Must-watch video shows a cliff dramatically collapsing into a river in Carlotta, northern California on March 14, creating a mini-tsunami in front of stunned onlookers.

The footage shows debris falling from a cliff face into the Van Duzen River at first. Eventually, large chunks of rock fall into the river below, causing a mini-tsunami and onlookers have to rush to safety.

The intense footage, lasting nearly two minutes, has 6.7 million views on YouTube.

Filmer Maureen Smithey was on a walk not far from her Humboldt home at the time and told Newsflare: "My husband and I were out for a wet morning walk along the banks of the wild and scenic Van Duzen River.

"We noticed that a constant stream of rubble was falling from the cliff face on the far side of the river so we stopped to observe it. I thought it would be a good idea to have a video to share with neighbors in the area of how unstable the cliff was becoming. Plus, the cliff is above my favorite summertime swimming hole so I have a vested interest in how stable or unstable it may be."

She added: "We certainly didn’t expect to capture that huge collapse! We were both so mesmerized watching the collapse that we didn’t notice the water rushing our way until it was just about upon us. My husband hollered, 'It’s time to run!' Which we did. The water engulfed our calves and gave us a heart-pounding few moments but swiftly subsided again. The rain continued all afternoon and we continued to witness more chunks of the cliff falling into the river but nothing like what I captured on my phone.

"The Van Duzen River is a federally designated National Wild and Scenic River. It was named after James Van Duzen who was a member of the Josiah Gregg exploration party that traveled to Humboldt Bay overland in 1849."

Intense clip shows collapsing cliff create mini-tsunami in northern California river: My husband and I were out for a wet morning walk on March 15th along the banks of the wild and scenic Van Duzen River. We noticed that a constant stream of rubble was falling from the cliff face on the far side of the river so we stopped to observe it. I thought it would be a good idea to have a video to share with neighbors in the area of how unstable the cliff was becoming. Plus, the cliff is above my favorite summertime swimming hole so I have a vested interest in how stable or unstable it may be. We certainly didn’t expect to capture that huge collapse! We were both so mesmerized watching the collapse that we didn’t notice the water rushing our way until it was just about upon us. My husband hollered, it’s time to run! Which we did. The water engulfed our calves and gave us a heart pounding few moments but swiftly subsided again. The rain continued all afternoon and we continued to witness more chunks of the cliff falling into the river but nothing like what I captured on my phone. The Van Duzen River is a federally designated National Wild and Scenic River. It was named after James Van Duzen who was a member of the Josiah Gregg exploration party that traveled to Humboldt Bay overland in 1849.