USA Seismic Hotspots Quiz
Where US earthquakes concentrate (AK, CA, Intermountain West, PR) (10 questions).
USA Seismic Hotspots Quiz: Quick Study Notes
The United States experiences significant seismic activity in several key regions, primarily due to its complex tectonic setting. From the subduction zones in Alaska to the transform faults of California and the extensional tectonics of the Intermountain West, understanding these hotspots is crucial for hazard assessment and preparedness. Puerto Rico also faces unique seismic challenges from its active plate boundary.
Key Seismic Regions in the U.S.
Key Takeaways
- Alaska experiences the most frequent and powerful earthquakes in the U.S. due to the subduction of the Pacific Plate.
- California’s seismicity is dominated by the San Andreas Fault system, a major transform plate boundary.
- The Intermountain West, including states like Utah and New Mexico, is characterized by extensional tectonics and normal faulting.
- Puerto Rico sits at an active plate boundary between the North American and Caribbean plates, leading to significant seismic and tsunami risks.
- Major fault systems like the Denali (Alaska), San Andreas (California), and Wasatch Front (Intermountain West) define these hotspots.
- Subduction zones, transform faults, and extensional rifts are the primary tectonic drivers of U.S. seismicity.
Frequently Asked Questions
Why is Alaska so seismically active?
Alaska sits on the Pacific Ring of Fire, specifically where the Pacific Plate subducts beneath the North American Plate, leading to frequent and powerful earthquakes, including megathrust events.
What is the primary cause of earthquakes in California?
Earthquakes in California are predominantly caused by movement along the San Andreas Fault system, a major right-lateral strike-slip (transform) fault that marks the boundary between the Pacific and North American plates.
Where are earthquakes concentrated in the Intermountain West?
Seismic activity in the Intermountain West is largely concentrated in the Basin and Range Province, with significant hotspots along the Wasatch Front in Utah and the Rio Grande Rift in New Mexico, driven by regional crustal extension.
What makes Puerto Rico a seismic hotspot?
Puerto Rico is located at an active convergent plate boundary where the North American Plate subducts beneath the Caribbean Plate, creating the deep Puerto Rico Trench and generating both shallow crustal and deeper megathrust earthquakes.
Are all U.S. seismic hotspots related to plate boundaries?
While most major U.S. seismic hotspots (like Alaska, California, and Puerto Rico) are directly on or very near plate boundaries, regions like the Intermountain West experience significant seismicity due to intraplate deformation related to broader tectonic stresses and crustal extension, even if not a direct plate edge.
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