I fully agree with how important is this question of HAZARD scale.
Some, not to say all, of the answer given so far, clearly illustrate how
difficult it is
to define a hazard scale.
It might be acceptable to say something like "the phenomenon scale is such that
it can destroy a straw house, a timber house or a brick house, like pigs 1,
2, 3 were able to build".
But this will depend on the location of the house relatively to the phenomenon.
My suggestion is we better work out a hazard scale in terms of energy.
For instance, regarding gravitary (gravity driven) phenomena, why don't we
define
some value like log(potential energy), the latter being reckoned as the product
of mass and potential vertical drop (and g).
For a given phenomenon, this will result in 5 to 10 degree wide scales.
A second step could be to "spatialize" this information, I mean calculating
energy density
for a given point of a predefined area.
This could be improved using techniques enabling us to account for
uncertainty etc..
Gérard
At 19:22 16/02/00 +0500, you wrote:
>fair question! sorry for missing it out in the first place. The purpose of
>finding this information is to feed training programs for voluntary field
>operators (non technical persons) in emergency management. For enabling
>them to understand the hazard zonation in areas that they are assigned to,
>and be prepared to expect disasters in accordance, as well as to able to
>appreciate the extent of an event, the issue of scales came up. It then got
>further complicated out of curiosity!
>
>anshu
>
>At 01:47 PM 2/15/00 -0000, you wrote:
> >Perhaps the issue here is between scales of measurement and scales of
> >classification. With landslides there are various physical measures that
> >could be employed to record relative size, the obvious one being volume. In
> >seismology the "Richter" magnitude is an analogue of energy released, and
> >while one can quote earthquake size in terms of an absolute physical
> >measurement, like moment, because the numbers involved are very large, it is
> >more convenient to compress them into an analogical logarithmic scale. It is
> >still a measurement of a sort.
> >
> >Alternatively, there are purely classificatory scales such as earthquake
> >intensity scales, where the effects at a particular place can be graded as
> >"generally noticeable", "strong", "slightly damaging" and so on. Similar
> >classifications have been suggested for windstorm damage, I know, and
> >probably other hazards as well.
> >
> >I suppose that ultimately the key questions are: what do you want to use the
> >scale for, and what resolution makes sense in terms of the available data?
> >
> >Roger Musson
> >
> >
> >-----Original Message-----
> >From: seeds [mailto:[log in to unmask]]
> >Sent: 15 February 2000 13:56
> >To: [log in to unmask]
> >Subject: more on scales
> >
> >
> >Thanks to those who responded to my earlier mail on hazard scales. I did
> >follow up the links and found some useful information. However, I am still
> >stuck for want of `hazard' scales rather than disaster scales.
> >
> >Basing hazard scales on deaths or damage caused does not really help. A
> >larger earthquake may kill less people and cause lesser damage than a
> >smaller one simply because it occurred in a less densely populated area. We
> >can still be sure that it was a bigger quake from its Richter scale
> >reading. The same applies for cyclones (SS scale). However, if out of two
> >landslides, the smaller one causes more deaths/damage, how can one
> >substantially record that the other one was actually larger? Same too for
> >droughts, though there do exist some basic practices of terming droughts as
> >low/med/high on severity based on percentage of normal rainfall over
> >specified period of time.
> >
> >any further ideas....??
> >
> >_______________________________________________________________
> >seeds
> >315, Tower I, Mount Kailash, New Delhi - 110065, INDIA.
> >Tel/Fax: (91-11) 6250475 Email: [log in to unmask]
> >
> >
>
>_______________________________________________________________
>seeds
>315, Tower I, Mount Kailash, New Delhi - 110065, INDIA.
>Tel/Fax: (91-11) 6250475 Email: [log in to unmask]
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