地震作文：What is earthquake?

详细内容

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anearthquakeistheresultofasuddenreleaseofenergyintheearth'scrustthatcreatesseismicwaves(地震波).earthquakesarerecordedwithaseismometer(地震检波器),alsoknownasaseismograph(地震仪).themomentmagnitudeofanearthquakeisconventionallyreported,ortherelatedandmostlyobsoleterichtermagnitude(里氏量级),withmagnitude3orlowerearthquakesbeingmostlyimperceptible感觉不到的andmagnitude7causingseriousdamageoverlargeareas.intensityofshakingismeasuredonthemodifiedmercalliscale(麦加利震级,麦氏震级).

attheearth'ssurface,earthquakesmanifestthemselvesbyashakingandsometimesdisplacement(位移)oftheground.whenalargeearthquakeepicenter(震中)islocatedoffshore,theseabedsometimessufferssufficientdisplacementtocauseatsunami(海啸).theshakinginearthquakescanalsotriggerlandslidesandoasionallyvolcanicactivity.

initsmostgenericsense,thewordearthquakeisusedtodescribeanyseismicevent—whetheranaturalphenomenonoraneventcausedbyhumans—thatgeneratesseismicwaves.earthquakesarecausedmostlybyrupture(破裂,裂开)ofgeologicalfaults(断层),butalsobyvolcanicactivity,landslides,mineblasts,andnuclearexperiments.

anearthquake'spointofinitialruptureiscalleditsfocusorhypocenter.thetermepicentermeansthepointatgroundleveldirectlyabovethis.