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 and EMO2 apply to hinterland areas, generally from Arthurs Seat southwards to Cape Shank 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. 

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:

• High (red) – Areas where significant landslides are possible
• Medium (yellow) – Areas where significant landslides are unlikely, but where creep movement or shallow slope failure is possible
• Low (green) – Areas unlikely to be susceptible to landslides

The Landslide Susceptibility Assessment, Stage 2, Mornington Peninsula Shire, Victoria (Cardno Lane Piper, 2012) used LIDAR data to calculate the slope-angle on a 2m-by-2m grid across the entire Shire. Slope-angle was a key input in determining the grading (high, medium, or low) of landslide susceptibility. 

Because the slope-angle has been calculated at such a fine-grain scale, the mapping has picked up many small, localised slopes and other man-made structures and earthworks. 

If your property is affected by a small, localised area of ‘red’ landslide susceptibility, and is now included in EMO7 as a result of Planning Scheme Amendment C312morn, it is quite possible it may be removed from EMO7 as a result of Stage 2 of Council’s planned update to our landslide planning controls. 

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 landslide susceptibility mapping is currently the best available data and is being reviewed as part of future planning scheme amendments (discussed below).

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: erosion@mornpen.vic.gov.au

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 landslide susceptibility areas - (Complete)

At the 17 November 2025 Council Meeting, Council resolved to request that the Minister for Planning approve planning scheme Amendment C312morn, which seeks to apply an interim EMO over high landslide susceptibility areas that are not already covered by an existing EMO. You can read more at Amendment C312morn – Highly susceptible landslide areas.

The Minister has approved Amendment C312morn and EMO7 is now formally included in the planning scheme. The EMO7 took effect when notice of the Minister’s approval of the amendment was published in the Government Gazette on 6 January 2026.

You can download copies of the amendment documents from the state government website for the amendment here:

Mornington Peninsula Planning Scheme - Amendments

This is a ‘Ministerial amendment’, 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.  

The interim EMO7 will apply until a permanent EMO is introduced to these areas (see Stage 3).

Stage 2: Geotechnical and planning review of existing EMOs including EMO7 - (Underway)

Council is working with geotechnical and planning specialists to review and refine the Shire’s existing EMOs, including EMO7 as implemented by C312morn (Stage 1). Council will consider another planning scheme amendment to implement Stage 2 of our update to our landslide planning controls in mid-2026. 

While it is expected that many small, localised areas of EMO7 may be removed from the planning scheme as part of Stage 2, some portions of ‘medium’ landslide susceptibility may also be proposed to be included in EMO7, or another EMO, based on improvements to the methodology to the mapping algorithm for determining landslide susceptibility.

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:

1. Council drafts the EMO mapping and planning controls
2. The Minister for Planning authorises Council to prepare the planning scheme amendment
3. Council puts the proposed EMO planning scheme amendment on public exhibition so anyone can make submissions about whether they support the EMO or want any changes made
4. Council reviews all submissions and likely refers them to a Planning Panel appointed by the Minister for Planning for independent review
5. The Planning Panel holds a public hearing and prepares a report for Council with findings and recommendations
6. Council reviews the Panel report and decides whether to adopt the EMO amendment with or without changes recommended by the Panel
7. If Council wishes to proceed with the EMO amendment, Council submits the adopted EMO amendment to the Minister for Planning
8. The Minister for Planning decides whether to approve the EMO amendment
9. If the Minister for Planning approves the amendment, the planning scheme is updated and the new EMO mapping and controls come into operation.

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 via email with your property address in the subject line: erosion@mornpen.vic.gov.au

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 that you will need to engage a suitably qualified and experienced geotechnical engineer or engineering geologist, who will inform the documentation requirements.

A landslide risk assessment (LRA) report will be required in many instances. The LRA will be specific to your land and will ensure 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, but this must be guided by a suitably qualified and experienced geotechnical engineer or engineering geologist.

Importantly, Council can vary or lessen these requirements if they are not relevant to the assessment of an application.

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 assessment as required under an EMO when most types of development are proposed).

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 one of:

• Chartered Professional Engineer (CPEng)
• Registered Professional Engineer, Victoria (meaning a person who is registered under Part 2 of the Victorian Professional Engineers Registration Act 2019)
• Chartered Professional Geologist (CPGeo)
• 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: South East Water | Faults and Works