tremblor: An earthquake or earth tremor. (OED 1913) from the front cover of _Popular Mechanics_, June 1906 online at: http://popularmechanics.com/albums/index.phtml?mode=view&album=1906&pic=1906 06.jpg&dispsize=400&start=0 "seismograph record of the tremblor" [re: the San Francisco earthquake]