The Role of the Asthenosphere and Mechanisms of Plate Motion

Flashcards covering the definition of the asthenosphere, plate movement rates, mechanisms of plate motion (convection, ridge push, slab pull), and subduction zones.

What is the asthenosphere and where is it located?

The asthenosphere is a denser and weaker layer of Earth that lies roughly $100-410\,km$ underneath the surface, below the lithosphere.

According to the notes, what is the annual rate of plate movement?

Plates move at different rates ranging from $2$ to $15\,cm$ every year.

What are two geological features formed by the interactions among tectonic plates mentioned in the transcript?

The Himalayas (a mountain range) in Asia and the San Andreas Fault in the United States.

What are the three primary mechanisms of plate motion?

A. Convection in the Mantle (Heat driven), B. Ridge push, and C. Slab pull.

How does mantle convection cause movement?

Different temperatures in the mantle cause hot, low-density material to rise and denser material to sink; when the denser material becomes heated and rises, the cycle continues.

What is another name for Ridge push?

Gravitational sliding plate.

Where does Ridge push serve as a driving force for plate movements?

In the mid-ocean ridges.

What is Slab pull?

A pulling force caused by a cold, dense oceanic plate as it sinks beneath continental plates that are less dense.

In which regions does Slab pull usually occur?

Along convergent boundaries and subduction zones.

What geological events and features are associated with subduction zones?

Subduction zones are regions where oceanic plates sink into the mantle, generating tsunamis, earthquakes, and volcanic ranges.

Where is the Cascadia Subduction Zone located?

It ranges from North California through the west of Oregon and Washington, up to British Columbia.

What are the names and locations of the two primary subduction zones near the Philippines?

1. The Manila Trench subduction zone (located between the South China Sea and the northern part of the country) and 2. The Philippine Trench (found on the east side of the country).