Potential - and overdue - disasters

Today I felt quite cheerful, so I decided to make a list of some of the potential disasters that I have learned of - especially those overdue. I have not included the usual fare like asteroids. For those of you who share this sense of "doom and gloom" I am sure you will be happy (or rather, properly concerned) to commiserate with me - and for you others, I am sure you will at least get a kick out of it:

1. Pandemic
It has been a good while since an epidemic like the Spanish Flu in 1918-1919 (that presumably infected 50% of the world's population and lead to 40-50 million deaths) or the Asian Flu in 1957-1958 (that caused upwards of 1,000,000 deaths). Studies point out that the interval between pandemics varies, from a decade to 60 years (closer together more recently) . An average 40 years period, taken from the last event that can be considered a pandemic (the Hong Kong flu of 1967-1968) places the next pandemic uncomfortably close. Thus, scares like Ebola, SARS and the more recent (and not yet extinguished) Avian Flu have but elevated steadily the WHO pandemic alert phase to 3.
To round up the picture there are other issues, like the antibiotic-resistant diseases, that compound the risks: see the highly publicized recent case of drug-resistant tuberculosis or the increased occurrences of MSRA and other superbugs in US hospitals and elsewhere. Not to mention that HIV/AIDS has gained by now a pandemic status (it is estimated that 25% of Africa's population is affected)
No matter when the next pandemic is going to occur, it is likely to spread faster - given how much more interconnected our world is these days.
I would take pandemic preparation seriously - it might serve even better than medical insurance in some cases...
Further reading: CDC article on influenza periodicity and C.W. Potter's article "A history of Influenza" in Journal of Applied Microbiology.

2. Magnetic pole shift
Apparently the Earth's magnetic field reverses polarity at irregular intervals, but roughly 4 times every 1,000,000 years. The pole shift is usually preceded by a period when the magnetic field weakens, leaving the planet exposed to violent cosmic radiation that it otherwise protects it from. The last pole shift took place 790,000 years ago so some scientists argue that next one is overdue (or, according to others, already taking place: Earth's Magnetic Field Fading). As with all things, there is no general agreement here either, as to how often these shifts happen, if there is any periodicity or they are random in time and how long it takes for such a shift to take place (estimates range from a couple of thousand years to 28,000). I believe someone will come up with a reasonably good model for this dynamical system and some chaos theory mix that will shed some light on the hidden order in this apparent irregularity - if you have any news of it, please let me know!
At any rate, this will not be a sudden flip. Well, I am not as worried about this one then...
Further reading: an article by Bradford Clement in the journal "Nature" (08 Apr 2004).

3. Supervolcano eruption
This could be a solution to global warming, as the ash darkening the sky can plunge the temperatures by up to 21 degrees at higher latitudes...
Although extremely rare occurrences, such eruptions (thousands of times bigger than anything recorded in human history) have a recorded history. A study by geologists in 2001 pointed out the possibility of such an event in Yellowstone, that has a history of such explosions every 600,000 years or so. It has now been 620,000 since the last one.
Further reading: Super Volcano eruption

4. Solar superstorm
In 1859, the Northern hemisphere witnessed the spectacular effects of a Perfect Sun Storm (the most powerful solar flare of the last 500 years) - when telegraph wires in the US and Europe shorted and equipment burst into flames. This happens when the superhot, electrified plasma ejected by the solar corona comes into contact with the Earth's own magnetic field. The flare in 1859 happened to have a particularly intense magnetic field directly opposed to Earth's fields - effectively taking down the planet's "shields" and allowing the flare to penetrate deeper towards the planet than usual.
Scientists expect this next solar cycle that is about to begin (due to peak in 2012) will be stronger than usual: Sun's Next Stormy Cycle Starts
Combine this with #2 above - a weakening magnetic field, and what you get is that smaller storms could potentially wreak even more havoc.
Some ideas along those lines: Solar Storm impact
Combine this with #2 and the incredible dependence of modern society on electricity and... write a book, to make it worth your time.

For those of us who live on the West Coast of the US I would add:

5. Megathrust Earthquake / the next Big One
Studies point the imminence of a magnitude 9 event on the West Coast, where the oceanic tectonic plate is subducted under the North American plate. The area has experienced on average 300 years between the quakes. It has now been 307 years since the last one took place in the year 1700. The event would be accompanied by massive tsunamis that would hit the coast too fast for any warning to be effective.
Further reading: Tsunami-Generating Earthquake
Besides this type of earthquake, even smaller ones could be disastrous and scientists are expecting another one like the 7.9 San Francisco 1906 earthquake to hit somewhere along the San Andreas fault any time now. Apparently, the 20th century was unusually quiet after that event. But the tectonic plates keep grinding, and the fact that so few (and relatively small) earthquakes have been recorded (note: the Loma Prieta 6.9 event in 1989 released only 3% of the energy of the 1906 quake) means that even more built up stress is waiting to be released.
Further reading: Preparing for the next 'Big One'

6. Tsunami
It does not take a big earthquake to generate a devastating tsunami, it seems. Smaller (or more distant quakes) have caused submarine landslides responsible for some deadly waves in recent years (such as the one in Papua New Guinea in 1998)
Further reading: Potential Southern California Tsunami

We have Hollywood to thanks for generously creating awareness about most of the possible disasters above. If you are fond of seeing the world close to its end in a couple of dozens different ways - not involving any other astral bodies or paranormal occurrences - you have a varied menu to choose from: "The Core", "Sunshine", "The Day After Tomorrow", "10.5", "Volcano", "Deep Impact", "28 days later" (and now "28 weeks later").

It seems it might be time to relocate to another planet. Time to go sweep the launchpad in my backyard...