Types of Plates BoundariesDivergent, Convergent and Transform

EARTHQUAKES EPICENTER

PLATE BOUNDARIE

S

Plate Tectonics

Describe the formation and movement of ocean and continental plates.

Plate Movement Plates continue to move, sliding along

at rates of up to 8 inches per year in some areas

Plates are affected by the movement of magma filling the cracks in mid-ocean floor ridges as plates move apart.

Pacific plate shows lots of overall movement

Types of Plate Boundaries

DivergentConvergentTransform

Oceanic Divergent Boundary

Mid-Atlantic Ridge

Red Sea

Continental Divergent Boundary

Red Sea / E. African Rift

Continental Divergent Boundary: Baja California

Remember: Divergent boundaries occur along

spreading centers where plates are moving apart and new crust is created by magma pushing up from the mantle.

Remember:

Effects that are found at a divergent boundary between oceanic plates include: a submarine mountain range such as the mid-Atlantic Ridge; volcanic activity in the form of fissure eruptions; shallow earthquake activity; creation of new seafloor; and a widening ocean basin.

Remember: If a divergent boundary is between continental plates, the effects are: rift valley formation which will soon develop into linear sea; shallow earthquake activities, and numerous normal faults.

Part A. Continent-Continent

Continental-Continental: Himalayas

Remember:

When two continental plates meet head-on, neither is subducted. Instead, the crust tends to buckle and be pushed upward causing formation of mountain ranges and other highlands.

Convergence: Continental - Oceanic

Volcanic Activity due to Plate subduction

Remember: During the convergence of an oceanic

and continental plate, the denser oceanic plate slides under the continental plate. The process is called subduction.

Geologic events such as formation of volcanoes and trenches as well as occurrence of earthquake will take place because of this process.

Part C. Oceanic-Oceanic

Eastern Caribbean

Remember: When two oceanic plates converge they

also undergo subduction process. This gives rise to the formation of volcanic island arcs, trenches and generates shallow, intermediate or deep earthquakes.

Strong earthquakes generated at the ocean floor may cause displacement of large volume of water and launch big waves called tsunami.

TRANSFORM BOUNDARIES

Recall: Describe

Fault FaultingReverse FaultTransform FaultNormal Fault

FAULT a fracture, fissure, or a zone of

weakness where ground movement or displacement has occurred or may occur again.

FAULTING is the cause of TECTONIC

EARTHQUAKES

Types of Fault:

Most transform faults join two segments of a mid-ocean ridge (represented by the gaps between 1

and 2, and between 3 and 4). Remember that the presence of a ridge is an indication of diverging plates, and as the plates diverge between the two segments of the mid-ocean ridge, the adjacent slabs of crust are grinding past each other (blocks 2 and 3, blocks 1 and 3, and

blocks 2 and 4).

Continental Transform Boundary: San Andreas