JPE 395S: Physics of the Earth
Lecture 1: Introduction
NASA ESA
Left: view of the earth from space (image taken by NASA satellite);
Right: Earth Geoid field (taken by the ESA GOCE satellite)
Course Organization
Course Website: See Quercus Course Page
Announcement & Assignments (submission) through Quercus
Grading Scheme:
4 Problem Sets: 17%,18%,18%,17%
Final exam: 30%
Prerequisites: PHY140Y/151H/255H/254H, MAT235Y/237Y/257Y, MAT244H (or permission of
instructor). Note: Engineering courses equivalent to those above are also acceptable.
You can find most of the following information on the Quercus website:
Lecturer: Prof. Qinya Liu (with occasional Guest Lecturer: Tianshi Liu)
TA: Arya Kimiaghalam (grad student in Physics)
Lecture hours: Tuesdays and Thursdays 1-2 pm
Location: UC 161
Office hour: Tuesdays 2:15-3 pm at MP504A (with Q. Liu) with additional office hours before
PS due dates.
Course Organization
No official textbook. These are listed for your reference:
• Fundamentals of Geophysics by W. Lowrie, 2nd edn (2007), 3rd edn (2020)
• The Solid Earth, 2nd edn (2005), by C.M.R.Fowler
• Geophysics: a very short introduction by W. Lowrie (2018)
• Physics of the Earth, 4th edn (2008), by Stacey and Davis
• Geodynamics, 3rd edn (2014), by Turcotte and Schubert (more advanced)
• A student's guide to geophysical equations (2011) by W. Lowrie (quick reference
for equations)
• Quantitative Plate Tectonics (2015) by A. Schettino (a recent book)
• Geodynamics of the Lithosphere 2nd edn (2007) by K. Stuwe
• The dynamic Earth: The Story of Plate Tectonics (1996) by W. J. Kious and R. I.
Tilliing
Full lecture pdf notes (complementary to the ppt slides) are here
Sign up for informal class discussion on slack workspace at 2025-JPE395-UofT
Earth
Systems
as a result of
internal and
external heat
engine
Physics of the Earth – Intro to Geophysics
• What is Geophysics: application of principles and concepts of physics,
mathematics, geology, and engineering to the study of the physical
characteristics of the earth (and other planets), including gravity and
magnetic/electric fields, seismic waves, thermal structure, etc.
Why study the course?
- Intellectual curiosity: how does the solid Earth work? evolution history,
natural hazard, etc.
- Geophysics as a tool: resources exploration, environmental applications, etc
Course Topics: (1) Earth’s interior structure
-The Earth is layered (e.g., like an onion), but the layers interact
-The layers have different chemical compositions (made of different
minerals/rocks) and rheological properties (responses to stress/force)
From Understanding Earth (7 th edn)
Course Topics: (2) Plate Tectonics
-The Earth’s rigid surface is broken up into plates
Course Topics: (2) Plate Tectonics
- Present day plate motion (velocity) vector inferred from GPS measurements
with reference to a hypothetical fixed Earth Center
8
ITRF, International Terrestrial Reference Frame
Course Topics: (2) Plate Tectonics
Plate motions models (cm/yr)
9
Course Topics: (2) Plate Tectonics: How is it manifested on the surface?
earthquakes and most volcanoes are associated with plate boundaries
earthquakes
image courtesy: NASA
active volcanoes
Course Topics: (3) Why is there Plate Tectonics: Thermal Evolution
Iceland - the Earth is cooling
-it removes heat
through conduction and
convection
Plate tectonics and thermal evolution
are strongly coupled
Course Topics: (4) Gravity
University of Texas Center for Space Research & NASA
-we can probe the Earth’s interior by studying its gravity (Earth’s gravity field as
measured by GRACE satellite)
-gravitational forces affect the earth: tides, isostasy, post-glacial rebound,…
Compared to other Planets
Jupiter:
giant red
spot
Mercury: N. Hemisphere
NASA/JPL topography measured by
laser altimetry from
MESSENGER spacecraft
flybys (2011-2015).
Mars topography: N-S Dichotomy
Plate Tectonics – Unique to Earth?
Intriguing questions:
- Plate tectonics on Earth started around 3.2-2.8 Ga (?),
lithospheric thickness and strength – active mobile lid plate
tectonics
- Tectonics unique to Earth (i.e., active mobile lid plate tectonics)?
• Tectonics vs life on Earth: regulated carbon cycle and long-term
stability of climate, atmospheric composition, etc? oxygenation
of the atmosphere? Evolution pressure exerted by dynamically
changing surface environment?
- Both tectonics (subduction) and life on Earth require WATER
- Transfer of minerals/rocks to surface through geological
processes
- More data points required – exoplanets?
Extra Slides: History of the Earth
Geological conventions/abreviations:
• time duration: 1 Myr: (1 million years in duration)
• a point in time: 4,560 Ma (for mega annum or “millions of years” ago); 4.56 Ga (for
giga annum or billions of years)
• approximate point in time: ca. 4,000 Ma (for Circa, or “around” or “approximately,”
usually appears with dates)
