What Is Geophysics? Research Areas, Funding, and Career Paths

Geophysics is the branch of Earth science that studies the physical properties and processes of the Earth — its interior structure, its gravitational and magnetic fields, and the dynamic forces (seismic, thermal, electrical) that shape it — using the tools and theory of physics. Where a geologist typically identifies and interprets rock and mineral evidence directly, a geophysicist measures physical signals — the way seismic waves travel through rock, the strength and direction of the magnetic field at a location, the tiny variations in gravity across a landscape — and works backward mathematically to infer what lies beneath the surface, often without ever taking a sample. Geophysics sits at the intersection of geology and physics: it borrows its subject matter (the solid Earth, its oceans, and its near-space environment) from geology and the Earth sciences, and its methods (wave mechanics, electromagnetism, fluid dynamics, inverse problems) from physics.

What Geophysics Actually Studies

At its core, geophysics asks: what is the physical state and structure of the Earth at a given location and depth, and what processes are driving change there? That question recurs across very different scales — from the composition of the Earth’s core thousands of kilometers down, to the fault rupture that produces a specific earthquake, to the slow flow of ice in a glacier.

• Earth’s interior structure — using seismic waves generated by earthquakes (or controlled sources) to image the crust, mantle, and core, the way a doctor uses ultrasound to see inside the body without cutting it open.
• Plate tectonics and geodynamics — the physical forces and mantle convection that drive plate motion, mountain building, and the deformation of the crust over time.
• Seismology and earthquake physics — how and where faults rupture, how seismic energy propagates, and what that means for hazard assessment.
• Geomagnetism and the Earth’s magnetic field — how the field is generated in the core, how it has reversed and varied through geologic time, and how it is measured and mapped today.
• Gravity and geodesy — precisely measuring the Earth’s shape, gravitational field, and how both change over time (ice-sheet mass loss, groundwater depletion, post-glacial rebound).
• Applied and exploration geophysics — using the same physical measurement techniques at a smaller scale to locate groundwater, mineral and energy resources, or subsurface hazards such as buried faults, voids, or contamination.

How Geophysics Relates to Geology and Physics

Geophysics is explicitly an interdisciplinary field, and most academic geophysics programs are housed in either a geology/Earth-and-planetary-sciences department or a physics department, sometimes both. For a fuller treatment of each parent discipline, see CASRAI’s What Is Geology? and What Is Physics? guides.

• From geology, geophysics inherits its subject — rocks, minerals, faults, basins, the ocean floor — and its practical questions: how old is this formation, where is the fault, how much groundwater is stored here. Many geophysical findings are validated or calibrated against direct geological observation (drill cores, outcrop mapping, radiometric dating of samples).
• From physics, geophysics inherits its methods: wave propagation theory for seismology, electromagnetism for magnetotellurics and ground-penetrating radar, fluid dynamics for mantle convection and groundwater flow, and the mathematics of inverse problems — reconstructing an unseen physical structure from indirect surface measurements, a technique shared with medical imaging and astrophysics.
• Overlap with oceanography and atmospheric science — marine geophysics (seafloor mapping, ocean-bottom seismology) overlaps with physical oceanography, and geospace physics (the upper atmosphere and magnetosphere) overlaps with atmospheric and space science. See CASRAI’s What Is Oceanography? guide for the ocean-science side of this boundary, and the What Is Meteorology? guide for the atmospheric side.
• Overlap with hydrology — near-surface geophysical methods (electrical resistivity, ground-penetrating radar, gravimetry) are widely used to characterize aquifers and groundwater systems; see CASRAI’s What Is Hydrology? guide.
• Overlap with nuclear physics — radiometric dating, a technique geophysicists and geologists both rely on to establish the age of rock and mineral samples, is built directly on the physics of radioactive decay; see CASRAI’s What Is Nuclear Physics? guide for the underlying physics.

For the full map of how geophysics fits among the natural sciences as a whole, see CASRAI’s branches of science guide, the anchor index for this entire series of discipline deep-dives.

Major Subfields of Geophysics

• Seismology — the study of earthquakes and the seismic waves they (or artificial sources) generate; used both to assess earthquake hazard and to image the Earth’s deep interior.
• Geodesy — precise measurement of the Earth’s shape, orientation, and gravity field, and how they change over time, using satellite positioning (GNSS), satellite radar interferometry (InSAR), and gravity satellites.
• Geomagnetism and paleomagnetism — the present-day magnetic field and its historical record preserved in rocks, used to reconstruct past plate positions and the field’s reversal history.
• Geodynamics and tectonophysics — the physics of mantle convection, plate motion, and crustal deformation over geologic timescales.
• Exploration (applied) geophysics — seismic, gravity, magnetic, and electromagnetic surveying to locate groundwater, mineral deposits, and hydrocarbon reservoirs, or to characterize a site for engineering and hazard purposes.
• Marine geophysics — seafloor mapping, ocean-bottom seismology, and the structure of oceanic crust.
• Planetary geophysics — applying the same physical techniques (seismometers, gravity measurement, magnetometry) to the Moon, Mars, and other planetary bodies, often via spacecraft instruments.
• Hydrogeophysics — near-surface geophysical methods applied specifically to characterizing aquifers, contaminant plumes, and the vadose zone.

How Geophysics Research Gets Funded

In the United States, academic and government geophysics research is funded across several agencies, each covering a different slice of the field:

• National Science Foundation (NSF) is the primary funder of academic, curiosity-driven geophysics in the US. The Division of Earth Sciences (EAR), within NSF’s Directorate for Geosciences (GEO), funds research into the structure, physics, and chemical evolution of Earth’s interior — the core territory of solid-Earth geophysics, seismology, geodynamics, and tectonophysics. Marine geophysics is funded largely through NSF’s Division of Ocean Sciences (OCE), also within the Geosciences directorate, and geospace/upper-atmosphere physics through the Division of Atmospheric and Geospace Sciences (AGS).
• U.S. Geological Survey (USGS) conducts and funds mission-oriented geophysical research directly tied to hazard monitoring and public safety — most visibly through its earthquake hazards and geomagnetism programs, which operate national seismic and magnetic observation networks and issue hazard assessments used by emergency management and building-code agencies.
• NASA funds solid-Earth and planetary geophysics primarily through its Earth Science Division (satellite geodesy, gravity missions, InSAR-based ground deformation monitoring) and its Planetary Science Division (seismometers and other geophysical instruments carried on planetary missions, such as those that have flown to the Moon and Mars).
• Department of Energy (DOE), through its Office of Basic Energy Sciences, funds geoscience research relevant to subsurface energy applications (geothermal energy, subsurface fluid flow, rock physics).
• Office of Naval Research (ONR) funds marine geophysics and ocean-bottom seismology relevant to naval operations, overlapping with NSF’s ocean-sciences funding.

The American Geophysical Union (AGU) is the field’s largest professional society and, while not a primary research funder itself, plays an outsized role in the field’s scholarly infrastructure — publishing its major journals, setting community norms, and administering some early-career and travel grant programs.

Research Methods, Tools, and Equipment

Geophysical research is built on physical measurement instruments and the computational methods used to interpret them:

• Seismometers and seismic arrays — instruments that record ground motion, deployed as single stations or dense networks/arrays to detect earthquakes and image subsurface structure through seismic tomography.
• Gravimeters — instruments that measure tiny local variations in the Earth’s gravitational field, used both in exploration surveys and, at the satellite scale, to track large-scale mass changes such as ice-sheet loss or groundwater depletion.
• Magnetometers — instruments that measure the strength and direction of the magnetic field, used in surveys and in dedicated satellite missions.
• GNSS/GPS geodetic networks — continuously operating satellite-positioning stations that measure millimeter-scale crustal motion over time.
• Satellite radar interferometry (InSAR) — a remote-sensing technique that measures ground deformation over wide areas by comparing radar images taken at different times.
• Electrical resistivity and electromagnetic surveying — methods that measure how subsurface materials conduct electricity, widely used in hydrogeophysics and near-surface site characterization.
• Ground-penetrating radar and borehole logging — near-surface and downhole tools that record physical properties of the subsurface directly.
• Computational modeling and inversion — the mathematical core of the field: reconstructing a physical model of the subsurface (or the deep Earth) that best explains a set of surface measurements, typically requiring substantial computing resources.

Career and Training Pathways

Most research careers in geophysics begin with an undergraduate degree in geology, Earth and planetary sciences, physics, or a dedicated geophysics program, followed by graduate study. A typical path:

• Bachelor’s degree — in geology, physics, Earth science, or geophysics, with a strong grounding in calculus-based physics and mathematics regardless of which department it’s housed in.
• Master’s degree — common as either a terminal degree for applied/exploration geophysics careers in industry (oil and gas, mineral exploration, environmental and engineering consulting) or a step toward a PhD.
• PhD — typically required for academic research positions, many federal research-scientist roles (USGS, NASA), and senior research roles elsewhere; usually structured around a dissertation built on original fieldwork, instrument deployment, or computational modeling, alongside coursework in the relevant physics and mathematics.

Career destinations include academic research and teaching, federal agencies (USGS, NOAA, NASA), the energy and mineral exploration industry, environmental and geotechnical consulting, and earthquake/hazard monitoring roles at state and federal agencies. The American Geophysical Union (AGU) is the field’s largest general professional society; the Society of Exploration Geophysicists (SEG) serves the applied/exploration side of the field specifically, and the Seismological Society of America (SSA) serves seismology specifically. All three publish major journals in the field and hold annual meetings that function as the discipline’s primary venues for presenting new research.

Frequently Asked Questions

What is the difference between geophysics and geology?
Geology broadly studies the composition, structure, and history of Earth materials, often through direct field observation and sample analysis. Geophysics applies physical measurement techniques — seismic, gravitational, magnetic, electromagnetic — to probe the Earth’s structure and monitor active processes, frequently without direct sampling. In practice the two overlap heavily and are often taught in the same department; many geophysicists have undergraduate training in physics rather than geology, or vice versa.

Is geophysics the same as physical geography?
No. Physical geography studies the Earth’s surface features and landscapes, often with an emphasis on human-environment interaction. Geophysics studies the Earth’s physical structure and processes, including deep interior structure that has no surface expression at all, using the quantitative methods of physics.

Do you need a PhD to work as a geophysicist?
No, not for every career path. Many applied/exploration geophysics roles in the energy, mining, and environmental-consulting industries are accessible with a bachelor’s or master’s degree. A PhD is generally expected for academic research positions and most federal research-scientist roles.

How is geophysics research typically funded in the United States?
Mainly through NSF’s Division of Earth Sciences and Division of Ocean Sciences (both within the Directorate for Geosciences), the USGS’s hazard-monitoring programs, NASA’s Earth Science and Planetary Science divisions, and, for energy-relevant subsurface research, the Department of Energy’s Office of Basic Energy Sciences — see the funding section above for how they divide the field’s territory.

What kind of math and physics background does geophysics require?
A solid grounding in calculus-based physics, differential equations, and linear algebra is standard, since core geophysical methods (wave propagation, potential-field theory, inverse problems) are built directly on that mathematical foundation. Programs vary in how much of this is required at the undergraduate level versus built up in graduate coursework.

Where Geophysics Fits Among the Sciences

For a broader map of how geophysics relates to the full set of major scientific disciplines — from physics and geology through to the other Earth and environmental sciences — see CASRAI’s branches of science guide, the anchor index for this whole series of discipline deep-dives.