h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I've heard that some animals seem to know an earthquake is coming and get anxious and run away, etc.

I have been in 2 not-so-big earthquakes in Montreal. Montreal is in an earthquake zone, although nothing too spectacular has happened yet. One, I did not notice as I was driving to a party in my 1980 Buick Lesabre, the driving experience being close to flying an aircraft, and had the road sensitivity to match - I only noticed my friends where all shocked and excited when I arrived (I thought the road was a little rough - but Montreal is famous for potholes).

The first one was in the mid-80s. I woke up about 5am for some strange reason, expecting something to happen. Lying awake in bed wondering why I had to wake up now rather than sleeping in for a few more hours, about 5 min later the whole house shuddered, and soon was swaying around violently, as we were hit with a significant earthquake. This woke me up for good. This earthquake actually did some minor damage to a few buildings, fortunately not our house and my bed stayed on the second floor (it would have squished my mum making breakfast in the kitchen), if I am not wrong it was about 4 or 5 on the Richter scale.

I think I woke up because I sensed this was coming. Could it be a small shock that comes before the main one that gets your attention? Could it be something else - I am usually right when predicting when it will actually rain - what I think is by sensing the pressure change rather than just a bunch of gloomy clouds ( a useful skill when you are biking in the wilderness).

Earthquakes are preceeded by an ultrasonic noise, much as a branch creaks before it cracks...but this would not be within your hearing range.
Another possibility is that there was a a build up of electrical charge preceeding the earthquake which affected you in some way..but this is a bit too unscientific for me

I have lately learnt about the different types of ultrasonic waves the earthquakes makes and how they are what the theory of the structure of the Earth is based on. It is very likely that animals with greater hearing range will sense the quake in advance if they are located far enough from the epicentre that the ultrasonic sound wave gets to them before the earth movement does.
It's interesting that it is hypothesised that the very core of the
Earth is thought solid, the outer core liquid followed by a vast amount of "solid" and finally the hard crust. The "solid" does flow however. That's what hard to grasp.
About San Franscisco - the interesting thing about this city is that not only was it built on a fault but a fault where three different plates meet so the probability of experiencing a quake is much greater. So, why exactly live on such a fault?!?

Or, I just woke up. Perhaps it was this woodpecker, I think the same year, that decided to drill into the roof above my bedroom about 5am every morning. It did not do it that morning, so perhaps I woke up in anticipation, or the woodpecker gave a quick drill to wake me up then took off, once it heard an earthquake was coming. I do have pretty good hearing though.

Could it also be that a small shock preceded the main one?

Well, there's a quake at http://www.h2g2.com/a268814
Did you sense that was coming?

In 1974 zookeepers in Tianjin China noted that several animals were behaving strangely. They called local authorities in the belief that such odd behaviour (Tiger wouldn't eat, Turtles refused to come out of the water, etc...) might mean that an earthquake was imminent. Several hours later an earthquake of M=7.4 occurred. To this day this remains the *only* case of a successful earthquake prediction due to animal behaviour.

Every other case I've come across was someone recounting, *after the earthquake,* that their cat pooped on the bed just beforehand, or the dog was whining, etc... It's not a prediction unless it's recorded, because our memory of events is selective, and animals behave oddly (from our perspective) pretty much all the time.

This is not to say that they can't sense something coming: there may be ultrasonic waves produced ahead of time, or they may sense changes in the local electric fields. But until you can interpret Rover's activities in such a way as to know (1) time, (2) location, and (3) size of the event, his behaviour is merely a curiosity (or the poodle next door is in heat again)...

I've heard the animals could smell radon 86, a gas which escapes through earth's shell just prior to an earthquake. But I'd doubt that. Why should some unknown odour provoke unusual behaviour. Anyway, scientists try to forecast earthquakes by using radon sensors, but until now to no avail.
There are subsonic waves as well, and how about animals sensing these subsonic waves not with their ears, but mistaking them for convulsions created by some huuuuge fierce enemy approaching?