The Portuguese town of Nazaré can deliver 100-foot (30.4 meters) waves.
How can we explain the Nazaré Canyon geomorphologic phenomenon?
In the 16th century, Portuguese people and army protected Nazaré from pirate attacks, in the Promontório do Sítio, the cliff-top area located 110-meter above the beach.
Today, from this unique site, it is possible to watch the power of the Atlantic Ocean. If you face the salt water from the nearby castle, you can easily spot the famous big waves that pump the quiet village.
What are the mechanics of the Nazaré Canyon? Is there a clear explanation for the size of the local waves? First of all, let us underline the most common swell direction in the region: West and Northwest.
A few miles off the coast of Nazaré, there are drastic differences of depth between the continental shelf and the canyon. When swell heads to shore, it is quickly amplified where the two geomorphologic variables meet causing the formation of big waves.
Furthermore, a water current is channeled by the shore – from North to South – in the direction of the incoming waves, additionally contributing to wave height. Nazaré holds the Guinness World Record for the largest wave ever surfed.
In conclusion, the difference of depths increase wave height, the canyon increases and converges the swell and the local water current helps building the biggest wave in the world. Add a perfect wind speed and direction and welcome to Nazaré.
The Mechanics of the Nazaré Canyon Wave:
1. Swell refraction: difference of depths between the continental shelf and the canyon change swell speed and direction;
2. Rapid depth reduction: wave size builds gradually;
3. Converging wave: the wave from the canyon and the wave from the continental shelf meet and form a higher one;
4. Local water channel: a seashore channel drives water towards the incoming waves to increase their height;
a) Wave fronts, b) Head of the Nazaré Canyon, c) Praia do Norte
Article from Surfer Today, surfertoday.com/surfing/8247-the-mechanics-of-the-nazare-canyon-wave
This section from telegraph.co.uk/news/earth/earthnews/10411252/How-a-100-foot-wave-is-created.html
Currents through the canyon combine with swell driven by winds from further out in the Atlantic to create waves that propagate at different speeds.
They converge as the canyon narrows and drive the swell directly towards the lighthouse that sits on the edge of Nazaré.
From the headwall to the coastline, the seabed rises gradually from around 32 feet to become shallow enough for the swell to break. Tidal conditions also help to increase the wave height.
According to Mr McNamara’s website charting the project he has been conducting, the wave produced here are “probably the biggest in all the world” for sandy a sand sea bed.
On Monday the 80 mile an hour winds created by the St Jude’s Atlantic storm whipped up the swell to monstrous proportions, leading to waves of up to 100 feet tall.
The previous day as the storm gathered pace, waves of up to 80 feet high formed and British surfer Andrew Cotton managed to ride one of these.
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