H005
WTC7 collapse resulted from fire-induced structural failure
NIST NCSTAR 1A proposition: fires following debris from WTC 1 caused buckling of Column 79 and then global collapse, without explosives. First known tall-building fire-induced global collapse, per NIST — uniqueness is a fact about the record, not automatically proof.
Likelihood — more or less than 50%
56%
More than 50% — weakly supported by the sources
Start at 50%. Move by half of the net source score after uncertainty. Net source score is 0.17 (from −1 contradict to +1 support). Uncertainty is 27%. So 50% + 50% × 0.17 × 73% remaining certainty = 56%.
0.5 + 0.5 × 0.17 × (1 − 0.27) = 0.562
Recalculate with sourcesAdversarial challenge
- Contradicting objects: 5
- Supporting objects: 3
- Distinct source classes: 3
- Objects with a zero quality dimension: 0
Version history
v1 · 2008-11-20 · conf 0.70 · unc 0.25
NIST 2008 fire-induced Column 79 sequence as the then-official account.
v2 · 2020-03-01 · conf 0.55 · unc 0.40
After NIST free-fall-stage FAQ and Hulsey 2020. Fire-only is still the official finding; uncertainty rose.
v3 · 2023-06-01 · conf 0.50 · unc 0.45
After 2023 instantaneous-free-fall paper plus Ryan 2012 girder-expansion arithmetic. Official fire-only sequence remains the institutional finding; uncertainty stayed first-class.
strongly supports1
NIST NCSTAR 1A: WTC 7 collapse initiated by fire-induced buckling of Column 79
NIST NCSTAR 1A — Final Report on the Collapse of World Trade Center Building 7 (2008) · 2008-11-20
NIST attributes WTC 7's collapse to fire-induced failure beginning at Column 79, with global collapse at 17:20.
human_seed · seeded · NIST Column 79 fire-induced sequence.
supports2
NIST: no corroborating evidence for explosives or thermite
NIST WTC investigation FAQs (towers and WTC 7) · 2019-11-20
NIST published a negative finding on explosives and thermite as collapse causes.
human_seed · seeded · NIST negative on explosives for WTC 7 as well as the towers.
FEMA 2002: WTC 7 fire-induced progressive collapse; further study needed
FEMA 403 — World Trade Center Building Performance Study (2002) · 2002-05-01
An early official engineering team attributed WTC 7 to fire while flagging that the mechanism was not fully understood.
human_seed · seeded · FEMA 2002 fire-induced working hypothesis.
indeterminate2
NIST FAQ: WTC 7 north face had a 2.25-second free-fall stage
NIST WTC investigation FAQs (towers and WTC 7) · 2019-11-20
NIST measured a 2.25-second free-fall stage of WTC 7's north face and described negligible support from the structure below.
human_seed · seeded · NIST free-fall stage is compatible with its buckling model and with demolition arguments.
9/11 Commission did not investigate WTC 7's collapse mechanism
9/11 Commission Report · 2004-07-22
The 9/11 Commission did not produce a collapse-mechanism finding for WTC 7.
human_seed · seeded · Commission silence on WTC7 mechanism is a scope gap, not a NIST finding.
weakly contradicts1
AE911Truth petition: thousands of architecture and engineering signatories dissent from NIST
Architects & Engineers for 9/11 Truth (Richard Gage and associated filings) · 2019-01-01
A public petition of architects and engineers calls the official collapse explanations incomplete and asks for a new investigation.
human_seed · seeded · Same petition is organised opposition to fire-only.
contradicts4
Hulsey et al. (UAF): fire did not cause the observed collapse of WTC 7
Hulsey, Quan, Xiao — University of Alaska Fairbanks WTC 7 study (2019–2020) · 2020-03-01
A University of Alaska Fairbanks team published a model concluding fire did not cause WTC 7's observed collapse.
human_seed · seeded · Hulsey: fire did not produce the observed collapse.
Chandler, Walter, Szamboti — Instantaneous free fall of WTC 7 and NIST's attempt to hide it (Jun 2023)
Journal of 9/11 Studies · 2023-06-01
Using multi-point tracking, Chandler/Walter/Szamboti report that after ~1.4 s of near-immobility of most of the north and west rooflines, those rooflines entered free fall together within ~0.2 s at ~8.0–8.2 s after east-penthouse collapse, ~9.8 m/s² for ~2.5 s.
human_seed · seeded · Authors say the motion is inconsistent with NIST global-collapse analyses.
Kevin R. Ryan — Why the NIST World Trade Center Reports are False (Toronto Report ch.3)
The 9/11 Toronto Report (2012), International Hearings on the Events of September 11, 2001 · 2012-09-11
Ryan cites NIST test and model figures (steel temperatures, sag, expansion, fire duration) and states they do not support the published collapse sequences; he notes NIST did not release its global models for independent runs.
human_seed · seeded · Ryan: WTC 7 girder walk-off arithmetic and unreleased models.
David Chandler — WTC 7: A refutation of NIST's analysis (Toronto Report ch.9)
The 9/11 Toronto Report (2012), International Hearings on the Events of September 11, 2001 · 2012-09-11
Chandler's 2012 hearing paper treats NIST's own Stage 2 free-fall interval as established and argues the 5.4 s overall figure is an artefact of start-time choice.
human_seed · seeded · Same paper as a NIST-refutation.
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