Earthquakes: Land / Ocean Distribution
The next stage in my earthquake analysis project is to partition the events into groups with epicentre over land or water. Since our existing catalog contains the latitude and longitude for the epicentres, it was a relatively simple matter to pipe these into gmtselect and label the events accordingly. The resulting data when sucked into R looks like this:
These data were then merged into the existing catalog using the id field.
A quick sanity check at this point would be good.
That looks about right: a clear distinction between land and ocean events.
Do the magnitude and depth of earthquakes on land differ significantly from those which occur under water? Looking at the plots below suggests that there is no qualitative difference.
Certainly it seems reasonable that an event happening deep beneath the surface of the Earth should not be affected by whether or not there is a (quite) thin layer of water on top! However, for my analysis of secondary effects it is probably going to be rather significant. But more on that later.