Science Reviewer Week 3 - 4: Earth's Interior

Study Notes

Seismic Waves are pivotal in understanding Earth's layers; S-Waves travel only through solids, indicating layer differences.
Rock Samples also provide insights into the Earth’s interior structure.

Crust constitutes 0.5% of Earth’s Mass.
- Continental Crust: Composed of granitic and sedimentary rocks, 30-50 km thick, less dense, and older due to minimal destruction.
- Oceanic Crust: Made of basaltic and igneous rocks, 6-7 km thick, denser and younger than continental crust.
- Lithosphere: Contains tectonic plates; characterized by brittle and rigid properties.
Mohorovicic Discontinuity (Moho) marks the boundary between the crust and mantle, discovered by Andreaha Mohorovicic in 1909; characterized by a change in seismic wave velocity.
Project Moho, initiated in 1958, aimed to sample the Earth's crust.
- Drilling began in 1960 but was limited to the crust.
- Conducted in Guadalupe, Mexico, ceased due to political, budgetary, and scientific challenges.
Mantle holds about 80% of Earth's mass and consists of minerals like Fe, Mg, Al, Si, and O.
- Asthenosphere is a plastic region of the upper mantle, named for its lack of strength.
- Contains Upper, Middle, and Lower Mantle sections.
Gutenburg Discontinuity is located between the mantle and core, where seismic wave velocity changes, discovered by Weichert Gutenburg in 1912.
Core comprises around 15% of Earth's volume, with the outer core being liquid (Fe and Ni) and the inner core being solid.
- Temperature and pressure increase with depth; 1 degree Celsius increase corresponds to 40 meters of depth.

Earthquakes result from sudden energy release, causing shaking or trembling of the ground, often linked to faults or rock breakage.
Most earthquakes occur in the Pacific Ring of Fire (90%), primarily due to convergent margin activity.
15% occur in the Mediterranean-Asiatic belt; 5% in the interiors of tectonic plates and spreading ridge centers.
Over 150,000 earthquakes are recorded annually.

Indonesia, Japan, Philippines, Chile, Mexico, Kamchatka Peninsula, United States, New Zealand, Alaska, Canada.

Normal Fault: Caused by tension, involves divergent plates, shallow focus, and low magnitude.
Strike-Slip Fault: Result of shearing forces, associated with transform plates, features high magnitude and deep focus.
Reverse/Thrust Fault: Associated with compression, involves convergent plates, typically has high magnitude and deep focus.

Describes energy generation and release during earthquakes.
Rocks bend until the strength limits are exceeded leading to rupture and a rapid return to their undeformed state.
Energy released manifests as waves radiating from the fault.
Proponent: Harry Fielding Reid, based on the 1906 San Francisco Earthquake study.

Characterized by numerous subduction zones, leading to high seismic and volcanic activities.

Area of seismological activity in the upper mantle below subduction zones, corresponding with down-going slab motion.
Named after Kiyoo Wadati and Hugo Benioff for their contributions to understanding seismicity in these regions.