1. Loud enough to shake the very earth 
2. Sufficiently significant to affect the whole world
   "earthshaking proposals"
   - world-shaking, world-shattering, earth-shattering

See also: important, loud, significant

• James Cagney
• James Callaghan
• James Clark Ross
• James Clerk Maxwell
• James Cleveland Owens
• James Cook
• James Crichton
• James Dean
• James Dewey Watson
• James Douglas Morrison
• James Earl Carter
• James Earl Carter Jr.
• James Edmund Scripps
• James Edward Meade
• James Fenimore Cooper
• James Francis Thorpe
• James Franck
• James Garfield
• James George Frazer
• James Gordon Brown
• James Grover Thurber
• James Hargreaves
• James Harold Doolittle
• James Harold Wilson
• James Harvey Robinson