The Collaborative International Dictionary of English v.0.48:

Earthquake \Earth"quake`\, n.
   A shaking, trembling, or concussion of the earth, due to
   subterranean causes, often accompanied by a rumbling noise.
   The wave of shock sometimes traverses half a hemisphere,
   destroying cities and many thousand lives; -- called also
   earthdin, earthquave, and earthshock.
   [1913 Webster]

   Earthquake alarm, a bell signal constructed to operate on
      the theory that a few seconds before the occurrence of an
      earthquake the magnet temporarily loses its power.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Earthquake \Earth"quake`\, a.
   Like, or characteristic of, an earthquake; loud; startling.
   [1913 Webster]

         The earthquake voice of victory.         --Byron.
   [1913 Webster]

WordNet (r) 3.0 (2006):

earthquake
    n 1: shaking and vibration at the surface of the earth resulting
         from underground movement along a fault plane of from
         volcanic activity [syn: earthquake, quake, temblor,
         seism]
    2: a disturbance that is extremely disruptive; "selling the
       company caused an earthquake among the employees"

The Free On-line Dictionary of Computing (19 January 2023):

earthquake

   (IBM) The ultimate real-world shock test for computer
   hardware.  Hackish sources at IBM deny the rumor that the
   San Francisco Bay Area quake of 1989 was initiated by the
   company to test quality-assurance procedures at its California
   plants.

   [Jargon File]

   (1995-04-22)