The former superintendent of the Tumbi quarry in Papua New Guinea's Southern Highlands province believes a build-up of water triggered last month's deadly landslide.
The quarry, which is located at the top of the landslide that buried at least 25 people, was used by Exxon Mobil's major Liquefied Natural Gas project.
Kevin Munday managed the quarry until it closed last September.
He denies local claims that explosives were used at the site, but says another nearby quarry did use explosives.
Mr Munday says the part of the Tumbi quarry which was lost in the landslide was not the part which his team had been excavating.
"At the bottom of the quarry there, at the old excavation area, there's two massive rivers that flow out of that old quarry face, and what I believe has happened is that prior to the landslide giving way, those two rivers have been blocked somehow, whether it's caused by the blast or a natural ground movement or whatever... What I believe has happened is those waterways have been blocked in some shape or form; the water's built up behind there and just finally given way, how water does."