Ƙarfin girgizar ƙasa

Sikeli na tsananin girgizar ƙasa yana rarraba tsakanin  tsananin ko tsananin sosai na raƙuman ƙasa (girgizar ƙasa) a wani wuri da aka ba shi, kamar sakamakon girgizar kasa. An rarrabe su daga sikelin Girman girgizar ƙasa, wanda ke auna girman ko ƙarfin girgizar kasa gaba ɗaya, wanda zai iya, ko watakila ba, haifar da girgizar da ake gani ba.

Sikeli na ƙarfi ya dogara ne akan tasirin da aka lura na girgizar, kamar matakin da mutane ko dabbobi suka firgita, da kuma girman da tsananin lalacewar ga nau'ikan tsari daban-daban ko siffofin halitta. Matsakaicin ƙarfin da aka lura, da kuma girman yankin da aka ji girgizar ƙasa (duba taswirar isoseismal, a ƙasa), ana iya amfani da su don kimanta wurin da girman girgizar ƙasar; wannan yana da amfani musamman ga girgizar kasa ta tarihi inda babu rikodin kayan aiki.

## Girgizar ƙasa
Za'a iya haifar da girgizar ƙasa ta hanyoyi daban-daban (girgizar ƙasa, guguwa, manyan fashewa, da dai sauransu), amma girgizar kasa mai ƙarfi don haifar da lalacewa yawanci saboda fashewar ɓawon duniya da aka sani da girgijen ƙasa. Ƙarfin girgizar ya dogara da dalilai da yawa:

* "Gidan" ko ƙarfin tushen taron, kamar yadda aka auna ta hanyar ma'auni daban-daban na girgizar ƙasa.
* Irin raƙuman Girgizar ƙasa da aka samar, da kuma yadda yake.
* Rashin zurfin taron.
* Tsakanin daga tushen taron.
* Amsawar shafin saboda ilimin ƙasa na gida

Amsawar shafin yana da mahimmanci musamman kamar yadda wasu yanayi, kamar su wuraren da ba a haɗa su ba a cikin kwandon, na iya kara motsi na ƙasa har zuwa sau goma.

Inda ba a yi rikodin girgizar ƙasa a kan seismographs ba, za a iya amfani da taswirar da ke nuna ƙarfin da aka ji a wurare daban-daban don ƙididdige wuri da girman girgizar.  Irin waɗannan taswirori kuma suna da amfani don ƙididdige ƙarfin girgizar, kuma ta haka ne za a iya sa ran matakin lalacewa daga girgizar ƙasa mai girman irin wannan nan gaba.  A kasar Japan, ana amfani da irin wannan bayanai ne a lokacin da girgizar kasa ta auku don hasashen irin barnar da za a yi tsammanin za ta yi a wurare daban-daban..

Ƙarfin girgiza ƙasa na gida ya dogara da abubuwa da yawa baya ga girman girgizar ƙasa, ɗayan mafi mahimmanci shine yanayin ƙasa.  Misali, kauri mai laushi na ƙasa mai laushi (kamar cika) na iya haɓaka raƙuman ruwan girgizar ƙasa, sau da yawa a nesa mai nisa daga tushen.  A lokaci guda, basins na sedimentary sau da yawa za su yi resonate, ƙara tsawon lokacin girgiza.  Wannan shine dalilin da ya sa, a cikin girgizar kasa na Loma Prieta na 1989, gundumar Marina na San Francisco na ɗaya daga cikin wuraren da aka fi lalacewa, ko da yake yana da kusan kilomita 100 (60 mi) daga cibiyar.  Har ila yau, tsarin nazarin halittu yana da mahimmanci, kamar inda raƙuman girgizar ƙasa da ke wucewa a ƙarƙashin ƙarshen ƙarshen San Francisco Bay daga tushen ɓawon burodin Duniya zuwa San Francisco da Oakland.  Irin wannan tasirin ya haifar da igiyoyin girgizar ƙasa tsakanin sauran manyan laifuffuka a yankin.

## Tarihi
Domenico Pignataro ne ya ƙirƙira farkon sauƙi mai sauƙi na tsananin girgizar ƙasa a cikin 1780s.   Ma'aunin ƙarfin farko da ake iya gane shi a ma'anar kalmar zamani, masanin lissafin Jamus Peter Caspar Nikolaus Egen ne ya zana shi a cikin 1828. Duk da haka, taswirar farko na zamani na ƙarfin girgizar ƙasa Robert Mallet, injiniya ɗan Irish ne wanda Kwalejin Imperial, London, ya aiko don yin bincike kan girgizar ƙasa na Disamba 1857 Basilicata da aka fi sani da Girgizar Kasa ta Nea18.  Ma'aunin ƙarfin da aka ɗauka, ma'aunin Rossi-Forel mai daraja 10, an gabatar da shi a ƙarshen ƙarni na 19.  A cikin 1902, masanin ilimin halitta dan Italiya Giuseppe Mercalli, ya kirkiro Scale Mercalli, sabon ma'auni na 12.  An sami ci gaba mai mahimmanci, musamman ta Charles Francis Richter a cikin shekarun 1950, lokacin da (1) aka sami alaƙa tsakanin ƙarfin girgizar ƙasa da haɓakar ƙasa ta Peak (PGA; duba lissafin da Richter ya samo na California).   da (2) an yi ma'anar ƙarfin gine-gine da rarrabuwar su zuwa rukuni (wanda ake kira nau'in gine-gine).  Sa'an nan, an ƙididdige ƙarfin girgizar ƙasa bisa ga girman lalacewar wani nau'in tsarin da aka bayar.  Wannan ya ba da Scale na Mercalli, da ma'aunin MSK-64 na Turai da ya biyo baya, adadi mai ƙima da ke wakiltar raunin irin ginin.   Tun daga wannan lokacin, ana kiran wannan sikelin da Modified Mercalli intensity scale (MMS) kuma kimantawar girgizar ƙasa ta fi dogaro..

Bugu da kari, an haɓaka ƙarin ma'auni mai ƙarfi kuma ana amfani da su a sassa daban-daban na duniya:

## Dubi kuma

* Injiniyancin girgizar ƙasa
* Babban saurin ƙasa
* Ayyukan girgizar ƙasa
* Saurin hasken rana