Nagging Doubts

Written by Holmes Charnley


There's always that nagging doubt isn't there? The nagging doubt that they just won't get it.

I went torepparttar Post Office yesterday,repparttar 110088 small local one roundrepparttar 110089 corner, to draw a relatively large amount of money out of my account. Whilst inrepparttar 110090 queue, I saw a packet of refill cartridges going cheap. Half-price. Which in consequence meant it was around 50p to keep an ink pen running for a good year or so.

Thinking they might come in handy, I procured some and when I was atrepparttar 110091 head ofrepparttar 110092 queue, placed them onrepparttar 110093 counter, saying casually torepparttar 110094 postmistress that I sincerely hoped thatrepparttar 110095 money I was drawing out would indeed coverrepparttar 110096 cost ofrepparttar 110097 cartridges.

As I was drawing out in excess of 300, there was a strong chance really and my comment was merely meant to make her smile.

"Yes, it will," she said. Indeed, it appeared that she had done some quick mental arithmetic to make sure. The whole transaction was rather icy, in retrospect.

It could almost have been a precursor torepparttar 110098 BBC2 programme I watched later, where on Horizon, it has been predicted that Britain could well, before long, be plunged into another ice age. (Postmistresses roamingrepparttar 110099 streets, doing unnecessary mental arithmetic, unsmilingly.)

That aside, Horizon proved compulsive viewing. At present, Britain enjoys its temperate climate due torepparttar 110100 warm air brought to us fromrepparttar 110101 Gulf Stream. But, due to global warming, wererepparttar 110102 ice sheets to continue to melt, we would have some major problems. It wouldn't get hotter, as you'd think. It would, conversely, get a hell of a lot colder here in Britain.

You see,repparttar 110103 North Atlantic is an incredibly important area. From a meteorological point of view, you could say it is "strategic." It isrepparttar 110104 point whererepparttar 110105 Gulf Stream sinks to join what is known asrepparttar 110106 Atlantic Conveyor, a massive rotating belt which takes cold water back alongrepparttar 110107 ocean floor torepparttar 110108 tropics, where again, it rises, to beginrepparttar 110109 journey again.

Earthquakes and Tsunamis

Written by Sam Vaknin


Tsunamis

Tsunami - a seismic sea wave - means in Japanese "harbor-wave". It is also misleadingly called "tidal wave". It is an ocean wave caused by an earthquake of magnitude 6.5 onrepparttar Richter scale (or greater) that occurs less than 50 kilometers beneathrepparttar 110087 seafloor. Tsunamis can also be caused by volcanic eruptions and by landslides.

Tsunami waves are followed by three to five oscillations ofrepparttar 110088 continental shelf waters. These convulsions may last up to a week. Ifrepparttar 110089 initial wave reachesrepparttar 110090 shore at its trough phase,repparttar 110091 water recede and exposerepparttar 110092 seafloor. This happened in Lisbon Port on November 1, 1755. A few minutes later,repparttar 110093 displaced waters return with energetic vengeance.

Inrepparttar 110094 ocean, tsunami waves are merely 0.5-2 meters high with a wavelength of up to 200 kilometers. Consequently, they are virtually impalpable though they move at speeds of up to 700 kilometers per hour. Asrepparttar 110095 waves nearrepparttar 110096 shoreline, friction withrepparttar 110097 shallow bottom reduces their velocity, shortens their wavelength, increases their amplitude and their height.

The tsunami wave that swept acrossrepparttar 110098 coasts of Indonesia, Sri Lanka, Thailand, India, and Africa on December 26, 2004 was 10-12 meters high. It traveled almost 6000 kilometers. It killed almost 150,000 people. An earthquake inrepparttar 110099 fjord-like Lituya Bay, Alaska, on July 9, 1958, generated a tsunami wave 524 meters (1719 feet) high, moving at a speed of 160 kilometers per hour. Luckily,repparttar 110100 area was largely uninhabited.

Other notable tsunamis:

In 1703 at Awa, Japan with more than 100,000 people dead.

On April 24, 1771, a tsunami caused by an underwater earthquake struckrepparttar 110101 Japanese island of Ishigaki (inrepparttar 110102 Ryuku chain). It was 85 meters high. It was so powerful that it hurled a 750 ton piece of coral to a distance of 2.5 kilometers inland.

Again in Japan, 27,000 people drowned in 1896, in a giant tsunami.

Inrepparttar 110103 wake ofrepparttar 110104 underwater volcanic eruptions that obliteratedrepparttar 110105 island of Krakatau (Krakatoa) on August 26-27, 1883, a wave 35 meters high swept acrossrepparttar 110106 East Indies killing in excess of 36,000 people.

Triggered by a submarine landslide, a tsunami at least 375 meters high struckrepparttar 110107 island of Lanai in Hawaii about 105,000 years ago.

The 1960 earhquake in Chile created tsunami waves that traveled more than 10,000 kilometers to Hilo, Hawaii. The 12 meters high water wall killed 61 people and destroyed many buildings.

The Seismic Sea Wave Warning System (SSWWS), based in Honolulu, is an early warning system coveringrepparttar 110108 entire, tsunami-prone, Pacific Ocean.

Earthquakes

Little known facts about temblors:

The epicenter of an earthquake is notrepparttar 110109 same as its hypocenter (focus, point of origin within a fault-line). The epicenter isrepparttar 110110 point onrepparttar 110111 surface ofrepparttar 110112 Earth directly aboverepparttar 110113 focus. Dangerous, shallow-focus quakes originate 0-70 kilometers belowrepparttar 110114 surface. Less damaging deep-focus tremors occur between 70-700 kilometers down. Subduction zone earthquakes (likerepparttar 110115 one that gave rise torepparttar 110116 lethal tsunami on December 26, 2004) occur when one tectonic plate moves under another (subducts). There are interplate and intraplate quakes, which take place along plate boundaries or withinrepparttar 110117 fracturing crust of a single plate, respectively.

Earthquakes are not rare at all - several hundred earthquakes occur every day. There are about 1 million of them annually - of which 50,000 can be felt withoutrepparttar 110118 aid of instruments. Tremors ofrepparttar 110119 magnitude of Kobe in 1995 (which caused an estimated damage of $100 billion ) are measured 20 times in an average year.

The Encyclopedia Britannica (2005 edition) describes a "swarm" of such events thus:

"Inrepparttar 110120 Matsushiro region of Japan, for instance, there occurred between August 1965 and 1967 a series of hundreds of thousands of earthquakes, some sufficiently strong (up to local magnitude 5) to cause property damage but no casualties. The maximum frequency was 6,780 small earthquakes on April 17, 1966."

The Pacific ocean isrepparttar 110121 unhappy recipient of well over 80 percent of allrepparttar 110122 energy released by earthquakes worldwide. Japan alone suffers from 1500 tremors annually (of which two thirds are greater than 3.5 in magnitude). Fault lines abound and new ones are discovered frequently. One fault line runs under 125th street in Manhattan, New-York.

Still, inrepparttar 110123 last 5 centuries, all earthquakes combined killed less than one tenthrepparttar 110124 victims of World War II - and this includesrepparttar 110125 240,000 who died inrepparttar 110126 1976 Tang-Shan, China event.

Earthquakes are composites of:

I. Primary (or compression) and secondary (or shearing) body waves (that travel inrepparttar 110127 rocks underrepparttar 110128 surface ofrepparttar 110129 Earth at speeds of up to 7 kilometers per second and frequencies of between 20 Hertz and one vibration per 54 minutes)

and

II. Two types of surface waves, named after British physicist Lord Rayleigh and British geophysicist A. E. H. Love (with frequencies of 1-0.005 Hertz).

Some earthquakes are caused by human activities (such asrepparttar 110130 filling of water reservoirs behind dams, injecting water into deep wells, and underground nuclear tests). More than 600 tremors were recorded inrepparttar 110131 decade followingrepparttar 110132 filling of Lake Mead behind Hoover Dam onrepparttar 110133 Nevada-Arizona state border.

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