A New Zealand inquest starting on Monday will look at why an office block collapsed during February's Christchurch earthquake, killing 106 people, including 65 foreign students.

The Canterbury Television (CTV) building collapsed then burst into flames when a 6.3-magnitude quake hit the country's second largest city on February 22, killing those trapped inside the twisted wreckage.

The structure's failure accounted for more than half the 181 fatalities in New Zealand's deadliest earthquake for 80 years, raising questions about why the country's stringent building codes failed to prevent the carnage.

Since the quake, the CTV building collapse has come to symbolise a tragedy that Prime Minister John Key described as "New Zealand's darkest day".

"It was a place where far too many people have lost their lives"," Key said in the days after the quake.

"The deaths of so many young students from foreign shores was keenly felt in his country. We know that they were entrusted to the people of New Zealand."

Built in the 1980s, the six-storey building housed the King's Education language school. Eight staff and 65 students, predominantly from China and Japan, died in the disaster that razed much of Christchurch's downtown area.

The building's disintegration and subsequent inferno were so destructive that forensic specialists had to use DNA testing to identify the remains of many victims.

In the quake's aftermath, New Zealand promised Japan and China it would "vigorously" probe the collapse of the building, which city engineers had declared safe after another 7.0 quake rocked Christchurch last September.

The three-day inquest is part of that response. It is being held on the outskirts of Christchurch because the city's court buildings remain unusable.

Coroner Gordon Matenga is expected to hear evidence about how the victims died and what caused the structure to crash to the ground when many other office blocks escaped with relatively minor damage.

However, it is unclear whether Matenga will immediately hand down his findings into the tragedy, as two other inquiries are also examining the CTV collapse, including a powerful royal commission.

An earlier inquest heard evidence that some people survived for hours trapped in the building's rubble, a number of whom made mobile phone calls to loved ones, before the flames killed them.

Christchurch city council engineer Steve McCarthy told reporters after the quake that it was impossible for inspectors who viewed the building in the wake of the September tremor to predict the collapse.

He said the February quake, which had an epicentre close to the Earth's surface, created unusual movement that hurled buildings upwards, as well as side-to-side, before dumping them back on the ground with immense force.

"Consequently the buildings have failed, sadly, and it couldn't have been expected and it certainly wasn't designed for," he said.

"Essentially Mother Nature dealt a blow that our buildings were not able to cope with."

The office block was "deconstructed" -- pulled apart piece by piece after the tremor as emergency crews combed the rubble for human remains.

All that remains is an empty site in the heart of the so-called "red zone", the area of the city that bore the brunt of the seismic jolt and remains sealed off because unstable buildings mean it is still too dangerous to enter.

Tweet

Related Links Bringing Order To A World Of Disasters When the Earth Quakes A world of storm and tempest