Landslide susceptibility

A landslide is the movement of a mass of rock, debris, or earth down a slope. Sometimes this can be a slow process taking months or years and primarily pose a risk to property and the environment. However, landslides pose a significant risk to the safety of people, especially if they happen quickly.  

Landslides can occur by natural processes but can also be caused or exacerbated by human activity. This makes them difficult to predict and a complex problem to deal with.  

Some of the common natural factors which contribute to landslides include: 

• Geology (including the thickness and type of soil overlying bedrock)
• The slope (steepness) of the land
• Aspect (direction the slope faces)
• Depth of the water table or perched water tables
• Poor drainage of soils
• Soil erosion lost through rain/wind
• Weather events such as intense storms/floods or bushfires and climatic conditions such as drought and rising sea levels. 

Some of the common human induced factors that contribute to landslides include: 

• Buildings and earthworks (including excavation or filling of land and inappropriate design or response to the site conditions)
• Vegetation removal
• Poor drainage of soils or concentration of water as a result of works
• Soil erosion lost through repeated movement of people, animals and vehicles 

Some factors which can trigger a landslide include: 

• Heavy or prolonged rainfall (including from major storms)
• Flooding, and
• Earthquakes  

Landslides are generally more likely to occur where soils are thicker, slope angles are steeper, or the amount of water in the ground is higher. Therefore, the more we can preserve the natural landform, vegetation and drainage, the less susceptible slopes will be to landslide. 

The Shire helps minimise landslide risk in many ways, including through land use and development planning, development engineering, drainage infrastructure maintenance, stormwater and flood management, asset management, coastal planning, capital works and erosion monitoring.  

A part of managing risk is applying planning controls to land that is susceptible to landslides to ensure future development responds appropriately to risk.  

Of the factors above that contribute to landslide risks, there are primarily three (3) that can be controlled by the planning system or used to avoid or control the negative impacts or likelihood of landslides occurring. These are: 

• Buildings and earthworks (including excavation or filling of land)
• Vegetation removal
• Drainage 

While there are many controls in the Mornington Peninsula Planning Scheme which address erosion or landslide risk, the main control is the Erosion Management Overlay (EMO).  

An Erosion Management Overlay (EMO) is a type of planning control that’s applied to land to protect areas prone to erosion, landslip and other land degradation or coastal processes by minimising land disturbance and inappropriate development.  

More information about erosion and landslide planning controls is also available on the Department of Transport and Planning website.

Six different EMOs currently apply to parts of the Peninsula which have been introduced since the 1970s and generally cover areas based on specific geotechnical studies: 

• EMO1 Erosion Prone Slopes applies to the hinterland parts of the Shire in Arthurs Seat, Rosebud, Red Hill, Main Ridge to Flinders, and EMO2 Unstable Slopes affects other parts of Arthurs Seat, Rosebud and Flinders.   
• EMO3 applies to land around Ballar Creek in Mount Eliza.  
•  EMO4 Landslide Susceptibility Area A and EMO5 Landslide Susceptibility Area B apply to land in the around Tanti Creek in Mornington and Flinders township. 
•  EMO6 Erosion Hazard – Beach and Foreshore Areas applies to the Westernport coastline from Somerville to Cape Schanck. 

You can view and download a free planning map and property report that outlines the zones and overlays that apply to your property at the VicPlan website: Visit Planning Maps Online.  

Please note that not all areas of known landslide susceptibility in the Shire are covered by an EMO.  

While there are several existing EMOs on the Peninsula, they don’t yet cover all land that is susceptible to landslides.

More areas susceptible to landslides have been identified in a landslide susceptibility assessment commissioned by Council called the Landslide Susceptibility Assessment, Stage 2, Mornington Peninsula Shire, Victoria (Cardno Lane Piper, 2012)(PDF, 46MB).

This landslide susceptibility assessment identifies areas of high, medium and low landslide susceptibility:  

You can see a map of these landslide susceptibility areas on our interactive Planning map.  

You can search for your address and the map will zoom to that location and display the ‘Landslide susceptibility’.  These will display as red (high), yellow (medium) and green (low).

Please note that this is the best available data and is being reviewed as part of future planning scheme amendments (discussed below). Any feedback or concerns will be taken into consideration through the Stage 3 review of the EMO and requests for changes to this mapping will not be actioned or considered at this stage. 

If you have feedback or concern about the landslide susceptibility mapping that you would like Council to take into consideration as part of the Stage 3 review of the EMO, you can lodge an enquiry via email with your property address in the subject line.  

If your matter relates to an immediate landslide risk, please call emergency services or the Shire on 1300 850 600. 

Council is undertaking a staged approach to applying the EMO to areas on the Peninsula identified on this map as susceptible to landslides that are not currently covered by an EMO.

Stage 1: Interim EMO for high priority, high susceptibility areas 

Council will request the Minister for Planning to apply an interim EMO over high priority, high susceptibility areas. 

The exact amount of land to be covered by the interim EMO in these areas is still being worked out by the Shire.  

It’s therefore likely that the Shire will formally request the Minister to apply the interim EMO to these areas by the end of 2025. 

If the Minister agrees to the Shire's request, the interim EMO will be applied to affected properties through a ‘Ministerial amendment’ to the Mornington Peninsula Planning Scheme.  

A ‘Ministerial amendment’ is a fast-tracked change to a planning scheme made by the Minister in special circumstances where there’s an urgent need. Unlike a regular planning scheme amendment process, there’s no community consultation.  

If approved, the interim EMO will apply until a permanent EMO is introduced to these areas (see Stage 3). Affected landowners will be able to see the new EMO and where it applies in our planning scheme.  

Stage 2: Interim EMO for other high susceptibility and possibly medium susceptibility areas 

Council will apply to the Minister for Planning to apply another interim EMO for all remaining high and possibly medium landslide susceptibility areas. 

Council is working with geotechnical and planning specialists to confirm the exact amount of land to be covered by this interim EMO, but it will be based on the Shire-wide landslide susceptibility mapping: Online Planning Map. 

Due to the complex nature of the mapping, it will take time to refine the interim EMO mapping. It is likely the Shire will make this request to the Minister in early 2026.  

Stage 3: Permanent EMO 

Council is commissioning detailed geotechnical and planning analysis to help prepare permanent EMOs to replace the interim EMOs from Stage 1 and 2 and other existing planning controls relating to erosion and landslip risk.  

This work is complex and is likely to take a couple of years to complete. It will then take at least another couple of years to complete a regular planning scheme amendment process to apply the permanent EMOs.   

The regular amendment process usually involves the following main steps: 

 
You can find out more about the planning scheme amendment process on the Victorian Government’s website.   

If you have feedback or concern about the landslide susceptibility mapping that you would like Council to take into consideration as part of the Stage 3 EMO amendment, you can lodge an enquiry here with your property address in the subject line. 

If your land is covered by an EMO, it’s highly likely that you’ll need a planning permit to construct new buildings or carry out works, including removing trees and vegetation.  

Some exemptions apply, but this will depend on the specific EMO controls applying to your land and what you propose to do.  

Other provisions of the planning scheme, including other overlays may require a planning permit. If unsure, it is best to check with the Statutory Planning team on 5950 1010. 

If you want to construct a building or carry out works and need a planning permit under an EMO, it’s likely you’ll need to provide a landslide risk assessment report from a suitably qualified and experienced geotechnical engineer or engineering geologist.  

A landslide risk assessment is specific to your land and ensures risks are properly identified and managed for the particular ground and slope conditions of your property (which vary widely across the Shire) and the type of development or works you want to do, including the amount of vegetation you may propose to remove.  

Some minor works may not require a full landslide risk assessment. It is best to engage a suitably qualified and experienced geotechnical engineer or engineering geologist. 

As per above, not all land that is prone to erosion or landslide risk is within an EMO. Other controls may apply to your land that control erosion or landslide risks.  

For many years Council has taken a cautious approach. If your land is shown as being highly susceptible to landslides, you may be required to submit a landslide risk assessment, depending on what you propose to do and whether it is likely to increase the risk of landslide occurring as a result, or pose a risk to property or safety.  

Council can request further information from you through the planning permit application process if it considers this to be the case. 

If you would like to confirm this before lodging an application, please contact the Statutory Planning team on 03 5950 1010 or submit a request for a written general enquiry.

You can use the online Planning mapping tool to check the susceptibility of your land. Please note that susceptibility mapping is not a substitute for site-specific investigations and risk assessments. 

If you have any concerns or would like more information about how susceptible your property is to landslides, speak to a suitably qualified geotechnical engineer or engineering geologist with experience in managing slope stability problems and landslide risk. They should be degree qualified, a member of a professional institute and be a:  

• Chartered Professional Engineer (CPEng), or
• Registered Professional Engineer, Victoria (meaning a person who is registered under Part 2 of the Victorian Professional Engineers Registration Act 2019), or 
•  Chartered Professional Geologist (CPGeo), or
• Registered Professional Geologist (RPGeo). 

Some things you can do to help reduce the risk of landslide on your property include: 

• Understand the landslide susceptibility of your property by consulting a qualified and experienced geotechnical engineer for advice.
• Find out whether you need a planning permit before carrying out any buildings or works. 
• Do not carry out any buildings or works without a planning permit if a permit is required.
• Minimise any changes in slope, vegetation, and drainage if you develop your land in accordance with the conditions on your planning permit. 
• Use properly designed and engineered retaining walls of durable materials (steel/concrete).
• Remove any surplus excavated material from your land. 
• Install subsurface drains for water tanks and pools. 
• Direct stormwater runoff to a Legal Point of Discharge. 
• Use modern wastewater treatment if you don’t have access to sewer. 
• Do not build in drainage paths. 
• Mark underground structures like septic tanks or bunkers. 
• Regularly inspect and maintain drains and retaining walls.
• Keep records of work done to your land.
• Contact the Shire or emergency services if you have a safety concern or to report landslides.
• Contact South East Water about any blocked or leaking water mains.