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eggshaped
42449.  Mon Jan 02, 2006 5:15 am Reply with quote

“what do you measure earthquakes in?”

Answer: I’m sure everyone is too savvy to have said the Richter Scale. This scale has become more or less obsolete (for larger earthquakes) these days, with the exception of news reports, who like to stick with a scale that everyone is familiar with.

The problem with the RS is twofold. First, it only measures the horizontal amplitude of the shock waves, when in fact an earthquake has many other features which are required for a full description; secondly, for larger earthquakes (over 8.0) there is a great deal of grouping. Two earthquakes, which in practice were clearly of a different order of magnitude, could both show 8.1 on the Richter scale.

However a famous name came to the fore. Tom Hanks* helped to derive the new pretender to Richter’s throne, the Moment Magnitude Scale (hmm not quite as catchy a name, I would have preferred the “Tom Hanks” scale.). This scale was created with the RS in mind, most measurements coincide roughly with the previous scale

*Obviously not the Tom Hanks, but the American geologist of the same name.

 
markvent
42529.  Mon Jan 02, 2006 12:41 pm Reply with quote

"Which volcanic explosion killed the most people?"

Answer: The eruption of Tambora in Indonesia in 1815. It was a huge eruption that sent ash into the stratosphere that then spread around the world.

The World climate was noticeably cooler the following year, and in places it was called "the year without a summer".

Closer to the eruption itself thousands of people were killed, and due to the destruction of crops, disease, contamination of water, etc., tens of thousands more died in the years that followed.

estimates put the overall death toll at around 200,000 people.

 
gibberingfool
42652.  Mon Jan 02, 2006 5:09 pm Reply with quote

How dangerous are natural disasters to Britain?

Answers: If the volcano on La Palma in the Canaries explodes, a 500m high mega-tsunami could engulf low-lying parts of the UK.

One of Britain's most severe tornadoes destroyed a church and 600 homes in central London in 1091.

In 1995, a hurricane doubled back from the Caribbean and hit Britain.

North-west Wales is one of the most seismically active places in the whole UK. In 1984, a quake registered 5.4 on the Richter scale. Another could hit any day now.

 
grizzly
42657.  Mon Jan 02, 2006 5:24 pm Reply with quote

markvent wrote:
"Which volcanic explosion killed the most people?"

Answer: The eruption of Tambora in Indonesia in 1815. It was a huge eruption that sent ash into the stratosphere that then spread around the world.

The World climate was noticeably cooler the following year, and in places it was called "the year without a summer".

Closer to the eruption itself thousands of people were killed, and due to the destruction of crops, disease, contamination of water, etc., tens of thousands more died in the years that followed.

estimates put the overall death toll at around 200,000 people.


We can't precisely work it out but Toba could well have rivelled that figure. When it exploded over 75,000 years ago it caused a global cooling of the climate that could have killed a considerable proportion of the worlds human population. If i remember from the episode of horizon correctly, research of mitochondrial DNA shows that the entire human population is descended from as little as 10,000 (possibly less) people although the population before hand was in the millions.

It doesn't rival the figure you show but Laki in Iceland could have killed as many as 40,000 in 1783. 10,000 died in Iceland (mainly from flourosis, a particularly horid death) but the Sulphur dioxide created an incredibly hot summer throughout Europe and poor air quality that killed several thousand. The winter of that year was also particularly bad causing many deaths.

 
grizzly
42666.  Mon Jan 02, 2006 5:42 pm Reply with quote

gibberingfool wrote:
How dangerous are natural disasters to Britain?

In 1995, a hurricane doubled back from the Caribbean and hit Britain.


Actually, you'll be surprised by how common that is. On average 2 or 3 extra-tropical hurricanes hit the UK in each season. Several did in 2005 as remnant lows. The strange process of a storm becoming extratropical (where incursions of colder maritime polar air change the trademark comma shape into the sprial shape that we see in Atlantic storms) can create particularly strong storms through a process that would actually destroy a hurricane. High shear caused by the jet stream over a hurricane will kill a hurricane (low level circulation and upper level circulation are seperated). If this happens over the North Atlantic the opposite happens. Passing directly over the centre of a low pressure system, the system will rapidly deepen as air rushes upwards into the jet stream. I forget the name (I'm sure someone will remind me) but it is the same phenomena that will make a ping pong ball float if it is placed in a bottle and you blow over the top of the bottle. It is this process that created a sudden storm that brought a hurricane to Corfe Castle last January and hurricane winds to Paris. Although difficult to verify it could well have been the same process that created the rapidly deepening 1987 great storm.

What should be more worrying was the path of Hurrican Vince. It developed in the NE Atlantic near the Azores and travelled East to hit Spain as a tropical depression - the first ever recorded to do so. Another tropical storm hit Northern Africa.

BTW last years hurricane season hasn't technically ended (although most normally finish in October and should end by November). Tropical storm Zeta is currently in the mid-Atlantic.

http://www.nhc.noaa.gov/index.shtml

 
djgordy
42673.  Mon Jan 02, 2006 5:54 pm Reply with quote

grizzly wrote:
Tropical storm Zeta is currently in the mid-Atlantic.



However, meteorologists expect it to be neutralised when it encounters the far older Hurricane Douglas.

 
grizzly
42676.  Mon Jan 02, 2006 5:59 pm Reply with quote

djgordy wrote:
grizzly wrote:
Tropical storm Zeta is currently in the mid-Atlantic.



However, meteorologists expect it to be neutralised when it encounters the far older Hurricane Douglas.


PMSL, made all the funnier by the fact that for the first few moments I hadn't realised that was a joke.

 
Flash
42715.  Mon Jan 02, 2006 8:28 pm Reply with quote

Quote:
the rapidly deepening 1987 great storm

We seem to have some expertise on hand here, so can you gents tell me: is it the case that the 1987 storm was not, technically, a hurricane - and therefore that Michael Fish was right?

 
grizzly
42731.  Tue Jan 03, 2006 4:55 am Reply with quote

Flash wrote:
Quote:
the rapidly deepening 1987 great storm

We seem to have some expertise on hand here, so can you gents tell me: is it the case that the 1987 storm was not, technically, a hurricane - and therefore that Michael Fish was right?


Technicaly no, it was not a hurricane. As a general rule, anything above 40 degrees latitude cannot be a hurricane. However, I say generally because this rule only relates to storms that develop beyond that boundary (and there are even exceptions to that). Effectively anything can be called a hurricane if it takes on "tropical characteristics" and it is the duty of the presiding authority (in the case of the North Atlantic and North Eastern Pacific this is the NHC as part of the NOAA) to rule whether a system has tropical characteristics.

Tropical Characteristics are not just wind speed. Due to the presence of certain air masses and particular Sea Surface Temperatures (SST's) tropical storms do not have the frontal nature (caused by seperate air masses forcing air to rise over one another) that a storm like the Great Storm of 87 will have. It is the major seperating feature. In deed storms in the North Atlantic can be very fierce. The maximum gust measured in the Great Storm of 121mph. A storm last year (not the one i refered to in my earlier post) had recorded sustained wind speeds in excess of 130mph, that's the equivalent of a category 3 hurricane (a major hurricane).

BTW Tropical Storm Zeta (still greek alphabet BTW) intensified over night and low shear conditions could make her the first ever January hurricane. It might not though.

 
Flash
42736.  Tue Jan 03, 2006 5:14 am Reply with quote

Thanks - I think I take that as saying that the '87 could be described as a hurricane without inaccuracy, which rather shoots my fox. Never mind, I'll find another.

 
grizzly
42754.  Tue Jan 03, 2006 6:19 am Reply with quote

87 definitely wasn't a hurricane. In fact from my recollection of the records the windspeeds could barely be described as hurricane force because you have to distinguish between maximum gusts and sustained wind speeds (I believe it was a mid cat 1 hurricane). The thing about 87 is that it did not start out in the tropics and did not have any tropical characteristics so it wasn't a hurricane.

However, I do believe that it is a reasonably well known fact that it wasn't a true hurricane.

If you want to find out more from the people that are a little more qualified to talk about it than me then i would suggest getting in contact with the NHC or Reading some of their info:

http://www.nhc.noaa.gov/contact.shtml

There's absolutely loads of QI stuff in there. Especially in the history.

Just to illustrate that hurricane can happen anywhere there is the example of hurricane Catarina (not its official name as it had none) in the South Atlantic where it is incredibly rare for hurricanes to form. You can read more here (a good idea to try enlarging the image of the hurricane, it is incredibly detailed):

http://www.nhc.noaa.gov/contact.shtml

 
djgordy
42762.  Tue Jan 03, 2006 6:33 am Reply with quote

In order to be a force 12 (hurricane) storm, winds need to be 73mph or more sustained for at least 10 minutes. There were some local gusts of these speeds but they were not widely felt or sustained so the storm was not a hurricane.

The other interesting thing about the 87 storm is the often misunderstood remarks of weather man Michael Fish.

"Earlier on today apparently a lady rang the BBC and said she heard that there was a hurricane on the way. Well don't worry if you're watching, there isn't."

This comment wasn't about the impending storm on its way to the UK, but was for the information of someone who was about to fly to Florida and referred to the aftermath of some devastation in the Caribbean. The UK forecast was fairly accurate with force 10 winds predicted.

 
Flash
42775.  Tue Jan 03, 2006 7:13 am Reply with quote

Seems the fox is alive and well after all. That last bit about the hurricane in question being (or not being) in Florida - is that verifiable? EG, is there a recording of Fish making the statement which makes his context clear, do we know?

 
eggshaped
42779.  Tue Jan 03, 2006 7:21 am Reply with quote

Fish seems quite adamant on the fact, or at least that's the impression I get from this interview:

Quote:
Fish is best remembered for his forecast given prior the great storm that battered the UK in October 1987. "Earlier on today apparently a lady rang the BBC and said she heard that there was a hurricane on the way," he said. "Well don't worry if you're watching, there isn't."

Fish insists that he wasn't referring to the UK at the time "My remarks referred to Florida and were a link to a news story about devastation in the Caribbean that had just been broadcast."

http://www.bbc.co.uk/cult/news/cult/2004/10/06/14727.shtml

 
eggshaped
42780.  Tue Jan 03, 2006 7:26 am Reply with quote

In addition:

Quote:
Do you get tired of seeing repeats of your broadcast in 1987 when editors carefully cut before you say 'it will get rather windy'?
- Richard Davis-Foster, High Wycombe.

"Yes! I wish I had a penny for each time that clip had been broadcast, I'd be a millionaire!"

Just who did ring in to say they'd heard a hurricane was on the way in '87?
- James Westcott, Witney.

"Nobody called in. Someone in the studio suggested that - their mum was going on holiday."

My son would like to know if the storm of 1987 was the back end of a hurricane.
- Josephine Fisher, Billericay.

"No it wasn't - the storm formed near the Bay of Biscay."

You obviously had no idea that day in October 1987 that your words would be forever immortalised in the annals of TV broadcasting. How does this feel now?
- Janet Franklin, Chislehurst.

"Well it's a bit annoying really as it is always misreported..."


Quote:
A hurricane is the term used for a storm that develops in the tropics, so in this sense, the Great Storm was not a hurricane. Hurricane Force (Force 12) winds are winds of 73+mph sustained for ten minutes or more, and don't include the strength of wind gusts. By this definition, Hurricane Force winds occurred locally, such as at Lee on Solent and Gorleston, but were not widespread.


http://www.bbc.co.uk/weather/bbcweather/forecasters/michael_fish_1987storm.shtml

From the tone of this, and other interviews, I would imagine MF would be more than happy to have the record set-straight.

 

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