This is an archive story, published in the December 1995 edition of Geographical.
All facts, figures and statistics were accurate at the time of original publication. The text has been lightly edited solely for house style reasons but otherwise remains unchanged.
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When seismologist Charles Richter (1900-1985) found a way to measure the magnitude of earthquakes in the 1930s, he became a household name. The science of seismology may be a mystery to the vast majority of people, but most know that the Richter Scale relates to earthquakes, and that the higher the rating, the bigger the quake.
There are a variety of ways to measure earthquakes these days. But, much to the irritation of the media, they usually all get lumped by the media under the banner of the Richter Scale. ‘The Richter Scale is still used, but most seismologists have newer and better ways of measuring earthquakes now,’ says Dr Wayne Richardson a senior seismologist at the International Seismological Centre based at Thatcham, near Newbury, Berkshire. ‘However, Richter produced a nice, simple method that formed the basis of them all.’
Early attempts to quantify earthquakes used a concept called ‘intensity'. This is an assessment of the strength of shaking caused by the earthquake based on its effects – for example the amount of damage caused to buildings, and public distress and is therefore partly subjective. Various scales were proposed by different scientists; the first to gain widespread international acceptance was that produced by Michele de Rossi and Alphonse Forel in the 1880s, known as the Rossi-Forel scale. This was subjected to various modifications, notably by Guiseppe Mercalli, whose name has been attached to a version of the scale.
Intensity is a useful concept, still much studied today, but assessing the size of an earthquake on its own is not enough, partly because it varies from place to place, being greatest near the epicentre and much less further away. If the epicentre happens to be in the sea, then intensity becomes hard to use.
During the 1930s, Charles Richter and Beno Gutenberg began to look at ways to classify earthquakes at the California Institute of Technology (CIT) into small, medium and large, using the instrumental records from seismographs. Richter and Gutenberg reasoned that if two earthquakes occur at the same distance from an observer, the one that produces a larger amplitude of ground motion can be considered to be the larger earthquake. But since the amplitude of ground motion decreases the further away the observer is from the epicentre, distance must also be taken into account. Working with data recorded in southern California at a number of seismograph stations – all of which used the Wood-Anderson seismometer – Richter plotted graphs showing the decay of ground motion amplitude with distance. By taking the response of the seismometer to one arbitrarily chosen small earthquake at a certain distance, and giving it the value zero, he could then assign values to other earthquakes according to the ground amplitudes they produced, when corrected for distance. Each step up in the scale represents a tenfold increase in the amplitude of ground motion. In energy terms, each step in the scale represents an increase of roughly 30.
It was a good basic system, which made it simple to calculate the magnitude of any earthquake measured on a seismograph. The problem was that it was really only applicable in southern California, where earthquakes tend to be quite shallow. In Japan, where seismic activity tends to be much greater and earthquakes are generally much deeper, anomalies in the calculations arose. Neither was it very helpful for measuring long-term seismic activity. ‘The scale was such a success that Richter almost regretted it,’ says Wayne Richardson. ‘It made the science look too simple.’ Nonetheless, important groundwork was laid for the accurate measurement of earthquakes, securing Richter a rightful place in history.
Beno Gutenberg’s role was played up in later years by Richter. ‘The usual designation of the magnitude scale in my name,’ he said in 1977, ‘though perhaps convenient, does less than justice to the great part played by Dr Gutenberg.’ But according to a colleague quoted in Richter’s obituary in the Los Angeles Times: ‘For many, many years, Charlie did very little to emphasise Beno’s role. If you wanted to think it had all been Richter's doing, then that was all right with Charlie.’
Critics said Richter was fascinated with earthquakes to the point of obsession. He kept a seismograph in his living room and visitors would find printed readouts permanently draped across the furniture. Richter used to say his wife liked them there as a conversation piece. He adored talking to the press about the latest earthquake and, when one occurred, he used to clutch the seismology lab telephone in his lap so that he could be the first to answer the calls when they came in.
Charles Francis Richter was born in April 1900 on a farm near Cincinnati, Ohio. He was raised by his maternal grandmother and, when he was nine, the family moved to Los Angeles. A year later, Richter experienced his first earthquake, which he said ‘surprised [him] no end’. He obtained a degree in physics from Stanford University before enrolling at the CIT for graduate study in 1920. In what was only supposed to be a temporary assignment, Richter began work in the fledgling seismology laboratory, where he stayed for virtually his entire career.
Over the years, he developed a reputation for being a deeply gifted but idiosyncratic man. ‘He had a brilliant mind, but it bordered on instability,’ said one colleague after Richter died. He married his wife Lillian in 1928 and the couple never had any children. They were thought of as an unusual, if contented, pair. To begin with, they were nudists – which was pretty shocking stuff in those days. But despite this daring behaviour, Richter hated socialising and had little time for the departmental get-togethers that are such a big part of academic life.
He remained totally immersed in his subject right up until his death, attending lectures into his eighties. Like many seismologists, Richter did not spend much time trying to predict earthquakes. As Wayne Richardson says: ‘The only thing you can really predict is that they are going to keep happening, but that's about it. Some say that accurate prediction is impossible.’
One of Richter’s chief concerns was to improve structural standards in buildings in southern California to minimise the effects of earthquakes. The Maharashtra earthquake in India in 1993 killed 10,000 people, while the Californian earthquake of January 1994, which was nearly twice as powerful, killed just 40. The difference in fatalities was mainly down to the stability of the buildings affected by the earthquake.
Every time a major earthquake strikes, a little more is learned about how to survive the next one. But one thing is certain: ‘We are becoming more at risk,’ says Wayne Richardson. His team records 5,000 earthquakes a month worldwide, including the smallest tremors. Their frequency is not rising but as the world’s population grows by 93 million each year, and cities become more crowded – 45 per cent of the world's population now live in towns and cities – so the risks increase. The science that so gripped the strange, brilliant mind of Charles Richter still has a long way to go.
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