This whole process relies on salinity of water. As salt water cools, it's density increases, causing this drop to floor I just mentioned. What could bugger this up?

Well, naturally, fresh water from melting ice-sheets, along with huge Siberian rivers, which are flooding more than ever, contributing to this fresh water being thrown into Atlantic.

Put simply, diluted salt water will not sink, Gulf Stream would call it a day and it would get bloody cold. No, really cold.

Dr Terry Joyce, of Woods Hole Oceanographic Institute believes there is a 50% chance of this happening within next 100 years. "The likelihood of having an abrupt change is increasing - global warming is moving us closer and closer to brink" he warned.

(It was sobering stuff. Again, vitriolic thoughts about world's leaders who continue to allow global warming to happen bombarded my brain, as Atlantic continues to be bombarded by this fresh water.)

It's been cold recently, more so since central heating has decided to pack up and damned landlord has taken aeons to sort it. So, it was a case of watching this programme whilst huddled round my Zippo.

I'm relatively new to this town, so whilst I was on playground today, picking up kids, I got talking to this chap that I have begun to know. In past, it has merely been a case of exchanging pleasantries. I was telling him about central heating having shut down. Turns out, he'd seen Horizon last night as well.

"Knowing my luck" I said, " this forecasted ice age will hit us tonight before landlord gets boiler sorted."

"Oh no, I think it would take around 10 years to fully hit us. It wouldn't happen overnight."

Is he related to postmistress? I'm beginning to get nagging doubts about this town.

Some earthquakes produce low-pitch sounds and light effects (flashes, streamers, and balls). Water in lakes and reservoirs oscillate causing flooding (a phenomenon called seiche). Seiches were observed in Scotland and Sweden following Lisbon quake of 1755. Similarly, Alaskan tremor in 1964 produced seiches in Texas and throughout southwestern parts of United States.

Measuring magnitude of earthquakes is more a fine art than an exact science.

Charles Richter developed his eponymous logarithmic scale in 1935. It measures amplitude (the height) of seismic surface waves. Each unit represents a tenfold increase in energy released by tremor. An earthquake of magnitude 9 is, therefore, 1000 stronger than a tremor of magnitude 6. The Kobe earthquake measured 6.8 on Richter scale, San Francisco tremor of 1906 was 8.3 (as was earthquake in Mississippi Valley in 1811), and both Alaskan quake of 1964 and South Asian underwater temblor of 2004 were around 9 (9.2 in Alaska to be precise)

The Richter scale is used mainly by media. Professional seismologists use Moment Magnitude Scale (MMS) which takes into account properties of area and amount of slippage (displacement). It captures total energy of tremor. The Kobe earthquake measured 7 on MMS, San Francisco tremor of 1906 was 7.6, and Alaskan quake of 1964 was 9.

Then there is still-used 12-grade Modified Mercalli Scale (adapted in 1931 by American seismologists H. O. Wood and Frank Neumann from original Mercalli scale, proposed in 1902 Italian seismologist Giuseppe Mercalli). It measures impact that an earthquake has on natural and man-made environment to gauge its magnitude. The Europeans have a similar 12-grade scale, called MSK.

Seaquakes are earthquakes that start on land and then travel into sea at speed of sound (about 1.5 kilometers per second).

Quakes occur even on moon which has no plates, volcanic activities, or ocean trenches. The five seismograph stations of Passive Seismic Experiment set up between 1969 and 1977 as part of United States Apollo Program detected up to 3,000 moonquakes every year. Mars, on other hand, seems not to have quakes at all!

Some notable earthquakes in history:

Lisbon, November 1, 1755, 09:40 AM (All Saints Day)

Property damage: 12,000 houses, fire raged for 6 days

Casualties: 60,000 dead

Felt as far as: Algiers (1100 kilometers to east)

Side effects: tsunami 20 meters high (at Cadiz) to 6 meters high (at Lisbon). Traveled to Martinique (6100 kilometers) in 10 hours and rose to 4 meters when it struck shore.

New Madrid, Missouri, USA - December 16, 1811, January 23 and February 7, 1812

Felt as far as: Louisville, Kentucky (300 kilometers away); Cincinnati, Ohio (600 km. away); Canada; Gulf Coast.

Side effects: 1874 aftershocks; The tremor affected 100,000 square kilometers. An area of 240X60 kilometers sank by 1-3 meters and was flooded as a nearby river rushed in.

San Francisco, April 18, 1906, 05:12 AM

Property damage: Fire destroyed business district of San Francisco. Cities along fault (e.g., San Jose, Salinas, and Santa Rosa) obliterated.

Casualties: 700 dead

Felt as far as: Los Angeles in south and Coos Bay, Oregon, to north

Side effects: At least a 430 kilometers fault slippage (break).

Tokyo–Yokohama, September 1, 1923

Property damage: Fifty four percent of brick buildings and one tenth of other, reinforced, structures collapsed. Hundreds of thousands of houses crumbled or burned.

Casualties: 140,000 dead

Felt as far as: Los Angeles in south and Coos Bay, Oregon, to north

Side effects: Twelve-meter high tsunami crashed against Atami on Sagami Gulf, destroyed 155 houses and killed 60 people.

Chile, 1960

Property damage: Pegged at millions of US dollars.

Casualties: 5700 killed and 3000 injured.

Felt as far as: Los Angeles in south and Coos Bay, Oregon, to north

Side effects: Seismic sea waves (tsunamis) struck Hawaii, Japan, and Pacific coast of United States.

Alaska, March 27, 1964

Casualties: 131 dead

Side effects: Felt over an area of 1,300,000 square kilometers and tilted an area of more than 120,000 square kilometers. Land was thrust up by as much as 25 meters and sank by up to 2.5 meters. Numerous tsunamis affected locales as far as Crescent City, California. The fault extended for 1000 kilometers and there were tens of thousands of aftershocks.

Tang-shan, China, July 28, 1976

Property damage: Entire city razed to ground.

Casualties: 240,000 killed and half a million injured.

Mexico, September 19, 1985, 07:18 AM

Property damage: Most buildings in Mexico City - 400 kilometers from epicenter - damaged extensively.

Casualties: 10,000 killed.

Felt as far as: Los Angeles in south and Coos Bay, Oregon, to north

Side effects: Seismic sea waves (tsunamis) struck Hawaii, Japan, and Pacific coast of United States.