GEO 210 Lecture 2 (4) PDF

Week 2: Geographical Hazards: Mitigating Dangers September 12, 2024 Layers of earth Inner core Outer core Mantle Crust Plate Tectonics A theory is that the earth outer shell (the lithosphere is made of plates that float independently...

Week 2: Geographical Hazards: Mitigating Dangers September 12, 2024 Layers of earth Inner core Outer core Mantle Crust Plate Tectonics A theory is that the earth outer shell (the lithosphere is made of plates that float independently over the mantle. At the boundaries, new crust forms where mountains are built and seismic activity that cause earthquakes Pangaea: All Earth Alfred Wegener: A german geophysicist proposed the idea of continental drift where the content drifted apart from one big supercontinent called Pangea, which was formed 225 million years ago Discussion: What were all the continents we know today ? North America South America Australia Asia Africa Antarctica Europe Video Watched: Earth 100 Million Years From Now Major Plates Movement along Plate Boundaries 1. Spreading (divergent boundary- coming apart) 2. Subduction (convergent boundary- colliding and being pushed under) 3. Slipping (transform fault boundary- sliding against to each other) Spreading: The Growing Atlantic The seafloor is spreading from the Mid-Atlantic ridge onwards because the Atlantic Ocean is growing The magma is getting pushed from the asthenosphere through pressure and the movement under the earth Subduction: A Crash Scene Convergence One plate forced under the other Melting = Volcanoes Slipping: Strike- Slip Fault lines 3 types of faults 1. Strike slip- caused by shearing 2. Normal- caused by tension 3. Reverse- caused by compression Locations of Earthquake and Volcanic Activity Volcanoes happens mostly around the border of the pacific plate Pacific Ring of Fire String of volcanoes and sites for seismic activity around the Pacific ocean 90% of earthquakes occur along Ring of Fire Several active and dormant volcanoes are present in Antarctica There are ocean trenches mountain trenches and hydrothermal vents Pacific ocean is shrinking because seafloor is folding under itself Volcanism When magma explodes and breaks through the crust and onto the surface of Earth This happens along subduction zones, seafloor centers and hot spots Pyroclastic flows= high density mix of hit lava rocks, pumice (light porous rock that forms when lava cools quickly with gas bubbles inside) and volcanic gas Volcanic Explosivity Index (VEI) Measure of explosiveness of volcanic eruptions Developed in 1980s The volume of products, eruption cloud height and other qualitative observations are used to determine the explosivity value Scale is open- ended, 8 being the highest in explosivity and 0 being the lowest in explosivity Lahar: Violet type of mudflow/debris that flows down a volcano. It is composed of pyroclastic material, rocky debris and water Mount Pinatubo Erupted in 1991 Proced a lot of ash about 15-20 million 12 times in volume of material produced then Mount Helens Took a measurable cooling period on Earth surface for 2 years Hot Spot: Yellowstone National Park. Wyoming, USA Collapse calderas: form when a large magma chamber is emptied by a volcanic eruption or by subsurface magma movement The unsupported rock that forms the roof of the magma ch,aber then collapses to form a large crater Volcanoes help create life Andisols (black soil)- weathering of volcanic materials resulting in mineral in soil Minerals have high capacity to hold nutrients and water creating the most fertile soil on the planet What is an earthquake Violent shaking of ground that happens suddenly because of the movements within the earth crust or volcanic action Earthquake happen at plate edges and fault lines Epicenter is above the focal point of the earth The Richter Scale Charles F Richeter developed this in the 1930s Used to compare size of earthquakes through a base-10 logarithmic scale that determines the amplitude of waves recorded by seismographs Richter Scale Magnitude 0-1= can’t be felt, 9=rare causes unbelievable damage Canada’s 10 Largest Earthquakes Cascadia Subduction Zone, off British Columbia (1700) with a magnitude of 9 on the richter scale is the largest of all the 10 earthquakes British Columbia Institute of Technology Department of Civil Engineering Seismologists look at many earthquakes each year that happen in Canada Most earthquakes occur at the edges of the country The West Quebec Seismic Zone Region that encloses the Ottawa Valley and is bounded by Montreal, Temiscaming, the Laurentians and eastern Ontario Ancient geologic stress Weight of glaciers (isostatic rebound) Failed fault in north american plate What makes Earthquakes Dangerous?  How close it could affect human activity and settlements Unpredictability- could happen at any time, at any rate or magnitude Not due to human activity Events associated to it like tsunami Fukushima Nuclear Disaster Tsunami occurred after an earthquake under the ocean Tsunami disabled emergency generators (deals with cooling) Insufficient cooling led to three nuclear meltdowns, hydrogen-air explosions, and the release of radioactive materia Why live in California? Southern California is where a lot of earthquakes occur frequently. Some earthquakes get dismissed, others create great damage. California passed a law requiring developers to set buildings away from active fault lines Often thought that if the magnitude of the earthquake is large then it;s less likely to occur but chances can’t be taken because it will definitely occur Earthquake Hazard/Risk- California 500 faults are categorized active (hazard) Many californians live within close proximity to an active fault (risk) Mojave Desert Earthquakes- 2019 Two earthquakes struck the region, one being of magnitude 6.4 shook Ridgecrest and across South California and the other being much stronger. Aftershocks also occurred within the area as well Damage was about $1 billion for Ridgecrest according to US Geological Survey Earthquake in Morocco- September 2023 6.8 magnitude earthquake struck Morocco in High atlas mountain range with about 2800 people dying due to this The buildings were not earthquake resistant Predicting earthquakes Laser beams- used to detect plate movement Ssiemetor- picks up vibration in the earth crust. Higher vibrations = higher chance of earthquake Radon gas - escaped from cracks in earth crust and is monitored Increase-=higher chance of earthquake Predicting Earthquakes Japan uses AI- based system to predict earthquakes using satellite images The system detect signs or landslides, aging buildings and detect areas that need to be improved before the earthquake happen Very useful tool for early warning systems Adapting to Earthquakes Earthquake resistant buildings. Ex: CN tower can withstand 8.5 magnitude on Richter scale Building away from fault lines Creating earthquakes: Disposal of Fracking Wastewater Oil and gas mining operations trigger earthquakes because of hydraulic fracturing (extracting oil and water by injecting high pressure fluid into rocks to cause fractures) and wastewater injected to earth Wastewater earthquakes are the main cause of creating earthquakes in several different states Dam-Induced Seismicity The landslides have worsened because of the Three Gorges’ reservoir behind the dam. The water puts pressure on the sides of the valley which induces seismicity Pacific Tsunami Warning Center One of two tsunami warning centers operated by National Oceanic and Atmospheric Administration (NOAA) in the United States in Hawaii It's apart of the tsunami warning system of the Pacific Issues bulletins and warning signals to members involved PTWC Bulletins The Tsunami information bulletin- no evidence of tsunami Tsunami Watch- PTWC determines an earthquake is likely to have created a tsunami. This watch may be upgraded to advisory or warning Tsunami Advisory- PTWC determine deathquake to have created a tsunami with strong winds Tsunami Warning- PTWC find conditions serious enough and immediate concern to Pacific Tsunami Forecast Model Animation Chile 2010 A earthquake hit Chile at magnitude of 8.8 PTWC saw this as a high magnitude for an earthquake would cause serious damage PWTC issued their first tsunami warning several minutes late for CHile and Peru The tsunami was a great devastation with waves reaching the mainland and killing the a few of residents Forecasting in Real Time PTWC can create animations of historical tsunami and ones happening now through thw Real-Time Forecasting of Tsunamis Forecast model Blue to green= no hazard Yellow to orange= low hazard Light red to bright red = significant hazard needs evacuation Dark red= serve hazard may need second tier evacuation Tsunami Forecast Model Animation Caused great devastation in Japan killing thousands of people Fukushima nuclear disaster Taking Measurements: The Dart System Deep- ocean Assessment and Reporting of Tsunamis (DART) =tsunami warning system Gives info about tsunamis while they are off shore Each station has seas bed bottom pressure that detects the passage of tsunami This data is transmitted and into a surface buoy and radios info to PTWC and goes into the satellite system Indian Ocean Earthquake and Tsunami Under the ocean, fault surface ruptured along subduction zone where the Indian Plate slides under the recording Burma Plate A series of large earthquakes were created by underwater seismic activity that became known as Boxing Day tsunamis Communities around the coast were seriously affected This was the third largest earthquake The propagation of the tsunami took 5 hrs to reach Western Australia, 7 hrs to reach Arabian Peninsula and 11 hours to reach South Africa No Warning System There was no tsunami warning system in the Indian Ocean to detect tsunamis or warn the general population living around ocean The system became active for Indian Ocean warning system in 2006 25 semasiographic stations relay info to 26 national tsunami information centers as well as 6 Deep-Ocean Assessment and Reporting of Tsunami (DART) buoys The Cost of Earthquakes in the U.S California and the West Coast experience high losses in costs and revenue due to earthquakes California Integrated Seismic Network (CISN) Operate a reliable, statewide system for earthquake monitoring, research, etc.. CISN seeks to reduce impact of future earthquakes by collecting, processing info about critical earthquakes before they happen or at least in a timely manner California Earthquake Preparedness ShakeAlert ShakeAlert is an experimental earthquake early warning system for West Coast of the United states and Pacific northwest It detects significant earthquakes, so people know ahead of time Used as Phase 1 in Altering states like Calfonia, Oregon and Washington Emergency Response Management 1. Preparedness- Emergency Response Plans 2. Response- Evacuation & shelters, Property/Preservation 3. Recovery- Economic Recovery, Housing 4. Mitigation (reduction)- Hazard & Vulnerability Assessment Predicting Earthquakes: How Japan is Learning From the Past Scientific research is being conducted to understand how to prevent future disasters from occurring. Teams have used the origination of 2011 Tohoku earthquake under the seabed to provide clues for identifying other areas in the Pacific that coil potentially trigger other huge earthquakes Designing of Earthquake Resistant Building Principles of Seismic Design Earthquake resistant design of buildings depends on factors like strength, stiffness, inelastic deformation capacity. To accomplish this, a selection of an appropriate structural configuration must be formed Advanced Techniques of Earthquake Resistant Design and Construction Base isolation- separate building from the foundation to absorb shocks. Its sits on bearing pads placed between building and foundation Diaphragms: floors and roofs that are rigid horizontal planes used to transfer lateral forces to vertical elements like rood and floors Shear Walls- strategically places stiffend walls that can transfer lateral forces from floors and roofs to the foundation Braced Frames- Vertical frames that transfer lateral loads from floors and roofs to foundations when shear walls are found impractical Moment-Resisting Frames- Column beam joints in moment resisting frames designed to take both shear and bending. They are designed to be stiff but flexible enough to absorb energy using the flexibility of steel. Reinforced concrete can also be used in these frames Energy- Dissipating Devices- Used to minimize shaking Learning to Live with Earthquakes UNCRD (United Nations Centre for Regional Development) film- how communities in Nepal, India, and Vietnam can learn to live with earthquakes by altering their building techniques and practices TUTORIAL WORK Lecture 2 Part 1: SLIDE 36 - How Big Do Tsunamis Get? (7 minutes) https://www.youtube.com/watch?v=7oaGUg7ik_c Lecture 2 Part 2: SLIDE 17 – Predicting Earthquakes: How Japan Is Learning from the Past (13 minutes) https://www.youtube.com/watch?v=uTxWztLm6Xw Lecture 2 Part 2: SLIDE 20 - Learning to Live with Earthquakes (6 minutes) https://www.youtube.com/watch?v=gvbQ06pPB-o For all videos make notes and note main arguments and points Shrestha, S.R., R. Sliuzas, and M. Kuffer (2018) “Open Spaces and Risk Perception in Post-Earthquake Kathmandu City”, Applied Geography, 93: 81-91. Please answer the following three questions related to the article: 1. As stated by the authors, what is the main aim of this paper? 2. According to the study, what size of communal space was preferred by most respondents? Medium or large? 3. With respect to distance traveled after an earthquake, did the authors find that many people choose to stay closer to their homes and people they know and trust, and hence they felt safer in their own neighborhoods? May show up on the UNIT 1 Test: October 3, 2024