E&ES 155 Hazardous Earth

Lecture 9

Earthquakes and Plate boundaries and

Faults

Recall: Earthquake epicenters map out plate boundaries

Different types of plate boundaries are typified by different types of earthquakes. Here is an idealized plate with the 3 main types of plate boundaries and their associated earthquake potential. The Pacific plate has the 3 types of plate boundaries, convergent margin, divergent margin, and transform.

Convergent Margins-Subduction Zones

Ocean plate-ocean plate

Ocean plate-continental plate Nazca-S. America

Continent-continent collisions-India-Asia

Divergent Margins

Interplate-Mid ocean-ridges

Intraplate-East Africa Rift

Transform Margins

San Andreas, Anatolian

Different plate boundary margins

Plate boundary cross-section

Earthquakes and Faults

Earthquakes are generated by volcanoes, meteorite impacts, underground nuclear explosions, undersea landslides. The most common type cause of an earthquake is the movement of earth along faults.

Orange grove

Faults and Mining-Permeability of fault zones, hanging wall and footwall

Strike and Dip

Types of Faults

Normal Faults

Reverse Faults

Strike-slip Faults-Right-lateral vs. left-lateral

Block diagram of fault surface