Imagine you are strolling peacefully along the port of Ciutadella, enjoying a sunny day in Menorca. Suddenly, the sea level begins to drop rapidly, leaving boats stranded at the bottom of the harbour. In a matter of minutes, the water returns with surprising force, wreaking havoc in its wake. This phenomenon, known as a rissaga, is one of the most impressive and, at the same time, destructive natural spectacles that can occur on this island.
What is a Rissaga?
Definition and Origin of the Term
A rissaga, also known as a meteotsunami, is a coastal weather phenomenon that causes abrupt and significant variations in sea level. This phenomenon is similar to tsunamis, but instead of being caused by earthquakes, rissagas are caused by changes in atmospheric pressure.
Main Causes
Tsunamis are caused by a combination of atmospheric and oceanic factors:
- Changes in atmospheric pressure: Rapid variations in pressure can generate waves at the sea surface.
- Strong, gusty winds: These winds interact with the sea surface, creating waves that are amplified as they approach the coast.
How Rissaga affects Menorca
Impact on Ciutadella Harbour
The port of Ciutadella in Menorca is particularly susceptible to rissaga due to its geographical configuration. The elongated and narrow shape of the harbour, together with its south-westerly orientation, makes it ideal for the resonance of sea waves generated by pressure changes. During a rissaga, sea levels can fall and rise rapidly, causing flooding and significant damage to vessels and port infrastructure.
Rissagas are more common during certain times of the year, especially in summer, when atmospheric conditions are more favourable for their formation. In Menorca, rissagas can occur several times a year, and historical events have been recorded with oscillations of up to 4 metres.
Last Rissaga in Ciutadella
On 19 June 2024, a significant rissaga affected the port of Ciutadella, with oscillations of more than 1 metre. This event generated concern among residents and local authorities, who issued an orange warning to warn of the risk of swell.
Fortunately, although the swings were significant, no serious damage was reported. However, fishermen and boat owners were on high alert, and precautionary measures were taken to minimise possible damage.
Prevention and Preparedness in the event of a rissaga
The Spanish Meteorological Agency (AEMET) issues warnings when conditions are expected to be favourable for the formation of a rissaga. These warnings allow residents and authorities to prepare adequately to minimise the impacts of these events.
Advice for Boat Owners and Residents
- Preventive actions: It is advisable to secure boats and remove loose objects from the harbour.
- Local resources and support: Local authorities often provide information and assistance during these events to ensure everyone’s safety.
Rissagas, while impressive, can cause significant damage. It is therefore crucial to stay informed and follow the authorities’ recommendations to be prepared for these natural phenomena.
Despite the challenges they present, rissagas are also a reminder of the importance of preparedness.
