At 12.51pm on February 22 last year, she was the only CTV employee on the ground floor when the violent quake hit.
"After about seven or eight seconds of shaking, I knew I had to get out of there and I ran to the front door.
"It felt like the building was chasing me as I ran," Mrs Jackson told the royal commission.
"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."
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.
Earlier, a manager at King's Education language school which occupied all of Level 4, told how she survived a three-storey plunge when the concrete office tower collapsed.
Margaret Aydon was lying trapped in the rubble and debris when her phone rang and lit up the darkness.
"It was my husband. I answered it but he couldn't hear me and the line just went dead," she told the hearing.
She was later rescued by some police officers scouring the scene for survivors.
CTV presentation director Tom Hawker had gone to buy lunch with colleague and girlfriend Penelope Spencer and was returning to the building to eat lunch inside the cafeteria when the quake hit.
He stood in front of the building and watched it "shake violently" for about five seconds before it began to come down.
"I saw cracking appear on Level 5 and then this level collapsed first and it sort of pancaked down, which in turn pancaked the rest of the floors below."
Seven other witnesses also gave evidence today, telling the commission how they saw the disaster unfold.
Michael Williams was working on the fourth floor of the Inland Revenue Department building on Cashel St and had an "unobstructed view" of the CTV office block coming down.
He likened its collapse to that of New York's twin towers on September 11, 2001.
Leonard Fortune, who was helping weatherclad the western wall of the CTV building, clung to a cherrypicker-style scissor lift as the quake hit.
He saved his workmate James Askew by grabbing him by his toolbelt and throwing him over the edge of the lift to safety, before leaping clear himself.
As he clambered for safety, Mr Fortune saw a column on the southwest corner, around levels 3 and 4, which had cracked in the middle and was "buckling under the weight".
His boss, Bruce Campbell told of his "surprise" that some masonry blocks were not filled in with concrete, while the horizontal beam and columns on the western wall had been poured approximately 20-40 millimetres out of line with each other.
However, he did not have any concerns about the structural integrity of the columns and beam.
Ex-builder David Bainbridge visited Relationship Services on Level 6 just days before the killer quake, and was so anxious about the cracks and water damage he witnessed that he "could not wait to get out".
The hearing continues tomorrow.
