Tremors, Earthquakes and Charles F. Richter

Over the last three days there have been earth tremors. These are movements of the earth's crust due to seismic shifts of the tectonic plates that form the surface of the earth. When these move, everything moves. Sometimes this movement can be so dramatic that it called an earthquake which is one of the most destructive of nature's forces.

Earthquakes are measured by the Richter Scale, a system of seismographic measurement that was developed by Charles F. Richter of the California Institute of Technology in 1935. This scale measures quakes according to a system that is based on logarithms. Unlike most methods of measurement where increases in measurement indicate a linear growth, in Richter's logarithmic scale increases are much more dramatic.

Putting this in English: 2 on the Richter Scale is 31.7 times greater than 1. This means, that when we hear that an earthquake is measured as being 7.4 on the Richter Scale, that it is roughly twice as strong as one that measures 7.3.

I once found myself  to be experiencing an earthquake that measured 5.8 on the Richter Scale: to give you an idea of the power of that earthquake, it was strong enough to throw me across the room. Just imagine the power behind some of the recent earthquakes that we have seen in different parts of the world that measured over 14 on the scale - a power beyond reckoning!!!

Many people don't realise that the only difference between an earth tremor and an earthquake is the power involved. Most earth tremors aren't even felt, but, once they pass 2 on the scale they will be noted by some people. These earth movements are generally classified as tremors (and not earthquakes) up to 4 on the Richter Scale - at 4 everyone notices that the earth is moving.

What we have experienced here over the last few days is a number of tremors, a little bit stronger each day, but nothing to worry about. Of course, the fact that they are increasing does leave open the possibility that something stronger is coming, but we'll deal with that if and when it comes.

So what does an earth tremor feel like? Actually, it feels a little bit like being in a boat. There is a gentle swaying (light bulbs swing a little bit, water moves a little in the toilet, sometimes cracks can appear in some of the plasterwork). Coupled with this is a very strange sensation of losing balance (just a bit - in an earthquake it can be quite scary) and, interestingly, birds and animals appear to go silent.

An earthquake is a very unsettling experience, quite apart from the damage to life and property it may cause, it creates a feeling of insecurity and fear in those who experience it - when you think about it, if you are attacked or if something really awful happens, you can throw yourself on the floor as a last line of defence: in an earthquake this last line of defence is taken from you thus leaving you with a very strong sense of having been undermined, threatened, and insecure - that is, of course, provided that you are lucky enough not to be hit by something that is falling about you which is, obviously, where most of the very real danger lies.

So far today there has been no tremor, so let's hope it stays that way.