Bush fires are threatening suburbs in Southern California. ...several homes in Los Angeles and Ventura counties were evacuated. Seven-hundred fire-fighters battled the blazes, the largest covered 2,800 hectares. The fires were whipped by high winds of up to 70 km/h. Some homes were destroyed and flames and smoke were visible for several kilometres.
Read more here: http://www.cbc.ca/world/story/2005/09/29/california_fires20050929.html
And that article is a couple of years old. Yesterday CBC was reporting:
Firefighters in Southern California are battling more than a dozen wildfires that have destroyed 16,000 hectares of land and forced the evacuation of more than 250,000 people from their homes in the area. ...Arnold Schwarzenegger, who declared a state of emergency late Sunday in seven counties where fires have killed one person and injured dozens, said Monday that "it's a tragic time for California."
Read more here: http://www.cbc.ca/world/story/2007/10/22/fire-california.html
I hate to think, cause what would happen if I got good enough at it to paid by some hard work individual who cause of their Tax being so great that they didn't time to use it thinking or trying to make the best choices in life, and could make conclusions like I'm reading supra. this puts in of the auzzie, linda hancock- gambling study. the barrer of bad news maybe dealt with harshly by the regalia, regardless of merit or station . I'am Sorry Standing for something not failing to stand for anything is not acceptable in my view and not worthy of a people or their ear. «hp »
Dave: Your references leading to CSIRO reports caused me to look again at info on the web. Fire storm weather in Victoria and fuels has been a big interest of mine so I challenge some of the info and conclusions re worst case wild fire phenomena.
Mountain Ash forests in the Dandenong Ranges were heavily burnt over wide areas in 1962 (32 perished) then again in 1968 we had more fires and lost firefighters in the Basin area (can’t recall the exact location of their burnt out truck). In between I had a good look at Hobart after that event in 1967. Then we had the 17 souls lost at Lara in grassland on the way to Geelong 1969. Up in the hills Mt Buffalo burnt all over in 1972 then again in 2003 along with Bright about the same time Canberra copped it.
Several other acquaintances remembered all the mess around Hobart so we got the maps out again after Jan. 2003 and reckoned on typical fire ground speeds up down and over what ever at about 15-18 km/h in the heat of the day. In private subs to inquiries I said experts had probably underestimated gas flow at the front on a bad day based on the flash through open woods, grass and scrub on a violent windy day. Note; fireballs, giant columns, brick houses exploding etc had been seen by many. Each had been scared out of their wits in the face of it all.
I also witnessed sheer panic by authorities in the Dandenongs as systems collapsed. During the 70’s after inquiries concluded much infrastructure in both states was upgraded. Towns on the outskirts of Melbourne got a new water supply, rural brigades got new equipment, states got better radios and Australia got a new disaster center based at Mt Macedon. Can you guess what got whipped out on Ash Wednesday?
Back to CSIRO -
“It is often said that bushfires generate their own wind. It is well known that wind boosts the intensity of a fire and the speed of its spread. The inference is that a bushfire will eventually become self-perpetuating—a beast with a mind of its own—spread in any direction and generally be unstoppable. Is this true? Fortunately, no.
Bushfires do generate wind. The strong convection set up by the heat of the fire creates an in-draw wind that can interact with the prevailing wind. Depending on the direction of the prevailing wind and the location of the fire, this in-draw wind may increase or decrease the strength of the prevailing wind”
http://www.ffp.csiro.au/nfm/fbm/ffotm/ffotm_13.html
“The strong updraughts in the flaming zone of the fire can produce sporadic fire whirls. These are wind vortices, much like turbocharged willy-willies, fuelled by the energy of the fire and are fairly commonly reported in forest and grass fires. They are generally only 1-2 m in diameter and last only a minute or two. However, in high intensity forest fires much larger whirlwinds can be produced, up to 150-200 m in diameter, which can last for some time, even outside the flaming zone. They can produce localised winds approaching cyclonic strength—the damage to trees and buildings is similar to that reported in cyclones”
“Preliminary measurements on the recent Canberra fires have noted a large whirlwind (or collection of whirlwinds) that travelled around 15 km, generally just ahead of the fire front. The destruction along the path of the whirlwind resembled that from a tornado, with large trees snapped off or uprooted, and the roofs lifted off many houses. Standard concrete roof tiles were transported in excess of 100 metres”
Thanks guys.
JD,
Have now read Bessie and Johnson (1995). No argument with the idea that extreme weather can cause extreme fires. However, given the same weather, the more fuel there is available, the fiercer the fire will be, at least in our eucalypt forests (they worked on Canadian data).
Also, there is interaction between fuel and weather, in that heavier fuels can create their own fire weather, ultimately a fire storm, like Hamburg in WW2. In severe weather, I know, from hard experience, which sort of fire I would rather face. It is not one in heavy fuel.
Another important point is that broad fire fronts tend to be hotter than narrow ones (Phil Cheney, Jim Gould and Lachie McCaw - Project Vesta?) Long fire exclusion leads to greater fuel patch connectivity, and broader fire fronts, so interaction again between fuel and weather and fire behaviour. Just like California, and Victoria in 2003? Not considered by Bessie and Johnson?
I am interested in your comments on this.
JD,
I am familiar with Fernandes and Botelho - useful review. Thanks for the other two - I will look them up. Glad to read any ideas, as long as the authors appear to be sane.
The FBI report is disturbing but not unexpected, man has a history of creating havoc. I have a blanket policy of not discussing specifics of threats but we must plan for odd events.
The Australian case is outlined here again
During the 20-year period from 1976-77 to 1995-96, some 2,499 fires (21%) on Victorian public land were assessed as deliberately lit (Davies 1997:�6). The only more prevalent cause was lightning strikes, which accounted for 3,024 fires (26%). The relative prevalence of fire causes was highly variable across different regions of the state, with deliberate lighting causing 12�per cent of fires in the north-east region but 39�per cent in the Port Phillip region (Davies 1997). Deliberately lit fires accounted for more than 80�per cent of the area burned in the Port Phillip region, but only six per cent in the north east (Davies 1997:�19). While further and closer analysis of the data would be needed to properly analyse the implications of this variation, it does suggest the perhaps expected conclusion that bushfire arson is far more prevalent in more urbanised areas
Prior to the period above I had a spot or two near Melbourne and could watch a long series of attacks. One experienced individual was nabbed after authorities twigged he was using their two way radio. Later another close to me interstate was likewise picked up from the air after the radios were silenced. Both had lit hundreds of fires under our noses.
On the second occasion my boyhood haunts became the center of a long investigation. We had to know but missed all clues except the pattern. Reflecting through shared childhood was the final key.Hazard reduction had been taken to excess at impressionable ages and that’s one good reason to back off with the burn to save rhetoric.
Green Davey Gam Esq,
You might also like to look at papers on the subject by Bessie and Johnson, Moritz and Fernandes and Botelho.
Stop being so selective.
JD in Australia we simply don’t know the numbers. I am aware of the report and probably contributed to background info on bushfire arson My previous post reflected experience in fire protection (biz) across a range of issues affecting urban and rural dwellers including detection of foul play round the margins.
“In the brief discussion above about causes of bushfires, a number of sources were cited which suggest that anywhere up to 90�per cent of bushfires are deliberately lit. A lack of consolidated national data makes this hard to confirm. In response to a question on notice in the Australian House of Representatives, which asked whether it was a fact that 70�per cent of bushfires are the result of arson, Dr�Brendan Nelson, Minister for Education, Science and Training stated that the Department of Education, Science and Training did not have any statistical information on bushfires arising from arson (Hansard 2003). In response to the same question, Wilson Tuckey, Minister for Regional Services, Territories and Local Government was also unable to advise whether the suggested rate was correct, stating that while a significant proportion of bushfires are suspected to be due to arson, there is no consistent national approach to the collection and analysis of bushfire data (Hansard 2003)”.
http://www.aic.gov.au/publications/rpp/61/06_part2.html
“A lack of consolidated national data makes this hard to confirm” is familular from from private discussions post Jan 2003.
During the 1980’s-90’s I had a lot of contact with communications staff servicing instalations in remote areas. Strike damage like fires and perhaps sabotage was part of our daily business. These days I need to conceed that bushfire ignition from dry lightening storms is probably on the increase.
Regardless of the situation, industrial or other emergency “evidence” either way on causes of damage was extreemly hard to get. The report above is only a review of the literature on bushfire causes ie the documented cases!