The geological signature of great earthquakes off Canada's west coast

Geoscience Canada

Volumn 26, Issue 1, 1999, Pages 1-16

  Clague, John J ^a,b   Bobrowsky, Peter T ^c  

^a SIMON FRASER UNIVERSITY   (Canada)

^b GEOLOGICAL SURVEY OF CANADA   (Canada)

^c GEOLOGICAL SURVEY OF CANADA   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

EARTHQUAKE RECURRENCE; GEOCHRONOLOGY; LIQUEFACTION; PALEOSEISMICITY; SEDIMENTARY STRUCTURE;

CANADA;

EID: 0033102613     PISSN: 03150941     EISSN: None     Source Type: Journal    
DOI: None     Document Type: Article

References (102)

1. Adams, J., Weichert, D.H., Halchuk, S. and Basham, P.W., 1996, Trial seismic hazard maps of Canada - 1995: final values for selected Canadian cities: Geological Survey of Canada, Open File 3283, 97 p.
2. Ando, M. and Balazs, E.I., 1979, Geodetic evidence for aseismic subduction of the Juan de Fuca plate: Journal of Geophysical Research, v. 84, p. 3023-3028.
3. Arima, E.Y., St. Claire, E., Clamhouse, L., Edgar, J., Jones, C. and Thomas, J., 1991, Between Ports Albemi and Renfrew: notes on west coast peoples: Canadian Museum of Civilization, Canadian Ethnology Service, Mercury Series, Paper 121.
4. Atwater, B.F., 1987, Evidence for great Holocene earthquakes along the outer coast of Washington state: Science, v. 236, p. 942-944.
5. Atwater, B.F., 1988, Geologic studies for seismic zonation for the Puget Lowland, in Jacobsen, M.L. and Rodriguez, T.R., eds., National Earthquake Hazards Reduction Program, Summary of Technical Records XXV: United States Geological Survey, Open-File Report 88-16, p. 120-133.
6. Atwater, B.F., 1992, Geologic evidence for earthquakes during the past 2000 years along the Copalis River, southern coastal Washington: Journal of Geophysical Research, v. 97, p. 1901-1919.
7. Atwater, B.F., 1994, Geology of liquefaction features about 300 years old along the lower Columbia River at Marsh, Brush, Price, Hunting, and Wallace Islands, Oregon and Washington: United States Geological Survey, Open File Report 94-209, 64 p.
8. Atwater, B.F., 1996, Coastal evidence for great earthquakes in western Washington, in Rogers, A.M., Walsh, T.J., Kockelman, W.J. and Priest, G.R.,eds., Assessing Earthquake Hazards and Reducing Risk in the Pacific Northwest: United States Geological Survey, Professional Paper 1560, p. 77-90.
9. Atwater, B.F. and Hemphill-Haley, E., 1997, Recurrence intervals for great earthquakes of the past 3,500 years at northeastern Willapa Bay, Washington: United States Geological Survey, Professional Paper 1576, 108 p.
10. Atwater, B.F. and Yamaguchi, D.K., 1991, Sudden, probably coseismic submergence of Holocene trees and grass in coastal Washington state: Geology, v. 16, p. 706-709.
11. Atwater, B.F., Stuiver, M. and Yamaguchi, D.K., 1991, Radiocarbon test of earthquake magnitude at the Cascadia subduction zone: Nature, v. 353, p. 156-158.
12. Atwater, B.F., Nelson, A.R., Clague, J.J., Carver, G.A., Yamaguchi, D.K., Bobrowsky, P.T., Bourgeois, J., Darienzo, M.E., Grant, W.C., Hemphill-Haley, E., Kelsey, H.M., Jacoby, G.C., Nishenko, S.P., Palmer, S.P., Peterson, C.D. and Reinhart, M.A., 1995, Summary of coastal geologic evidence for past great earthquakes at the Cascadia subduction zone: Earthquake Spectra, v. 11, p. 1-
13. Barrientos, S.E. and Ward, S.N., 1990, The 1960 Chile earthquake - inversion for slip distribution from surface deformation: Geophysical Journal International, v. 103, p. 589-598.
14. Benson, B.E., Grimm, K.A. and Clague, J.J. 1997, Tsunami deposits beneath tidal marshes on northwestern Vancouver Island, British Columbia: Quaternary Research, v. 48, p. 192-204.
15. Bourgeois, J. and Reinhart, M.A., 1989, Onshore erosion and deposition by the 1960 tsunami of the Rio Lingue estuary, southcentral Chile [abstract]: EOS, v. 70, p. 1331.
16. Clague, J.J., 1997, Evidence for large earthquakes at the Cascadia subduction zone: Reviews of Geophysics, v. 35, p. 439-460.
17. Clague, J.J. and Bobrowsky, P.T., 1994a, Evidence for a large earthquake and tsunami 100-400 years ago on western Vancouver Island, British Columbia: Quaternary Research, v. 41, p. 176-184.
18. Clague, J.J. and Bobrowsky, P.T., 1994b, Tsunami deposits beneath tidal marshes on Vancouver Island, British Columbia: Geological Society of America, Bulletin, v. 106, p. 1293-1303.
19. Clague, J.J., Naesgaard, E. and Sy, A., 1992, Liquefaction features on the Fraser delta: evidence for prehistoric earthquakes?: Canadian Journal of Earth Sciences, v. 29, p. 1734-1745.
20. Clague, J.J., Bobrowsky, P.T. and Hamilton, T.S., 1994, A sand sheet deposited by the 1964 Alaska tsunami at Port Alberni, British Columbia: Estuarine, Coastal and Shelf Science, v. 38, p. 413-421.
21. Clague, J.J., Naesgaard, E. and Nelson, A.R., 1997, Age and significance of earthquake-induced liquefaction near Vancouver, British Columbia, Canada: Canadian Geotechnical Journal, v. 34, p. 53-62.
22. Clague, J.J., Bobrowsky, P.T., Hutchinson, I. and Mathewes, R.W., 1998, Geological evidence for past large earthquakes in southwest British Columbia, in Current Research 1998-A: Geological Survey of Canada, Ottawa, ON, p. 217-224.
23. Clague, J.J., Hutchinson, I., Mathewes, R.W. and Patterson, R.T., 1999, Evidence for late Holocene tsunamis at Catala Lake, British Columbia: Journal of Coastal Research, v. 15, p. 45-60.
24. Clarke, S.H., Jr., and Carver, G.A., 1992, Late Holocene tectonics and paleoseismicity, southern Cascadia subduction zone: Science, v. 255, p. 188-192.
25. Darienzo, M.E. and Peterson, C.D., 1990, Episodic tectonic subsidence of late Holocene salt marshes, northern Oregon coast, central Cascadia margin, U.S.A.: Tectonics, v. 9, p. 1-22.
26. Darienzo, M.E. and Peterson, C.D., 1995, Magnitude and frequency of subduction-zone earthquakes along the Oregon coast in the past 3,000 years: Oregon Geology, v. 57, n. 3, p. 3-12.
27. Darienzo, M.E., Peterson, C.D. and Clough, C., 1994, Stratigraphic evidence for great subduction-zone earthquakes at four estuaries in northern Oregon: Journal of Coastal Research, v. 10, p. 850-876.
28. Devoy, R.J.N., 1987, Sea surface studies - a global view: Croom Helm, London, 649 p.
29. Dragert, H., 1987, The fall (and rise) of central Vancouver Island: Canadian Journal of Earth Sciences, v. 24, p. 689-697.
30. Dragert, H. and Hyndman, R.D., 1995, Continuous GPS monitoring of elastic strain in the northern Cascadia subduction zone: Geophysical Research Letters, v. 22, p. 755-758.
31. Dragert, H., Lambert, A. and Liard, J., 1981, Repeated precise gravity measurements on Vancouver Island, British Columbia: Journal of Geophysical Research, v. 86, p. 6097-6106.
32. Dragert, H., Hyndman, R.D., Rogers, G.C. and Wang, K., 1994, Current deformation and the width of the seismogenic zone of the northern Cascadia subduction thrust: Journal of Geophysical Research, v. 99, p. 653-668.
33. Fletcher, C.H., III, Van Pelt, J.E., Brush, G.S. and Sherman, J., 1993, High-resolution stratigraphic framework, Holocene sea-level and climate history, and evolution of a tidal wetland: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 102, p. 177-213.
34. Goldfinger, C., Kulm, L.D., Yeats, R.S., Appelgate, B., MacKay, M. and Moore, G.F., 1992, Transverse structural trends along the Oregon convergent margin: implications for Cascadia earthquake potential: Geology, v. 20, p. 141-144.
35. Goldfinger, C., Kulm, L.D., Yeats, R.S., Appelgate, T.B., Jr., MacKay, M.E. and Cochrane, G.R. 1996, Active strike-slip faulting and folding of the Cascadia subduction zone plate boundary and forearc in central and northern Oregon, in Rogers, A.M., Walsh, T.J., Kockelman, W.J. and Priest, G.R., eds., Assessing Earthquake Hazards and Reducing Risk in the Pacific Northwest: United States Geological Survey, Professional Paper 1560, p. 223-256.
36. Guilbault, J.-P., Clague, J. J. and Lapointe, M., 1995, Amount of subsidence during a late Holocene earthquake - evidence from fossil tidal marsh foraminifera at Vancouver Island, west coast of Canada: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 118, p. 49-71.
37. Guilbault, J.-P., Clague, J.J. and Lapointe, M., 1996, Foraminiferal evidence for the amount of coseismic subsidence during a late Holocene earthquake on Vancouver Island, west coast of Canada: Quaternary Science Reviews, v. 15, p. 913-937.
38. Hanks, T.C. and Kanamori, H., 1979, A moment magnitude scale: Journal of Geophysical Research, v. 84, p. 2348-2350.
39. Hansen, W.R., Eckel, E.B., Schaem, W.E., Lyle, R.E., George, W. and Chance, G., 1966, The Alaska earthquake March 27, 1965: field investigations and reconstruction effort: United States Geological Survey, Professional Paper 541, 111 p.
40. Heaton, T.H. and Hartzell, S.H., 1986, Source characteristics of hypothetical subduction zone earthquakes in the northwestern United States: Seismological Society of America, Bulletin, v. 76, p. 675-703.
41. Heaton, T.H. and Hartzell, S.H., 1987, Earthquake hazards on the Cascadia subduction zone: Science, v. 236, p. 162-168.
42. Heaton, T.H. and Kanamori, H., 1984, Seismic potential associated with subduction in the northwestern United States: Seismological Society of America, Bulletin, v. 74, p. 933-941.
43. Hemphill-Haley, E., 1995, Diatom evidence for earthquake-induced subsidence and tsunami 300 yr ago in southern coastal Washington: Geological Society of America, Bulletin, v. 107, p. 367-378.
44. Holdahl, S.R., Faucher, F. and Dragert, H., 1989, Contemporary vertical crustal motion in the Pacific Northwest, in Cohen, S.C. and Vanicek, P., eds., Slow Deformation and Transmission of Stress in the Earth: American Geophysical Union, Geophysical Monograph Series, v. 49, p. 17-29.
45. Hutchinson, I., Clague J.J. and Mathewes, R.W., 1997, Reconstructing the tsunami record on an emerging coast: a case study of Kanim Lake, Vancouver Island, British Columbia, Canada: Journal of Coastal Research, v. 13, p. 545-553.
46. Hyndman, R.D. and Wang, K., 1993, Tectonic constraints on the zone of major thrust earthquake failure: the Cascadia subduction zone: Journal of Geophysical Research, v. 98, p. 2039-2060.
47. Hyndman, R.D. and Wang, K., 1995, The rupture zone of Cascadia great earthquakes from current deformation and the thermal regime: Journal of Geophysical Research, v. 100, p. 22, 133-22, 154.
48. Hyndman, R.D., Wang, K. and Yamano, M., 1995, Thermal constraints on the seismogenic portion of the southwestern Japan subduction zone: Journal of Geophysical Research, v. 100, p. 15,373-15,392.
49. Jacoby, G.C., Bunker, D.E. and Benson, B.E., 1997, Tree-ring evidence for an A.D. 1700 Cascadia earthquake in Washington and northern Oregon: Geology, v. 25, p. 999-1002.
50. w = 7.8) and its implications for systematics of subduction earthquakes: Earthquake Prediction Research, v. 3, p. 305-317.
51. Kelsey, H.M., Witter, R.C. and Polenz, M., 1993, Cascadia paleoseismic record derived from late Holocene fluvial and lake sediments, Sixes River valley, Cape Blanco, south coastal Oregon [abstract]: EOS, v. 74, n. 43, Fall meeting supplement, p. 199.
52. Kelsey, H.M., Engebretson, D.C., Mitchell, C.E. and Ticknor, R.L., 1994a, Topographic form of the Coast Ranges of the Cascadia margin in relation to coastal uplift rates and plate subduction: Journal of Geophysical Research, v. 99, p. 12,245-12,255.
53. Kelsey, H.M., Witter, R.C., Nelson, A.R. and Hemphill-Haley, E., 1994b, Repeated abrupt late Holocene environmental changes in south coastal Oregon: stratigraphic evidence at Sixes River marsh and Bradley Lake [abstract]: Geological Society of America, Abstracts with Programs, v. 26, p. A-524.
54. Lisowski, M., Prescott, W.H., Dragert, H. and Holdahl, S.R., 1989, Results from 1986 and 1987 GPS survey across the Strait of Juan de Fuca, Washington and British Columbia [abstract]: Seismological Research Letters, v. 60, p. 1.
55. Mathewes, R.W. and Clague, J.J., 1994, Detection of large prehistoric earthquakes in the Pacific Northwest by microfossil analysis: Science, v. 264, p. 688-691.
56. McCaffrey, R. and Goldfinger, C., 1995, Forearc deformation and great subduction earthquakes: implications for Cascadia offshore earthquake potential: Science, v. 267, p. 856-859.
57. McInelly, G.W. and Kelsey, H.M., 1990, Late Quaternary tectonic deformation in the Cape Arago-Bandon region of coastal Oregon as deduced from wave-cut platforms: Journal of Geophysical Research, v. 95, p. 6699-6714.
58. Mitchell, C.E., Vincent, P. and Weldon, R.J., 1994, Present-day vertical deformation of the Cascadia margin, Pacific Northwest, United States: Journal of Geophysical Research, v. 99, p. 12,257-12,277.
59. Moses, L.J., Obermeier, S.F. and Palmer, S.P., 1993, Liquefaction along the Chehalis and Humptulips Rivers, Washington [abstract]: EOS, v. 74, n. 43, Fall meeting supplement, p. 201.
60. Murty, T.S. and Boilard, L., 1970, The tsunami in Alberni Inlet caused by the Alaska earthquake of March 1964, in Mansfield, W.M., ed., Tsunamis in the Pacific Ocean (Proceedings, International Symposium on Tsunamis and Tsunami Research, Honolulu, 1969): East-West Center Press, Honolulu, HI, p. 165-187.
61. 14C ages from buried tidal-marsh soils in the Cascadia subduction zone, southern Oregon coast: Quaternary Research, v. 38, p. 75-90.
62. Nelson, A.R., 1992b, Holocene tidal-marsh stratigraphy in south-central Oregon - evidence for localized sudden submergence in the Cascadia subduction zone, in Fletcher, C.P. and Wehmiller, J.F., eds., Quaternary Coasts of the United States: Marine and Lacustrine Systems: Society of Sedimentary Geology, Special Publication 48, p. 287-301.
63. Nelson, A.R. and Kashima, K., 1993, Diatom zonation in southern Oregon tidal marshes relative to vascular plants, foraminifera, and sea level: Journal of Coastal Research, v. 9, p. 673-697.
64. Nelson, A.R. and Personius, S.F., 1996, Great-earthquake potential in Oregon and Washington - an overview of recent coastal geologic studies and their bearing on segmentation of Holocene ruptures, central Cascadia subduction zone, in Rogers, A.M., Walsh, T.J., Kockelman, W.J. and Priest, G.R., eds., Assessing Earthquake Hazards and Reducing Risk in the Pacific Northwest: United States Geological Survey, Professional Paper 1560, p. 91-114.
65. Nelson, A.R., Atwater, B.F., Bobrowsky, P.T., Bradley, L.-A., Clague, J.J., Carver, G.A., Darienzo, M.E., Grant, W.C., Krueger, H.W., Sparks, R., Stafford, T.W. and Stuiver, M., 1995, Radiocarbon evidence for extensive plate-boundary rupture about 300 years ago at the Cascadia subduction zone: Nature, v. 378, p. 371-374.
66. Nelson, A.R., Jennings, A.E. and Kashima, K., 1996a, An earthquake history derived from stratigraphic and microfossil evidence of relative sea-level change at Coos Bay, southern Oregon coast: Geological Society of America, Bulletin, v. 108, p. 141-154.
67. Nelson, A.R., Kelsey, H.M., Hemphill-Haley, E. and Witter, R.C., 1996b, A 7500-yr lake record of Cascadia tsunamis in southern coastal Oregon [abstract]: Geological Society of America, Abstracts with Programs, v. 28, p. 95.
68. Nelson, A.R., Shennan, I. and Long, A.J., 1996c, Identifying coseismic subsidence in tidal-wetland stratigraphic sequences at the Cascadia subduction zone of western North America: Journal of Geophysical Research, v. 101, p. 6115-6135.
69. 14C dating of a 7300-year earthquake history from an Oregon coastal lake [abstract]: Geological Society of America, Abstracts with Programs, v. 30, n.7, p. A-162.
70. Ng, M.K.-F., LeBlond, P.H. and Murty, T.S., 1991, Simulation of tsunamis from great earthquakes on the Cascadia subduction zone: Science, v. 250, p. 1248-1251.
71. Obermeier, S.F., 1995, Preliminary estimates of the strength of prehistoric shaking in the Columbia River valley and the southern half of coastal Washington, with emphasis for a Cascadia subduction zone earthquake of about 300 years ago: United States Geological Survey, Open-File Report 94-589, 48 p.
72. Pacheco, J.F., Sykes, L.R. and Scholz, C.H., 1993, Nature of seismic coupling along simple plate boundaries of the subduction type: Journal of Geophysical Research, v. 98, p. 14, 133-14, 159.
73. Peterson, C.D. and Darienzo, M.E., 1996, Discrimination of climatic, oceanic and tectonic mechanisms of cyclic marsh burial, in Rogers, A.M., Walsh, T.J., Kockelman, W.J. and Priest, G.R., eds., Assessing Earthquake Hazards and Reducing Risk in the Pacific Northwest of the United States: United States Geological Survey, Professional Paper 1560, p. 115-146.
74. Peterson, C.D. and Madin, I., 1997, Coseismic paleoliquefaction evidence in the central Cascadia margin, USA: Oregon Geology, v. 59, p. 51-74.
75. Peterson, C.D., Darienzo, M.E. and Parker, M., 1988, Coastal neotectonic field trip guide for Netarts Bay, Oregon: Oregon Geology, v. 50, n. 9-10, p. 99-106, 117.
76. Peterson, C.D., Barnett, E.T., Briggs, G.G., Carver, G.A., Clague, J.J. and Darienzo, M.E., 1997, Estimates of coastal subsidence from great earthquakes in the Cascadia subduction zone, Vancouver Island, B.C., Washington, Oregon, and northernmost California: Oregon Department of Geology and Mineral Industries, Open File Report 0-97-5, 44 p.
77. Plafker, G., 1969, Tectonics of the March 27, 1964, Alaska earthquake: United States Geological Survey, Professional Paper 543-I, 74 p.
78. Plafker, G. and Savage, J.C., 1970, Mechanism of the Chilean earthquakes of May 21 and 22, 1960: Geological Society of America, Bulletin, v. 81, p. 1001-1030.
79. Reilinger, R. and Adams, J., 1982, Geodetic evidence for landward tilting of the Oregon and Washington coastal areas: Geophysical Research Letters, v. 9, p. 401-403.
80. Reinhart, M.A. and Bourgeois, J., 1987, Distribution of anomalous sand at Willapa Bay, Washington - evidence for large-scale land-ward-directed processes [abstract]: EOS, v. 68, p. 1469.
81. Reinhart, M.A. and Bourgeois, J., 1989, Tsunami favored over storm or seiche for sand deposit overlying buried Holocene peat, Willapa Bay, WA [abstract]: EOS, v. 70, p. 1331.
82. Riddihough, R.P., 1984, Recent movements of the Juan de Fuca plate system: Journal of Geophysical Research, v. 89, p. 6980-6994.
83. Riddihough, R.P. and Hyndman, R.D., 1976, Canada's active western margin - the case for subduction: Geoscience Canada, v. 3, p. 269-278.
84. Rogers, G.C., 1988, An assessment of the megathrust potential of the Cascadia subduction zone: Canadian Journal of Earth Sciences, v. 25, p. 844-852.
85. Satake, K., Shimazaki, K., Tsuji, Y. and Ueda, K., 1996, Time and size of a giant earthquake in Cascadia inferred from Japanese tsunami records of January 1700: Nature, v. 378, p. 246-249.
86. Savage, J.C., 1983, A dislocation model of strain accumulation and release at a subduction zone: Journal of Geophysical Research, v. 88, p. 4984-4996.
87. Savage, J.C., Lisowski, M. and Prescott, W.H., 1981, Geodetic strain measurements in Washington: Journal of Geophysical Research, v. 86, p. 4929-4940.
88. Savage, J.C., Lisowski, M. and Prescott, W.H., 1991, Strain accumulation in western Washington: Journal of Geophysical Research, v. 96, p. 14,493-14,507.
89. Shennan, I., 1986, Flandrian sea-level changes in the Fenland, I, The geographical setting and evidence of relative sea-level changes: Journal of Quaternary Science, v. 1, n. 2, p. 119-154.
90. Shennan, I., 1987, Holocene sea-level changes in the North Sea region, in Tooley, M.J. and Shennan, I., eds., Sea-Level Changes: Blackwell, Cambridge, MA, p. 109-151.
91. Shennan, I., Long, A.J., Rutherford, M.M., Green, R.M., Innes, J.B., Lloyd, J.M., Zong, Y. and Walker, K.J., 1997, Tidal marsh stratigraphy, sea-level change and large earthquakes, 1, A 5000 year record in Washington, USA: Quaternary Science Reviews, v. 15, p. 1023-1059.
92. Siskowic, J., Anderson, D., Peterson, B., Peterson, C., Soar, M., Travis, P. and Volker, K., 1994, Possible coseismic liquefaction evidence at the Sandy River delta, Portland: tentative correlation with the last great Cascadia rupture [abstract]: Geological Society of America, Abstracts with Programs, v. 26, p. A-92.
93. Stuiver, M. and Becker, B., 1993, High-precision decadal calibration of the radiocarbon time scale, AD 1950-6000 BC: Radiocarbon, v. 35, p. 35-65.
94. Thomson, R.E., 1981, Oceanography of the British Columbia coast: Canada Department of Fisheries and Oceans, Canadian Special Publication of Fisheries and Aquatic Sciences, n. 56, 291 p.
95. Tooley, M.J., 1978, Sea-level changes in northwest England during the Flandrian Stage: Clarendon, Oxford, 228 p.
96. van de Plassche, O., 1982, Sea-level change and water-level movements in the Netherlands during the Holocene: Mededeling Rijks Geologische Dienst, Nieuwe Series, v. 36, n. 1, 93 p.
97. van de Plassche, O., 1991, Late Holocene sea-level fluctuations on the shore of Connecticut inferred from transgressive and regressive overlap boundaries in salt-marsh deposits: Journal of Coastal Research, Special Issue 11, p. 159-179.
98. Wells, D.R. and Coppersmith, K.J., 1994, New empirical relationships among magnitude, rupture length, rupture width, rupture area, and surface displacement: Seismological Society of America, Bulletin, v. 84, p. 974-1002.
99. Whitmore, P.M., 1993, Expected tsunami amplitudes and currents along the North American coast for Cascadia subduction zone earthquakes: Natural Hazards, v. 8, p. 59-73.
100. Wigen, S.O. and White, W.R., 1964, Tsunami of March 27-29, 1964, west coast of Canada: Canada Department of Mines and Technical Surveys, Ottawa, ON, 6 p.
101. Yamaguchi, D.K., Atwater, B.F., Bunker, D.E., Benson, B.E. and Reid, M.S., 1997a, Tree-ring dating the 1700 Cascadia earthquake: Nature, v. 389, p. 922.
102. Yamaguchi, D.K., Jacoby, G.C., Atwater, B.F., Bunker, D.E., Benson, B.E., Reid, M. and Woodhouse, C., 1997b, Tree-ring dating of an earthquake at the Cascadia subduction zone to within several months of January 1700, in Proceedings of the First Joint Meeting of the U.S.-Japan Conference on Natural Resources (UJNR) Panel on Earthquake Research: United States Geological Survey, Open-File Report 97-0467, p. 143-150.