Frequently Asked Questions (FAQ)

Climatology | Impacts | Extremes| TCs affecting WA towns | Forecast Accuracy
Frequently Asked Questions | Annual summaries

Definitions | Characteristics and Formation | Climatology | Extremes | Forecasting | More Information

Definitions

8. What is the difference between a storm surge and storm tide?

The combination of storm surge and astronomical tide is known as 'storm tide'. The worst impacts occur when the storm surge arrives on top of a high tide. When this happens, the storm tide can reach areas that might otherwise have been safe.

The graphic below shows the actual tide (blue) and the astronomical tide (red) at Exmouth during cyclone Vance (1999). The black line is the storm surge component that peaked at 3.5 metres. At this time the predicted tide was 1.4 metres so the resultant peak storm tide was 4.9 metres. If the peak surge had of occurred at the time of high tide the actual tide would have been 6.0 m or 2.6 metres above the highest astronomical tide (pink line).

Data courtesy of WA Department of Planning and Infrastructure.

What about tsunamis?

A tsunami is a series of ocean waves with very long wavelengths (typically hundreds of kilometres) caused by large-scale disturbances of the ocean, such as:

• earthquakes
• landslide
• volcanic eruptions
• explosions
• meteorites