1. Earthquakes Hazards in North America A. Both plate boundary and within plate earthquakes Most of these are at ancient (former) plate boundaries now buried beneath younger sedimentary rocks or in deeply eroded mountain belts B. Central & Eastern N. America (within plate) C. Western North America (plate boundary)

2. B. Eastern & Central N. America (within plate) New Madrid seismic zone (buried ancient continental rift zone) ○ New Madrid, Mo (winter of 1811-1812; est. 8.2M, 7.8M, 8.1M, 8.3M) buried ancient continental rift zone Earthquakes Hazards in North America Geophysical (seismic) imaging of the subsurface in the New Madrid area with earthquake epicenters plotted as overlay

3. B. Eastern & Central N. America (within plate) East coast regions ○ Charleston, S.C. (1886 – intensity X; 1906 – intensity VII) ○ Newfoundland (1929; 7.2M) ○ Ancient faults at paleo-plate boundaries Former cont-cont collision zones = Appalachian Mountains Transform fractures (former transform faults) related to Mid Atlantic ridge Earthquakes Hazards in North America

4. Major plates and plate margins A slightly different representation from This Dynamic Earth USGS poster Shading (red) shows diffuse zones of crustal deformation, most of these are associated with (adjacent to ) plate boundaries and are areas of high earthquake activity Earthquakes Hazards in North America

5. C. Western North America (plate margin) Transform Margin and Strike-slip fault systems ○ Strike-slip faults w/ assoc. normal and reverse (thrust) faults ○ San Andreas (right lateral, strike slip) fault system 1989 Loma Prieta earthquake 1994 Northridge earthquake ○ Garlock and Walker Lane fault systems (East Sierra Nevada ranges) Earthquakes Hazards in North America

6. Western N. America Transform Margin and Strike-slip fault systems San Andreas fault system Garlock and Walker Lane fault systems (East Sierra Nevada ranges)

7. Western N. America Transform Margin and Strike-slip fault systems San Andreas fault system Garlock and Walker Lane fault systems (East Sierra Nevada ranges)

8. C. Western North America (plate margin) Subduction Margins ○ Cascade margin (N. California, Oregon, Washington) Seattle (Nisqually) earthquake Feb 2001, 6.8M (max intensity ~VIII ) Jan 1700 - ~9M ○ Central American margin Mexico City earthquake 1985, 8.0 M ○ Alaska – Aleutian margin 1964 Good Friday Anchorage earthquake, 9.0 M Earthquakes Hazards in North America

9. North American subduction zone earthquake areas Aleutian margin (Pacific plate subducted under N. American plate) Cascadian margin (Juan de Fuca plate subducted under N. American plate) Central American margin (Cocos plate subducted under N. American plate) Near to N. America but not a N. American plate margin Earthquakes Hazards in North America

10. Western N. America Continental Rift zones Basin and Range province A Continental Rift Zone

11. Western N. America Continental Rift zones Basin and Range province A Continental Rift Zone

12. Western N. America Continental Rift zones Basin and Range province Central Nevada Earthquake Zone

13. C. Western North America (plate margin) Continental Rift zones ○ Basin and Range province (includes most of Nevada, eastern Utah) Wells, NV – Feb 2008; 6.0M; intensity ~VIII Earthquakes Hazards in North America