Thankfully I have far too many things to worry about already...
What are the chances of another super-eruption at Yellowstone in 2009? Certainly, the more than 500 small earthquakes recorded since 27 December are unusual and the seismic activity is now more intense than anything recorded in the last few decades. On top of this, the ground surface has swelled more than 20cm since 2004: a rate three times faster than other episodes of uplift measured since monitoring began in 1923.
Against this, however, super-eruptions at Yellowstone happen every 600,000 to 800,000 years, meaning that the probability of such an event happening in any single year is extremely small. In fact, eruptions of any size at all are rare, and the last time magma breached the surface was a good 70,000 years ago.
The current bout of twitchiness at Yellowstone may be the result of new magma breaking rock as it heads towards the surface, but there are other possible explanations too. The quakes may be related to movements along a fault due to the simple relief of stresses accumulated in the crust, or caused by rock fracturing associated with the subterranean movement of super-heated water.
In fact, explosions of boiling water could well present the main threat, and looking back over the past 15,000 years, such hydrothermal explosions have punched their way through to the surface on more than 20 occasions, leaving behind impressive craters that are now largely water-filled. Around 13,000 years ago, a huge steam blast opened up a hole as wide as inner London, an event that would certainly spoil the day of any hikers in the vicinity should it happen today.
Even if it does turn out that the recent unrest is due to the movement of a new batch of magma, the chances are that its volume is small and that it will cool and solidify before it reaches the surface. Then again, we can never be absolutely certain. The problem is that we don't know exactly what signs to expect before a super-eruption, because – fortunately for all of us – they happen on average only every 50,000 years or so, with the last one battering much of New Zealand's North Island 26,000 years ago.