Ukuhlolisisa Inyikima
“NGENDLELA ESELE SIKUQHELE NGAYO UKUHLALA KUMHLABA OZINZILEYO XA WONA UQALISA UKUGUNGQA SISUKA SIBHIDEKE.”—“ITHE VIOLENT EARTH.”
“ITHE WORLD BOOK ENCYCLOPEDIA ithi: “Iinyikima ziphakathi kwawona mandla atshabalalisayo endalo.” Xa isitsho ayibaxi zinto kuba amandla akhutshwa yinyikima eqatha asenokuyidlula ngokuphindwe kangange-10 000 ibhombu yokuqala yeathom! Eyona nto yongezelela kweso sishiqi kukuba iinyikima zinokuqhambuka nakweyiphi na imozulu, ngalo naliphi na ixesha lonyaka, nangalo naliphi na ixesha lemini. Yaye nangona izazinzulu zisenokuyazi indawo ezinokuqhambuka kuyo iinyikima ezinamandla, azikwazi ukuchaza ukuba ziya kwenzeka nini.
Iinyikima zibakho xa kushukuma amatye ngaphantsi komhlaba. Le nto iyaqhubeka isenzeka. Ngokufuthi, oku kushukuma akunamandla ngokwaneleyo ukuba kungavakala emhlabeni, kodwa kuyakwazi ukunakanwa ngesixhobo esibizwa ngokuba yiseismograph.a Ngamanye amaxesha, kuqhekeka amatye amaninzi ngokwaneleyo ukuba ashukumise umhlaba ngendlela endlongondlongo.
Kodwa kutheni ungayeki ukushukuma nje umhlaba? INational Earthquake Information Center (NEIC) ithi: “Ingcaciso yoku ifumaneka kwingcamango yezenzululwazi ebizwa ngokuba yiplate tectonic, ngcamango leyo eye yalutshintsha uluvo lwezazinzulu eziphanda ngemeko-bume yoMhlaba.” INEIC yongezelela ngelithi: “Ngoku siyazi ukuba umhlaba unemigangatho esixhenxe, eyahlulahlulwe yayimigangatho emincinane, yonke ishukuma ngokuqhubekayo, ngomlinganiselo osusela kwiimilimitha ezili-10 ukuya kwezili-130 ngonyaka.” INEIC ithi uninzi lweenyikima luba kwimimandla enale migangatho. Kulapho ke ama-90 ekhulwini eenyikima asenokwenzeka khona.
Umkhamo Nobunzulu Bayo
Amandla enyikima anokulinganiswa ngomkhamo okanye ngobunzulu bayo. Ngeminyaka yee-1930, uCharles Richter wavelisa isikali sokulinganisa umkhamo weenyikima. Njengoko lalikhula inani lamaziko eseismograph, kwaveliswa izikali ezitsha ezisekelwe kwezikaRichter. Ngokomzekelo, isikali somkhamo silinganisa amandla akhutshwa kumthombo wenyikima.
Kambe ke, ezi zikali azisoloko zivelisa umlinganiselo womonakalo obangelwe yinyikima. Khawucinge nje ngenyikima kumantla eBolivia ngoJuni 1994, eyayinomkhamo osisi-8,2, ekunikelwa ingxelo yokuba yabulala abantu abahlanu kuphela. Kodwa, inyikima yowe-1976 eTangshan, eTshayina—eyayinomkhamo ongaphantsi osisi-8,0—yabulala amakhulu amawaka!
Ngokwahlukileyo kumkhamo, ukubalwa kobunzulu kubonisa umphumo eba nawo inyikima ebantwini, kwizakhiwo nakwimeko-bume. Oku kuwabonisa kakuhle amandla enyikima ebantwini. Ngapha koko, ukushukuma nje komhlaba akudli ngokubenzakalisa abantu. Kunoko, ukudilika kweendonga, ukugqabhuka kweegesi okanye amandla ombane, ukuwa kwezinto nezinye izinto, kokona kwenzakalisayo kuze kubulale.
Olunye usukelo lwabo balinganisa inyikima kukukwazi ukulumkisa kuselithuba ngenyikima. Kuye kwaveliswa inkqubo yokubala ebizwa ngokuba yiAdvanced Seismic Research and Monitoring System. Ngokwengxelo yeCNN, le nkqubo—efikeleleka ngokukhawuleza neneenkqubo ezinamandla zekhompyutha—iya kunceda amagosa “akwazi ukukhawuleza abone imimandla eye yahlaselwa kukushukuma okunamandla okubangelwa yinyikima.” Oku kuya kwenza kube lula ngamagunya ukuthumela uncedo kwiindawo ezichaphazelekileyo.
Licacile elokuba, ukuyilungela inyikima kunokunciphisa ukwenzakala, kuphungule ukonakaliswa kwezinto yaye—eyona nto ibalulekileyo—kukhusela ubomi. Sekunjalo, iinyikima ziqhubeka zisibakho. Ngoko kuphakama lo mbuzo: Abantu baye bancedwa njani bahlangabezana neli shwangusha?
[Umbhalo osemazantsi]
a Iseismograph sisixhobo sokulinganisa ukushukuma komhlaba ebudeni benyikima. Eyokuqala yaveliswa ngowe-1890. Namhlanje, angaphezu kwama-4 000 amaziko aneseismograph ehlabathini lonke.
[Isicangca esikwiphepha 19]
(Ukuba ufuna inkcazelo ehlahlelwe kakuhle, yiya kwimpapasho)
Zingaphi Iinyikima?
Inkcazelo Umkhamo Umlinganiselo Waminyaka Le
Ezinkulu 8 nangaphezulu 1
Enkulu 7-7,9 18
Enamandla 6-6,9 120
Engenamandla Kangako 5-5,9 800
Elula 4-4,9 6,200*
Encinane 3-3,9 49 000*
Encinane Gqitha <3.0 Umkhamo 2-3:
malunga ne-1 000 ngemini
Umkhamo 1-2:
malunga 8 000 ngemini
* Uqikelelo.
[Inkcazelo]
Source: National Earthquake Information Center By permission of USGS/National Earthquake Information Center, USA
[Inkcazelo Ngomfanekiso okwiphepha 19]
Seismogram on pages 18 and 19: Figure courtesy of the Berkeley Seismological Laboratory