21. Geology News » Blog Archive » Possible Tsunamis From A Cascadia Earthquake The latest and greatest news in geology, from around the world. Possible Tsunamisfrom a Cascadia Earthquake. Pardon me for digging up some old articles http://geology.rockbandit.net/2005/07/20/possible-tsunamis-from-a-cascadia-earth

Geology News The latest and greatest news in geology, from around the world. MTBE Ground Water Contamination Geological Spacesuits Possible Tsunamis from a Cascadia Earthquake This one talks about a professor at UC Santa Cruz who is modeling how a tsunami would propogate down the Pacific Coast. This article talks about scientists are using deposits of sand that have been washed ashore during past tsunamis to help them model future events. This entry was posted on Wednesday, July 20th, 2005 at 11:51 pm and is filed under Earthquakes, Seismology and Geophysics Climate and Oceans . You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed. Comments are closed. Geology News is proudly powered by WordPress Entries (RSS) and Comments (RSS)

22. GEsource: Natural Disasters And Hazards - Tsunamis including tornadoes, earthquakes, tsunamis, historical events, storms, flooding, tsunamis Natural Disasters geology 204 Full GEsource record http://www.gesource.ac.uk/hazards/Tsunamis-Lecture.html

Droughts Earthquakes Flooding Mass Movements ... Wildfires Natural Hazards Information Hazards Home Historical Events Satellite Images All Articles ... Current US Weather Tsunamis Resources Tsunamis Home Tsunamis Images Historical Tsunamis Events Tsunamis Articles ... December 2004 Tsunami Tsunamis Websites Academic departments Case studies Databases Field studies ... Research Projects Other areas of GEsource Home World Guide Subject Packs Navigate: Tsunamis Home This page contains a selection of GEsource resources. There are 9 records in this section 2004 Sumatra Earthquake and Indian Ocean Tsunami : Lecture Notes : GSC 350 : Natural Disasters Full GEsource record This lecture forms part of the course entitled GSC 350: Natural Disasters provided by Dr. Jeff Marshall of the Geological Sciences Department, Cal Poly Pomona University. The notes for this specific lecture provide an overview the Sumatra Earthquake and Indian Ocean Tsunami; why it was such a tremendous disaster; the earthquake itself; and Internet links to further Sumatra earthquake and Indian Ocean tsunami resources. Keywords : natural disaster, natural hazards, earthquake, tsunamis, floods, storms, Sumatra, Indonesia, Indian Ocean, Southeast Asia, warning systems

23. GEsource - Search Results For tsunamis Natural Disasters geology 204 This lecture is part of the courseentitled geology 204 Natural Disasters created by Professor Stephen A. http://www.gesource.ac.uk/roads/cgi-bin/browsesql2.pl?toplevel=physical&limit=75

24. Major Caribbean Earthquakes And Tsunamis A Real Risk Ten Brink, who studies earthquakes, tsunamis and geology in the Caribbean andPuerto Rico region, and has studied earthquake hazards in the Dead Sea in the http://www.sciencedaily.com/releases/2005/02/050205102502.htm

@import "/styles/navbar.css"; @import "/styles/tabStyles.css"; Set home page Bookmark site Add search Latest News ... Email to friend Text Size A A A Front Page ... Advertise With Us Source Woods Hole Oceanographic Institution Date Print this page Email to friend Major Caribbean Earthquakes And Tsunamis A Real Risk A dozen major earthquakes of magnitude 7.0 or greater have occurred in the Caribbean near Puerto Rico, the U.S. Virgin Islands and the island of Hispaniola, shared by Haiti and the Dominican Republic, in the past 500 years, and several have generated tsunamis. The most recent major earthquake, a magnitude 8.1 in 1946, resulted in a tsunami that killed a reported 1,600 people. 3-D view of the Puerto Rico Trench. (Image Credit: Christopher Polloni, USGS and Jack Cook, Woods Hole Oceanographic Institution) Related News Stories Major Caribbean Earthquakes And Tsunamis A Real Risk (February 8, 2005) A dozen major earthquakes of magnitude 7.0 or greater have occurred in the Caribbean near Puerto Rico, the U.S. Virgin Islands and the island of Hispaniola, shared by Haiti and the Dominican ... full story Network Of Underwater Sensors To Measure Dangerous Tsunamis In Real Time (October 27, 1997)

25. ScienceDaily -- Browse Topics: Science/Earth_Sciences/Geology/Geologic_Hazards/T South Asia Disaster Shows tsunamis Are An Ongoing Threat To Humans (May 3, Search tsunamis Case Studies and Recent Developments (Advances in Natural http://www.sciencedaily.com/directory/Science/Earth_Sciences/Geology/Geologic_Ha

@import "/styles/navbar.css"; @import "/styles/tabStyles.css"; Set home page Bookmark site Add search Latest News ... Email to friend Text Size A A A Front Page ... Geologic Hazards : Tsunami Subtopics Multimedia Warning Centers See Also: Science: Earth Sciences: Geophysics: Earthquakes Search Google: Tsunami News Books Links ... New Tooth Enamel Dating Technique Could Help Identify Disaster Victims (September 15, 2005) full story Researchers Create Meta-search Engine To Help Locate Displaced People (September 14, 2005) full story Dartmouth Flood Observatory Tracks The Aftermath Of Katrina (September 13, 2005) full story Cornell Web Site Will Aid Gulf Coast Recovery (September 9, 2005) full story International Move To Train More Forensic Medicine And Science Experts (August 19, 2005) full story The Sound Of A Distant Rumble: Researchers Track Underwater Noise Generated By December 26 Earthquake (July 23, 2005) full story Native Lore Tells The Tale: There's Been A Whole Lotta Shakin' Goin' On (July 14, 2005) full story MIT Team Designs Tsunami-resistant Houses (June 9, 2005) full story [ More news about Tsunami List Price: Amazon.com's Price:

26. Earth Science Sites General Sites Volcanoes Earthquakes Water and Ice (tsunamis) Rocks. General EarthScience Sites geology Link from Houghton Mifflin for older students http://www.kathimitchell.com/earthsci.htm

Geological Processes General Sites Volcanoes Earthquakes Water and Ice ... Rocks General Earth Science Sites: Kathy Schrock's Guide for Educators - Earth Science http://discoveryschool.com/schrockguide/sci-tech/scies.html Earth Science on the Web from NASA at Goddard - Earth Science Educator http://webserv.gsfc.nasa.gov/metadot/index.pl?iid=1803 Earth Sciences Directorate - http://earthsciences.gsfc.nasa.gov/metadot/index.pl NASA Earth Science sites http://www.cotf.edu/ete/teacher/othersites.html Earth Science for Kids Only from NASA - Air Land Water Natural Hazards http://kids.earth.nasa.gov/ E arth S cience Resources from Geocities for 4th and 5th graders http://www.geocities.com/EnchantedForest/Tower/1217/earthsci.html Global Access to Educational Sources http://www.geocities.com/Athens/Academy/6617/earthsci6.html Volcanoes and Earthquakes http://vathena.arc.nasa.gov/curric/land/index.html Earth Science Links from The Science Spot http://sciencespot.net/Pages/kdzethsci2.html CyberSleuth Earth Science for Kids http://cybersleuth-kids.com/sleuth/Science/Earth_Science/

27. Untitled Document The cataclysmic blasts of August 27 generated mountainous tsunamis, tsunamis wereclearly responsible for most of the fatalities at Krakatau. http://www.geology.sdsu.edu/how_volcanoes_work/Krakatau.html

KRAKATAU, INDONESIA (1883) OVERVIEW Early in the morning of May 20, 1883, the captain of the German warship Elizabeth LOCATION AND PLATE-TECTONIC SETTING Indonesia contains over 130 active volcanoes, more than any other country on earth. They comprise the axis of the Indonesian island arc system, which is generated by northeastward subduction of the Indo-Australian plate. The great majority of these volcanoes lie along the topographic crest of the arc's two largest islands - Java and Sumatra. The islands are separated by the Sunda Straits , which is located at a distinct bend in axis of the island arc volcanoes, from a nearly east-west orientation in Java to a northwest-southeast orientation in Sumatra. Krakatau is one of a several volcanic islands in the Sunda Straits located above an active north-northeast trending fault zone, an orientation quite distinct from the main island-arc trend. Although relatively small when compared to the largest volcanoes along the island arc, Krakatau and its associated volcanoes have shown the capacity to generate highly explosive eruptions. PHYSIOGRAPHY BEFORE AND AFTER THE 1883 ERUPTION The pre-eruption island of Kratatau was composed of three coalsced volcanoes aligned along a north-northwest direction, parallel to the volcanoes on Sumatra. From north to south, these were Perboewatan, Danan, and Rakata.

28. USATODAY.com - Resources: Earthquakes And Tsunamis Resources Earthquakes and tsunamis Earthquakes are one of the most feared naturaldisasters because scientists have found no way to predict them. http://www.usatoday.com/news/science/geology/understanding-earthquakes.htm

Home News Main Categories Top News Nation States Washington/Politics ... Offbeat More News Columnists Lotteries City Guides Government Guide ... Click here to get the Daily Briefing in your inbox document.write(''); 04/26/2002 - Updated 10:49 AM ET Resources: Earthquakes and tsunamis Earthquakes are one of the most feared natural disasters because scientists have found no way to predict them. Tsunamis are large ocean waves caused by undersea earthquakes or landslides. They are often called "tidal waves" even though they have nothing to do with the tides. The links below to USATODAY.com graphics and text and to other Web sites are a guide to the science of earthquakes and tsunamis. USATODAY.com information Surviving natural disasters Ask Jack earthquake questions, answers Graphics Earthquake risk map for the USA Global tectonic plates, their movements Undersea quakes cause tsumanis Wonderquest answers 'Tsunamis, why water leaves bays ahead of one Highest tsunami was in Alaska in 1958 Stories from USATODAY.com Scientists have little hope of quake predictions - March 4, 2001

29. Nearctica - Geology - Earthquakes - Tsunamis Return to geology. Main Page. Click Here Books About Earthquakes. tsunamis arelarge water, typically oceanic, waves, and are usually http://www.nearctica.com/geology/quake/tsunami.htm

Earthquakes - Tsunamis Special Segments Butterflies of North America Conifers of North America Eastern Birds List of N.A. Insects Home Eastern Wildflowers General Topics Natural History Ecology Family Environment Evolution Home Education Home Conservation Geophysics Paleontology Commercial Organizations Return to Geology Main Page Books About Earthquakes Tsunamis are large water, typically oceanic, waves, and are usually generated by seismic activity. They are sometimes mistakenly called "Tidal Waves". The Tsunami Page of Dr. George Pararas-Carayannis . A great site on tsunamis with a series of frequently asked questions about these gigantic waves, extensive articles on famous tsunamis throughout history, and links and information about the warning systems in place to help protect people. Highly recommended. Tsunami . University of Washington. This great web site has information about tsunamis including material about how tsunamis are generated. There is also a survey of great tsunamis of the past, the tsunami warning system, and ways to mitigate the hazards of these tidal waves. You'll also find information on recent tsunami events, research, and a set of links to other sites on the web with tsunami information. Tsunami Database National Geophyiscal Data Center, NOAA

30. Department Of Geology And Mineral Industries Geologic Hazards On The Oregon Coas Department of geology and Mineral Industries An Introduction to tsunamis.New information on Cascadia earthquakes Tsunami hazard maps and evacuation http://www.oregon.gov/DOGAMI/earthquakes/Coastal/TsunamiIntro.shtml

Text-Only Site State Directory Agencies A-Z Accessibility ... Strategic Plan Geologic Hazards on the Oregon Coast An Introduction to Tsunamis New information on Cascadia earthquakes Tsunami hazard maps and evacuation brochures Japanese historical records of 1700 A.D. tsunami The science of tsunamis ... Tsunami links The past occurrence of seismic sea waves in the Pacific Northwest has come to light with recent research that matches records from Japan with carbon-isotope-14 data from wood buried in tsunami sands on the West Coast. Because the Japanese data are so accurate, exact dates can be given for sea wave occurrences. The date of the last large tsunami, recorded in the sands and correlated with Japanese records, was January 26, 1700. The earthquake that generated the wave registered M 9, and the ensuing tsunami destroyed coastal villages in Japan. In Oregon, prehistoric runups (i.e., how high a tsunami wave reaches above mean sea level) can be deduced with numerical methods. From such models, it was concluded that a tsunami that struck Salishan Spit in Lincoln County between 300 and 800 years ago had a runup of up to 40 feet above sea level. It is likely that the same wave probably overtopped a 16-foot-high barrier ridge at Cannon Beach and breached a 20-foot ridge at Seaside. One of the largest subduction zone earthquakes ever recorded was the M 9.2 quake on March 27, 1964, centered in Prince William Sound, Alaska. This generated a tsunami that struck the Oregon coast at 11:30 p.m. with waves as high as 10 feet, swamping houses, destroying bridges and sea walls, and tragically killing four children. A family was camping at Beverly Beach and sleeping in a small driftwood shelter at the time. The second wave reached them, throwing the mother out onto the beach and the father up against a cliff, while the children were washed out to sea. In March 1999, a plaque remembering the children and providing information about tsunamis was dedicated at Beverly Beach State Park.

31. Department Of Geology And Mineral Industries Geologic Hazards On The Oregon Coas tsunamis are large ocean waves generated by major earthquakes beneath the tsunamis caused by nearby earthquakes may reach the coast within minutes. http://www.oregon.gov/DOGAMI/earthquakes/Coastal/HistoricTsunamis.shtml

Text-Only Site State Directory Agencies A-Z Accessibility ... Strategic Plan Geologic Hazards on the Oregon Coast Prehistoric and Historic Tsunamis Japanese historical records of 1700 A.D. tsunami The science of tsunamis An introduction to tsunamis Tsunami hazard maps for the Oregon coast and evacuation brochures ... Tsunami links Tsunamis are large ocean waves generated by major earthquakes beneath the ocean floor. Tsunamis caused by nearby earthquakes may reach the coast within minutes. When the waves enter shallow water, they may rise to devastating force. People on the beach or in low coastal areas need to be aware that a tsunami could arrive within minutes after a severe earthquake. Tsunamis also may be generated by very large earthquakes far away in other areas of the Pacific Ocean. Waves caused by these earthquakes travel at hundreds of miles per hour, reaching the Pacific Northwest several hours after the earthquake. The International Tsunami Warning System monitors ocean waves after any Pacific earthquake with a magnitude larger than 6.5. If waves are detected, warnings are issued to local authorities, who can order evacuation of low lying areas if necessary. HISTORIC TSUNAMIS IN THE UNITED STATES Twenty-four tsunamis have caused damage in the United States and its territories during the last 204 years. Just since 1946, six tsunamis have killed more than 350 people and damaged a half billion dollars of property on Hawaii, Alaska and the West Coast.

32. Tsunami! How To Survive This Hazard On The Oregon Coast INFORMATION ON OREGON EARTHQUAKES AND tsunamis. Oregon Dept. of geology and Mineral tsunamis, AND geology. Nature of Oregon Information Center http://www.wsspc.org/tsunami/OR/Ore_wave.html

TSUNAMI! HOW TO SURVIVE THIS HAZARD ON THE OREGON COAST IF YOU FEEL AN EARTHQUAKE WHEN YOU ARE ON THE OREGON COAST, PROTECT YOURSELF FROM THE EARTHQUAKE UNTIL IT IS OVER. THEN MOVE QUICKLY INLAND OR TO HIGH GROUND. A TSUNAMI MAY BE COMING IN A FEW MINUTES, AND ADDITIONAL LARGE WAVES MAY CONTINUE FOR SEVERAL HOURS. THE INFORMATION IN THIS BROCHURE MAY SAVE YOUR LIFE. PLEASE TAKE THE TIME TO READ IT AND SHARE WHAT YOU HAVE LEARNED WITH YOUR FAMILY AND FRIENDS. TSUNAMI FACTS Two kinds of tsunamis could affect the Oregon coast: Tsunamis generated by undersea earthquakes just off the Oregon coast can strike the coast within five to thirty minutes, possibly disrupting power lines and communications and leaving little time for an official warning. The actual ground shaking of the earthquake may be the only warning you receive. Tsunamis generated by earthquakes occurring thousands of miles away will take several hours to reach the coast. There would be time for official warning, but if you are in an isolated area, you may not hear the official warning, you will feel no earthquake, and the only warning you may have is a sudden unexpected change in sea level. If the sea level suddenly drops or rises without any obvious reason, nature may be warning you of impending danger, and you should move inland or to high ground immediately. Recent research shows that at any time the Pacific Northwest can experience large earthquakes and accompanying tsunamis, and that tsunamis have affected the Oregon coast on a regular basis over time. Scientists have not yet had time to do local studies that will be able to tell you how high a tsunami may be in any one area and how far you must run inland or how high you must climb to escape. The best general advice available today is to (1) go up to 2 miles inland if you are in a low-lying area or at least 100 feet above sea level if you can; and (2) go on foot if at all possible because of traffic jams and earthquake damage.

33. Humboldt State University: Department Of Geology Current Events Faculty Staff Course Materials geology Resources Alumni Contact Us. Earthquakes tsunamis. Earthquakes, Tsunami and Preparedness http://www.humboldt.edu/~geology/eq_tsu.html

@import url(geology_styles.css); /*IE and NN6x styles*/ Humboldt State University Location: Home Home Academics For Current Students ... Contact Us

34. Geology 308 Natural Hazards On The Pacific Rim Introductory geology or Physical Geography recommended. Junior standing.Overview of earthquakes, volcanoes and tsunamis and the geologic setting of the http://www.humboldt.edu/~geodept/geology308/308_intro.html

Geology 308 Natural Hazards on the Pacific Rim Reducing the Risk of Geologic Hazards The causes, effects and management of natural hazards: an overview of human efforts to mitigate geologic hazards through technology, cultural adaptation, risk assessment and prediction, warning systems and communication of hazard information. Emphasis on case studies of earthquakes, volcanoes, tsunamis, and/or weather-hazards from different regions of the Pacific basin. 3 units, 3 lectures and no labs per week No Prerequisites: Students should have at least Algebra 1 level math skills. Introductory Geology or Physical Geography recommended. Junior standing. Overview of earthquakes, volcanoes and tsunamis and the geologic setting of the Pacific Rim. Sample Case Studies: Earthquakes Volcanoes Tsunamis 1992 Cape Mendocino 1980 Mt. St. Helens 1946 Aleutian Islands 1994 Northridge 1991 Mt. Pinatubo 1960 Chile 1995 Kobe 1985 Nevado Del Ruiz 1964 Alaska 1985 Mexico City Long Valley, California 1998 Papua New Guinea Prediction and Warning Systems. Field trip: National Weather Service Office, Eureka

35. What Causes A Tsunami? - Tsunami Geology - GEOLOGY.COM What Causes a Tsunami by geology.com. Most tsunamis are caused by earthquakesgenerated in a subduction zone, an area where an oceanic plate is being http://geology.com/articles/tsunami-geology.shtml

Geology.com Geology Dictionary Geologist Jobs Geology News ... Satellite Images Satellite Images Africa Asia Australia Canada ... United States US Geology Alabama Alaska Arizona Arkansas ... Wyoming Web geology.com usgs.gov nasa.gov Tsunami Geology - What Causes a Tsunami? What causes a tsunami?... A tsunami is a large ocean wave that is caused by sudden motion on the ocean floor. This sudden motion could be an earthquake, a powerful volcanic eruption, or an underwater landslide. The impact of a large meteorite could also cause a tsunami. Tsunamis travel across the open ocean at great speeds and build into large deadly waves in the shallow water of a shoreline. Subduction Zones are Potential Tsunami Locations Most tsunamis are caused by earthquakes generated in a subduction zone, an area where an oceanic plate is being forced down into the mantle by plate tectonic forces. The friction between the subducting plate and the overriding plate is enormous. This friction prevents a slow and steady rate of subduction and instead the two plates become "stuck". Image by USGS Accumulated Seismic Energy As the stuck plate continues to descend into the mantle the motion causes a slow distortion of the overriding plage. The result is an accumulation of energy very similar to the energy stored in a compressed spring. Energy can accumulate in the overriding plate over a long period of time - decades or even centuries.

36. Geology: Earthquakes The geology of Japan Earthquakes. Lecture Outline tsunamis can travel atspeeds up to 1000 km/h (620 mph) and as they reach shore, they can mount up http://www.seinan-gu.ac.jp/~djohnson/natural/quakes.html

The Geology of Japan: Earthquakes Lecture Outline Cause and Occurrence of Earthquakes. The same plate tectonic activity that causes volcanoes also causes earthquakes. Subduction can create stress in the rock crust that results in slippage causing earthquakes. Earthquakes and Faults. As two plates collide, stress is built up and faults (or cracks) appear in the crust. (Active faults of Kyushu Kanto ) If there is little friction along the fault, creep may occur, that is, there may be gradual movement of the ground on one or both sides of the fault. This type of fault activity does not usually result in death or injury, since there are no sudden movements. If, however, friction prevents gradual movement, the stress will built up until sudden slippage occurs along the fault. This is an earthquake. Sometimes, slippage occurs along the subduction zone. These quakes can be rather large ones, like the Indian Ocean earthquake of December 26, 2004 (magnitude 9.0). If the stress occurs in deep crust layers where rock is hot, the crust may gradually fold rather than slip (no earthquake occurs: example photo of folding Earthquake Focus and Epicenter.

37. Geology Rocks :: Forums :: View Topic - Tsunamis Post Posted Wed Dec 29, 2004 1050 am Post subject tsunamis, Reply with quote Select a forum, geology Rocks, , geologyRocks.co.uk http://www.geologyrocks.co.uk/phpBB2/viewtopic.php?p=689&

38. International Tsunami Symposium 2001--- Foreword recent tsunamis, tsunami geology and paleotsunamis, Atlantic and Mediterraneantsunamis, tsunami measurements and data analysis, landslides and other http://www.pmel.noaa.gov/its2001/index_main.html

Foreword Overall, ITS 2001 was a great success due to the Herculean efforts of many people. I sincerely thank the following people who made ITS 2001 possible. Science Committee (chair), NOAA Brian Atwater, USGS Jody Bourgeois, University of Washington Marie Eble, NOAA Viacheslav Gusiakov, Russian Academy of Sciences Fumihiko Imamura, Tohoku University Sin-Iti Iwasaki, National Research Institute for Earth Science and Disaster Prevention Aurelio Mercado, University of Puerto Rico Andrew Moore, Tohoku University Emile Okal, Northwestern University Catherine Petroff, University of Washington George Priest, Oregon Department of Geology and Minerals Industries Kenji Satake, Geological Survey of Japan Costas Synolakis, University of Southern California Stefano Tinti, University of Bologna Vasily Titov, NOAA Harry Yeh, University of Washington The Local Organizing Committee Ann Thomason (chair), NOAA Brian Atwater, USGS Robert Goodwin, University of Washington William Steele, University of Washington

39. Tsunami Links Designing for tsunamis A mulstistate mitigation project of the National Tsunami Tsunami Warning Systems and Procedures Oregon Department of geology and http://www.pmel.noaa.gov/tsunami-hazard/links.html

Federal Links NOAA Tsunami Web Site NOAA Tsunami Hazard Mitigation Program brochure in Spanish "Ask the White House" Tsunami Questions and Answers with Admiral Conrad C. Lautenbacher, Administrator, National Oceanic and Atmospheric AdministrationJanuary 14, 2005 NOAA/ NWS Tsunami Web Site ... Surviving a TsunamiLessons from Chile, Hawaii, and Japan from USGS. Contains true stories that illustrate how to survive a tsunami and how not to survive a tsunami. The booklet is an educational tool meant for those who live and work or who visit coastlines that tsunamis may strike. Copies of the booklet can be obtained from USGS Information Services, Box 25286, Denver, CO 80225, by calling 888-ASK-USGS. The Next Big Earthquake in Alaska and what to do to prepare. Includes tsunami information. Provided by USGS and UAF Alaska Sea Grant. Tsunamis and Earthquakes: Life of a Tsunami - USGS Tsunamis and Earthquakes - tsunami research at USGS Local Tsunamis in the Pacific Northwest - USGS USGS Recent Earthquakes in California and Nevada ... Tsunami Glossary (ITIC) For Kids Links for For Kids Multi-state Partnerships TsuInfo Alert Newsletters Provided by the Washington Department of Natural Resources Designing for Tsunamis A mulsti-state mitigation project of the National Tsunami Hazard Mitigation Program Designing for Tsunamis Background Papers

40. GLY Class Notes. Univ Kentucky Geology Dept. Physical geology. Notes 8B tsunamis. A Big Quake on Dec 26, 2004 in northernSumatra (Indonesia), offshore from the Aceh region. http://www.uky.edu/AS/Geology/howell/220/notes08b-Tsunamis-gly220-spring-2005.ht

Class Notes: GLY 220, Paul Howell Physical Geology Notes 8B: Tsunamis A Big Quake on Dec 26, 2004 in northern Sumatra (Indonesia), offshore from the Aceh region. * Mag 9.0, possibly as much as 9.3 * 1200km rupture length * 15m average slip along fault * one to several meters of vertical surface displacement Tsunami: What is it? * A long-wavelength, low-amplitude surface wave in the ocean, or a very large lake. * The long wavelength gives the wave great speed (~800 km/hour) in deep water. * The wave amplitude (height) increases dramatically as the wave enters shallow water, because the wave slows down in front due to friction with the sea floor, and the back end catches up, making it taller. Figure: Tsunami: Earthquake causes uplift, uplift moves water, causing tsunami. Tsunami: Why? * Caused by a rapid (minutes) and significant change (meters ++) in seafloor depth (either shallower or deeper) over a broad area => this displaces the ocean surface (up or down) over a wide region. * Earthquakes: large areas of uplift or subsidence due to large earthquakes * Undersea Landslides: downslope movement of enormous blocks of slope materials * Volcanic explosions: massive sudden displacements, usually phreatic (steam) eruptions

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