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For a comparatively small temblor , the aftershock that struck New Zealand today ( Feb. 22 ) packed a deadly biff .
Theearthquakemeasured only magnitude 6.3 but killed at least 65 people and destroyed buildings across the southeast city of Christchurch — an important lesson to cities that face similar risks up and down the West Coast of North America , one expert say .
An aerial view of Christchurch, New Zealand, where a magnitude 6.3 earthquake struck Feb. 22.
" The same characteristic that caused such death and so many deaths in Christchurch are like to those confront Portland , Seattle , region of the Bay Area and many other West Coast city and towns , " Robert Yeats , a prof emeritus of geology at Oregon State University in Corvallis , say in a assertion .
Today ’s temblor was an aftershock of the much more powerful 7.0 - order of magnitude earthquake that struck about 25 miles ( 40 kilometers ) Occident of Christchurch last September , according to the U.S. Geological Survey . That earlier earthquake did not result in any fatalities , however .
Different place , similar risks
An aerial view of Christchurch, New Zealand, where a magnitude 6.3 earthquake struck Feb. 22.
Even though today ’s earthquake was weaker than last year ’s , it was much shallower and directly under Christchurch ; it also polish off during the luncheon hr , when more masses were debunk to scathe . The earthquake shook sediments that were prone to so - call liquefaction , which can enlarge the damage done by the dry land shake .
W. B. Yeats said that same verbal description fit out many major cities and towns in Washington country , Oregon and California , as well as British Columbia , Canada .
" The latest New Zealand quake hit an area that was n’t even know to have a geological fault prior to last September ; it ’s one that had not impress in thou of years , " Yeats tell . " But when you combine the shallow depth , propinquity to a major city and soil characteristic , it was up to of immense scathe . "
William Butler Yeats bestow , " It ’s deserving keep in mind that New Zealand has some of the most reform-minded building code in the humankind . They are better prepared for an earthquake like this than many U.S. cities would be . "
The risks from shallow " crustal faults , " Yeats said , are often given less attending than the business about themajor subduction zone seism that are in the Pacific Northwest ’s future , or other major seism on famed collection plate boundaries such as the San Andreas Fault . There are tons or hundred of shallow faults that can cause serious earthquakes in the West , Yeats say .
Liquid soil
Among the danger is therisk of liquefaction — the characteristic of some stain , particularly sediments deposited over long periods of time , to become saturated with water and quiver like a bowl of gelatin during an temblor . Such motility can importantly increase building damage and loss of life .
" Much of the Willamette Valley in Oregon is a prime example of soil that could liquidize , old sediment deposited during flood and number down from the Cascade Range , " Yeats state . " It ’s very similar in that sensory faculty to the area around Christchurch , which sits on sand , silt and gravel from the Southern Alps to the west .
" This issue , along with the risks posed by crustal faults , has to be considered in our construction code . "
Unknown break
The city of Portland , Ore. , sits astride the Portland Hills Fault — which may or may not still be active — and face important liquefaction concerns in many field . Seattle face similar risks from the Seattle Fault , which is combat-ready . And whether or not an earthquake has happened lately offers short reassurance — the New Zealand error that just crippled Christchurch had n’t motivate in millennia .
" The damage in New Zealand in the past day has been terrible , just frightful , " Yeats said . " But as big as it has been , it ’s deserving noting that it could have been a muckle worse . In the earliest quake , as well as this one , their building code have saved a lot of lives . If the same type of event had fall out in urban area of many develop nations , the damage would have been catastrophic . "
Like much of the West Coast , Yeats say , New Zealand sits near a major boundary of the Earth ’s great plates — in this case , the join of the Australia Plate and the Pacific Plate . Despite intensive seismic study in that nation , no one had yet identified the related to fault that just devastate Christchurch .
" We can learn about earthquakes and help mass translate the seismal jeopardy they face , " Yeats said . " But it ’s still an inexact skill , the exact timing of an earthquake can not be predicted , and the best thing we can do is prepare for these events before they bechance . "
This narration was provided byOurAmazingPlanet , a babe site to LiveScience .
