time 15 Minutes Fast:

It came to light that for thousands of people, digital clocks and watchers, from computers to alarm clocks, were all running 15 minutes fast. RIA Novosti also reported that in Palermo digital clocks and watches in Sicily were running more than 15 minutes fast.

From The Daily Mail: Mount Etna eruption closes airports and 'knocks clocks 15 minutes fast':

Bemused Sicilians, meanwhile, were quick to blame the volcano after thousands noticed that their clocks were running 15 minutes fast. The fast forward time keeping has affected a wide spectrum of digital clocks and watches - from computers through to alarm clocks.

Did a Mt. Etna eruption cause clocks, watches, and computers to run fast?

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This was covered by the Skeptics' Guide to the Universe, episode 317.

Electric, digital clocks keep time by using the frequency of the power lines to keep time (60 Hz in the US, and 50 Hz in Europe).

If you change the frequency of the AC current, you will change the pace of the clock.

The frequency of the AC current coming out of power plants does regularly fluctuate, but that fluctuation is regulated such that the correct number of cycles happens in each day. (Wikipedia:Utility frequency stability)

In North America, adjustment occurs whenever the error exceeds 10 seconds (in the East), 3 seconds (in Texas), or 2 seconds (in the West). (See Manual Time Error Correction)

The synchronous grid of continental Europe is re-calibrated every morning at 8:00am. You can see the real-time frequency at http://www.mainsfrequency.com/.

Italy is part of this synchronous grid, but Sicily being an island, this connection is via a single underwater cable.

During the time of this Volcanic eruption, for about 20 days in May, this cable was disconnected for routine maintenance. Sicily relied largely on its local hydro power. The more unstable hydro power production combined with the smaller Sicily-only grid resulted in the clock error.

This article and this article (both in Italian) tell the story.

The power supplied to users has fluctuated between 50 and 50.13 Hz, creating small accelerations in timer appliances.

It will happen again at the next detachment from the continental network.

Not only common alarm clocks, but also microwave ovens and appliances with timers are victims of hectic times.

The Daily Mail claimed that watches were also affected, but that is impossible. Skeptics Guide speculates that either it was mass delusion or poor reporting or mistranslation on the part of the Daily Mail.

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  • Perhaps Italian uses the same word "orologi" for watches and for clocks: so "watches" is a mistranslation or misinterpretation of Italian news source.
    – ChrisW
    Commented Sep 28, 2013 at 22:36
  • Good point. Skeptics Guide mentioned that the translation of that word could have been an issue.
    – user5582
    Commented Sep 28, 2013 at 23:38
  • Computers have crystal oscillators and are regularly reset over the internet. Line frequency errors would not explain reported clock errors in computers.
    – DJohnM
    Commented Sep 29, 2013 at 4:01
  • @User58220 Correct. The claimed computer errors are also probably impossible.
    – user5582
    Commented Sep 29, 2013 at 4:49
  • 2
    Looking through some Italian press, you would indeed find that the fact was limited to electronic appliances. For instance, these links all mention alarm clocks and microwave ovens, while there is no mention of watches. livesicilia.it/2011/06/09/… style.it/news/le-notizie-del-giorno/2011/06/09/… sciaccaonline.com/prima-pagina/…
    – nico
    Commented Sep 29, 2013 at 8:19

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