Ni ibiki biri mu nda y’iy’Isi dutuye ni ibiki bibera mu kuzimu
Niba hari ibintu byagoye abahanga kumenya, ni imiterere yo mu nda y’Isi, ndetse n’ibiberamo. Ibi biterwa nuko hari inzitizi nyinshi zituma bigorana gukorera ubushakashatsi harimo izijyanye n’imiterere y’ibigize Isi ndetse n’iryiyongera rikabije ry’ubushyuhe uva ku Isi ugana mu ndani yayo. Koko rero ubushakashashatsi bugaragaraza ko ku gice cy’inyuma cy’Isi (ecorce terrestre), ubushyuhe ( gradiant geothermique) bwiyongeraho ku mpuzandego iri hagati ya 10- 30°C, buri kilometero ujya mu nda y’Isi. Ibi nibyo bituma abahanga mu bumenyi bw’Isi nanone bemeza ko mu mutima w’Isi ( noyau interene) hari ubushyuhe bwa 5 500°C.
Kugira ngo aba bahanga bamenye ibibera mu nda y’Isi bifashisha ubuhanga bunyuranye harimo isesengura ry’imiraba ( ondes sismiques) yoherezwa igihe habaye imitingito y’Isi, ubushakashatsi muri laboratoire hakorwa igisa no mu nda y’isi ( simulation de hautes pressions et de hautes temperatures de l’interieur de la terre),……
Ibice bigize isi byagereranywa n’ibice bigize igi dusanzwe tuzi.
Uva inyuma ugana mu nda y’Isi hari:
- La croute Terrestre (5)
Iki gice cyagereranywa n’igishishwa cy’inyuma cy’igi ( coquille).
Ni icyo gice kiri inyuma cy’Isi kigizwe n’ubutaka n’amabuye anyuranye ( roches). Nubwo iki gice kigize 2% by’umwuzuro wose w’Isi, nicyo gice kizwi cyane kuko imirimo yose umuntu akora ayikorera kuri iki gice.
Iki gice nacyo kigizwe nacyo n’ibice 2, igipande cy’imusozi kigizwe n’imigabane y’Isi( continent) n’igipande cy’inyanja, kigizwe n’indiba z’inyanja( fonds des oceans).
Igice cy’imusozi kigira umubyimba ( epaisseur) urihagati y’ibilometero 10 na 30 naho icyo mu ndiba z’inyanja kikagira ibilometero 10.
Manteau
Mnteau yagereranywa n’umweru w’igi.
Igizwe n’ibitare bikomeye ( roche solide) n’ibindi bisukuma ( roche en fusion).
Ni igice kirangwa n’ubushyuhe bugera kuri 1000c, kandi ibice byayo byombi: meateau superieur na manteau inferieur, bigize 81% by’umwuzuro wose w’Isi.
- Manteau superieur (4)
Igice kinini cyayo kirakomeye (solide), umubyimba wayo ukaba uri hagati y’ibilometero 550 n’ibilometero 770.
- Manteau inferieur (3)
Ni igice gisukuma cya mentau kuko igizwe n’ibitare bihora bibira ( roche en fusion) bita magma. Iki gice kikagira umubyimba wa w’ibilometero 2100
Noyau
Noyau iri rwagati mu nda y’isi .Iki gice kigize 17% by’umwuzuro wose w’Isi, igice kinini cyayo kigizwe n’ubutare bwa Fer harimo n’ubutare bwa Nicker ku gipimo cyo hasi. Nicyo gice gishyuha cyane kandi gifite ireme rinini ( densite). Noyau igizwe n’ibice bibiri: Nayau superieur na noyau inferieur
- Noyau Superieur (2)
Igereranywa n’umuhondo w’igi mu gice cy’amazi.
Ubushyuhe muri iki gice bugera kuri 3800c, igituma ubutare bwose buba bushonga ( fusion), aha hakaba ariho hari inkomoko ya champ magnetique y’Isi. Uumbyimba w’iki gice ni ibilometero 2300
5.Noyau interne (1)
Igereranywa n’umuhondo w’igi mu gice gikomeye
Noyau interene irakomeye ( solide), ibi bikaba biterwa no kuba iki gice gitsikamiwe ( pression exercee sur lui), kiremerewe n’ibindi bice by’Isi. Ubushyuhe kuri iki gice bugera ku gipimo cya 6000 C naho umubyimba wayo ukangana n’ibilometero 1200.
Ubutare bwa Fer na nickcel buba bwashongeshejwe muri noyau superieur nibyo bituma Isi igira champ magnetque, ifatiye runini Isi dutuye
Umwanditsi: Musengimana Emmanuel
