The latest work to go on show at Tate Modern, in London, has depth. It also has considerable length.

A 548ft fissure (167m) has been installed the length of the Turbine Hall, starting as a hairline crack in the concrete floor and widening to a few inches in breadth and a depth of perhaps 2ft. Neither the artist, Doris Salcedo, from Colombia, nor the Tate management would say yesterday exactly how it had been created.

The gallery declined to disclose whether Salcedo had drilled down into the floor or whether the crack had been created by digging into a “false” floor that sits on top of the original.

A spokeswoman said that Shibboleth had been created by the artist “opening up the floor” and inserting a concrete cast of a Colombian rockface. “She’s not specifying how it’s been done. What she wants is for people to think about what’s real and what’s not,” the spokeswoman said.

According to the artist – whose previous works have included filling a wardrobe with cement “to suggest the violation of domestic space and the human body” – it is a statement about racism, with the crack representing the gap between white Europeans and the rest of humanity.

The work has health and safety implications for Tate Modern. Staff are on hand at the front door to advise visitors on the potential danger that they may trip over a work of art.

They will be handed a leaflet that reads: “Warning. Please watch your step in the Turbine Hall. Please keep children under supervision.”

Salcedo said of Shibboleth: “It represents borders, the experience of immigrants, the experience of segregation, the experience of racial hatred.

“It is the experience of a Third World person coming into the heart of Europe. For example, the space which illegal immigrants occupy is a negative space. And so this piece is a negative space.”

Salcedo’s previous works have involved filling a derelict building in Istanbul with 1,550 chairs to evoke the faceless migrants who underpin our globalised economy, and tying two bedsteads together with animal intestines.

As for the new work, “it clearly represents a tear in the fabric of society”, said one visitor, Robyn Menzel, a teacher from Australia. “But my husband would look at it and say, ‘It’s just a crack’.”

Christine Beluriee, a market researcher from Paris, likened the work to “the frontier between a lot of things – between modern life and ancient life, the young and the elderly, ugliness and beauty”.

John Knights, a photo-illustrator who lives near the gallery, which is on the South Bank, remarked: “I rather liked the floor as it was. I’m not overly impressed.”

Achim Borchardt-Hume, the Tate’s curator, said: “It is so important for the work not to focus on the making and how it got here.”

Sir Nicholas Serota, the Tate director, said: “There is a crack, there is a line, and eventually there will be a scar. It will remain as a memory of the work and also as a memorial to the issues Doris touches on.”

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