Essential Earth Science Glossary: From Seismograms to Flow Diagrams
Key Earth Science Terms and Definitions
Seismic Activity and Measurement
Seismogram
A seismogram is a chart created by a seismograph, a device that detects earthquakes and deformations. These graphs allow us to locate the epicenter of an earthquake, determine its magnitude, and identify the depth of focus.
Richter Scale
The Richter scale indicates the magnitude of an earthquake. It is logarithmic and has values from 1 to 10 degrees of elastic energy. For each degree of increase, the earthquake is 10 times more destructive.
Mercalli Scale
The Mercalli scale measures the destructiveness of an earthquake, valued in grades represented by Roman numerals (I-XII). It allows for the creation of a map with data on the intensity of an earthquake that has been registered in different localities around the epicenter. With this data, isoseismal lines are drawn.
Land Movements and Formations
Subsidence
Subsidence is the slow and gradual sinking of the soil. This can occur as soil settles after the extraction of fluids (water and oil) or due to seismic liquefaction phenomena.
Collapses
Collapses are sharp drops in the vertical plane, such as the collapse of a cave resulting from the dissolution of limestone or gypsum, or the collapse of a mine gallery.
Diapirs
Diapirs are natural geological formations derived from internal sources. They are caused by the upward movement of salt layers located at some depth towards the surface because they are less dense than the overlying strata.
Tombolo
A tombolo is a sedimentary landform, such as a bar, that forms a narrow strip of land between an island or a large rock off the coast and the mainland, or between two islands or large rocks.
Albufera
An albufera is a saltwater or slightly brackish lagoon, separated from the sea by a sandy tongue or cord but in communication with the sea at one or more points.
River Dynamics and Landforms
Base Level
Base level is the theoretical level below which a river cannot perform incisive work. It can be absolute (sea level) or local (lake, reservoir, or another river in the main channel).
Equilibrium Profile
All rivers tend to reach an equilibrium profile in which they invest all their kinetic energy to overcome friction and transport materials, with no erosion or sedimentation.
Flood Plains
Flood plains are broad, flat-bottomed valleys occupied by alluvial sediments. When a flood occurs, the water flows through them, losing speed and dissipating energy.
Fluvial Terraces
Fluvial terraces are a series of flat steps at different heights that are parallel to the riverbed.
Geological Processes and Phenomena
Karst
Karst refers to the phenomena of erosion, transport, and sedimentation that take place on water-soluble rocks, affecting both limestone and gypsum.
Pyroclastic Flow
A pyroclastic flow occurs when glowing fragments stop glowing and solidify.
External Geological Processes
External geological processes take place in the most superficial part of the lithosphere. Different external geological agents (gas, water) act through geological processes (weathering, erosion, transport), ultimately resulting in the modeling of the relief.
Internal Geological Processes
Internal geological processes occur due to geothermal energy. The causes of this rapid rise in temperature are due to the radioactive energy released by the process of nuclear decay of radioactive elements. These processes include the movement of lithospheric plates and the appearance of associated phenomena (volcanoes, earthquakes).
Hydrological Concepts
Flow Diagram
A flow diagram is used to plot events, situations, movements, and relationships of all kinds using symbols.
Peak Flow
Peak flow is the maximum flow rate corresponding to heavy rains. When flooding occurs in a short period and the peak flow is high, there is a danger of flooding. This problem can be solved by building dams.
Response Time
Response time is the time between precipitation and the arrival of a flood.