Precursors would be the locations of Earthquake Clouds, thermal changes that can be observed from space, solar and geomagnetic storm activity, ground and well water level changes, large fresh cracks in building foundations, various types of electromagnetic signals, elevated levels of radon gas being detected, unusual animal behavior, more people than normal getting headaches, people hearing Ear Tones. The list goes on and on.

This has been extensively studied. Books have been written on the subject. But you don't usually see too much about it because there is no organized approach to collecting and displaying those data. Government researchers in China don't openly display their data as far as I know. I believe that there is a program in the Philippines that involves collecting those data. But they are again not openly displayed.

There are also numerous instrumental methods involving EM signal monitoring, ground shift monitoring, gravity change monitoring, and on and on.

Then there are statistics based methods that rely on records of past earthquakes in different areas and higher probability time windows associated with tidal forces etc.

Unfortunately, none of the groups and individuals around the world are able to effectively combine their data and compare notes. It has to be done largely by E-mail which is too inefficient. A Web site CGI program might work. It could start as a simple program and be expanded. I have my own forecasting computer program to work on or I would create the CGI program myself.

The forecasting conference in Japan at the end of March, 2009 was organized so that researchers could compare their forecast data for four specific earthquakes to see what agreements there were. Some of my own data are supposed to be presented there by a research colleague. I am trying to get the documents prepared right now.