Personal tools
 

Deep Earth Research

The Earth's Interior_BNL_p12525A
[The Earth's Interior - Brookhaven National Laboratory]

- Overview

The Deep Earth is fascinating because it is largely unexplored, with extreme conditions of heat and pressure, and plays a crucial role in shaping our planet's surface through processes like plate tectonics, while also holding secrets about the Earth's composition and how it generates its magnetic field, making it a subject of intense scientific curiosity despite our inability to directly access its depths. 

Scientists study the earth's interior using seismology, which involves recording and analyzing earthquake waves.

Deep within earth, you'll find the core, mantle, and minerals. 

The core:

  • The core is made of iron and nickel.
  • The inner core is solid, while the outer core is liquid.
  • The core is very hot and dense.
  • The core is about 2,900 kilometers (1,802 miles) below the surface.


The mantle: 

  • The mantle is solid and makes up two-thirds of Earth's mass.
  • The mantle is the source of magma that can erupt as volcanoes.
  • Heat and pressure in the mantle change the atoms in olivine into bridgmanite and ferropericlase.


Minerals:

  • Minerals like coal, gold, iron, copper, diamond, potassium, magnesium, and zinc are found deep within Earth.


Life:

  • Some life forms, like nematodes, live deep within Earth.
  • The deep biosphere contains viruses and microbes.

 

- Key Characteristics about the Deep Earth

At the bottom of the Earth's lower mantle, just above the liquid outer core, there is a region about 300 km thick called the D'' zone. Despite its thinness, this region plays a crucial role in the evolution of the earth because it regulates heat exchange from the metallic core to the silicate mantle and is the source of columnar mantle convection.

  • Unseen world: Humans have only drilled a tiny fraction of the way into the Earth's crust, so most of the deep interior remains unknown and can only be studied through indirect methods like seismic waves from earthquakes.
  • Extreme conditions: The deep Earth experiences immense pressure and temperature, with the core being hotter than the surface of the sun.
  • Internal structure: The Earth's interior is divided into distinct layers: the crust, mantle, outer core (liquid iron), and inner core (solid iron), each with unique properties.
  • Plate tectonics engine: The movement of tectonic plates on the Earth's surface is driven by convection currents in the mantle, which are influenced by heat generated deep within the Earth.
  • Magnetic field generation: The Earth's magnetic field, which protects us from harmful solar radiation, is believed to be generated by the movement of molten iron in the outer core.
  • Mystery of the deep: Scientists are still actively researching the composition, dynamics, and interactions between different layers of the deep Earth, leading to ongoing discoveries. 


- Deep-focus Earthquakes

Earthquakes occurring deep within the Earth, often referred to as "deep-focus earthquakes," are primarily associated with the process of subduction, where one tectonic plate dives beneath another at convergent plate boundaries, and are typically less damaging at the surface due to the energy dissipating as the seismic waves travel further to reach the surface compared to shallow earthquakes; their depth provides valuable information about the structure of the Earth's mantle. 

Key characteristics about deep-earth earthquakes:

  • Cause: Most deep earthquakes happen when the descending oceanic plate in a subduction zone experiences stress and ruptures at great depths within the mantle.
  • Location: These earthquakes are concentrated along subduction zones, often occurring hundreds of kilometers below the surface.
  • Impact on surface: Due to the distance seismic waves travel from the deep source, the shaking at the surface is usually less intense compared to shallow earthquakes of the same magnitude.
  • Scientific value: Studying deep earthquakes helps scientists understand the composition and physical properties of the Earth's mantle, including the behavior of rocks under extreme pressure.


- Research Topics in Deep Earth

Research topics in deep earth primarily focus on studying the composition, structure, and dynamics of the earth's mantle and core using various geophysical methods, including seismology, to understand phenomena like plate tectonics, mantle convection, the generation of the Earth's magnetic field, and the behavior of materials under extreme pressure and temperature conditions within the deep earth.

Key areas of research include:

  • Seismic tomography: Using earthquake waves to create 3D images of the Earth's interior, revealing variations in temperature and composition within the mantle and core.
  • Mantle plumes and hotspots: Investigating the origin and movement of large-scale upwellings of hot mantle material that can manifest as volcanic hotspots on the Earth's surface.
  • Subduction zone dynamics: Studying the process of tectonic plates diving beneath each other, including the fate of subducted oceanic crust and its impact on mantle flow.
  • Core-mantle boundary (CMB): Examining the interface between the Earth's mantle and liquid outer core, including the dynamics of this boundary and its role in generating the Earth's magnetic field.
  • Composition of the Earth's core: Determining the chemical composition of the solid inner core and liquid outer core, considering the potential presence of elements like iron, nickel, and lighter elements.
  • Geochemical modeling: Using chemical analyses of volcanic rocks to infer the composition of the deep mantle and trace the movement of mantle material.
  • High-pressure mineral physics: Conducting laboratory experiments to study the physical properties of minerals under extreme pressure and temperature conditions found in the deep Earth.
  • Earth's thermal structure: Investigating the distribution of heat within the Earth, including the role of radioactive decay and its impact on mantle convection.
  • Paleomagnetism:
  • Studying the Earth's ancient magnetic field to understand past plate movements and mantle dynamics.
  • Fluid flow in the mantle: Exploring the movement of fluids within the mantle, including their role in melting processes and the generation of magma.



[More to come ...]

 

Document Actions