Choose the correct answer to fill in the blanks. Avalanche

On March 21, 2002, Steven Borg, a Swiss ski enthusiast,
near his hometown, when something unexpected : "There was a terrible avalanche. Suddenly I through the air with my hands above my head and a sea of white all around me... Then, I myself one foot deep under the snow. The snow like cement and I to free myself when I some people trying to rescue me."
This is how he explained the disaster to his rescuers afterwards. Borg was lucky that he
the disaster, but not everybody is so lucky.
Every year, avalanches - or snowslides -
about 200 people worldwide, and deaths are not the only part of the problem. Avalanches also
billions of dollars of damage annually to buildings, roads and livestock, and
many mountain communities.
In Switzerland, for example, an estimated 65% of the population
in areas at risk for avalanches. About two decades ago, most countries
establishing networks of centers to monitor and forecast snowslides, an action which
to limit the number of victims since. It so works that the centers
people when a high risk of avalanche
and
skiers to avoid dangerous areas, and in the meantime, authorities
taking the necessary steps to protect people and infrastructure. So far, such passive defenses against avalanches
evacuating villages, bridges, roads and ski resorts. And over the past years, scientists
the possibilities of active prevention of avalanches.