you say it yourself:

To answer those questions I have created the Year Chart picture files. They provide a comparison between my EM Signal data projections for possible approaching earthquakes with records of powerful earthquakes that did actually occur. And they go from the present back to the beginning of 2001.

So, researchers can put together a list of earthquakes that occurred at 120 W (or any longitude they wish) and then look at the Year Charts and determine if there were line peak groups at 120 W around the time a given earthquake occurred at that longitude.

The usual process for discovery is showing some evidence that an idea works, exactly as Roger was just testing, before claiming an idea works or that 25,000 drowned people could have saved their own lives had they listened to you.