http://speclab.cr.usgs.gov/wtc

Environmental Studies of the World Trade Center area after the September 11, 2001 attack.

U. S. Geological Survey, Open File Report OFR-01-0429

by Roger N. Clark, R. O. Green, G. A. Swayze, G. Meeker, S. Sutley, T. M. Hoefen, K. E. Livo, G. Plumlee, B. Pavri, C. Sarture, S. Wilson, P. Hageman, P. Lamothe, J. S. Vance, J. Boardman I. Brownfield, C. Gent, L. C. Morath, J. Taggart, P. M. Theodorakos, and M. Adams

This WTC report is now being served from the USGS pubs server. Click here to go to the full report Use the back button or a link to come back to speclab. (There are no links back to speclab from the pubs server.)

Photos involving our WTC work

Our first report concerned the fires (but the above report, OFR-01-0429, contains more analysis of the fires):
Images of the World Trade Center Site Show Thermal Hot Spots on September 16 and 23, 2001,
U.S. Geological Survey Open-File Report 01-0405,
By Roger N. Clark, Robert O. Green, Gregg A. Swayze, Todd M. Hoefen, K. Eric Livo,
Betina Pavi, Chuck Sarcher, Joe Boardman, and J. Sam Vance
(Last updated Nov. 2, 2001) Use the back button or a link to come back to speclab. (There are no links back to speclab from the pubs server.)

Fact Sheet:
USGS Environmental Studies of the World Trade Center Area, New York City, after September 11, 2001 U.S. Geological Survey Fact Sheet 0050-02. (Nov. 6, 2002)

Other Reports

Clark, R.N., G.A. Swayze, T.M. Hoefen, R.O. Green, K.E. Livo, G., Meeker, S. Sutley, G. Plumlee, B. Pavri, C. Sarture, J. Boardman, I., Brownfield, L.C. Morath, 2006, Chapter 4: Environmental mapping of the World Trade Center area with imaging spectroscopy after the September 11, 2001 attack: in Urban Aerosols and Their Impacts: Lessons Learned from the World Trade Center Tragedy, Jeff Gaffney and N. A. Marley (eds), American Chemical Society, Symposium Series 919, Oxford University Press, p. 66-83, plates 4.1-4.6. http://www.us.oup.com/us/catalog/general/subject/Chemistry/EnvironmentalChemistry/?view=usa&ci=9780841239166

• Figures from paper: click on figure caption to see the figure. Full text: see book.

• Figure 1. False color images showing the core affected area around the World Trade Center extending from 5 to 12 days after the collapse. Hot spots appear orange and yellow. Dozens of hot spots are seen on September 16th and 18th, but most had cooled or the fires had been put out by September 23. The image on the 18th is dark because of clouds which blocked sunlight but not light emitted by the fires. The key shows hot spot locations in Table I. Analysis of the data indicates temperatures greater than 700o C. Over 3 dozen hot spots are identified in the core zone. By September 23, only 4, or possibly 5, hot spots are apparent in the image, with temperatures cooler than those on September 16. Figure 1 also shows vegetated areas as green. Water appears blue, and the smoke from the fires appears as a light blue haze. White and lighter blue areas are rooftops, roads, and concrete as well as dust and debris from the collapsed buildings. Dust, probably more than a few millimeters thick (the optical depth), appears in shades of brown around the core WTC area on the 16th.

• Figure 2. AVIRIS spectra for thermal hot spot C (black lines) are shown with the fitted thermal response for September 16 (orange) and 18 (red). The spectral shape is used to constrain temperature and the intensity constrains area. The small rise near 2.5 fm in the spectrum from September 18 indicates another thermal component at a temperature lower than 330o C.

• Figure 3. Spectra of the field samples show a general range of spectral characteristics. Samples WTC01-37B and WTC01-37Am are concrete that display ferrous iron absorptions (most likely due to the minerals in the aggregate). The spectrum of concrete minus the aggregate is shown in sample WTC01-37A(c): the cement shows less ferrous iron absorption. Pervasive in the spectra of the debris is gypsum, with variations in abundance of other components. These spectra were used to map the WTC plume.

• Figure 4. WTC AVIRIS dust/debris plume map. The plume map indicates an asymmetry in the dust/debris distribution, with more iron bearing materials to the south by southeast. The colors match the colors of the spectra in Figure 3.

• Figure 5. Spectral reflectance mapping keyed to minerals that can have asbestiform morphology shows only scattered possible occurrences at the surface around the WTC area. Spectroscopy identifies mineralogy by detecting absorptions, due to molecular bonds, at a characteristic wavelength and with a diagnostic band shape. The grain size of a mineral affects the intensity and, to some extent, the shape of its spectral absorptions, but spectroscopy may not be sensitive to whether or not a mineral has an asbestiform shape (long needle-like shapes with diameters less than a micrometer), especially at the relatively low spectral resolution of AVIRIS. Therefore this map indicates possible areas of asbestiform mineralogy. The colored pixels show only small scattered locations. Locations are enhanced on Figure 6.

• Figure 6 The AVIRIS dust plume data, field sample data and field observations were combined to show the extend of the WTC dust plume on September 16, 2001 (green to yellow). Locations of asbestiform mineral spectral signatures from Figure 5 are shown as small orange spots. Note the asbestiform mineral signatures may indicate non-asbestiform amphibole and serpentine group minerals that are part of building materials. The locations of AVIRIS derived amphibole and serpentine group minerals is representative, and not exact because viewing angles of the sensor displaces positions of the tops of tall buildings relative to the ground (buildings appear to tilt at the edge of the scan lines compared to the center). For more accurate position of any one spot, use the data in Figure 5.

Meeker, G.P., S.J. Sutley, I.K. Brownfield, H.A. Lowers, A.M. Bern, G.A. Swayze, T.M., Hoefen, G.S. Plumlee, R.N. Clark, C.A. Gent, 2006, Chapter 5: Materials characterization of dusts generated by the collapse of the World Trade Center: in Urban Aerosols and Their Impacts: Lessons Learned from the World Trade Center Tragedy, Jeff Gaffney and N. A. Marley (eds), American Chemical Society, Symposium Series 919, Oxford University Press, p. 84-102. http://www.us.oup.com/us/catalog/general/subject/Chemistry/EnvironmentalChemistry/?view=usa&ci=9780841239166

Plumlee, G.S., Hageman, P.L., Lamothe, P.J., Ziegler, T.L., Meeker, G.P., Theodorakos, P., Brownfield, I., Adams, M., Swayze G.A., Hoefen, T., Taggart, J.E., Clark, R.N., Wilson, S., Sutley, S., 2006, Chapter 12: Inorganic chemical composition and chemical reactivity of settled dusts generated by the World Trade Center building collapse: in Urban Aerosols and Their Impacts: Lessons Learned from the World Trade Center Tragedy, Jeff Gaffney and N. A. Marley (eds), American Chemical Society, Symposium Series 919, Oxford University Press, p. 238-276, plates 12.1-12.2. http://www.us.oup.com/us/catalog/general/subject/Chemistry/EnvironmentalChemistry/?view=usa&ci=9780841239166
Local preprint: http://speclab.cr.usgs.gov/PAPERS/wtc.asc.ch3

Swayze, G.A., R.N. Clark, S.J. Sutley, T.M. Hoefen, G.S. Plumlee, G.P. Meeker, I.K. Brownfield, K.E. Livo, and L.C. Morath, 2006, Chapter 3: Spectroscopic and x-ray diffraction analyses of asbestos in the World Trade Center dust: in Urban Aerosols and Their Impacts: Lessons Learned from the World Trade Center Tragedy, Jeff Gaffney and N. A. Marley (eds), American Chemical Society, Symposium Series 919, Oxford University Press, p. 40-65. http://www.us.oup.com/us/catalog/general/subject/Chemistry/EnvironmentalChemistry/?view=usa&ci=9780841239166

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This page URL= http://speclab.cr.usgs.gov/wtc
This page is maintained by: Dr. Roger N. Clark rclark@usgs.gov
Last modified July 07, 2005.