Richter chose to use the term " magnitude " to describe an earthquake 's strength because of his early interest in astronomy ; stargazers use the word to describe the brightness of stars . Gutenberg suggested that the scale be logarithmic so an earthquake of magnitude 7 would be ten times stronger than a 6 , a hundred times stronger than a 5 , and a thousand times stronger than a 4 . ( The 1989 Loma Prieta earthquake that shook San Francisco was magnitude 6.9 . ) The Richter scale was published in 1935 and immediately became the standard measure of earthquake intensity . Richter did not seem concerned that Gutenberg 's name was not included at first ; but in later years , after Gutenberg was already dead , Richter began to insist for his colleague to be recognized for expanding the scale to apply to earthquakes all over the globe , not just in southern California . Since 1935 , several other magnitude scales have been developed
1989 Loma Prieta earthquake
1989 Loma Prieta earthquake
Charles Francis Richter