Is the number of earthquakes increasing with time?
If you look at any raw earthquake catalog, you will find that by far most of the earthquakes listed took place in the last few decades. An earthquake catalog, by the way, is a list of historic earthquakes for a region or the world, made with the idea of having the most complete list possible giving the seismographic coverage, data processing methods, etc. For this apparent increase in activity, we can thank modern electronics & computers. Many more instruments are installed now than has been so in the past & the data can be analyzed much more easily. To take the Southern California catalog as an example, many of yesterday’s earthquakes were between magnitude 1.0 and 2.0. These quakes are not large enough for a person to feel. In the 1930’s & 40’s, when the network included less than 10 stations, we simply did not record most earthquakes in this size range, so they are not in the catalog. To find out if the number of earthquakes is increasing, we need to search the catalog for only eart
