Where Earthquakes Come From.

Hokitika Guardian, 1 February 1923, Page 4

Where Earthquakes Come From.

By Charles David.-on, Sc-D... anther j ot "The Origin of Earthquakes." ’ Though lew details have a.s yet reached this country, it is clear that j the recent disturbance mi Chile must be reckoned as one o* the world’s i. a . es: eartbqtia kes. To be fell along the coast for more Cmi l.ltttl miles, to lie strong enough to stop clocks at Buenos Aires, about >,1(1 miles across fit,- continent, the iron disturbed by the earthquake must have far exceeded 21 million square mde- and have closely approached that a He, ied h, the destructive Chinese earthquake of nearly two years ago, probably the most extensive known to use. in the sillily (J an earthquake, great or smalt, the main "point to he determined is the position ot its origin. This "ill be definitely known as soon as the records from several distant at.uue- can lie measured and "i.mpaivd. In tiie meantime we have to rely on some.' hat scantv daJa. oil our knowle' .e of the are:* of greatest damage, on tiie fact that the sh.,ek. • - in -o munv ether Beni', iait and Chilean j earthquakes, was lellowed soon alter hv a ve;ies of destructive sea-waves. The existence id' such waves shows Diat not only was the origin'submarine hut also Gnu the earthquake was nceiunpanie.l hv a marked change of level in the iieenti-l ; d -not by -ueh a change as that ti-si reported of I'iXtO to "il(> ; ~! but i l -' cue of some lew teet only, the gre,•'(•:- known ttphit in any earthquake being nearly ISfl. The next point of signihcaiice is that the damage caa.-ed by the eartlupiake •, as ~,,,5L serious along a portion of the "a-1 about ?IKI mile- in leligtb. reaebing I reto Ca(|uiuibo northwards to CopUipn. the town that suffered most of ill being \'a!!cn"r. about- half-way !><•- tween these place.-. It is therefore pro!: tide that tiie origin lay some distance out at sea and in the neighbourhood of a place directly opposite, to Yallenar. I Along the margins of the Pacific Ocean are some of the most potent earthquake region- ill the world. Indied, tic"ed en a large scale, the .•ccan seems to he almost engirdled by these regions. There a large one to the east of ,| span, and, farther south, another which includes Mi*' Philippine island- and the Malay Archipelago. ' !a the ot lut side of the ocean lies a ■bird D ginning in Alaska and extending south eastwards. A fourth roaches from a little north of San Francisco, co; or.- Central A meric i, and ends in the south of Colombia : while the fifth clings to the we-tern eo:'-.i i f Smith America, and which in times past hint 1 ravaged the ;nasi * of Chile and Peru. Out of every ten world-shaking oni*t’* quakes ,-oven originate in tlv limes productive in great .-hoik- alam i l; can. T •* Cardie Ocean, unlike tlv AHanI Lie. is also remarkable in pas-es-in: ‘ i.;'.r: - ,v (roughs ol immon-'e depth. Oli j e:.-t const <t Japan lies tin* us- ' ! miles. ..u l below t's ’.'".tern slope , I'lgiuate mans ot the greatest ot J o ne . . .. 11 !|(('lak"-. The 'hopes: a!!, oil’ the i-linid of level. Tee sts of Chile and IV it are bcnlered liy a series of these troughs -' G e I i ruiualel D.*e;» I I } mil oli Ar.*(i III! a . t hr L; (•! ■ i I, HU",'. I ) p I 111 do -1 , elf A re a. lb.- Hi. •!•,•* rd - ! ' . i • i'll ' ofiapo, and I lie llaa.-kei Deep !P j miles) i ll Valparaiso and Santiago. D j i - .meg the -loping -id: -• of t i:e-e

Iroughs that- tlio most destructive! Peruvian and Chilean earthquakes Humiliate, ami the centre of the recent shock will probably be found not tar dislani frani the southern end oi the Iliclmrds Deep. What the connection hetween the occur sene 1 of earthquakes end a steeply sloping surface ratty be is less clear than the fact .hat sue': a connection does exist. ,\! ,t of onr great oartliq lake regions arc partly or entirely submarine. Hat. there is one that lie • on land, extending from Italy across j the Balkan Peninsula to the Himalayas, in which two out of every ten The central ranee- or the Himalayas consist of am iem rocks which have been elevated into id loftiest peaks upon the globe. Bordering them on the smilh are the üb-l I imaiayan chains, composed for the most part oi recent tertiary bed-. and sloping rapidly into the plain- of India. The occurrence of groat earlliquakes. like that which ruined K nigra and PbarmIbc Himalaya, is not yet at an end an ! that the central masses are still, as of obi, pressing forwards towards the south, crushing and grinding over the advanced guaid of teitmvy mountains. 11l the shelving slopes of the Pacific d oos it would seem that we have but an i'ii: I lor stage of a similar stnicl.irc, and that in the earthquakes of Chile and Peru we have from time to linn' the movements that will culminate in tlic formation of a new series of moan-