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Andrew Michael

Research Geophysicist

Contact Info

Short Biography

Andy Michael has been a geophysicist with the U.S. Geological Survey’s Earthquake Science Center in Menlo Park since 1986 where he combines observations of earthquake processes and statistical models to determine long-term and short-term earthquake probabilities, to evaluate proposed earthquake prediction methods, and to better understand how stress and structure function as part of the seismogenic process.  A graduate of MIT (B.S., 1981) and Stanford University (M.S., 1983, Ph.D. 1986), he has authored over 70 papers and reports.  He was the Editor-in-Chief of the Bulletin of the Seismological Society of America from 2004 to 2010 and is now the chair of the Seismological Society's Publications Committee. In 2011, for that work, he received the Society's Distinguished Service award.  His outreach efforts include founding the Earthquake Science Center web site ( which became part of to facilitate the rapid dissemination of earthquake information and a lecture and performance titled “The Music of Earthquakes,” which combines music and seismology and features “Earthquake Quartet #1,” his composition for voice, cello, trombone, and seismograms.  He is one of the founders of a new online educational resource: The Community Online Resource for Statistical Seismicity Analysis.

He currently works on the USGS Earthquake Probabilities and Occurrence Project, the Working Group for California Earthquake Probabilities, and is a member of the National Earthquake Prediction Evaluation Council.


If you do not have access to these publications, please contact me via email for reprints of any of these papers.

While this is the most complete list, my publications and citations can also be found via the following databases:
ResearcherID, Google ScholarScopus, and ORCID.

1. Toksoz, M. N., Shakal, A. F., and Michael, A. J.  , 1978, Space time migration of earthquakes along the North Anatolian Fault zone and seismic gaps, in Methodology for Identifying Seismic Gaps and Soon-To-Break Gaps, Isacks, B. L., Plafker, G., and Evernden, J. F., Editors, U.S.G.S. Open File Report 78-943, 829-856. 

2. Toksoz, M. N., Shakal, A. F., and Michael, A. J.  , 1979, Space-time  migration of earthquakes along the North Anatolian Fault Zone and seismic gaps,  Pageoph, 117, 1258-1270. 

3. Pulli, J. J., Stewart, R. R., Johnston, J. C., Tubman, K. M., and Michael, A. J.  , 1980, Field investigation and fault plane solution of the Bath, Maine earthquake of April 18, 1979, Earthquake Notes, 51, 39-46. 

4. Michael, A. J.  , Gildea, S. P., and Pulli, J. J., 1982, A real-time digital seismic event detection and recording system for network applications, Bull. Seism. Soc. Am., 72, 2339-2348. 

5. Michael, A. J.  , and Toksoz, M. N., 1982, Earthquake swarms as a long-range precursor to large earthquakes in Turkey,  Geophys. J. R. Astr. Soc., 68, 459-476. 

6. Michael, A. J.  , and Geller, R. J., 1984, Linear moment tensor inversion for shallow thrust earthquakes combining first-motion and surface wave data, J. Geophys. Res., 89, 1889-1898. 

7. Michael, A. J.  , 1984, Determination of stress from slip data: faults and folds, J. Geophys. Res., 89, 11,517-11526. 

8. Park, S., and in alphabetical order Brome, I., Cunningham, P., Harris, R., Hess, T., Hodges, J., Kirkpatrick, D., Madden T., Mellen, M., Menoher, J., Michael, A. J.  , Molnar, P., Murray, M., Olgaard, D., Standley P., Stock, J., Stork, C., and Wray, S. T., 1985, A geophysical study of Mesquite Valley: Nevada-California border, J. Geophys. Res., 90, 8685-8689. 

9. Michael, A. J.  , 1985, Regional stress and large earthquakes: an observational approach, Ph.D. thesis, Stanford University, 165 pages. 

10. Michael, A. J.  , 1987, The use of focal mechanisms to determine stress: a control study, J. Geophys. Res., 92, 357-368. 

11. Michael, A. J., 1987, Stress rotation during the Coalinga aftershock sequence, J. Geophys. Res., 92, 7963-7979. 

12. Hauksson, E., Jones, L., Davis, T., Hutton, K., Brady, G., Reasenberg, P., Michael, A. J.  , Yerkes, R. , Williams, P., Reagor, G., Stover,C., Bent, A., Shakal, A., Bufe, C., Helmberger, D., Johnston, M., and Cranswick, E., 1988, The 1987 Whittier Narrows earthquake in the Los Angeles Metropolitan Area, California, Science, 239, 1409-1412. 

13. Michael, A. J., 1988, Effects of three-dimensional velocity structure on the seismicity of the 1984 Morgan Hill, CA aftershock sequence, Bull. Seis. Soc. of Am., 78, 1199-1221. 

14. Michael, A. J., 1989, Spatial Patterns of aftershocks of shallow focus earthquakes in California and Implications for deep focus earthquakes, J. Geophys. Res., 94, 5615-5626. 

15. Nishioka, G. N., and Michael, A. J., 1989, A detailed study of the seismicity of the Middle Mountain zone at Parkfield, California, U.S.G.S. Open-File Report 89-546, 39 pages. 

16. Staff of the U.S.G.S., 1990, The Loma Prieta, California earthquake: an anticipated event, Science, 247, 286-293.

17. Nishioka, G. N., and Michael, A. J., 1990, A detailed study of the seismicity of the Middle Mountain, CA zone, Bull. Seis. Soc. of Am.., 80, 577-588. 

18. Editors: Plafker, G., and Galloway, J. P., Contributors: Bennet, M. J., Boore, D. M. , Borcherdt, R. D., Brown, W. M. III, Burford, R. O., Celebi M., Clark, M. M., Dietrich, J. H., Eberhart-Phillips, D. M. , Ellsworth, W. L., Hanks, T. C., Haugerud, R. A., Holzer, T. L., Johnston, M. J., Keefer, D. K., Kockelman, W. J., Lajoie, K. R., Lisowski, M., Michael, A. J.  , Ponti, D. J., Prentice, C. S., Prescott, W. H., Reasenberg, P. A., Rymer, M. J., Savage, J. C., Schwartz, D. P., Sharp, R. V., Thenhaus, P. C., Tinsley, J. C. III, Ward, P. L., Wells, R. E., 1989, Lessons learned from the Loma Prieta, California earthquake of October 17, 1989, U.S.G.S. Circular 1045, 52 pages. 

19. Michael, A. J., 1990, Energy constraints on kinematic models of oblique faulting: Loma Prieta versus Parkfield-Coalinga, Geophys. Res. Lett., 17, 1453-1456. 

20. Michael, A. J., Ellsworth, W. L., and Oppenheimer, D. H., 1990, Coseismic stress changes induced by the 1989 Loma Prieta, California earthquake, Geophys. Res. Lett., 17, 1441-1444. 

21. Eberhart-Phillips, D., Labson, V. F., Stanley, W. D., Michael, A. J.  , and Rodrigues, B., 1990, Preliminary velocity and resistivity models of the Loma Prieta earthquake region, Geophys. Res. Lett., 17, 2035-2038. 

22. Michael, A. J., 1991, Spatial variations in stress within the 1987 Whittier Narrows, California, aftershock sequence: new techniques and results, J. Geophys. Res., 96, 6303-6320. 

23. Michael, A. J., and Eberhart-Phillips, D. M., 1991, Relationships between Fault Behavior, Subsurface Geology, and Three-Dimensional Velocity Models, Science, 253, 651-654.

24. Michael, A.J.  1992, Three's a crowd in California, Nature, 357, 111-112. 

25. Michael, A.J., D. Oppenheimer, and P. Reasenberg, 1992, Preliminary seismological results, in "Special Issue: The Cape Mendocino Earthquakes of April 25-26, 1992", Earthquakes and Volcanoes, 23, 110-115. 

26. Michael, A.J. , and J. Langbein, 1993, Parkfield: learning while waiting, EOS, 74, pages 145, 153-154. 

27. Parkfield Working Group, 1993, Parkfield: First short-term earth- quake warning, EOS, 74, 152-153.

28. Eberhart-Phillips, D., and A.J. Michael, 1993, Three-dimensional velocity structure and seismicity in the Parkfield region, central California, J. Geophys. Res., 98, 15,737-15,758. 

29. Hill, D.P., P.A. Reasenberg, A.J. Michael  , W.J. Arabaz, G. Beroza, D. Brumbaugh, J.N. Brune, R. Castro, S. Davis, D. dePolo. W.L. Ellsworth, J. Gomberg, S. Harmsen, L.  House, S.M. Jackson, M.J.S. Johnston, L. Jones, R. Keller, S. Malone, L. Munguia, S. Nava, J.C. Pechmann, A. Sanford, R.W. Simpson, R.B. Smith, M. Stark, M. Stickney, A. Vidal, S. Walter, V. Wong, J. Zollweg, 1993, Seismicity remotely triggered by the magnitude 7.3 Landers, California, earthquake, Science, 260, 1617-1623. 

30. Scientists of the U.S. Geological Survey and the Southern California Earthquake Center, 1994, The magnitude 6.7 Northridge, California, earthquake of 17 January 1994, Science, 266, 389-387. 

31. Michael, A.J., P. Reasenberg, P.H. Stauffer, and J.W. Hendley II, 1995, Quake forecasting - an emerging capability, USGS Fact Sheet 242-95, 2 pp.  

32. Michael, A.J., L.M. Jones, 1995, A reevaluation of the seismicity alert probabilities at Parkfield, California, USGS Open-File Report 95-630, 24pp. 

33. Michael, A.J., 1996, The evaluation of VLF guided waves as possible earthquake precursors, USGS Open-File Report 96-67, 29pp.

34. Michael, A.J., 1997, Testing prediction methods: earthquake clustering versus the Poisson model, Geophys. Res. Lett., 24, 1891-1894.

35. Michael, A.J., and L.M. Jones, 1998, Seismicity alert probabilities at Parkfield, California, revisited, Bull. of the Seis. Soc. of Am., 88, 117-130. 

36. Eberhart-Phillips, D. and A.J Michael, 1998, Seismotectonics of the Loma Prieta, California, region determined from three-dimensional Vp, Vp/Vs, and seismicity, Journ. of Geophys. Res., 103, 21,099-21,120.

37. Michael, A.J., 1999, How well can we predict earthquakes?, in Is the reliable prediction of individual earthquakes a realistic scientific goal, an online debate edited by I. Main, at Online.

38. Michael, A.J., 1999, Realistic predictions are they worthwhile?, in Is the reliable prediction of individual earthquakes a realistic scientific goal, an online debate edited by I. Main, at Online.

39.  Bawden, G.W., A.J. Michael, and L.H. Kellogg, 1999, Evidence for a blind strike-slip fault in the southern Sierra Nevada, California, Geology, 27, 601-604. 

40.  Michael, A.J., S.L.  Ross, D.P. Schwartz, J.W. Hendley II, and Peter H. Stauffer, 1999, Understanding earthquake hazards in the San Francisco Bay Region: Major quake likely to strike between 2000 and 2030, USGS Fact Sheet 152-99, 4pp.  

41.  Jones, A., A. Michael, B. Simpson, S. Jacob, and D. Oppenheimer, 2000, Rapid distribution of earthquake information for everybody, Seis. Res. Lett., 71, 355-358. 

42.  Michael, A.J., and D. Eberhart-Phillips, 2000, The Loma Prieta aftershocks: heterogeneous stress or fault normal compression?, Proceedings of the 3rd Conference on Tectonic Problems of the San Andreas Fault System, Stanford University, Stanford, CA, 237-251. 

43.  Li, S-L., X-K Zhang, W.D. Mooney, X-L. Lai, A.J. Michael, Y-H. Duan, 2002, Structures and earthquake-generating faults in the Jiashi region, NW China, preliminary results, Chinese J. of Geophysics, 45, 72-77.  Also, in Chinese in Acta Geophysica Sinica pages 76-82. 

44.  Michael, A.J., S.L. Ross, H.D. Stenner, 2002, Displaced rocks, strong motion and the mechanics of shallow faulting associated with the Hector Mine, California, earthquake, Bull. Seis. Soc. of Am., 92, 1561-1569. 

45.  Participants of The Workshop on Effective Hazard Warnings, 2002, Improving the effectiveness of the homeland security advisory system,, 14 pp. 

46.  Participants of The Workshop on Effective Hazard Warnings, 2002, Developing  a unified all-hazard public warning system, PPW Report 2002-02,, 47 pp. 

47.  Michael, A.J., 2003, A scientist’s view of warning, International Association of Emergency Managers Newsletter, v. 20, 13-14.

48.  Michael, A.J., S.L.  Ross, F.W. Simpson, M.L. Zoback, D.P. Schwartz, M.L. Blanpied , 2003, Understanding earthquake hazards in the San Francisco Bay Region: Is a powerful quake likely to strike in the next 30 years?, USGS Fact Sheet 039-03, 4pp.  

49.  Ben-Zion, Y., Z. Peng, D. Okaya, L. Seeber, J. G. Armbruster, N. Ozer, A. J. Michael, S. Baris, and M. Aktar, 2003, A shallow fault zone structure illuminated by trapped waves in the Karadere-Duzce branch of the North Anatolian Fault, western Turkey, Geophys. J. Int., 152, 699-717, doi: 10.1046/j.1365-246X.2003.01870.x. 

50.  Michael, A.J., N. Field, A. Frankel, J. Gomberg, and K. Shedlock, 2003, USGS and Partners: Approaches to Estimating Earthquake Probabilities, in Earthquake  Science and Seismic Risk Reduction, ed. F. Mulargia and R.J. Geller, Kluwer, 159-175. 

51.  Michael, A.J., N. Field, A. Frankel, J. Gomberg, and K. Shedlock, 2003, USGS and Partners: Earthquake Probability Research Directions, in Earthquake  Science and Seismic Risk Reduction, ed. F. Mulargia and R.J. Geller, Kluwer, 181-185. 

52.  Partnership for Public Warning, 2003, A national strategy for integrated public warning policy and capability, PPW Report 2003-01,, 44 pp. 

53.  Peng, Z., Ben-Zion, Y. Michael, A.J., and Zhu, L., 2003, Quantitative analysis of seismic fault zone waves in the rupture zone of the 1992 Landers, California, earthquake: evidence for a shallow trapping structure, Geophys. Jour. Int., 155, 1021–1041.doi: 10.1111/j.1365-246X.2003.02109.x.

54.  Kastrup, U., M.L. Zoback, N. Deichmann, K. Evans, D. Giardini, and A.J. Michael, 2004, Stress field variations in the Swiss alps and the northern Alpine foreland derived from inversion of fault plane solutions, J. of Geophys. Res., 109, B01402, doi:1029/2003/JB002550.

55.  Hardebeck, J.L., and A.J. Michael, 2004, Stress orientations at intermediate angles to the San Andreas  fault, California, J. Geophys. Res., 109, B11303, doi: 10.1029/2004JB003239.

56. Eberhart-Phillips, D. and A.J Michael, 2004, Seismotectonics of the Loma Prieta, California, region determined from three-dimensional Vp, Vp/Vs, and seismicity, in The Loma Prieta, California, Earthquake of October 17, 1989 – Geologic Setting and Crustal Structure, ed. R.E. Wells, USGS Prof. Pap. 1550-E, 165-188.

57. Manaker, D.M., A.J. Michael, and R. Bürgmann, 2005, Subsurface structure and mechanics of the Calaveras-Hayward fault stepover from three-dimensional Vp and seismicity, San Francisco Bay region, California, Bull. Seis. Soc. of Am., 95, 446-470, doi: 10.1785/0120020202 .

58. Bakun, W.H., B. Aagaard, B. Dost, W.L. Ellsworth, J.L. Hardebeck, R.A. Harris, C. Ji, M.J.S. Johnston, J. Langbein, J.J. Lienkaemper, A.J. Michael, J.R. Murray, R.M. Nadeau, P.A. Reasenberg, M.S. Reichle, E.A. Roeloffs, A. Shakal, R.W. Simpson, and F. Waldhauser, 2005, Implications for prediction and hazard assessment from the 2004 Parkfield earthquake, Nature, 437, 969-974, doi:10.1038/nature04067.

59. Michael, A.J., 2005, Viscoelasticity, postseismic slip, fault interactions, and the recurrence of large earthquakes, Bull. Seis. Soc. of Am., 95, 1594-1603, doi 10.1785/0120030208

60. Thurber, C., H. Zhang, F. Waldhauser, J. Hardebeck, A.J. Michael, and D. Eberhart-Phillips, 2006, Three-dimensional compressional wavespeed model, earthquake  relocations, and focal mechanisms for the Parkfield, California, region, Bull. Seis. Soc. of Am., 96, S38-S49, doi 10.1785/0120050825.

61. Hardebeck, J.L, and A.J. Michael, 2006, Damped regional-scale stress inversions: methodology and examples for southern California and the Coalinga aftershock sequence,J. Geophys. Res., 111, B11310, doi:10.1029/2005JB004144.

62. Hardebeck, J.L., A.J. Michael, and T.M. Brocher, 2007, Seismic velocity structure and seismotectonics of the eastern San Francisco Bay region, California, Bull. Seis. Soc. of Am., 97, 826-842, doi 10.1785/0120060032.

63. Hardebeck, J.L., K.R. Felzer, and A.J. Michael, 2008, Improved tests reveal that the accelerating moment release hypothesis is statistically insignificant, J. Geophys. Res.,doi:10.1029/2007JB005410.

64.  Michael, A.J., 2009, BSSA: worth thinking about, 2009, Seismolological Research Letters, 80, 405-408.

65.  Michael, A.J., and S. Wiemer, 2010, CORSSA: the Community Online Resource for Statistical Seismicity Analysis, Community Online Resource for Statistical Seismicity Analysis, doi:10.5078/corssa-39071657. Available at 

66.  Michael, A.J., 2011, Earthquake sounds, in Encyclopedia of Solid Earth Geophysics, Seismology, ed. Harsh Gupta, Springer, 188-191.

67.  Zechar, J.D., J.L. Hardebeck, A.J. Michael, M. Naylor, S. Steacy, S. Wiemer, J. Zhuang, and the CORSSA Working Group, 2011, “Community Online Resource for Statistical Seismicity Analysis, Seismological Research Letters, 82, 686-690.

68.  Michael, A. J., 2011, Random variability explains apparent global clustering of large earthquakes, Geophys. Res. Lett., 38, L21301, doi:10.1029/2011GL049443.

69.  Kilb, D., Z. Peng, D. Simpson, D., A.J. Michael, M. Fisher, and D. Rorhlick, 2012, Listen, Watch, Learn: SeisSound Video products, Seismological Research Letters, 83, 281-286, doi: 10.1785/gssrl.83.2.281.

70. Michael, A.J., 2012, Do aftershock probabilities decay with time?, Seismological Research Letters, 83, 630-632, doi: 10.1785/0220120061.

71. Michael, A.J., 2012, Fundamental Questions of Earthquake Statistics, Source Behavior, and the Estimation of Earthquake Probabilities From Possible Foreshocks, Bull. Seis. Soc. of Am., 102, 2547-2562, doi: 10.1785/0120090184.

72. Tormann, T., S. Wiemer, S. Metzger, A. Michael, and J.L. Hardebeck, 2013, Size distribution of Parkfield’s microearthquakes reflects changes in surface creep rate,Geophys. Journ. Int., 193, 1474-1478, doi:10.1093/gji/ggt093. 

73. Llenos, A.L., and A.J. Michael, 2013, Modeling Earthquake Rate Changes in Oklahoma and Arkansas: Possible Signatures of Induced Seismicity, Bull. Seismol. Soc. of Am., 103, 2850-2861, doi:10.1785/0120130017

74. Michael, A.J., 2013, The Music of Earthquakes and Earthquake Quartet #1, For the Book “S.T.R.H.” Accompanying Konrad Smoleński’s installation S.T.R.H, ed. Kamila Wielebska, Łaźnia Centre for Contemporary Art, Gdańsk,Poland, p. 52-77, in English and Polish, ISBN 978-83-61646-8.

75.  Field, E.H., Biasi, G.P., Bird, P., Dawson, T.E., Felzer, K.R., Jackson, D.D., Johnson, K.M., Jordan, T.H., Madden, C., Michael, A.J., Milner, K.R., Page, M.T., Parsons, T., Powers, P.M., Shaw, B.E., Thatcher, W.R., Weldon, R.J., II, and Zeng, Y., 2013, Uniform California earthquake rupture forecast, version 3 (UCERF3)—The time-independent model: U.S. Geological Survey Open-File Report 2013–1165, 97 p., California Geological Survey Special Report 228, and Southern California Earthquake Center Publication 1792,

76.  Michael, A.J., 2014, How complete is the ISC-GEM global earthquake catalog?, Bull. Seismol. Soc. of Am.104, 1829-1837, doi: 10.1785/0120130227.

77.  Field, E.H., Biasi, G.P., Bird, P., Dawson, T.E., Felzer, K.R., Jackson, D.D., Johnson, K.M., Jordan, T.H., Madden, C., Michael, A.J., Milner, K.R., Page, M.T., Parsons, T., Powers, P.M., Shaw, B.E., Thatcher, W.R., Weldon, R.J., II, and Zeng, Y., 2014, Uniform California earthquake rupture forecast, version 3 (UCERF3)—The time-independent model, Bull. Seismol. Soc. of Am.104, 1122-1180, doi:10.1785/0120130164

78.  Jordan, T.H., W. Marzocchi, A.J. Michael, M.C. Gerstenberger, 2014, Operational Earthquake Forecasting Can Enhance Earthquake Preparedness, Seismol. Res. Lett.85, 955-959, doi:10.1785/0220140143. 

79. Felzer, K.R, M.T. Page, and A.J. Michael, 2015, Artificial seismic acceleration, Nature Geoscience, 8, 82-83 plus 9 pages of supplementary material.

80. Field, E.H., Biasi, G.P., Bird, P., Dawson, T.E., Felzer, K.R., Jackson, D.D., Johnson, K.M., Jordan, T.H., Madden, C., Michael, A.J., Milner, K.R., Page, M.T., Parsons, T., Powers, P.M., Shaw, B.E., Thatcher, W.R., Weldon, R.J., II, and Zeng, Y., 2015, LongTerm TimeDependent Probabilities for the Third Uniform California Earthquake Rupture Forecast (UCERF3), Bulletin of the Seismological Society of America, April 2015, v. 105, p. 511-543, First published on March 10, 2015, doi:10.1785/0120140093

81. Petersen, M.D., Mueller, C.S., Moschetti, M.P., Hoover, S.M., Rubinstein, J.L., Llenos, A.L., Michael, A.J., Ellsworth, W.L., McGarr, A.F., Holland, A.A., and Anderson, J.G., 2015, Incorporating induced seismicity in the 2014 United States National Seismic Hazard Model—Results of 2014 workshop and sensitivity studies: U.S. Geological Survey Open-File Report 2015–1070, 69 pp.,


My Science Topics

Science Topic
Natural Hazardsearthquake occurrences
Natural Hazardsearthquake probabilities
Natural Hazardsearthquakes

My USGS Science Strategy Areas

A National Hazard, Risk, and Resilience Assessment Program

Interesting Items, Available Software, and Seminars

Image of Interesting Items, Available Software, and Seminars

Listen to  my "Earthquake Quartet #1" for Voice, Trombone, Cello, and Seismograms and learn about why I composed it.

Visit the "Listening to Earthquakes" web page for a fun way to learn about how seismic waves are shaped by the earthquakes that cause them and the path they travel through the earth.

SLICK The slick package uses fault slip data (either field observations or from focal mechamism) to find the stress tensor that best explains the observations. Inputs are the orientation and slip direction of a set of fault planes. Outputs are the oreintation and shape of the stress ellipsoid, including confidence regions, and statistics used to judge the success of the inversion. This method uses the linear inversion agorithm and non-parametric bootstrap statistics.

SATSI (Spatial And Temporal Stress Inversion), developed by Jeanne Hardebeck and I, is a modified version of the SLICK stress inversion program that inverts focal mechanism data for a spatially and/or temporally varying stress field.  The inversion finds the least complex stress field model that is consistent with the data. It uses an adaptive smoothing method that discriminates between variations that are or aren't strongly required by the data and retains only variations that are well-resolved.

Public Lecture

The Parkfield 2004 Earthquake:Lessons From the Best-Recorded Quake in History, October 26, 2006

Earthquake Science Center Seminars

How Many Earthquakes Does It Take to Be Unusual?, May 5, 2010

Was that a foreshock? A tale of earthquake fundamentals and public warnings, July 22, 2009


Contact Information

Andrew Michael
345 Middlefield Road
Menlo Park, CA 94025
650-329-5163 - Fax
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