NRC Workshop on Mmax in the Central and Eastern U.S. EQ Hazards Workshop September 9-10, 2007

NRC Workshop on Mmax in the Central and Eastern U.S.EQ Hazards WorkshopSeptember 9-10, 2007USGS, Golden, CO

U.S. Department of the InteriorU.S. Geological Survey

Figure A8–1

Walter D. Mooney USGS-Menlo ParkMmax in CratonsOutline:

1. Introduction2. Continental Evolution3. Earthquakes and Tectonics4. Lithospheric Structure5. Lith-EQ Correlation (Mmax)6. Conclusion: Mmax = 6.8 (?)

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North American Geology Figure A8–3

3.0 Ga (Archean): Formation of Cratons Figure A8–4

Diamonds form here

2.0 Ga (Early Proterozoic): Suturing of Cratonic Blocks

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1.0 Ga (Late Proterozoic): Mantle Metasomatism at Lithospheric Suture, Intraplate Zone of Weakness

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Earthquake

• Schulte, S. M., and Mooney, W. D., 2005, An updated global earthquake catalogue for stable continental regions: reassessing the correlation with ancient rifts: Geophysical Journal International, v. 161, p. 707-721.

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Figure A8–8

Extended margin earthquakes. Red circles denote earthquakes that are associated with extended margins, green circlesdenote events that are possibly associated with extended margins. Regions of concentrated seismicity are numbered.

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Interior rift earthquakes. Red circles identify earthquakes that are associated with interior rifts, green circles identify eventsthat are possibly associated with interior rifts. Regions of concentrated seismicity are numbered.

Non extended crust earthquakes. Earthquakes are indicated with blue circles. Regions of concentrated seismicity are numbered.

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Figure 9. Eastern United States, taken from the Exxon tectonic map of the world [Exxon, 1985]. Rifts have been highlighted in red and blue. Earthquakes from the database have been plotted on top. Red circles denote events associated with extended crust, green circles denote events that might be associated with extended crust. Events that occurred within non-extended crust are indicated in blue. Earthquakes that occurred within the St. Lawrence depression are indicated in orange.

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Lithospheric RootFigure A8–12

Model of Precambrian Lithosphere Figure A8–13

Lithosphere is Generally in a State of Failure EquilibriumFigure A8–14

Tomographic ModelFigure A8–15

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