Information on the July-94 "Palm" Fire

The following is a late July 1994 accounting of the July-94 fire which burned through the observatory. After the short text is a list of photos.

We had a most exciting Fourth-of-July (1994) weekend at Pinon Flat Observatory. We had a not-so- small ``brush'' fire (officially 19,200 acres - 30 square miles) sweep through the observatory, pushed by strong winds and with a flame front estimated at 50 feet high. Since that time we've been scrambling to make sense of the damage and to restore what we could as quickly as possible.

Amazingly, nearly all the critical structures were saved -- we are thus extremely grateful to the fire-fighters. The things that were severely damaged were mostly those elements of the site that extended laterally above ground, there being no way to defend the long lines. This means some of the power distribution, much of the signal wiring outside the area of the central-recording facilities, and ~35% of the long-base laser strainmeter vacuum pipes were destroyed by the fire. Only a few instrumented vaults were destroyed. The site, away from the areas that were defended by the fire fighters and away from the areas immediately downwind of the defended structures, now has the look of lunar landscape. About 30 to 40% of the site is burned.

The fire-fighters -- there must have been two dozen or more crews at the site when the fire came through in the night -- evidently positioned themselves between the oncoming flames and each structure they chose to protect, and their strategy worked incredibly well. We now understand much more about this kind of fire, and how hard it is to gain control when the winds push the flames. We understand especially that it's not so much things catching on fire that's the big problem (at least when you have as many crews in action as this fire did, 3,000-plus people; they just axed away at odds and ends that were on fire), but rather the incredible heat given off as trees and thick bushes burst into flames. Signal wire, vacuum pipes and the like were partially melted wherever a tree or substantial bush was close by. When we first arrived at the site we found many (~60) sections of the strainmeter vacuum pipe sucked flat by the combination of the incredible heat and the vacuum inside the pipe.

All instrumentation was off-the-air when we first were allowed into the area, almost two days after the main fire - with small fires still underway in various places around the site. The power was off everywhere with most of the circuit breakers tripped on account of the power cabling having been melted in a number of places; the standby automated motor- generator was happily running with no load. Within 24 hours we succeeded in getting the power restored to most of the site, and the power company restored power to the mains (they had to replace poles, wires, and transformers). By week's end phone service was restored and we'd done the patch work to have the seismic and GPS receivers up and running. Both structures that housed the (2) permanent GPS receivers got singed, but escaped without serious damage. The antennas were in fine shape. We were lucky there.

At this point we're focusing on rerouting key signals from working instruments to the recording trailer, using undamaged lines. We estimate the site is about 50-70% functional; the one key bit of instrumentation that's not working, and will remain so until we spend some serious dollars in the machine-shop, are the laser strainmeters. [With University support all of these were rebuilt within the next two years.] Fortunately none of the critical components of these systems (the optical/laser/vacuum equipment in the end-vaults) were damaged in the slightest. All the components that would have required many months of skilled effort to rebuild survived.

Photos from the July-94 brushfire

Vacuum pipes from the University of California San Diego (UCSD) NS Laser Strain Meter (LSM) (342 KBytes)

The UCSD EW LSM at the east end (369 KBytes)

The UCSD NW/SE LSM viewed from the SE end (326 KBytes)

Vacuum pump along the UCSD NW/SE LSM (381 KBytes)

Remains of the Kyushu University (Japan) magnetometer (93 KBytes)

Above ground view of Lamont-Doherty Geophiyical Observaroty (LDGO) tiltmeter vault (west end) (333 KBytes)

Below ground view of LDGO tiltmeter vault (west end) (333 KBytes)

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