The subject is Earthquakes.
1. LOCALLY… First we’ll consider the types of faulting we have in southern and central California (up to Cape Mendocino). They’re called strike-slip faults, and are found where one block of crust is sliding horizontally past another. The most famous of these is the San Andreas Fault (SAF), which runs from the corner of the Salton Sea 700 miles north-by-northwest to Cape Mendocino, The earthquakes produced by this fault can be large as 8.0+ which is rather impressive, but pale in comparison to truly “great” earthquakes like the 2011 Japan (Tohoku) earthquake and tsunami.So for the first part of this assignment, let’s take a look at our local ‘cousin’ of the SAF, the Rose Canyon Fault (RCF).Study the following resources:
- The web page “Significant Earthquakes and Faults” at http://scedc.caltech.edu/significant/ – note the various faults in our neighborhood, and how often each has produced earthquakes.
- The video “The Rise and Fall of San Diego” which I have posted in YouTube, with Closed Captioning (cc), at http://youtu.be/-drjJoRGfAk – thanks, Dr. Pat Abbott!
- Another Pat Abbott video “Earthquake Country Los Angeles” (note that the Newport-Inglewood Fault he talks about continues south from Newport Beach underwater, until it emerges as the Rose Canyon Fault at LaJolla and continues through Old Town, Downtown San Diego and across the bay past Coronado. It’s on my YouTube Channel (cc) at http://youtu.be/axLLD80Aa9I, again with closed captions.
- The web page “Recent Earthquakes in California and Nevada” at http://scedc.caltech.edu/recent/ – note the number at the lower left of the map (758, as I write this). That is the total number of temblors detected by seismometers in the last week. Most are too feeble to be felt, fortunately!
- From Scripps Institution of Oceanography comes a very recent (7 March 2017) study of the Newport-Inglewood/Rose Canyon Fault which suggests that an earthquake with a magnitude of up to M7.4 could happen. The link to the actual SIO study is http://news.agu.org/press-release/fault-system-off-san-diego-orange-los-angeles-counties-produce-magnitude-7-3-quake/ – if you’d like an abbreviated version, do a Google search.
Question #1:I want you to think about earthquake preparation. You have probably been bombarded with information from all sorts of government entitiesa. Which scenario should someone in San Diego be more concerned about, a magnitude 8.1 on the stretch of the San Andreas Fault from the Salton Sea to San Bernardino, Wrightwood and Palmdale, or a magnitude 7.1 on the offshore portion of the Rose Canyon / Newport-Inglewood Fault (Dana Point to LaJolla)? Explain your answer.b. What steps should you take to lessen the effects of an earthquake to you and your loved ones? Remember, you will be responsible for taking care of yourself for three days with no power, no cell service and streets impassible. Think about your furniture, your food and water supplies, medications, etc.c. Just for fun, think about the worst place(s) to be when a big earthquake strikes. (I know that after the Northridge quake in 1994, I neither wanted to be on top of an overpass, nor stopped under one!)Your answer should be no less than 300 words. (50 points)
2. GLOBALLY… Let’s take a look at how many earthquakes occur in the world every hour of every day. Even discounting the tiny shakers that most people can’t feel (less than about 2.5 or so), the number is staggering – for the year 2011, there were more than 9,000 earthquakes with a magnitude of 4.5 or greater, which is quiet impressive when put into an animation like the one shown in the animation in Blackboard entitled “2011 World earthquakes Visualization map” (web link is https://youtu.be/h4SULuWS9eQ) – note the pattern of the yellow dots (epicenters) left behind. Doesn’t it look a lot like the figure in your book showing earthquake concentrations?But note that the really big quakes are only at convergent plate boundaries, especially where subduction is involved. The biggest earthquake ever recorded happened in 1960, off the coast of Chile. It was a magnitude 9.5, and created an ocean-crossing, devastating tsunami. All of the really big tsunami-creating earthquakes have been on the so-called Ring of Fire, plus one off the northwest edge of Sumatra. I’ve already mentioned the San Andreas Fault, which is NOT capable of generating tsunami (in spite of the really bad 2015 Hollywood movie “San Andreas” (starring Dwayne “The Rock” Johnson)). But where the San Andreas ends, at Cape Mendocino the Cascadia Fault begins. It stretches from just south of Eureka, California more than 700 miles to the north end of Vancouver Island, California, and generated a M9.0 earthquake on January 26th, 1700, with a tsunami that crossed the Pacific Ocean and washed on shore in Japan.Study the following resources:
- The previously-mentioned video entitled “2011 World earthquakes Visualization map” (web link is https://youtu.be/h4SULuWS9eQ) It appears that the total amount of energy released by earthquakes on a year-by-year basis is relatively steady.
- A video entitled “Tsunamis Generated by Megathrust Earthquakes” at https://youtu.be/VJIdMvL9KcA – a ‘megathrust’ fault is the kind found at a subduction margin. In this animation we explore different tsunami-producing mechanisms by examining three famous earthquakes: Japan 2011, Chile 2010, and Alaska 1964 (text on YouTube says 2014, but no…).
- Another video, “Tectonic Earthquakes of the Pacific Northwest” at https://youtu.be/_belQwGNolY, shows the different types of earthquakes that can be expected in the Pacific Northwest.
- Brian Atwater gave a talk at a U.S. Geological Survey in 2015 about the solving of a mystery that had been vexing Japanese scientists since 1700 AD. The talk was entitled “Cascadia Earthquake of January 26, 1700 – Detective Stories from North America and Japan” and can be found at https://youtu.be/AiojgMBQPBM – the study is an Open-File Report, and can be downloaded from http://pubs.usgs.gov/pp/pp1707/. It’s another case that shows how the Scientific Method in action.
- Check out the San Diego County Office of Emergency Services “Tsunami Facts and Preparedness” web page at http://www.sandiegocounty.gov/oes/disaster_preparedness/oes_jl_tsunami.html – check out the brochures and inundation maps to see how you might be affected.
Question #2:I live in Point Loma, at an altitude of 17 feet above sea level, 240 meters from Point Loma Sportfishing. Should I be concerned about preparations in the event of a tsunami generated by an earthquake off the coast of Chile (like the one in 2010)? The answer is, yes I am ‘concerned’ although in 2010 the tsunami did considerable damage in both San Diego Bay and Mission Bay, but did not rise up over the sidewalk. My questions to you, though:a. What is the altitude above sea level at you residence? Where you work? Along your customary route of travel? Have you considered those ‘Tsunami Evacuation Route’ signs you may have seen along the coast?Please explain the different ways a great earthquake like Tohoku 2011, Alaska 1964 or Cascadia 1700 can generate an ocean-crossing tsunami.Your answer should be no less than 300 words. (50 points)
Earthquake links from my ‘Tectono-links’ page
This is from my geology-guy.com page: (http://geology-guy.com/tectono-links.htm)
Earthquakes and Faults
- Earthquake Country Alliance
All sorts of great information, including videos and pamphlets.
- DRAFT Provisional Fault Map for San Diego/Tijuana Earthquake Scenario
“clickable” map of known western San Diego County (and offshore) faults
- Recent Earthquakes in California and Nevada
Best resource for finding out what’s going on right now, and for the last week.
- USGS Earthquake Scenario Map (BSSC 2014)
What are the odds?
- Recent Earthquakes List and Map
‘fuss with’ it, it takes patience at first!
- Significant Earthquakes and Faults Historical Earthquakes & Significant Faults in Southern CA
Southern California Earthquake Data Center at Caltech
- Volcanic and Seismic Hazards on the Island of Hawaii
- Southern California Earthquake Data Center (a.k.a. “SCEC”)
- University of Memphis
Center for Earthquake Research and Information (CERI)
- Saint Louis University Earthquake Center
Information about mid-continent earthquakes
- Latitude/Longitude Distance Calculator
Updated April 2018
- Earthquake Country Alliance
Rise and Fall of San Diego
This is SDSU Geology Professor Dr. Pat Abbott’s first installment in his “Written In Stone” series, about the last million years of Earth history along our coast, produced in 2002.With Dr. Abbott’s permission, I have added the video to my YouTube channel, now closed captioned. Here’s the link: http://youtu.be/-drjJoRGfAkWatch this video, and note the three “acts” that Pat has divided the story into. Note the Rose Canyon fault and consider that it is an active fault, capable of producing earthquakes as big or bigger, than the faults in Los Angeles that have caused quakes like the M6.7 1994 Northridge quake.
Earthquake Country â€” Los Angeles
- Earthquake Country Los Angeles transcript.pdf (171.703 KB)
Earthquake Country â€” Los Angeles
With Dr. Pat Abbott, Professor of Geology, San Diego State University
Through live-action demonstrations and vivid animations, Dr. Pat Abbott explains how earthquakes have shaped the scenery and the character of the greater Los Angeles area. Dr. Abbott shows how faults capable of large earthquakes lie beneath most of the area, posing great risk to the millions of people living in earthquake country. Animations illustrate how and why earthquakes happen, how mountains and valleys have formed as a result, how the ground will shake in large earthquakes, and why this shaking is so destructive to buildings. Dr. Abbott also shows how to evaluate your home for earthquake safety and explains how to reduce the devastating effects of earthquakes. This video is part of Dr. Abbott’s “Written in Stone” series.
It can now be found on my YouTube Channel, with closed captioning (CC), at http://youtu.be/axLLD80Aa9I – turn on the CC’s if you need them.
I have also attached the transcript of the audio.
You may also download the entire video or watch it online chapter by chapter! Go to http://www.earthquakecountry.info/video/complete.html (open in a new window).
From the American Geophysical Union (AGU), on 7 March 2017:
Fault system off San Diego, Orange, Los Angeles Counties could produce magnitude 7.3 quake
Study finds rupture of offshore Newport-Inglewood/Rose Canyon fault is possible
So what, you say? The Rose Canyon fault runs through La Jolla and along I-5 (Rose Canyon) and the east side of Mission Bay and through Old Town and Downtown San Diego.Ponder what an earthquake that close to your home might mean…
The year 2011 was a big one for the Pacific Ocean basin. On March 11th of that year, there was a “Great” earthquake off the east coast of Honshu at the trench and subduction zone marking the boundary between the Pacific and Eurasian Plates. The tsunami waves caused a great deal of damage and loss of lives in Japan all around the Pacific Rim, including Hawaii, California and even San Diego.But this video animation shows all of the earthquakes in 2011 greater than a Magnitude of 4.5. As each quake is recorded, it leaves behind a yellow dot – note that the pattern created approximates the worldwide tectonic plate boundaries.Screenshots from the animation above and below.Total quake count for the year: 9323 (only greater than M4.5)
Tsunamis Generated by Megathrust EarthquakesEarthquakes Subduction-zone mega-thrust earthquakes, the most powerful earthquakes in the world, can produce tsunamis through a variety of structures that are missed by simple models including: fault boundary rupture, deformation of overlying plate, splay faults, and landslides during earthquakes. From a hazards viewpoint, it is critical to remember that tsunamis are multiple waves that often arrive on shore for many hours after the initial wave.In this animation we explore different tsunami-producing mechanisms by examining three famous earthquakes: Japan 2011, Chile 2010, and Alaska 1964.
Written & directed by Robert F. Butler, University of Portland
Animation & graphics by Jenda Johnson, Earth Sciences Animated
Narrated by Katryn Wiese, City College of San Francisco
U.S. Geological Survey consultants:
Peter J. Haeussler, Alaska Science Center
Robert C. Witter, Alaska Science Center;
Reviewed by Susan Beck, seismologist, University of Arizona and George Zandt, seismologist, University of Arizona
Funding from the National Science Foundation
Here’s a new video (19 July 2015) posted by IRIS EPO.“The Pacific Northwest is host to more than the anticipated megathrust quake that will happen off the Cascadia coast in the future. There are also deep earthquakes within the subducting plate, and shallow earthquakes in the overlying continental crust. This is because of additional forces acting on the region besides subduction-zone processes.Written and directed by Dr. Robert Butler, University of Portland, ORAnimation and graphics by Jenda Johnson, Earth Sciences AnimatedNarrated by Roger Groom, teacher, Mount Tabor Middle School Portland ORScience advisor: Dr. Ray Wells, U.S.Geological SurveyReviewed by: Dr. Rob Witter, U.S. Geological Survey”
Thursday, July 30th, 2015, 7:00 p.m. (PDT)USGS, Rambo Auditorium, Bldg. 3, Menlo Park, California, 94025
The Giant Cascadia Earthquake of January 26, 1700
Detective Stories from North America and Japan
Brian Atwater, USGS Seattle
- A tsunami from western North America entered Japanese written history in Jan 1700
- Decades of basic research on both sides of the Pacific led to this discovery
- The findings underpin public-safety measures in the United States and Canada
Mount Fuji along the highway between Kyoto and Edo, 1687. Pines on the spit at lower left were entered by puzzling waves in 1700. Picture map courtesy of East Asia Collection, University of California Berkeleyhttp://pubs.usgs.gov/pp/pp1707/).(Acrobat PDF) July Flyer
Here’s a little cartoon making light of a serious subject: the 17 January 1994 Northridge Earthquake. I had moved from the San Fernando Valley to Point Loma less than two years earlier, thankfully! At 4:35 AM, I was awakened by a rolling sensation, 130 mile from the epicenter. It was quite a sobering experience!
Before you turn in this assignment…
- Before you turn in this assignment.pdf (34.471 KB)
Before you turn in this assignment, check your work – ask yourself:
- Have you finished the Mastering homework associated with the subject matter? (if you haven’t, I won’t grade it!)
- Did you check out the extra study material provided, such as videos and web links, etc.?
- Did you answer all parts of the questions?
- Are the essays of sufficient length (check the word counts in your word processor)?
You should submit your work in Blackboard, as an attachment to the assignment.*** acceptable attachment format: Adobe Acrobat (PDF), periodDo not paste your text into the comments box, or you will lose your hard-won formatting (and I won’t be able to read it, which makes me cranky and out of sorts!
Before you turn in this assignment, check your work – ask yourself: â€¢ Have you finished the Mastering homework associated with the subject matter? (if you haven’t, I won’t grade it!) â€¢ Did you check out the extra study material provided, such as videos and web links, etc.? â€¢ Did you answer all parts of the questions? â€¢ Are the essays of sufficient length (check the word counts in your word processor)? You should submit your work in Blackboard, as an attachment to the assignment. *** acceptable attachment format: Adobe Acrobat (PDF), period