National Hurricane Center. HS3. Volcano Live, John Seach. Nicaragua's San Cristobal volcano forces mass evacuation. 8 September 2012Last updated at 19:57 ET The plume of ash and smoke stretches miles into the atmosphere The Nicaraguan government says about 3,000 people are being evacuated from areas near the San Cristobal volcano, which is spewing ash and gas.
Soldiers have been sent to the region, northwest of the capital Managua, after the government ordered local communities to leave. The volcano began erupting on Saturday morning, shortly after powerful explosions were heard. The authorities say they expect more gas emissions and sporadic explosions. What causes tornadoes? Americans know tornadoes like no one else.
The U.S. averages at least 10 times more twisters each year than any other country on Earth, and their intensity is infamous — the worst can be a mile wide, rotate at 300 mph and plow along at 70 mph. Yet despite being target practice for these atmospheric power drills, America's tornado mythos is still cloaked in mystery and misunderstanding. That's understandable, considering tornadoes' stealthy nature — sudden appearances, erratic behavior and brief lifespans make them elusive subjects to study — but science has nonetheless learned a lot in recent decades. Tornadoes can occur any time of year, but they wage all-out war on the U.S. during spring and summer.
With another tornado season already ramping up, below is a guide to how tornadoes work, when and where to expect them, and what you can do to make it out alive. Satellite images of Joplin, Mo., before and after the tornado. Earthquakes - 7 days, M2.5+