Earthquake News

Why was the Magnitude 6.3 New Zealand Earthquake so Destructive?

Despite being weaker than the one that shook the area last September, it caused more damage and killed more people, owing to its location.

The magnitude-6.3 earthquake that struck Christchurch on Tuesday was located around 3 miles from the city center, toppling buildings, killing scores, and trapping others. It was also just approximately 3 miles deep and struck in the middle of the day, when business buildings were bustling with workers.

Seismologist Egill Hauksson of the California Institute of Technology stated the jolt "lies squarely beneath the city itself."
"All of the ancient historic structures are being shook with more force than they were designed to withstand." 

It was classed as an aftershock of the devastating magnitude-7 earthquake that struck on Sept. 4 last year, according to scientists.

Because the quake was centered 30 miles west of the city core, no one was killed in the early morning quake, which was 11 times greater.
It was also twice as strong as the aftershock on Tuesday.
Shallower quakes are much more destructive.

While New Zealand has strong building rules, the September earthquake in Christchurch severely damaged a number of pre-World War II structures, causing landslides in the area. 

Another reason this quake was more fatal was because buildings that had already been compromised by ground shaking were more likely to be damaged or perhaps collapse this time, according to Tom Jordan, the director of the Southern California Earthquake Center.

Experts say several cities on the US West Coast suffer comparable earthquake threats.

According to Robert Yeats, retired professor of geology at Oregon State University, the West Coast's soil is similar to that of New Zealand, which can turn to mush after an earthquake and exacerbate damage caused by shaking. 

"New Zealand's construction codes are among the most innovative in the world.
They are more equipped for an earthquake than many American communities are "In a statement, Yeats stated.

About a half-dozen aftershocks larger than magnitude-5 have jolted Christchurch since September.
The aftershock on Tuesday was the most powerful to date.

"You can get an aftershock months after the primary shock," said U.S. Geological Survey geophysicist Paul Earle of Golden, Colo.
"Just because a few months have passed doesn't rule out the possibility of a huge, destructive earthquake." 

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