Hot Spots

• What They Are

• Their Characteristics

• How They Behave

• How We Know What We Do

• Why You Should Know

Definition

• A volcanic center, 60 to 120 miles (100 to 200 km) across and persistent for at least a few tens of million of years, that is thought to be the surface expression of a persistent rising plume of hot mantle material. Hot spots are not linked to arcs and may not be associated with ocean ridges.

Diagram of a Typical Oceanic Hot Spot

Convection in the Earth’s Mantle

The Hawaiian Islands & theHawaiian-Emperor Seamount Chain

Mantle PlumeNote: This concept is being debated…

Possible Motion of Heated RockInside the Earth

Compositional vs. Mechanical Layering

Earth’s Major Plates

Hot Spot Time Progression

Life Cycle of a Typical Oceanic Hot Spot

USGS Map of Worldwide Hot Spots

Hawaiian Island Hot Spot Track

Yellowstone Hot Spot Track

Latest Ideas

• Hot Spots may be related to huge blobs of magma that rise from within the mantle and pool against the base of the lithosphere

• May not be associated with “plumes”

Mantle Plume Concept Phasing Out?

Some geologists think that the mantle plume idea isn’t holding up; they think theycan explain magma melting by drops in pressure, rather than deep-seated heatsources…

Summary• ~50-100 miles wide

• Live for 10’s of millions of years

• Are fixed in the mantle

• Are NOT linked to arcs

• May not be associated with ridges

• Have a life cycle

• Leave a track of volcanic features on the landscape (or seascape)