>> reporter: living in california, it's a topic that caltech faculty member is used to talking about. >> i find it fascinating. >> reporter: but experiencing a powerful earthquake is another thing. according to the recent research the state may be in a earthquake alone. >> i hear people wanting to plan and prepare for that because it's something that can be potentially catastrophic. >> reporter: in a study released today and author said california is experiencing seismic silence. >> the next century seems like it needs to be busier. it could be six earthquakes or more. >> reporter: in the research, that is 2 1/2 years in the making. the study data from faults that carry the most traffic. they include the san andreas, and heyward faults. he concluded that there has not been enough ground rupturing earthquakes in the last 100 years. and one is overdue. >> these are earthquakes where the ground surface is actually physically broken. if you went there and there was a fence line that was initially straight, it would be offset. >> reporter: one of the ground rupturing quakes mentioned in th