"It felt like the building was chasing me as I ran," Maryanne Jackson told the royal commission today.
"I ran straight across Madras St. About three quarters of the way across the road, I looked over my shoulder. I could see the building collapsing behind me."
Her graphic evidence came on the second morning of the royal commission of inquiry into the collapse of the six-storey CTV Building on February 22, 2011.
A written statement read out this morning told how Mrs Jackson would run out of the building after every major aftershock following the magnitude 7.1 jolt which sparked the killer Canterbury earthquake sequence.
It was a practice that would save her life.
At 12.51pm on February 22, she was the only CTV employee on the ground floor when the violent quake hit.
She described the sound as "horrific", and as loud as a jet plane.
As the shaking grew more intense, she made the decision run for her life.
"After about seven or eight seconds of shaking, I knew I had to get out of there and I ran to the front door.
"I looked at my handbag but I knew I had no time to get that.
"All the windows started coming in as I was running and I thought the building was going to come down on me as I ran out.
"I hit my head on the side of the door or something hit me as I went through."
She ran across Madras St in Christchurch city centre, and when she crossed the road and turned around, and building had "pancaked, with all six floors down to just rubble".
Mrs Jackson was the only CTV worker inside the building at the time of the quake who survived. A total of 115 people died in the collapse.
"I knew the other staff members who were upstairs on level 2 did not have a chance," she added.
The royal commission, which started the CTV building hearing yesterday with some other remarkable evidence from collapse survivors, is trying to establish what caused the catastrophic failure of the building.
Eleven people will tell the commission later today how they saw the six-storey office block pancaked "almost immediately" in the violent magnitude-6.3 quake.
They will each give their own story in seeing the disaster unfold before their eyes, each offering a different angles and perspectives.
The rest of the week will hear from Urban Search And Rescue workers after the collapse.
The Canterbury Earthquake Royal Commission, chaired by Justice Mark Cooper, will report on the causes of building failure as a result of the earthquakes as well as the legal and best-practice requirements for buildings across New Zealand CBDs.
It has until November 12 to deliver its final report.
