eager — See bore. 



earbone — See otolith. 



earth current — See telluric currents. 



earthquake — A sudden, transient motion or 

 trembling of the earth's crust resulting from 

 the propagation in the earth of elastic "waves 

 caused by faulting of the rocks or by volcanic 

 activity. 



earthquake intensity — A number describing the 

 effects of an earthquake on man, on man-made 

 structures, and on the earth's surface. The num- 

 ber is rated on the basis of an "earthquake inten- 

 sity scale." The scale in common use in the U. S. 

 today is the modified Mercalli scale of 1931. 



earth radiation — See terrestrial radiation. 



earth structure — The postulated structure and 

 composition of the earth by assuming concentric 

 layering around a core based upon gravity, 

 density distribtition, seismology, and laboratory 

 determinations of physical and chemical proper- 

 ties of rocks. See mantle, crust, centrosphere. 



earth tide — The periodic movement of the earth's 

 crust caused by the tide-producing forces of 

 the moon and sun. (68) 



East Africa Coast Current — (or Somali Cur- 

 rent). A seasonal current influenced by the 

 monsoon drifts of the Indian Ocean. It flows 

 southwestward along the coast of Somalia in 



EARTH STRUCTURE 



the Northern Hemisphere winter and northeast- 

 ward from about 10°S during the Northern 

 Hemisphere summer. 



East Australia Current — The current which is 

 formed by part of the South Equatorial Cur- 

 rent and flows southward along the east coast 

 of Australia. The East Australia Current turns 

 and joms the northeast flow through the Tasman 

 Sea. 



In the Southern Hemisphere summer a small 

 part of this current flows westward along the 

 south coast of Australia into the Indian Ocean. 



East Greenland Current — A current setting 

 south along the east coast of Greenland and 

 carrying water of low salinitj' and low tempera- 

 ture. The East Greenland Current flows 

 through Denmark Strait between Iceland and 

 Greenland and joins the Irminger Current. 

 The greater part of the current joins the counter- 

 clockwise circulation south of Greenland; part 

 curves to the right around the tip of Greenland 

 and flows northward into Davis Strait as the 

 West Greenland Current. 



The main discharge of the Arctic Ocean is via 

 the East Greenland Current. 



East Ice — 1. The sea ice which drifts from the 

 Arctic Ocean south along the east Greenland 

 coast, around Kap Farvel, and up the southwest 

 coast of Greenland. See storis. 



2. To Xorwegians, "East Ice," or "Des-isen" 

 is the ice in the Barents Sea. 

 (59) 



East Wind Drift — A west-setting current close to 

 the Antarctic Continent caused by the polar 

 easterlies. (Approved AGUE name.) 



ebb axis — The average direction of the tidal cur- 

 rent at strength of ebb. (59) 



ebb current — The tidal current associated with the 

 decrease in the height of a tide. Ebb currents 

 generally set seaward, or in an opposite direction 

 to the tide progression. Erroneously called ebb 

 tide. (See figure for current curve.) 



ebb interval — The interval between the transit of 

 the moon over the meridian of a place and the 

 time of the strength of the following ebb tidal 

 current. (50) 



ebb strength — The ebb tidal current at the time 

 of maximum speed, usually associated with the 

 lunar tide phases at springs near perigee and/or 

 maximum river discharge. {See figure for 

 current curve.) 



ebb tide — See falling tide, ebb current. 



54 



