Those of you who are expecting an exposition on the chemistry of earthquakes are going to be sorely disappointed.
For earthquakes are physical processes involving the movement of tectonic plates which comprise the Earth's crust, and are therefore more the domain of physicists or geologists.
The Christchurch earthquake was only one of tens of thousands that are felt around the Earth every year, of which the earliest recorded appears to have been one in 1831BCE in Shandong province, China.
However, such phenomena have surely been occurring since the Earth's crust solidified. But how long ago was this? Or, in other words, how old is the Earth? And how do we know? The answers to these questions, you may be surprised to know, have a New Zealand connection.
One of the earliest attempts to determine the age of the Earth dates from 1654 and one Bishop James Ussher in Ireland. Using biblical texts as his basis, he proposed that the Earth was created on the nightfall preceding October 26, 4004BCE (it was presumably 12 hours later here in New Zealand), thus making the Earth only a few thousand years old.
Thanks to the efforts of scientists, we now know this not to be the case.
One of the first people to apply scientific principles to the question of the Earth's age was the eminent (and highly religious) scientist Lord Kelvin. In the late 19th century, he proposed that the Earth was 20 million to 40 million years old, a result somewhat at odds with Bishop Ussher, and which he obtained by calculating the time it would take for the initially molten Earth to have cooled to its current temperature.
As we will see, Lord Kelvin's estimations, while more accurate than those of Bishop Ussher, were still quite some way out. It was not until the discovery of radioactivity by Henri Becquerel in 1896 that relatively accurate calculations of the age of the Earth could be made.
And it was none other than Ernest Rutherford at the forefront of this work.
Lord Rutherford was one of the first people to understand how radioactivity worked - indeed, it was for his endeavours in this field that he was awarded the Nobel prize - and he realised that radioactivity could be profitably used in dating rocks.
Lord Rutherford knew that the radioactive decay of uranium resulted in the formation of helium, and he also knew the rate at which this decay occurred. Therefore, measuring the amount of helium trapped in uranium-containing rock should give a measure of the time elapsed since the rock solidified.
Using this method, Lord Rutherford, with input from his American collaborator, Bertram Borden Boltwood, proposed an age of 500 million years for a sample of a mineral called fergusonite, thus giving a lower limit to the age of the Earth.
Subsequent studies found problems with this method, one of which was the fact that not all of the helium liberated from radioactive decay is necessarily retained within the rock.
However, refinements to this method over many years, most importantly studies of the decay of uranium, lead, potassium and argon isotopes, have now led to a generally accepted age of the Earth of 4.55 billion years.
And even after all these years, it seems the Earth still hasn't settled down.
• Dr Blackman is an associate professor in the chemistry department at the University of Otago.
