The eye of typhoons and hurricanes isn't always reflected at the same location on the ground as it is aloft; it's canted. From what I recall, as we were looking at the imagery, it looked like the volcano was erupting directly through the eye.
This was the only information we had. The Navy had a meteorology office near Subic Bay that I'd visited in the past, but it had been effectively shut down because of all the ash fall. A: As we pulled up pierside, it was an eerie experience. The ash had been accumulating over several days, so they had swept most of the roofs and taken road construction equipment and plowed the roads, much like you would plow the roads for snow.
I'm from upstate New York, and when I was a kid, I'd look out my bedroom window and see snowbanks all the way down the street. It wasn't a nice bright white snowbank, but it looked much a typical winter scene after a real heavy snowfall. The volcanic ash was dull gray with some brown, and some of the roofs still had significant ash accumulation on top of them.
A: Yunya created a real humanitarian disaster. Much of the area around there became totally uninhabitable, so many local inhabitants who could evacuate had gone to other parts of the island. The rainfall was so heavy, however, that the night before we arrived, a large group of people who remained had sheltered in a gymnasium for protection from the hurricane.
Once saturated, several feet of ash on the roof became like heavy concrete, and the roof collapsed. There were a significant number of fatalities from that. In addition, there were many structural failures off base due to the weight of the ash on buildings. The combined effect of the water and the ash was devastating.
Some of the military was redeployed to other areas, but the civilian dependents who couldn't get out on their own, had to be evacuated by us. We embarked many of these families on board the aircraft carrier and made two trips from Subic Bay south to the island of Cebu, where the Air Force was flying large transport aircraft out from an old airstrip left over from World War II.
We were taking thousands of people. Interestingly, people come with a lot of stuff, including pets! Down in the hangar bay, there are tie-down spots in the deck every 10 feet or so to secure aircraft. Many now had a dog carrier, cat carrier, or birdcage attached.
The U. People had to go down periodically to comfort, feed, and clean up after them. In addition to a very unhappy Doberman giving birth to a litter of puppies under some yellow gear aircraft tows , at least one other unusual situation also stuck with me.
There were some local people who had been potentially stranded, and it appeared that a few hastily arranged marriages may have occurred. The eruptions have dramatically changed the face of central Luzon, home to about 3 million people. About 20, indigenous Aeta highlanders, who had lived on the slopes of the volcano, were completely displaced, and most still wait in resettlement camps for the day when they can return home.
About , people who evacuated from the lowlands surrounding Pinatubo before and during the eruptions have returned home but face continuing threats from lahars that have already buried numerous towns and villages.
Rice paddies and sugar-cane fields that have not been buried by lahars have recovered; those buried by lahars will be out of use for years to come. Chris Newhall, James W. Hendley II, and Peter H. Graphics by Susan Mayfield and Sara Boore. Banner design by Bobbie Myers. Web design and layout by Carolyn Donlin.
For more information or paper copies of this fact sheet contact: U. Related Fact Sheets. What Are Volcano Hazards? See a list of other volcano-related fact sheets published by the U. The silting of river channels and trapping of rainwater in an area of km2 mi2 formed Lake Pinatubo, now 10 m 33 ft deep.
Permanently submerged in this lake are structures, including houses, churches, and schools. The eruptions are believed to be the major reason why temperatures dropped globally in and the largest hole yet recorded in the ozone layer occurred over the South Pole. But by the end of the eruption, magma was fully dacite. Instead, it rose into the dacite and mixed with it.
But how? First, when the fresh, water-rich, and considerably hotter basalt hit the cooler dacite reservoir, the basalt crystallized, Newhall explained. That added even more volatiles. The resulting slurry was still less dense than its surroundings, so it kept rising and was the first erupted.
Eventually, the dacite itself heated enough to rise to the surface and erupt. This magma mixing manifested as subtly rumbling quakes that at times lasted about a minute long, called deep long-period DLP earthquakes. Long-period earthquakes indicate that magma is intruding into surrounding rock , but scientists had more frequently observed these events at depths less than 10 kilometers. Before Pinatubo, DLP earthquakes had been rarely observed and were not fully understood.
Collecting this information involves studying crystals of cooled lava after an eruption, Ewert said. This implied that emissions of water vapor and carbon dioxide—the gases that dominate emissions—were also more than scientists expected. But a whopping 17 megatons of sulfur dioxide was released by the explosion, as measured by satellite spectrometer.
This implied that large amounts of gas could accumulate as bubbles and remain in the magma chamber, Newhall explained. Because this excess gas makes an eruption more explosive, it might even be that such free gas is required for a Pinatubo-like eruption, Newhall said. If volatiles are already in excess, they can expand immediately once the pressure drops, without any delay from diffusing through melt. Knowing that magmas can hold excess gas can help with forecasting efforts, Newhall explained.
For example, if a volcano has been plugged since its previous eruption yet has been continuously recharged with fresh magma and gas from depth, scientists can examine the time between its eruptions to gauge whether the volcano has accumulated enough excess gas to make it particularly explosive.
The total amount of sulfur dioxide released before and during the eruption caused the most profound effect on the stratosphere since Krakatau in The sulfuric aerosols that formed from the sulfur dioxide circled the Earth within 3 weeks and remained in the atmosphere for 3 years , reflecting enough sunlight to cool the entire planet by half a degree Celsius during that time.
However, during the following winter, Europe experienced surprisingly warm temperatures. What could be going on? This temperature gradient strengthened the Arctic Oscillation , a wind pattern circling the Arctic.
The shifted jet stream allowed warm winds to flow over the Northern Hemisphere during the winter, Robock said. Because the jet stream flows like a wave, while Europe was receiving warm air from the south, the Middle East received colder air from the north, bringing to Jerusalem the worst snowstorm in 40 years. The eruption helped scientists definitively declare that human emissions of greenhouse gases are to blame for at least the past 60—70 years of warming.
Temperatures rose again once the cooling aerosols fell out of the atmosphere.
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