More Comments on Data Issues ("Wonkish")

As discussed in previous posts, incomplete or unavailable data can seriously impact the quality of earthquake forecasts. In our case, these problems are associated with the Global Digital Seismic Network, funded and maintained by the US National Science Foundation, and the US Geological Survey, among others.  The data catalogs also contain contributions from local networks in various countries.

It is therefore interesting to examine the distribution of the stations to look for clues as to where data issues might reasonably be expected to occur.  You can go to the web page at http://earthquake.usgs.gov/monitoring/gsn/ to see the status and distribution of the seismic stations. 

At the left we see the global station distribution that seems to show a reasonable geographic distribution of stations. 

The various colors indicate how frequently data streams update.  In general, most of the stations are of course associated with continental areas or islands (it is difficult and expensive to locate stations underwater, although it can be done.

However, a closer look at the map, particularly in the area of southern Asia, tells a somewhat different story.  At right, we can see an image of the station distribution in southern Asia, India, and the middle east. 

Here it can be seen that there is a distinct lack of stations in some of the most seismically active areas in the world, including the Himalayas, Iran-Iraq, the Pakistan-India border, and in the interior of China. 

The lack of these stations, and the relatively recent installation of what stations exist in the area mean that the data stream that we have to analyze for forecasting is very limited.  Until the situation changes, we will have difficulty with forecasts in regions such as these.