Jerin girgizar ƙasa a California

Jerin girgizar ƙasa a California
jerin maƙaloli na Wikimedia
Bayanai
Bangare na	Jerin girgizar ƙasa da tsunami a Amurka

Taswirar haɗarin girgizar ƙasa mai yiwuwa

Girgizar ƙasa ta farko da aka sani a jihar California ta Amurka an rubuta ta ne a cikin 1769 ta hanyar masu binciken Mutanen Espanya da mishaneri na Katolika na balaguron Portolá yayin da suke tafiya zuwa arewa daga San Diego tare da Kogin Santa Ana kusa da shafin Los Angeles na yanzu. Shugabannin jiragen ruwa da sauran masu bincike sun kuma rubuta girgizar kasa. Kamar yadda aka gina Ayyukan Mutanen Espanya tun daga ƙarshen karni na 18, an adana bayanan girgizar ƙasa. Bayan an lalata ayyukan a cikin 1834, rubuce-rubuce sun kasance kaɗan har zuwa lokacin da aka fara samun zinariya a California a cikin shekarun 1840. Daga 1850 zuwa 2004, akwai game da wani abu mai yuwuwa a kowace shekara a matsakaici, kodayake da yawa daga cikin waɗannan ba su haifar da mummunan sakamako ko asarar rai ba.

Tun da girgizar asa guda uku da ta faru a tsakiyar Yammacin Amurka da Gabas ta Gabas ta Amurka (1755 Cape Ann, 1811-1812 New Madrid, 1886 Charleston) sun kasance sananne, ya bayyana ga mazauna cewa haɗarin girgizar ƙasa ya bambanta a California.  Yayin da 1812 San Juan Capistrano, 1857 Fort Tejon, da 1872 Owens Valley girgiza sun kasance a mafi yawan yankunan da ba a cika su ba kuma kawai suna da lalacewa, abin da ya faru na Hayward na 1868 ya shafi tattalin arziki na San Francisco Bay Area, tare da lalacewa daga Santa Rosa a arewa zuwa Santa Cruz a kudu.  A wannan lokacin, masana kimiyya sun san wannan barazanar da kyau, amma ilimin kimiyyar ƙasa yana cikin ƙuruciya.  Biyo bayan girgizar ƙasa mai lalacewa a ƙarshen 19th da farkon ƙarni na 20, masu haɓaka gidaje, latsawa, da masu haɓakawa sun rage tare da rage haɗarin girgizar ƙasa saboda fargabar cewa haɓakar tattalin arziƙin da ke gudana za a yi mummunan tasiri.

Girgizar ƙasa ta California (1769-2000)

A cewar masanin girgizar kasa Charles Richter, girgizar kasa ta San Francisco ta 1906 ta sa gwamnatin Amurka ta amince da matsalar. Kafin wannan, babu wata hukuma da ta mayar da hankali musamman kan binciken ayyukan girgizar kasa. Ofishin Yanayi na Amurka ya yi rikodin lokacin da suka faru kuma wasu masana kimiyyar binciken ƙasa na Amurka sun ɗan yi watsi da ayyukansu na yau da kullun na taswirar albarkatun ma'adinai don rubuta rahotanni game da abubuwan da suka faru na New Madrid da Charleston, amma babu wani ƙwararrun masanin ilimin ƙasa da ke aiki akan matsalar har sai bayan 1906 lokacin da Amurka Coast Coast da Geodetic Survey aka sanya alhakin. Hankalin ya inganta lokacin da Farfesa Andrew Lawson ya kawo shirin sa ido na farko na jihar a kan layi a Jami'ar California, Berkeley a cikin 1910 tare da masanin kimiyyar girgizar kasa Harry Wood, wanda daga baya ya taka rawa wajen samun dakin gwaje-gwaje na Seismological Caltech a Pasadena a cikin 1920s..

Abubuwan da suka faru na farko a dakin gwaje-gwaje na Caltech sun haɗa da cibiyar lura da girgizar ƙasa ta amfani da ma'aunin girgizar kasa na ɗan gajeren lokaci, sikelin Richter, da sikelin ƙarfin Mercalli mai canzawa (wani sabuntawa na sikelin ƙarfin mercalli). A cikin 1933, Girgizar kasa ta Long Beach ta faru a cikin wani yanki mai yawan jama'a kuma ta lalata ko lalata gine-ginen makarantun jama'a da yawa a Long Beach da Los Angeles. Bayan 'yan shekarun da suka gabata, Girgizar kasa ta San Fernando ta shafi Kwarin San Fernando a arewacin Los Angeles tare da mummunar lalacewa ga asibitoci da yawa. A lokuta biyu, ra'ayi na masu tsara manufofin California ya canza, kuma an canza dokokin jihohi da lambobin gini (tare da muhawara mai yawa) don buƙatar gina kadarorin kasuwanci da na zama don tsayayya da girgizar ƙasa. An kafa ka'idoji mafi girma don tashoshin wuta, asibitoci, da makarantu, kuma an ƙuntata gina gidaje kusa da kuskuren aiki.

Yanayin tectonic

A cikin Shekaru miliyan 66 da suka gabata, kusan dukkanin gabar yammacin Arewacin Amurka sun mamaye yankin subduction, tare da farantin Farallon da ke ƙarƙashin Farantin Arewacin Amurka. A halin yanzu, farantin Juan de Fuca (tare da farantin tauraron dan adam na Explorer da Gorda) da farantin Rivera da Cocos sune kawai ragowar farantin Farallon da ya Mai Girma. Yankin farantin da ya kasance a California shine na San Andreas Fault (SAF), iyakar farantin Pacific-North American wanda ya kai gabas zuwa Lardin Basin da Range na gabashin California da yammacin Nevada (wani yanki mai aiki da girgizar ƙasa da ake kira Walker Lane) da kudu maso yamma zuwa yankin California Continental Borderland daga tsakiyar da kudancin gabar teku. Wannan tsarin kuskuren ya ƙare a arewa a mahaɗar uku ta Mendocino, ɗaya daga cikin yankuna masu yawan girgizar ƙasa a cikin jihar, inda girgizar kasa a wasu lokuta sakamakon lalacewar intraplate ne a cikin farantin Gorda. Ya ƙare a kudu a Tekun Salton inda motsi ya sauya zuwa jerin Cibiyoyin yadawa da canza kuskuren, farawa da yankin Brawley a cikin kwarin Imperial.

A cikin Yankin San Francisco Bay, tsarin laifuffuka na San Andreas ya ta'allaka ne a cikin teku da kuma yankin Gabashin Bay, tare da mafi yawan laifuffukan suna kwance a gabas na babban laifin San Andreas (SAF). Akwai yuwuwar kashi 70 cikin ɗari cewa ɗaya daga cikin waɗannan kurakuran zai haifar da girgizar ƙasa mai karfin Mw 6.7 ko mafi girma kafin 2030, gami da yankin Hayward Fault Zone, wanda ya wuce matsakaicin lokacin dawowar sa na shekaru 130 (shekaru 156 da suka gabata kamar na Agusta 2025). Yayin da SAF ke da shiru a arewacin San Francisco, sashin tsakiya na SAF kusa da San Juan Bautista shine inda aka fara nazarin raƙuman ruwa, kuma a kudu shine inda girgizar ƙasa ta Parkfield ke faruwa. Laifi na biyu sun kasance zuwa yamma na babban SAF a matsanancin yanki na kudu, gami da yankin San Jacinto Fault mai aiki da matasa, wanda maiyuwa ne zai mamaye a matsayin babban kan iyaka kudu da Cajon Pass. Wani bincike na paleoseismic ta amfani da Lidar ya nuna cewa sama da ƙafa 16 (5 m) na zamewa sun taru tun a shekarar 1857 a kudancin SAF, wanda ke iyaka da Hamadar Mojave zuwa arewa da gabas na Babban Yankin Los Angeles. Kusa da Matsakaicin Matsakaicin, kurakuran juyawa da tuƙi sun haifar da girgizar ƙasa mai lahani a Santa Barbara da Kwarin San Fernando..

Girgizar ƙasa da aka sani

Date	Name	Area	Mag.	MMI	Deaths	Injuries	Total damage	Notes
2022-12-20	Ferndale	North Coast	6.4 Mw	VIII	2	17
2019-07-05	Ridgecrest	Eastern	7.1 Mw	IX		5	$5.3bn	Doublet
2019-07-04	Ridgecrest	Eastern	6.4 Mw	VIII	1	20	$5.3bn	Doublet
2014-08-24	South Napa	North Bay	6.0 Mw	VIII	1	~200	$362M–$1bn
2014-03-28	La Habra	LA Area	5.1 Mw	VII		Few	$10.8M
2010-04-04	Baja California	Baja California	7.2 Mw	VII	2–4	100–233	$1.15bn
2010-01-09	Eureka	North Coast	6.5 Mw	VII		35	$21.8–43M
2008-07-29	Chino Hills	LA Area	5.4 Mw	VI		8	Limited
2007-10-30	Alum Rock	Bay Area	5.6 Mw	VI			Limited
2003-12-22	San Simeon	Central Coast	6.6 Mw	VIII	2	40	$250–300M
2000-09-03	Yountville	North Bay	5.0 Mw	VII		41	$10–50M
1999-10-16	Hector Mine	Eastern	7.1 Mw	VII		4–5	Limited
1994-01-17	Northridge	LA Area	6.7 Mw	IX	57	8,700+	$13–40bn
1992-06-28	Big Bear	Inland Empire	6.5 Mw	VIII		63	More than $60M	Triggered
1992-06-28	Landers	Inland Empire	7.3 Mw	IX	3	400+	$92M
1992-04-26	Cape Mendocino	North Coast	6.6 Mw	VIII			Some	Triggered
1992-04-26	Cape Mendocino	North Coast	6.5 Mw	VIII			Some	Triggered
1992-04-25	Cape Mendocino	North Coast	7.2 Mw	IX		98–356	$48–75M	Tsunami
1992-04-22	Joshua Tree	Inland Empire	6.3 Ms	VII		32	Light–moderate
1991-06-28	Sierra Madre	LA Area	5.6 Mw	VII	2	100–107	$34–40M
1990-02-28	Upland	LA Area	5.7 Mw	VII		30	$12.7M
1989-10-17	Loma Prieta	Santa Cruz Mts	6.9 Mw	IX	63	3,757	$5.6–6bn	Tsunami
1989-08-08	Loma Prieta	Santa Cruz Mts	5.4 ML	VII	1		Minor
1987-11-24	Elmore Ranch	Imperial Valley	6.5 Mw	VIII	2	90+		Triggered
1987-11-23	Superstition Hills	Imperial Valley	6.1 Mw	VIII			$3M
1987-10-01	Whittier	LA Area	5.9 Mw	VIII	8	200	$213–358M
1986-07-21	Chalfant Valley	Eastern	6.2 Mw	VI		2	$2.7M	Sequence
1986-07-13	Oceanside	South Coast	5.8 Mw	VI		1	$700k
1986-07-08	N. Palm Springs	Inland Empire	6.0 Mw	VII		29–40	$4.5–6M
1984-04-24	Morgan Hill	South Bay	6.2 Mw	VIII		21–27	$7.5–8M
1983-05-02	Coalinga	Central Valley	6.2 Mw	VIII		94	$10M
1981-04-26	Westmorland	Imperial Valley	5.9 Mw	VII			$1–3M
1980-11-08	Eureka	North Coast	7.3 Mw	VII		6	$2–2.75M
1980-05-25	Mammoth Lakes	Eastern	6.2 Mw	VII		9	$1.5M	Swarm
1980-01-26	Livermore	East Bay	5.4 Mw	VII				Doublet
1980-01-24	Livermore	East Bay	5.8 Mw	VII			$11.5M	Doublet
1979-10-15	Imperial Valley	Imperial Valley	6.4 Mw	IX		91	$30M
1979-08-06	Coyote Lake	South Bay	5.7 Mw	VII		16	$500k
1978-08-13	Santa Barbara	Central Coast	5.8 Mw	VII		65	$12M
1975-08-01	Butte County	Butte County	5.7 ML	VIII		10	$3M
1973-02-21	Point Mugu	South Coast	5.8 Mw	VII		Several	$1M
1971-02-09	San Fernando	LA Area	6.6 Mw	XI	58–65	200–2,000	$505–553M
1969-10-01	Santa Rosa	North Bay	5.7 Mw	VIII				Doublet
1969-10-01	Santa Rosa	North Bay	5.6 Mw	VII	1		$8.35M	Doublet
1968-04-08	Borrego Mtn	Imperial Valley	6.5 Mw	VII			Some	Rockslides
1957-03-22	San Francisco	Bay Area	5.7 Mw	VII	1	40	$1M
1954-12-21	Eureka	North Coast	6.5 ML	VII	1	Several	$2.1M
1952-08-22	Kern County	Central Valley	5.8 Mw	VIII	2	Several	$10M
1952-07-21	Kern County	Central Valley	7.3 Mw	XI	12	Hundreds	$60M
1948-12-04	Desert Hot Springs	Inland Empire	6.4 Mw	VII		Several	Minor
1941-11-14	Torrance–Gardena	LA Area	5.4 Ms	VIII			$1.1M
1941-06-30	Santa Barbara	Central Coast	5.9 Mw	VIII			$100k
1940-05-18	El Centro	Imperial Valley	6.9 Mw	X	9	20	$6M
1933-03-10	Long Beach	South Coast	6.4 Mw	VIII	115–120		$40M
1932-06-06	Eureka	North Coast	6.4 Mw	VIII	1	3	Severe
1927-11-04	Lompoc	Central Coast	7.3 Mw				Moderate	Tsunami
1925-06-29	Santa Barbara	Central Coast	6.8 Mw	IX	13		$8M
1923-01-22	Humboldt County	North Coast	7.2 Ms				Severe	Tsunami
1920-06-21	Inglewood	LA Area	4.9 ML	VIII			More than $100k
1918-04-21	San Jacinto	Inland Empire	6.7 Mw	IX	1	Several	$200k
1915-06-22	Imperial Valley	Imperial Valley	5.5 Mw	VIII	6		$900k	Doublet
1906-04-18	San Francisco	Northern–Central	7.9 Mw	XI	700–3,000+			Conflagration / tsunami
1899-12-25	San Jacinto	Inland Empire	6.7 Mw	IX	6		$50k or more
1898-03-30	Mare Island	North Bay	5.8–6.4 Mw	VIII–IX			$350k
1892-04-21	Vacaville–Winters	Central Valley	6.2 MLa	IX				Doublet
1892-04-19	Vacaville–Winters	North Bay	6.4 MLa	IX	1		$225–250k	Doublet
1892-02-23	Laguna Salada	Baja California	7.1–7.2 Mw	VIII			Moderate
1873-11-23	Crescent City	North Coast	6.7 MLa	VIII			Some	Ground cracks
1872-03-26	Owens Valley	Eastern	7.4–7.9 Mw	X	27	56	$250k
1868-10-21	Hayward	Bay Area	6.3–6.7 Mw	IX	30		$350k
1865-10-08	Santa Cruz Mts	Santa Cruz Mts	6.3 MLa	VIII			$500k
1857-01-09	Fort Tejon	Central–Southern	7.9 Mw	IX	2		Severe
1838-06-??	San Andreas	Bay Area	6.8–7.2 Mw	VIII			Minor
1812-12-21	Ventura	Central Coast	7.1 MLa	VIII	1			Tsunami
1812-12-08	San Juan Capistrano	South Coast	6.9–7.5	VII–IX	40		Moderate
Stover & Coffman 1993 uses various seismic scales. Mla is a local magnitude that is equivalent to ML (Richter magnitude scale) and is used for events that occurred prior to the instrumental period. It is based on the area of perceptibility (as presented on isoseismal maps). Mw = moment magnitude scale and Ms = surface wave magnitude. The inclusion criteria for adding events are based on WikiProject Earthquakes' notability essay that was developed for stand alone articles. The principles described are also applicable to lists. In summary, only damaging, injurious, or deadly events should be recorded. k= thousand, M = million, bn = billion