A report into a landslide in Albany has recommended the demolition of two homes and a more detailed investigation into the root cause of the slide. 

The Mira Mar hillside has dropped by more than 3 metres in some areas in recent months leading to evacuation orders on six properties with two on Sleeman Avenue on the brink of collapse.

A state government-commissioned geotechnical report into the situation was tabled in parliament today, coming as residents and authorities remain locked in a battle over what caused the incident.

Some residents blame a burst water main on Sleeman Avenue on July 30, which Water Corporation flatly rejected.

The water authority and the City of Albany have blamed high winter rainfalls, however, the report said further "detailed geotechnical investigation" and "detailed forensic study of the root causes of the landslide" were needed.

Demolitions, further investigation needed

The preliminary assessment included five recommendations.

The report by CMW Geosciences recommended the demolition of 10 and 12 Sleeman Avenue due to hazard concerns.

It also recommended improvements to security and signage at the site to prevent access to what it described as "very high risk to people traversing the landslide".

The report also recommended further detailed geotechnical investigation into the landslide, its current stability, sensitivity to changes, and potential to enlarge.

Further recommendations included aerial surveying of the hillside and installation of more dewatering wells.

The report revealed the slide created "subsurface cavities and voids" that without mediation could form sinkholes creating further hazards.

Movement in the area was first confirmed in 2013 due to rainwater ingress into uphill cracks, with the report concluding that some features of that event coincided with the most recent slide and it was "likely the 2021 landslide is a reactivation, albeit larger than earlier landslide".

Cause of the landslide still not known

A petition calling on Water Corporation and Water Minister Dave Kelly to take responsibility for the landslide was launched by some residents this week.

However, the report said further investigation was required and the scope of the study did not include forensic assessment into the "root cause of the landslide".

The report said increased rainfall in recent weeks had coincided with the landslide movement accelerating.

"This however does not necessarily signify that rainfall is the primary initiation mechanism of the landslide," it read.

Some residents on Anzac Road have shifted encroaching earth and boulders from their properties, but the report said "it should be noted that excavating into a toe of a landslide has a significant risk of causing the landslide to accelerate".