SAN ANDREAS FAULT SYSTEM

RESEARCH ASSIGNMENT:

- TECTONICS, GEOLOGY, FAULT DYNAMICS, AND HAZARDS -

A. Introduction:

This writing assignment involves the research, analysis, and writing on the San Andreas Fault System of California, with focus on the Southern California segment. The San Andreas Fault System (SAFS) is a network of related active faults that occur in California. Here, in Southern California, the SAFS is quite complicated and extensive, being nearly 200 kilometers wide - from the Salton Sea to Catalina Island - comprised of many interconnected, side-by-side, transform fault lines. Your textbook and the various websites listed below will be your primary sources of information.

The assignment topic includes the review and discussion of the tectonic setting of Southern California, the development and evolution of the SAFS, the present day dynamics and activity of the SAFS in So Cal, and the associated seismic hazards and precautions of living on within or near the SAFS.

B. Assignment Resources:

The primary source of information for completing this assignment, besides your textbook, comes from USGS publications along with other helpful sources listed below. If for some reason you cannot find the needed information from the following online sources, please feel free to search the Internet for additional reliable sources of information. Please list your sources at the end of your assignment document.

I. Overview - General Info about Earthquakes and Faulting:

Earthquakes 101:

URL1: https://earthquake.usgs.gov/learn/kids/eqscience.php

URL2: https://earthquake.usgs.gov/research/eqproc/

Magnitude, Size, Measuring of Earthquakes:

URL1: https://earthquake.usgs.gov/learn/topics/measure.php

URL2: http://www.geo.mtu.edu/UPSeis/magnitude.html

URL3: http://www.geo.mtu.edu/UPSeis/intensity.html

II. General Overview of the San Andreas Fault Zone:

URL1: http://www.thulescientific.com/QuickFacts.htm

URL2: http://www.sci.sdsu.edu/salton/San%20AndreasFaultSyst.html

URL3: http://geomaps.wr.usgs.gov/archive/socal/geology/geologic_history/san_andreas_history.html

URL4: http://en.wikipedia.org/wiki/List_of_earthquakes_in_California

USGS Text and Image documents on the SAFS:

URL1: http://pubs.usgs.gov/gip/earthq3/contents.html

URL2: http://pubs.usgs.gov/of/2005/1127/chapter1.pdf

In-depth/Detailed Reports: SAFZ - USGS Professional Paper 1515 -

URL1: http://pubs.usgs.gov/pp/1990/1515/pp1515.pdf

III. Images and Maps of SAFZ:

URL1: http://thulescientific.com/san-andreas-fault-map.html

URL2: http://thulescientific.com/san-andreas-fault-map.html

IV. History and Prediction of Earthquakes along the SAFZ:

URL1: http://en.wikipedia.org/wiki/List_of_earthquakes_in_California

URL2: http://foreshock.wordpress.com/significant-la-area-earthquakes-1769-present/

The Future "Big One" on the SAF

URL1: http://www.earthquakecountry.info/roots/scenario.html

URL2: http://www.earthquakecountry.info/roots/scenario.html

V. Earthquake Hazards and Safety of SAFS:

URL1: https://earthquake.usgs.gov/hazards/learn/basics.php

URL2: http://www.earthquakecountry.org/sevensteps/

1) Carefully review the three sets of assignment questions.

2) Read and study the listed URL s for the necessary information for answering questions.

3) Answer the question sets listed in Section D below. Minimize using quoted information.

4) Make sure to organize your paper into SEPARATE responses - leave space between each answer. Please include the stated questions as listed below at the beginning of each response. Color your answer text with a different text color from that of the question set text. An example of the required writing format is linked in the assignment folder.

5) Include a bibliography of the sources of information that you used at end of your paper.

D. Answer the following 3 question sets on Californiaï¿½s San Andreas Fault System below:

Part 1 - Overview of San Andreas Fault System (27 points - 3 points per lettered question set).

a) Where exactly is the San Andreas Fault system (SAFS) located in California? Be as specific as possible in describing the geographic regions/city centers where the fault system runs through. Also include the geographic points where it starts and stops.

b) What are the dimensions of the fault system? How long (in kilometers) from its north end to its south end? How wide (in kilometers) from the west side to the east side across southern California? How deep does the SAF fault extend down into the crust?

c) What is the most common type of fault found in the San Andreas Fault system in California? What specific type of fault is the San Andreas fault? Include its relative offset motion direction

d) What specific type of plate tectonic boundary does the SAFS represent? (Include the following in you answer: 1) tectonic boundary type; 2) the names of the two tectonic plates that are involved; and 3) indicate the specific lateral movement direction relative to each other)

e) How long ago did the SAFS first develop (in millions of years)? Also note where in California did it first show up. Lastly, what geologic events lead to the initiation of the SAF in the first place?

f) What type of plate tectonic boundary occurred prior to the development of the present-day SAFS (Include the tectonic boundary type and the names of the two plates involved and their movement relative to each other)?

g) What are the names of the five most major active faults found within the Southern California_segment of the SAFS? Note that you need to list the names of at least five active Southern California faults found between the Salton Sea and Catalina Island.

h) What is the name for the closest active SAFS fault here in the San Diego area? (Hint: it

runs right through downtown San Diego, and it has the word "Canyon" in it!). How large of

an earthquake is this fault currently believed to be able to generate?

I) What is the most active fault today in the southern segment (Southern California) of the

SAFS (most active over the last several decades)? Which fault in Southern California is

considered the most dangerous today and why?

Part 2 ï¿½ History of San Andreas Fault (24 points - 3 points per lettered question set).

a) What is the total transform offset movement (in kilometers) along the San Andreas Fault, based on the roughly 20 million year life-history of the fault? This question is asking you how far has the two adjoining plates moves laterally past each other in the last 20 million years.

b) How do geologists determine the total amount of transform offset along the SAF? This question asks you how geologists go about finding clues (offset markers) to how much total lateral movement has occurred between the adjoining plates over the fault s 20 plus million history.

c) What is the average annual slip rate measured along the San Andreas Fault proper?

(Note that there may be slight variations in average slip rate for each of the three

segments: northern, middle and southern).

How do geologists determine the average annual slip rate along the SAF? Hint: Itï¿½s not by

using a seismometer. Think about both collected real time data and historic data

e) Great quakes or ï¿½Big Onesï¿½ have a Richter magnitudes of 7.8 or greater. When and where did the last two "Big Ones" (7.8M or larger earthquakes) occur along the San Andreas Fault? (List the location, year, and magnitude of each of the two great quakes).

f) What is the average frequency, or recurrence rate, for a "Big One" quake along the San Andreas Fault? In others words, how often (how many years apart) do we get a "Big One" on the SAF? Again, this is only for quakes 7.8M or larger.

g) Finally, what is the average rupture offset (in meters) for a "Big One" quake along the San Andreas Fault? In other words, how much lateral wrenching movement occurs between the two adjoining plates when the fault zone breaks with sudden lateral offset during the quake.

h) What types of methods and tools are used by seismologists to monitor fault activity and fault displacement along the San Andreas Fault and its associated faults? In other words, how do seismologists measure and record fault stresses, and local movement on active faults? Briefly describe each method, including the specific types of scientific tools and equipment used. Note: You need to list and describe at least two different methods/tools for full credit.

Part 3 ï¿½ Quake Prediction and Hazards (24 points - 3 points per lettered question set).

a) Can geologists accurately predict earthquakes in the SAFS, or anywhere else in the world? For example, a seismologist at Cal Tech predicts that the southern segment of the San Andrea fault will rupture 10 miles NW of the town of Palm Springs on July 4th of 2020 with a magnitude of 7.9M. Is this currently possible or not? Why, or why not? Briefly explain why, or why not.

b) Can geologists determine the statistical probability of when (how often and the odds of one occurring at any given time) a major earthquake will take place along a specific fault in the SAFS? For example, a seismologist at Cal Tech states that the probability that the southern segment of the San Andrea fault will rupture somewhere between Palmdale and Palm Springs with a magnitude of 7.9M in the year 2016 is roughly 1 in 500, and that that particular segment of the fault ruptures on average every 400 years or so. Why or why not? Briefly explain why or why not.

c) Accurately define an ï¿½earthquake hazard". What are the specific types of seismic hazards associated with large earthquake events within the SAFS and the sorts of damage that it causes? Be thorough (you should have listed and described at least four types of earthquake hazards associated with a quake event.

d) Which type of seismic hazard do you think are the most dangerous for the San Andreas fault system and why? What is the likelihood that a large SAF earthquake causes the formation of a tsunami (like in the movie ï¿½San Andresï¿½ with the Rock? Explain your answer as whether itï¿½s likely or unlikely.

e) List and discuss some the ways that governments, engineers and emergency agencies address those hazards, in terms of infrastructure (buildings, bridges, dams, power lines, roads, gas lines, etc) integrity, action protocols for dealing with these hazards: before, during, and after a big quake - everything they do to minimize negative effects? Try to be thorough.

f) What are some of the most important things that you should do (or not do) DURING and AFTER a large earthquake - at home, at the office, and/or while driving?

g) How currently prepared are you for a big earthquake? List and describe the various ways that you and your family can be best prepared for the coming "Big One" - at home, at the office, and/or while driving.

h) How much has this research project increased your knowledge and understanding of the San Andreas Fault system? If you live in coastal California, did this research change your feelings about living here, in terms of comfort level and sense of personal security? In other words, are you any more or less frightened or concerned about being caught in a large earthquake someday?

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