Earthquake Magnitude Quotes

Small earthquake in Chile. Not many dead.

As seismologists gained more experience from earthquake records, it became obvious that the problem could not be reduced to a single peak acceleration. In fact, a full frequency of vibrations occurs.

If one introduces the concept of energy of an earthquake then that is a theoretically derived quantity.

Magnitude may be compared to the power output in kilowatts of a [radio] broadcasting station; local intensity, on the Mercalli or similar scale, is then comparable to the signal strength noted on a receiver at a given locality. Intensity, like signal strength, will generally fall off with distance from the source; it will also depend on local conditions at the point of observation, and to some extent on the conditions along the path from source to that point.

I'm glad to see the press now referring to the open-ended Richter scale.

Lately there have been complaints that the use of the magnitude scale is confusing, or at least the reporting of magnitudes in the newspapers 'confuses the public.

I repeatedly have to correct this belief. In a sense, magnitude involves steps of 10 because every increase of one magnitude represents a tenfold amplification of the ground motion. But there is no 'scale of 10' in the sense of an upper limit.

There is another common misapprehension that the magnitude scale is itself some kind of instrument or apparatus. Visitors will frequently ask to 'see the scale.'

I suggested that we might compare earthquakes in terms of the measured amplitudes recorded at these stations, with an appropriate correction for distance.

I was awakened by a tremendous earthquake, and though I hadn ever before enjoyed a storm of this sort, the strange thrilling motion could not be mistaken, and I ran out of my cabin, both glad and frightened, shouting, "A noble earthquake! A noble earthquake" feeling sure I was going to learn something.

What emerged, of course, was that the magnitude scale presupposed that all earthquakes were alike except for a constant scaling factor. And this proved to be closer to the truth than we expected.

Incidentally, the usual designation of the magnitude scale to my name does less than justice to the great part that Dr. Gutenberg played in extending the scale to apply to earthquakes in all parts of the world.

[In plotting earthquake measurements] the range between the largest and smallest magnitudes seemed unmanageably large. Dr. Beno Gutenberg then made the natural suggestion to plot the amplitudes logarithmically.

The most remarkable feature about the magnitude scale was that it worked at all and that it could be extended on a worldwide basis. It was originally envisaged as a rather rough-and-ready procedure by which we could grade earthquakes. We would have been happy if we could have assigned just three categories, large, medium, and small; the point is, we wanted to avoid personal judgments. It actually turned out to be quite a finely tuned scale.

We learn geology the morning after the earthquake.