GEOLOGY 460 - SOLID EARTH GEOPHYSICS, 3 units,
Lecture: TuTh 1 -1:50 PM; Lab* Th 8 - 10:50 AM
Instructor
Office Hours
Lori Dengler, Founders 7, 826-3115, email: lad1@ humboldt.edu
MW 9-11, Tu 10-12
I am usually available (outside of lecture). Please feel free to drop by my office. The
hour before class is not a good time!
This course surveys the principal geophysical methods (seismology, geomagnetism, geodesy, heat flow)
used to study the deep interior of the earth. We use these techniques to examine in more detail the
Cascadia subduction zone and the tectonics of the Pacific Northwest.
Prerequisites:
Physical Geology, one year physics, one semester calculus, or my consent. Structural
Geology recommended (may be taken concurrently).
Reading:
Text: Fowler The Solid Earth 2nd Ed., discount coupons available (good through
Jan. 31). Additional notes and handouts will be distributed in class. A drawer in VM
109 (labeled “Geophysics Drawer” will have copies of articles and publications for
your use.
Requirements:
• Attendance and participation. I expect you to attend class, ask questions, and
contribute to class discussions. If you notice news stories or publications relevant to
this class, please share them with us. During the first week of class, you will choose
a region of the world to monitor during the term. At the beginning of each lab
session, be prepared to talk about any significant earthquake activity in your region.
• Tests. There are 3 tests scheduled - 2 midterms and a final. You can use notes
during the tests.
• *Laboratories. Most of the lab work can be arranged at your own convenience
outside the scheduled lab time. However, it is essential that you be able to attend
the first hour. Wireless internet access is now available in Van Matre Hall – I
encourage you to bring your own laptops to lab. Some of the labs may involve use
of Geology Dept. equipment. Our equipment is fragile and we have no insurance
for replacing it if it becomes lost or damaged. You must follow operating and
handling instructions. Don’t try to fix something on your own, even if you think the
problem is minor. ASK questions if you are even the tiniest bit uncertain about how
something works or what to do.
LATE LAB policy: I give you ample time to complete the assignments. Labs must
be turned in ON TIME so that I can grade them all together and return them to you
in a timely manner. I will dock 25% for each day late.
• Paper related to the geophysics of the Cascadia subduction zone. The paper (4 to 7
pages of double-spaced text) will critique published papers related to the tectonics
of the Pacific Northwest. You will define a question – such as “Where is the
southern edge of the subducted Gorda plate?”, select three published papers related
to this question and prepare an outline, first draft and final draft for evaluation.
More information on the paper assignment is attached.
Grading:
• Tests
35%
• Laboratory
35%
• Paper
30%
Outline
5%
First Draft 10%
Final Draft 10%
Everyone who participates fully in the class should receive a decent grade.
Access to Electronic Geophysical Information:
Internet and the Web have greatly changed the collection and dissemination of geophysical information.
This is particularly true for seismology. Global and regional seismic networks are linked by computers
and automatically locate and estimate magnitudes of earthquakes within minutes of the event. Volcanic
eruptions are monitored, and in some cases, videotaped while in progress and displayed on the web.
Geophysical data sets are archived on the web. I receive earthquake and tsunami bulletins within
minutes of the occurrence of an event, and follow-up news stories shortly after. I’ve listed some good
web sites on the “What to Keep Watch On” handout. I suggest you become familiar with them, and if
you find others of note, share them with the class.
Blackboard: I have established a Blackboard account for the class and post announcements for each
lecture summarizing what we’ve covered, geophysical events and any changes in requirements. Please
check frequently – especially if you miss a class.
e-mail: I expect all of you to check your mailboxes regularly – it is the best way for me to contact you.
If you change your email address in the term - let me know. My address is lad1@ humboldt.edu and I
usually monitor my messages frequently. I have established a special e-mail account for my classes
where I post current geophysical events information. You can access this account via WebMail at
https://webmail.humboldt.edu/.
LogIN ID: geophs
Password: Equake
I leave new messages in the inbox for a few weeks, then stash older messages in a number of folders
which you can view by scrolling down to the bottom of the page and selecting different folders. If you
are having trouble accessing the account, ask for my help.
Paper on North Coast Seismotectonics
The purpose of this assignment is:
a. To become familiar with the tectonics of the north coast area - one of the most active (and
geotectonically controversial) regions of the western United States.
b. To look at examples of the application and limitation of Geophysical techniques in the study
of real problems.
c. To read and critically review scientific literature.
d. To gain experience in writing (and rewriting) a scientific paper.
e. To share what you have learned with the rest of the class.
During the course of the term I expect you to work closely with me in order to produce a satisfactory
final product. This will include meeting with me early in the term to discuss general ideas for the
paper, preparing an outline of the paper and meeting with me again to discuss the outline, preparing a
complete draft of the paper which I will extensively critique, and responding to my comments in a
final draft.
Due Dates:
1st meeting: before the end of February to discuss ideas and suggest references
Outline: 5 PM, Tuesday March 6 (earlier outlines gladly accepted)
2nd meeting: before the end of March to discuss outline
First Draft: 5 PM Friday, April 6
Final Draft: 5 PM Friday, April 27
Discussion of papers during last scheduled lab period May 3
Please read the following instructions carefully before beginning this assignment.
Content: The Gorda Basin and its boundaries define one of the most seismically active regions in
California. A number of studies of this area have been reported in the literature. The Cascadia
subduction zone which includes the convergent boundary between the Gorda-Juan de Fuca-Explorer
plates and North American plate has been recognized as capable of producing very large earthquakes.
The number of published papers on this region has increased yearly. They vary as to the type(s) of
data used, in the interpretation of that data and in the tectonic models that they propose. Your
assignment is to choose a problem and critically review three papers which use geophysical evidence
to study this problem. At least one of these papers must include seismic evidence.
A partial list of references will be distributed early in the term. Paper copies of some of these
references are in the Geophysics Drawer, VM 109.
Some examples of previous paper topics:
Is the Cascadia subduction zone locked?
Is the Gorda plate really a plate?
The dynamics of the Mendocino triple junction
The state of stress in the Gorda plate
The nature of the Mendocino fault
Was the 1992 Cape Mendocino earthquake on the Cascadia subduction zone?
Evidence for segmented rupture of the Cascadia subduction zone
Your review should make clear the type of data each study uses, how the authors have interpreted this
data and the model proposed to explain their interpretation. You should comment on any limitations
of their data or analysis (i.e.. sparse seismic station coverage, ambiguities in fault plane solutions, etc.).
You should also point out any areas of conflict or controversy among the different papers and explain
whether the controversy is due to different types of data gathered, different interpretations of the same
data and/or different proposed models. Finally you should add your own comments as to which
studies (or parts of studies) you think are most accurate, which are the weakest and why. I expect you
to have at least looked at recent papers using the type of data your paper covers. (For example - only
using Bolt et al's 1968 paper to describe the seismicity of the Basin is inadequate!).
Requirements: You are to turn in a short outline (1 page or less) and two drafts of this paper. See
above deadlines.
1. Outline: This should include a brief statement of the problem your paper will focus on (for example
- what earthquakes tell us about the stress state in the Gorda Plate, the seismicity of the southern
portion of the Cascadia subduction zone, etc.), the three main papers you intend to work with, and the
points you plan to discuss.
2. First draft: This should be written as a final copy (in other words, do your best job!). The text must
be between 4 and 7 pages of word-processed, double-spaced, clean text (no fonts sizes smaller than
12 point! and margins at least 3/4's of an inch on both sides!). The paper must include an abstract and
a bibliography (these don't count in your 4 - 7 pages). You may also include additional pages for
figures. Unless the figures are your own original work, you must cite their source. It is all right to
copy figures from a published paper; however please write your own figure caption and include the
citation in it. I will return these drafts with comments by April 20 or earlier if you get your draft to
me before the deadline.
3. Final draft: Your final draft should address any comments/criticisms I've raised on your first draft.
Attach the copy of your first draft with my comments on it!
NO LATE PAPERS WILL BE ACCEPTED!!! I will be glad to receive papers early and return
them to you early.
Suggestions on Format: If you are not quite sure how to put a scientific paper together, I suggest
you look at the format of a few papers in the literature first (this is not to say all published papers are
good - some are terrible - but it will give you an idea of the typical style). My own suggestions are to
start out with a rough outline of what you want to say.
You should begin with an introduction. The introduction should tell the reader what the subject
matter of the paper is, something about why this subject is of interest and most important, explain
what the plan or intent of your paper is - i.e.., why are you writing it!
The body of your paper should have some logical organization to it - feel free to use subheadings
if it helps you. There are a number of different ways to proceed here; if you are having organizational
problems - please see me.
Be sure to include some type of summary or conclusion section that reiterates the main points of
your paper.
I suggest writing your abstract after you've written the paper. An abstract is just that - a brief
description of the salient points of your paper. Its length should be commensurate with the length of
your paper. For this assignment, a paragraph should suffice. Again - look at examples in the literature
if you're uncertain about format and style.
Feel free to use figures (I encourage them!) - if you take figures out of the papers, reference them
properly.
Grading: Grading is based on content and quality of writing. It is impossible to separate these two since
it is very difficult to decipher the content of a very badly written paper! As to content, I am particularly
interested in how well you understood what the authors were trying to do and what assumptions they
made in their respective studies. You may find that the authors of your papers disagree on some or many
points. That’s fine – just point out their areas of disagreement and what data supports them. I don’t
expect you to become a supporter of one point of view or another – it is fine to point out weaknesses and
strengths in the papers and, if you wish, include how you feel about these arguments in the discussion
section, but try to be objective in your treatment. As to writing, there is no excuse for misspelled words,
run-on sentences and blatantly poor grammar! I will also consider how well your paper is structured and
whether you've cited references appropriately. Usually the rewritten version will get a better grade than
the first version if you've addressed all the comments I have made. However, occasionally papers don't
improve much and rarely they've gotten worse. If you are unclear as to how to proceed, please see me.