|
<br />
<br />U02221
<br />
<br />'A UNilED &TATES
<br />OEPAATMENT OF
<br />COMMERCE
<br />PUB,lICATlON
<br />
<br />'ebruary J2, 1971
<br />la/ume 2
<br />'lumber 6
<br />
<br />
<br />~v"'"
<br />
<br />
<br />C.........J..<fcID...'>:uL". [oJ' "0'. ... . '.' <"0.' ..... '.'
<br />< , (' -.<,. - --, : ' - '. -~ - ,
<br />" -. -,'
<br />,- , ,., "
<br />.' :. - ....' .-
<br />,- - "
<br />"'.' " - ,<.' " "-' '.
<br />
<br />
<br />~~rn~
<br />
<br />-,
<br />
<br />!~~i
<br />:.:~~,~<;<~
<br />
<br />':.:".- .,~. ;
<br />
<br />~,';;S':;~
<br />!t~
<br />! :~;~~j~~t~~
<br />Ii ~:~;9;
<br />'...,-",,-,,-
<br />
<br />I:~~l~
<br />
<br />1,,,<, ,
<br />
<br />i~
<br />
<br />I ,;:~\',;.:-''!.
<br />
<br />I~:~I
<br />
<br />'''--',,'-'~'
<br />~t~~~
<br />
<br />,I
<br />
<br />
<br />["'..".,,.
<br />
<br />
<br />,I
<br />[",'t"l"'"
<br />Jkt~~~~~
<br />!<"."'<-
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />I'"''
<br />
<br />\.!.to. i.J'=t:::r.~:,=.~~'r ~~~.j1~'/f'=r~(~?:i~.J"\l?""l:{f~1.HJ~fun.ili.0~i{G^~llm.ilil.~)
<br />
<br />NEIC Records Earthquake
<br />At 6.7 on Richter Scale
<br />
<br />The NOAA National Earthquake Informa-.
<br />tioD Center pinpointed the major eart~-
<br />quake of Feb. 9 at 26 miles north of
<br />downtown Los Angeles-with a magnitude
<br />of 6e7 on the Richter Scale. This shock
<br />was the strongest in the Los Angeles
<br />area since 1933 when a 6.3 magnitude
<br />earthquake caused 115 deaths and 40 mil-
<br />lion dollars damage in Long Beach, Calif.,
<br />and surrounding counties. The Feb. 9
<br />earthquake was centered in the San Ga-
<br />briel mountains near towns of Newhall
<br />and Saugus. This area has a number of
<br />active faults mapped, including the Sole-
<br />dad and Pole Canyon Faults. A'portion
<br />of the San Andreas Fault zone runs north
<br />'of the epicenter. The strongest after-
<br />shock recorded at NEIC headquarters oc-
<br />curred at about 11 a.m. EST and regis-
<br />tered at a magnitude of 5.5.
<br />
<br />Major Quakes May Relate
<br />To Shift in Polar Axis
<br />
<br />with the "wobble" in the earth's north-
<br />south axis of rotation reaching the peak
<br />of its seven-year cycle i~ 1971, seismol-
<br />ogists are alert for a possibl~ incr~ase
<br />in major earthquakes. New studies during
<br />the past three to five years of the so-
<br />called polar wobble have heightened in-
<br />terest in the poss.ible effects it may
<br />have on the earth's structure. Charles
<br />A. Whitten, 'chief geodesist oT the Nation-
<br />al Ocean S'..1rvey,said that "the year 1971
<br />should be a critical year. This is the
<br />year in the seven~year cycle of the
<br />earth's wobbling wh~n the daily shift of'
<br />the pole reaches its -maximum."
<br />The earth wobbles slightly as it spins
<br />in space and as it does so, its axis of
<br />rotation shifts. The maximum range of
<br />the polar shift is 72 feet over a 14-
<br />month period.
<br />
<br />x'.
<br />
<br />Graph shows correlation, especially during the past 20 years, between th~
<br />earth's polar'wobble and major earthquakes. Shaded area indicates energy
<br />released by recorded earthquakes in the period 1900-1970.' Dotted lines,
<br />indicate the m~an daily shift or the polar wobble during the same period.
<br />
<br />
<br />o
<br />>.<<
<br />1
<br />
<br />~
<br />"'
<br />t
<br />ill
<br />"
<br />
<br />~.
<br />
<br />tll
<br />
<br />III
<br />
<br />1111
<br />
<br />1111
<br />
<br />
<br />'v,<< ,::,,?':~A.:,:,..?...;~:
<br />.oJ'
<br />
<br />r,- ..
<br />'.~'r'. .:;-,::'
<br />
<br />':""
<br />
<br />,~
<br />
<br />1111
<br />
<br />lilt
<br />
<br />111I
<br />
<br />1111
<br />
<br />".',' .:. ';'~);::-"<':.~.$.',::"~.~;:: ::;f,o:'::~",;,.' :", ;-.~:_:":,~ -"'.
<br />'.- ,.'-,.".',;-, "-c.:,"
<br />
<br />-,",?~;" ,j ,
<br />
<br />-,"
<br />
<br />,.:.-..;
<br />
<br />,,>0';,.,:<
<br />
|