Of, subject to, or caused by an earthquake or earth vibration.(adjective)
Earthshaking: an issue of seismic proportions and ramifications. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "seismic" in a sentence
"NEARY: Now, David Cameron said in that news conference yesterday that this coalition could mark what he called a seismic shift in British politics."
"At about 5: 40 a.m. Eastern Time, the Mine Safety and Health Administration was informed of what they call a seismic event or ground failure near the site of the mine in question."
"It far exceeds masonry walls in seismic resistence."