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Show THE WQ QUAKES I A BRIEF STUDY OF BEOENT BjVJ AXARMIN5 DISTURBANCES ,BBJ Oolebrated English Professor Din- BBJ cusses Relations Between Earth- ;BBJ quakes and Volcanic Eruptions BBJ The Earthquake Area. BBJ Curiosity, not unmlngled with alarm, BBJ has not unnaturally been awakened by BBJ the volcanic outbursts and earthquake BBJ shocks which have followed one an- BBJ other so rapidly since tho commence- BBJ ment of tho present year. In a period BBJ of little more than two months we BBJ hare received news of volcanic erup- BBJ tlons in the West Indies, Las Palmas, BBj and Vesuvius, while, tn addition to BpJ innumerable minor shocks In every IHB quarter of the globe, great and de- BBJ structlve earthquakes have been re- BBJ ported from Columbia, the West In- BBJ dies, the Caucasus, Northern India, BBJ and the Sandwich Islands, culmtnat- ABB Ing in the awful tragedy of San Fran- BBj BBj That a connection exists between flJB seismic (earthquake) and volcanic BBj i ijim i I a sot. j ! pi . ! I "i is iff l iJijoi 5 bbbbbI phenomena has been recognized from the earliest times. Volcanic eruptions, BJ indeed, are Invariably heralded or ac- Bfl companted by earthquake shocks. The Bfl eruptions of Vesuvius and other vol- Bj canoes nro nearly always preceded Bfl either by a considerable earthquake, or Bfl by a succession of small ones. While tho volcano of Kllnuoa, In the Sand- Bj wlch Islands, was In eruption In 1887, Bfl G18 curthquako shocks woro folt In the Bfl courso of 19 hours; In an oruptlon In Hj tho preceding year, 41 earthquakes Bj woro recorded In a single night, while Bfl during tho eruption In 18 GO more than Bfl 2,000 shocks aro said to 'havo been IB counted In five days. At ono time, in- flflj deed, tho connection botweon earth- IB quakes and volcanoes wns bollovod to Bfl bo so Intlmnto that earthquakes wore B defined as resulting from "uncompleted Bfl efforts to form n volcano." Moro ex- Bfl tended study, however, has convinced Bfl geologists thnt, whllo volcanic out- Bfl bursts aro always accompanlod by Bfl earthquakes, tho converse of this state- Bfl ment Is by no means true. Many Bfl earthquakes and perhaps the greatest Bfl and most dcstuctlvo of them may and IB do occur In districts whoro no signs of Bfl volcanic activity exist. Tho groat dts- B placements accompanied by fractures Bfl ("faults"), which wo now know to be IB continually occurring In tho earth's Bfl solid crust, account for many of the Bfl vibrations or waves transmitted JB through tho solid rock-masses which flflj constitute earthquakes. In some fll cases does molten mntorlal And a way pB of cscnpa through theso fractures. IJJ Observations carrlod on In deep pH mines, tunnels nnd wells, have shown flflj that thoro Is overywhero In tho oarth's IH crust a rise of temperature as wo go IH downwards, and this rise of tempore- turo is sufficiently rapid to lend to the IB Inference that, If It Is maintained, tho IH rocks at a fow miles from the surface must bo so hot as to bo either tn a IH fluid condition, or only retained tn the flj solid stato by the enormous presauro IH under which thoy lie. When wo como H to analyze theso temporaturo observn- tlons, howevor, we find In different Bfl areas tho most dlvorao results havo jflj been attained. In some cases the In- BJ cronso of tomperaturo Is so rapid that Bfl It amounts to ono degreo F. for ovory ShH 20 fcot of descent, while In others we K havo to pass through ten or 12 times ljj the distance to find the same rlso of ono degroo. Until the discovery of the development of hoat by radium It was i'Ji vory difficult to account for this local " WfJ nnd seemingly capricious distribution EfJ of heat In dlfforent parte of tho earth's crust Now, tt Is posalblo to And at least a probable explanation of these 1' effects In tho slow but certain changes which have boon proved to bo going on tn cortnln of tho chomlcal elements which build up rocks. But evory chnngo of tomporaturo Is - accompanlod by changes of bulk ex- J 'iSjj panslon or contraction In tho great . rock-mas8os building up tho earth's )ht crust. A rlso or fall of tomporaturo of jK&J n vory fow degrees must rosult In enor- u2 mous displacement of mnsses of rock, having n bulk of hundreds or thou- Bj sands of cubic miles. Wo must not bo BJ surprised, therefore, when tn studying the rock-manses of tho earth's crust ;BJ wo flud evorywhero signs of great In- ,. . '' BJ ternal movoments bending, folding, crumpling, fracturing nnd crushing, -,BJ I'HOF J. Y. JUDD, c. ij. amm HSS 'SSBBI . 'iH tm-j m nii, htwwh.iii n WPtSMBCTltgMMMMmfffaMMMMMfrmBBBBl |