Knowledge Discovery in an Earthquake Text Database: Correlation between Significant Earthquakes and the Time of Day

In this paper, we take a real world application from a text database and present a case history. The techniques ultimately led to a discovery contradicting an accepted paradigm in seismology. Using simple, tailored, keyword extraction, we examined a text collection of earth-quake data. A discovery was made when an unusual pattern emerged from the text. We then tested a more comprehensive numerical database, treating the the text discovery as a hy-pothesis. It was verified using a standard 2 statistic. The hypothesis was significant earthquakes in the longitude re-gions that include California, occur more often in the morning hours than any other time of day.