to buildings was widespread but not severe – except in one very localized area. This was, or to a considerable extent had been, the Veterans’ Administration Hospital. Before the earthquake it had consisted of three parallel blocks of buildings. The two outer blocks had remained virtually intact: the central one had collapsed like a house of cards. Destruction was total; no part of it was left standing. Over sixty patients died.
The contrast between this ruin and the virtual immunity of the two sister blocks would have seemed incomprehensible to anyone without some knowledge of the Californian building codes. With some such knowledge it was all too readily understandable. The city of Los Angeles has the misfortune to have its very own private and personal structure fault running under its streets. This is known as the Newport-Inglewood Fault, and when one side of the fault suddenly jerked forward in respect to the other in 1933 it produced the Long Beach earthquake in which a disconcertingly large number of buildings fell down, solely because they had been shoddily built on unreinforced, made-up ground.
This prompted the authorities to introduce a new building code, designed to result in structures as nearly earthquake-proof as possible, a code that is as rigorously enforced as it is rigorous in nature, and it was under the enforcements of this code that the two outer blocks of the Veterans’ Hospital had been built, one in the late 1930s, the other in the late 1940s: the destroyed block had been constructed in the mid-twenties.
Nevertheless, it had been destroyed by an earthquake the epicentre of which had been some eight miles distant to the north-east. But what was important – and significant – about the earthquake that had caused this considerable damage was the factor of its power – or lack of it. The power, or magnitude, of an earthquake is registered on an arbitrarily chosen Richter scale which ranges from zero to twelve. And what is important to bear in mind is that the Richter scale progresses not arithmetically but logarithmically. Thus, a six on the Richter scale is ten times as powerful as a five or a hundred times as powerful as a four. The San Fernando earthquake which levelled this hospital block in Sylmar registered six-point-three on the Richter scale: the one that wreaked havoc on San Francisco in 1906 registered seven-point-nine (according to the recent modifications of the Richter scale). Thus, the earthquake that caused this damage in Sylmar was possessed of only one per cent of the effective power of the San Francisco one. It is a sobering and, to those burdened with an over-active imagination, a fearful reflection.
What is even more sobering and frightening is the fact that, to the best of our knowledge, no great earthquake – ‘great’ is arbitrarily taken to be anything eight and above on the Richter scale – has ever occurred beneath or in the immediate vicinity of any major city. (Such a disaster may have occurred in that awesome North Chinese earthquake of 1976 when a third of a million people are reported to have died: but the Chinese have dropped a total news blanket over this tragedy.) But the law of averages would indicate strongly that somewhere, some time, a major earthquake will occur in a place which is not conveniently uninhabited or, at least, sparsely populated. There is no reason not to imagine, unless one chooses to take refuge behind I-don’t-want-to-know mental blinkers, that this possibility may even today be a probability.
The word ‘probability’ is used because the law of averages is strengthened by the fact that with the exception of China, Turkey and, to a lesser extent, Italy, earthquakes largely tend to take place in coastal areas, whether those coastal areas be of land masses or islands; and it is in those coastal areas, for the purposes of trade and because they are the points in ingress to the hinterland, that many of the world’s great cities have been built. Tokyo, Los Angeles and San Francisco are three such examples.
That earthquakes should be largely confined to those areas is in no way fortuitous: their cause, as well as that of volcanoes, is now a matter of almost universal agreement among geologists. The theory is simply that in the unimaginably distant past when land first appeared it was in the form of one gigantic super-continent surrounded by – inevitably – one massive ocean. With the passage of time and for reasons not yet definitely ascertained this super-continent broke up into several different continental masses, which, borne on what are called their ‘tectonic plates’ – which float on the still molten magma layer of the earth – drifted apart. Those tectonic plates occasionally bang or rub against one another; the effects of the collisions are transmitted either to the land above or the ocean floor and appear in the form of earthquakes or volcanoes.
Most of California lies on the North American plate which, while tending to move westward, is not the real villain of the piece. That unhappy distinction belongs to that same North Pacific plate which deals so hardly with China, Japan and the Philippines and on which that section of California lying to the west of the San Andreas Fault so unhappily lies. Although the North Pacific plate appears to be rotating slightly, its movement in California is still roughly to the north-west and, now and then, when the pressure between the two plates becomes too much, the North Pacific plate eases this pressure by jerking north-west along the San Andreas Fault and so producing one of those earthquakes that Californians don’t care so much about.
The extent of the dislocation along this right-slip fault – so called because if you stand on either side of the fault after an earthquake the other side appears to have moved to the right – is crucial in relation to the magnitude of the shock. Occasionally there may be no lateral slip at all. Sometimes it may be only a foot or two. But, even though its consequences are not to be contemplated lightly, a lateral slip of forty feet is eminently possible.
In fact, and in this context, all things are possible. The active earthquake and volcanic belt that circumgirdles the Pacific is commonly – and appropriately – known as the ‘ring of fire’. The San Andreas Fault is an integral part of this, and it is on this ring of fire that the two greatest monster earthquakes (in Japan and South America) ever recorded have occurred. They were on the order of eight-point-nine on the Richter scale. California can lay no more claim to divine protection than any other part of the ring of fire and there is no compelling reason why the next monster, about six times as powerful as the great San Francisco one, shouldn’t occur, say, in San Bernardino, thus effectively dumping Los Angeles into the Pacific. And the Richter scale goes up to twelve!
Earthquakes on the ring of fire can show another disadvantageous aspect – they can occur offshore as well as under land. When this occurs huge tidal waves result. In 1976 the town of Mindanao in the Southern Philippines was inundated and all but destroyed and thousands of lives were lost when an undersea earthquake at the mouth of the crescent-shaped Morro Bay caused a fifteen-foot tidal wave that engulfed the shores of the bay. Such an ocean earthquake off San Francisco would devastate the Bay area and, in all probability, wouldn’t do any good to the Sacramento and San Joaquin Valleys.
As it is said, it is the wandering nature of those tectonic plates that is the prime cause of earthquakes. But there are three other imponderable possibilities that could well act as triggering factors which could conceivably cause earthquakes.
The first of those is emissions from the sun. It is known that the strength and content of solar winds alter considerably and wholly unpredictably. It is also known that they can produce considerable alterations in the chemical structure of our atmosphere which in turn can have the effect of either accelerating or acting as a brake on the rotation of the earth; an effect which, because it would be measurable in terms of only hundredths of a second, would be wholly undetected by many but could have (and may have had in the past) an influence ranging from the considerable to the profound on the unanchored tectonic plates.
Secondly, there is a respectable body of scientific opinion that holds that the gravitational influences of the planets act on the sun to modulate the strength of these solar winds. This is of immediate concern since a rare alignment of all the planets of the Solar System is due in 1982. If this theory, known as The Jupiter Effect from the title of a book by Drs John Gribbin and Stephen Plagemann, is correct that alignment will be the trigger for unprecedented solar activity, with repercussions on the stability of planet Earth. So scientists are waiting for 1982 with considerable interest, and
