214 NATIONAL OCEANOGRAPHIC PROGRAM LEGISLATION 



The objectives of the geomagnetic program are to define the time and space 

 variations of the earth's magnetic field as an aid to air and marine navigation 

 and to land surveyors ; to facilitate forecasting radio propagation conditions ; to 

 indicate solar-terrestrial physical relationships with respect to cosmic rays, 

 auroral phenomena, ionospheric physics, and interplanetary space physics ; and 

 to aid in the study of the core, mantle, and crust of the earth. 



The Bureau operates 13 magnetic observatories, many of which axe on a co- 

 operative basis with universities, research institutes, and other Government 

 agencies. The principal function of the observatories is to record changes in 

 the magnetic fields. 



Magnetic surveys are conducted to portray the distribution of the magnetic 

 field over the surface of the earth. The secular change of the magnetic field 

 is not predictable. Because the annual rate of change is small compared with 

 the daily changes and irregular variations, several years are required to detect 

 and evaluate a new rate of annual change or impulse. It is necessary, therefore, 

 to maintain a continuing program of repeat surveys, in addition to observatory 

 operation and the regular magnetic surveys, in order to provide the necessary 

 data. 



Seismology. — The seismological program is concerned with teleseismic seis- 

 mology including operation of a worldwide standard semismograph network ; 

 strong motion earthquake studies ; operation of a seismic sea wave warning 

 system ; analysis and dissemination of seismological data ; research and de- 

 velopment in seismological equipment and interpretation of data ; and special 

 seismological investigative projects. 



Under the teleseismic function, the Bureau conducts a worldwide earthquake 

 location service for use in the protection of life and property throughout the 

 world, and to furnish pertinent data for seismological research. Studies are 

 also made of the mechanics of earthquake phenomena and the earth's structure. 

 Through an integrated worldwide network of seismograph stations, part of 

 which are operated by the Bureau and the remainder by universities, private 

 institutions, and foreign governments, data on earthquakes are collected, 

 analyzed, and disseminated. 



A network of strong motion stations is oijerated in the Western United States 

 to study the nature and magnitude of destructive earthquake motions. The 

 information obtained indicates the acceleration and displacement of ground 

 motion and building motion from earthquake forces. This information is used 

 in the design of eathquake resistant structures in areas of known disturbance 

 and for establishing earthquake codes and regulations. 



The seismic sea wave warning system is operated in the Pacific Ocean area 

 for the protection of life and property along the rim of the Pacific and among 

 the islands likely to be affected by a seismic sea wave. The systems headquarters 

 is at the Honolulu Observatory, operated by this Bureau, where the technical 

 data are compiled for evaluating the sea wave potential. Upon the confirmation 

 of the existence of a seismic sea wave generated by a coastal or submarine 

 earthquake, the observatory issues alerts and warnings as to probable time 

 of its arrival to the countries around the Pacific that are participating in the 

 warning service. 



Geodesy. — The program in geodesy is concerned with the precise measure- 

 ment of the various physical parameters of the earth, including its configura- 

 tion and the properties of its gravity field. The operations involved include the 

 establishment of horizontal and vertical control stations ; gravity and astro- 

 nomical observations ; studies of earth movement ; observation of satellites 

 for the expansion of horizontal control networks ; publication and distribution 

 of geodetic control data ; and research and development in new techniques and 

 procedures. 



The primary objective of the program is to provide a spacing of accurately 

 determined control points, horizontal and vertical, that will meet the needs of 

 our national program for the conservation and development of natural resources, 

 the needs of broad scientific and engineering projects such as the microwave 

 network for communication, the Interstate Highway System, petroleum explora- 

 tion, transcontinental pipelines, transmission lines, urban development and 

 renewal, and the national mapping program. 



