51. Does all of Earth spin at the same rate?
The solid inner core -- a mass of iron comparable to the size of the Moon -- spins faster than the outer portion of the iron core, which is liquid. A study in 1996 showed that over the previous century, the extra speed caused the inner core to gain a quarter-turn on the planet as a whole. So the inner core makes a complete revolution with respect to the rest of Earth in about 400 years. Immense pressure keeps it solid.
52. How many people have been killed by volcanoes during the last 500 years?
At least 300,000. Between 1980 and 1990, volcanic activity killed at least 26,000 people.
53. How much of the Earth’s surface consists of volcanic rock?
Scientists estimate that more than three-quarters of Earth’s surface is of volcanic origin-- that is, rocks either erupted by volcanoes or molten rock that cooled below ground and has subsequently been exposed at the surface. Most of Earth’s volcanic rocks are found on the sea floor.
54. Can an earthquake cause a tsunami?
If the earthquake originates under the ocean, yes. Near the earthquake’s epicenter, the sea floor rises and falls, pushing all the water above it up and down. This motion produce s a wave that travels outward in all directions. A tsunami can be massive but remain relatively low in height in deep water. Upon nearing the shore, it is forced up and can reach the height of tall buildings. One in 1964 was triggered in Alaska and swamped the small northern California town of Crescent City , moving train cars several blocks and killing several people there. Asteroids can cause tsunami, too.
55. Are all tsunamis high waves when they strike a coastline?
Asteroid-generated tsunami
No, contrary to many artistic images of tsunamis, most do not result in giant breaking waves. Rather, most tsunamis come onshore more like very strong and fast tides. The water can rise higher than anyone along a given shore area has ever seen, however. [Model of an East Coast tsunami]
56. How much of the Earth’s land surface is desert?
About one-third.
57. What's the deepest place in the ocean?
The greatest k nown depth is 36,198 feet (6.9 miles or 11 kilometers) at the Mariana Trench, in the Pacific Ocean well south of Japan near the Mariana Islands .
58. What is the fastest surface wind ever recorded?
The fastest "regular" wind that's widely agreed upon was 231 mph (372 kph), recorded at Mount Washington , New Hampshire , on April 12, 1934 . But during a May 1999 tornado in Oklahoma , researchers clocked the wind at 318 mph (513 kph). For comparison, Neptune 's winds can rage to 900 mph (1,448 kph).
59. How much fresh water is stored in the Earth?
More than two million cubic miles of fresh water is stored in the planet, nearly half of it within a half-mile of the surface. Mars, too, appears to have a lot of water near its surface, but what's been detected so f ar is locked up as ice; nobody has estimated how much might be there.
60. How old is Earth?
Our planet is more than 4.5 billion years old, just a shade younger than the Sun. Recent evidence actually shows that Earth was formed much earlier than previously believed, just 10 million years after the birth of the Sun, a stellar event typically put at 4.6 billion years ago.
Saturday, May 3, 2008
Facts About Earth - V
41. How much surface area does Earth contain?
There are 196,950,711 square miles (510,100,000 square kilometers).
42. What is the largest lake in the world?
By size and volume it is the Caspian Sea , located between southeast Europe and west Asia .
43. Where do most earthquakes and volcanic eruptions occur on Earth?
The majority occur along boundaries of the dozen or so major plates that more or less float on the surface of Earth. One of the most active plate boundaries where earthquakes and eruptions are frequent, for exa mple, is around the massive Pacific Plate commonly referred to as the Pacific Ring of Fire. It fuels shaking and baking from Japan to Alaska to South America .
44. How hot are the planet's innards?
The temperature of Earth increases about 36 degrees Fahrenheit (20 degrees Celsius) for every kilometer (about 0.62 miles) you go down. Near the center, its thought to be at least 7,000 degrees Fahrenheit (3,870 Celsius).
45. What three countries have the greatest number of historically active volcanoes?
The top three countries are Indonesia , Japan , and the United States in descending order of activity.
46. How many people worldwide are at risk from volcanoes?
As of the year 2000, USGS scientists estimated that volcanoes posed a tangible risk to at least 500 million people. This is comparable to the entire population of the world at the beginning of the seventeenth century!
47. Which of the following sources stores the greatest volume of fresh water worldwide: lakes, streams or ground water?
Groundwater comprises a 30 times greater volume than all freshwater lakes, and more than 3,000 times what's in the world’s streams and rivers at any given time. Groundwater is housed in natural underground aquifers, in which the water typically runs around and through the stone and other material.
48. Which earthquake was larger, the 1906 San Francisco earthquake or the 1964 Anchorage, Alaska, temblor?
The Anchorage earthquake had a magnitude of 9.2 , whereas the San Francisco earthquake was a magnitude 7.8. This difference in magnitude equates to 125 times more energy being released in the 1964 quake and accounts for why the Anchorage earthquake was felt over an area of almost 500,000 square miles (1,295,000 square kilometers).
49. Which earthquake was more destructive in terms of loss of life and relative damage costs, the 1906 San Francisco earthquake or the 1964 Anchorage earthquake?
The 1906 San Francisco earthquake tops this category. It was responsible for 700 deaths versus 114 from the Anchorage earthquake. Property damage in San Francisco was also greater in relative terms due to the destructive fires that destroyed mostly wooden structures of the time.
50. Is Earth's core solid?
The inner portion of the core is thought to be solid. But the outer portion of the core appears molten. We've never been there though, so scient ists aren't sure of the exact composition. A radical Hollywood-like idea was recently put forth to blow a crack in the planet and send a probe down there to learn more. An interesting bit of recent evidence shows Mars' core may be similarly squishy. Scientists figured this out by studying tides on Mars (tides on Mars?).
There are 196,950,711 square miles (510,100,000 square kilometers).
42. What is the largest lake in the world?
By size and volume it is the Caspian Sea , located between southeast Europe and west Asia .
43. Where do most earthquakes and volcanic eruptions occur on Earth?
The majority occur along boundaries of the dozen or so major plates that more or less float on the surface of Earth. One of the most active plate boundaries where earthquakes and eruptions are frequent, for exa mple, is around the massive Pacific Plate commonly referred to as the Pacific Ring of Fire. It fuels shaking and baking from Japan to Alaska to South America .
44. How hot are the planet's innards?
The temperature of Earth increases about 36 degrees Fahrenheit (20 degrees Celsius) for every kilometer (about 0.62 miles) you go down. Near the center, its thought to be at least 7,000 degrees Fahrenheit (3,870 Celsius).
45. What three countries have the greatest number of historically active volcanoes?
The top three countries are Indonesia , Japan , and the United States in descending order of activity.
46. How many people worldwide are at risk from volcanoes?
As of the year 2000, USGS scientists estimated that volcanoes posed a tangible risk to at least 500 million people. This is comparable to the entire population of the world at the beginning of the seventeenth century!
47. Which of the following sources stores the greatest volume of fresh water worldwide: lakes, streams or ground water?
Groundwater comprises a 30 times greater volume than all freshwater lakes, and more than 3,000 times what's in the world’s streams and rivers at any given time. Groundwater is housed in natural underground aquifers, in which the water typically runs around and through the stone and other material.
48. Which earthquake was larger, the 1906 San Francisco earthquake or the 1964 Anchorage, Alaska, temblor?
The Anchorage earthquake had a magnitude of 9.2 , whereas the San Francisco earthquake was a magnitude 7.8. This difference in magnitude equates to 125 times more energy being released in the 1964 quake and accounts for why the Anchorage earthquake was felt over an area of almost 500,000 square miles (1,295,000 square kilometers).
49. Which earthquake was more destructive in terms of loss of life and relative damage costs, the 1906 San Francisco earthquake or the 1964 Anchorage earthquake?
The 1906 San Francisco earthquake tops this category. It was responsible for 700 deaths versus 114 from the Anchorage earthquake. Property damage in San Francisco was also greater in relative terms due to the destructive fires that destroyed mostly wooden structures of the time.
50. Is Earth's core solid?
The inner portion of the core is thought to be solid. But the outer portion of the core appears molten. We've never been there though, so scient ists aren't sure of the exact composition. A radical Hollywood-like idea was recently put forth to blow a crack in the planet and send a probe down there to learn more. An interesting bit of recent evidence shows Mars' core may be similarly squishy. Scientists figured this out by studying tides on Mars (tides on Mars?).
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