|Giovanna formed as a tropical storm over the southern Indian Ocean on February 9 [NASA]
A category four cyclone has struck Madagascar's eastern shores, killing at least one person and causing power shutdowns in some major towns, local authorities say.
In the eastern port city of Tamatave, schools and offices were closed for a second day on Tuesday as heavy rains and powerful gusts struck the seaboard after Cyclone Giovanna hit the island.
"One person died in Brickaville after an electricity pole fell on her," Alain Mahavimbina, the top official in the capital Antsinanana, told the Reuters news agency.
The eye of the storm made landfall south of Tamatave.
"Tamatave is like a ghost town," Joel Milamaro, a resident told the Reuters news agency. "The roads are deserted."
In Antananarivo, the authorities cut off power and ordered drivers to stay off the roads and businesses to shut their doors as torrential rains persisted into Tuesday.
John Yoon-Yak Davis, the country director of the aid organization Care International, said preliminary assessments showed 60 per cent of homes were partially or completely damaged in some districts.
“Wood homes have lost roofs, more traditional structures made of palm leaves and bamboos have been completely destroyed. There is going to be great need in terms of reestablishing infrastructure and food supply for the population."
Al Jazeera's senior meteorologist, Steff Gaulter, says Giovanna has a well-defined eye, indicating that it is a very big storm.
A special weather bulletin in the morning gave warning of "imminent danger".
Data supplied by the US Navy and Air Force Joint Typhoon Warning Center showed sustained winds of around 231km per hour driving the category four cyclone into Madagascar.
Twitter, the micro-blogging site, was also abuzz with reports from the island, with one user saying that heavy winds were "damaging structures and everything" in its wake.
Madagascar is prone to cyclones and tropical storms, especially in the rainy season from February to May.
In 2008, Cyclone Ivan hit Madagascar, killing more than 80 people and leaving over 200,000 homeless.
The US space agency NASA's website said the cyclone was expected to weaken as it moved across the world's fourth largest island, where foreign firms are mining nickel and ilmenite and exploring for oil.
"It is expected to move into Mozambique Channel and may re-intensify," NASA said.
Another Twitter user tweeted at 2:16pm local time that Cyclone Giovanna was expected hit Maputo in 48 hours.
Madagascans have set up a citizen reporting platform to map the various areas of need. View the map below: