According to University of Washington geologist and tsunami expert Jody Bourgeois, the idea that chevrons – a type of large U- or V-shaped formations found along certain coasts – were caused by mega-tsunamis is pure nonsense.

The term chevron refers a special type of vast dunes shaped a bit like the stripes on soldier’s uniform. They can be anything from hundreds of meters to a kilometre in length and can be seen in places such as Egypt, the Bahamas, Madagascar, and Australia.

Some scientists have suggested that a possible explanation for these mysterious stripes is mega-tsunamis caused by asteroid or comet impact. According to this school of thought, the chevrons may be deposits left by gigantic tsunamis 4,800 to 5,000 years ago, tsunamis that might have been up to 10 times larger than the earthquake-caused Indian Ocean tsunami of December 2005. Due to the location of known chevrons, the Indian Ocean has been suggested as ground zero for the comet or asteroid impact.

Bourgeois, a professor of Earth and space sciences who has studied earthquakes and tsunamis in various parts of the world, does not agree. According her, the chevrons are not lined up the way you would expect from deposits caused by gigantic waves. Many of the chevrons on Madagascar are for instance parallel to the coastline, instead of perpendicular to the shore.

Models created by Bourgeois’ colleague Robert Weiss, assistant professor of geology at

Texas A&M University, show that deposits formed by gigantic tsunamis would point in the same direction as the waves were travelling when the reached land, which is mostly perpendicular to the shore.

“And if it really was from an impact, you should find evidence on the coast of Africa too, since it is so near,” Bourgeois explains.

The computer model generated actual conditions for a tsunami which made it possible to use the model to explore the effects of an asteroid or comet hitting the part of the Indian Ocean suggested by mega-tsunami chevron proponents. According to the model, the gigantic waves would approach land at a 90-degree orientation to the chevron deposits.

“The model shows such a tsunami could not have created these chevrons, unless you have some unimaginable process at work,” Bourgeois says.

Bourgeois and Weiss have used satellite images from Google Earth to get close-up looks at chevrons in different locations. Chevron are most common in coastal regions but you can find quite a lot of them in semiarid inland areas as well.

Bourgeois and Weiss wrap up their paper, which can be found in the May issue of the journal Geology, by stating that “the extraordinary claim of ‘chevron’ genesis by megatsunamis cannot withstand simple but rigorous testing. […] There are the same forms in the Palouse in eastern Washington state, and those are clearly not from a tsunami.”

Thanks to the efforts of local resident Pak Dodent, coral destroyed around Sumatra by the 2004 tsunami is now making a remarkably recovery.

Dodent lives on the island of Pulau Wey off the north coast of Sumatra and the narrow channel between his small village Ibioh and a nearby island was particularly devastated by the enormous forces unleashed by the tsunami.

“It was like a washing machine out there and all of the coral was broken,” Dodent explained to a reporter from the Telegraph. Afterwards I thought to myself what can I do to make the coral grow again and I started to experiment.“

After some experimentation, Dodent decided to aid the corals by dropping concrete mounds over the sandy bottom, since reef building corals need a suitable surface to attach them selves to. He creates the concrete mounds by pouring concrete into a bucket, and he also embeds a plastic bottle or tube into the concrete so that a part of the plastic sticks up.

When the concrete is set, the devoted reef gardener drops his mounds by boat in the shallow waters near the beach and leaves them there for a month to allow any potentially harmful chemicals present in the concrete to dissipate. After that, he carefully begins to transplant corals to the mounds by harvesting small patches of corals from the healthy reef on the far side of the island. “I am careful to only take a little from here and there so that I don’t affect the healthy eco system”, says Dodent.

Dodent uses cable ties to attach the transplants to the plastic bottles and tubes to prevent the corals from being dislocated by water movements.

Almost four years after the tsunami, Dodent’s coral garden is now covered with coral and has attracted an abundance of fishes and other animals. The coral is thriving and there is virtually impossible to the underlying concrete mounds. The garden currently comprises over 200 square metres and is home to over 25 different species of coral.

To prevent algae from overgrowing the new coral and killing it, Dodent regularly cleans infested coral patches with a toothbrush, but fishes and other coral eating organisms will soon alleviate him of this task. “I monitor and clean it for one year, after that it is up to the fishes,” he says.

Dodent has now recently received a small grant from Fauna and Flora International to develop his project.