A cikin duniya akwai nau'ikan tsaunuka daban-daban bisa ga halaye da asalinsu. Daya daga cikinsu shine stratovolcano. Stratovolcano an san shi da nau'ikan tsaunuka masu tsayi masu tsayi iri-iri, waɗanda aka samo su ta hanyoyi daban-daban na ƙayyadaddun tsarin lava, sauye-sauyen pyroclastics da aka haifar yayin lokutan musanyawa na ayyukan volcanic, da koguna na lava na ruwa da toka mai aman wuta.
A cikin wannan labarin za mu mayar da hankali ga gaya muku menene halaye, asali da zaɓuɓɓukan stratovolcano.
Babban fasali
Stratovolcanoes ana siffanta su da manyan bayanan martaba da kuma haifar da fashewar lokaci-lokaci. Tushen da aka zubo daga waɗannan tsaunuka yana da ɗanɗano sosai kuma yana taurare yayin da yake sanyi kafin ya yi tafiya mai nisa. Tushensa na magmatic yana da wadatar silica ko acid kuma ya ƙunshi dacite, rhyolite da andesite. Yawancin waɗannan tsaunuka sun wuce tsayin mita 2.500.
Masu binciken volcano sun zaɓi yin amfani da kalmar "stratovolcano" maimakon "ƙananan dutsen mai fitad da wuta" da ake amfani da shi akai-akai don nuna bambanci tsakanin su biyun, tun da dutsen mai aman wuta gabaɗaya ana siffanta shi da samun nau'ikan abubuwa daban-daban waɗanda suka fashe daban-daban.
stratovolcanoes sun kasance irin na yanki na yanki na subduction kuma suna faruwa a cikin arcs ko sarƙoƙi na tsayi a gefuna na faranti na tectonic. Wadannan gefuna sune inda ɓawon teku ya fi ƙasa da ɓawon nahiyoyi (kamar yadda yake a cikin Andes) ko tsakiyar tsakiyar teku (kamar yadda aka gani kusa da Iceland). Magma da ta yi su ta fito ne a lokacin da ruwa ya makale a cikin basalt da ma'adanai suka zubo a cikin asthenosphere (farantin sama na rigar Duniya), wanda ya sa ta rushe.
Fashewar wani stratovolcano
Desiccation (wato, cikakken cire ruwa ta hanyar ma'adanai) yana faruwa lokacin da yanayin yanayin zafi da matsa lamba ya kasance ga wasu ma'adanai saboda ƙaddamar da farantin karfe. Ruwan da ke cikin ƙasan Layer yana saukar da wurin narkewar dutsen yana motsawa a kan sa yayin da aka sake shi, don haka narkewar wani yanki yana faruwa, yana sa ya zama ƙasa da yawa fiye da dutsen da ke kewaye. Sai ta fitar da magma ta cikin ɓawon burodi. sakewa ma'adinai mahadi masu arziki a silica.
Magma ta samu kusa da saman kasa, a matsayin tafkuna a cikin dakunan magma, kasa da tsaunuka. Ƙananan matsi na magma yana taimakawa iskar gas (sulfur, carbon dioxide, da chlorine) da ruwa suna amsawa, kamar bude kwalban soda, don samar da fissures mai volcanic da tarkace pyroclastic. Lokacin da wani adadin magma da iskar gas suka taru, rufin mazugi mai aman wuta ya fashe, wanda ya haifar da fashewar fashewar.
Yankin yanki
Ka'idar tectonics ta Plate tana kwatanta raguwar faranti azaman jerin abubuwan da ke haifar da nutsewar farantin ɗaya ƙarƙashin wani farantin lithospheric mai haɗuwa. Wannan tsari yana faruwa ne a yankunan da ke cikin yankin da a halin yanzu ke cikin Ring of Fire na Pacific tare da tekun Pacific, a wasu sassan Tekun Bahar Rum, da kuma bakin tekun Indiya da Kudancin Antilles a Indonesia.
Misalai na stratovolcano
- Chilean Andes. Nevado Ojos del Salado shine dutsen dutse mafi girma a duniya. Wannan volcano na Chile yana da nisan mita 6.887 sama da matakin teku. Dutsen Llullaillaco na kusa da shi, kuma a cikin Andes na Chile, shine dutsen dutse mafi girma a duniya a tsawon mita 6.739. Nevado Ojos del Salado yana da wani tafki mai tsayi kimanin mita 6.390 sama da matakin teku, daya daga cikin tafkuna mafi girma, idan ba mafi girma a duniya ba. Masana kimiyya sun yi imanin cewa fashewar baya-bayan nan ta faru ne kimanin shekaru 1300 da suka gabata, amma ba su da tabbas, saboda mai yiwuwa dutsen mai aman wuta ya harba wani karamin toka a shekarar 1993.
- Llullaillaco yana kan iyakar Chile da Argentina. Wani matashi mai aman wuta ne ya kafa dutsen a saman wani tsohon dutse mai aman wuta wanda samansa ya ruguje kimanin shekaru 150.000 da suka wuce. Ƙananan tsaunuka sun fara tasowa kimanin shekaru 10.000 da suka wuce.
- Dutsen St. Helens. Duk da take a matsayin daya daga cikin ƙarami stratovolcanoes a cikin Cascades, Dutsen St. Helens ne mafi aiki. Fashewar ta ta haifar da aƙalla nau'ikan toka 35 a cikin shekaru 3500 da suka wuce kawai. Dutsen mai aman wuta ya yi fice a shekara ta 1980 da fashewar da ya yi sanadiyar mutuwar mutane 57, da kuma lalata hanyoyin mota mai nisan mil 185, titin jirgin kasa mai nisan kilomita 15, gadoji 47 da gidaje 250. Girgizar kasa mai karfin awo 5,1 ta afku ne sakamakon fashewar tarkace mai girman kilomita 0,7.
- Dutsen Rainier. Dutsen Rainier shine mafi girman kololuwa a cikin Rawan Cascade a mita 4.392. Ko da yake Dutsen Rainier da kansa ya haɓaka a cikin shekaru rabin miliyan na ƙarshe, irin wannan mazugi ya kasance tsakanin shekaru miliyan 1 zuwa 2 da suka wuce. Fashewar da ta barke shekaru 5.600 da suka gabata ta haifar da wani katon caldera a taron, wanda daga baya ya cika yayin da aka sake gina taron ta hanyar fashewar abubuwa. Yayin da dutsen magma na karshe ya faru kimanin shekaru 1.000 da suka wuce, ya yi tashin bama-bamai da dama wadanda suka warwatsa toka a fadin jihar Washington.
- Krakatoa Tsibiri ne mai aman wuta wanda ke cikin mashigin Sunda. A shekara ta 1883, dutsen mai aman wuta ya gamu da wani tashin hankali da ya jefa toka sama da kilomita 50 cikin sararin samaniya kuma ana iya jin shi akalla mil 2200 daga wurin da yake. Babban makamashin da girgizar ta fitar ya haifar da tsunami da ta yi sanadiyar mutuwar mutane 36.400 a tsibiran Sumatra da Java.
- Dutsen Tambora Dutsen mai aman wuta ne a Indonesiya da ya barke a shekara ta 1815. Haƙiƙa, waɗannan fashe sun yi tashin hankali har aka rubuta su a matsayin mafi girma a tarihi. Yanayin zafi a duniya ya ragu da kusan ma'aunin Celsius 3 a lokacin da dutsen mai aman wuta ya barke, wanda ba abin mamaki ba ne tun da aka fitar da tokar a cikin nisan kilomita 50 a sararin samaniya. Saboda dutsen mai aman wuta ya fitar da abubuwa da yawa, ya rushe bayan fashewar, wanda ya haifar da wani rami mai girma wanda za a iya gani daga sararin samaniya a cikin aikin.
Ina fatan cewa tare da wannan bayanin za ku iya ƙarin koyo game da stratovolcano da halayensa.