Earthquake and tornado Quiz

Ben Franklin

" ...I therefore imagine that the internal parts [of the Earth] might be a fluid more dense, and of greater specific gravity than any of the solids we are acquainted with, which therefore might swim in or upon that fluid. Thus the surface of the Earth would be a shell, capable of being broken and disordered by the violent movements of the fluid on which it rested. " 1782

"Severe repetitive loss properties"

"2,100 properties across the U.S. enrolled in the National Flood Insurance Program have flooded and been rebuilt more than 10 times since 1978, according to a new analysis of insurance data by the Natural Resources Defense Council (NRDC). One home in Batchelor, Louisiana has flooded 40 times over the past four decades, receiving $428,379 in insurance payments. More than 30,000 properties in the program, run by the Federal Emergency Management Agency, have flooded multiple times over the years. Those homes, known as "severe repetitive loss properties," make up just 0.6 percent of federal flood insurance policies. But they account for 10.6 percent of the program's claims — totaling $5.5 billion in payments...." Katherine Bagley, Yale Environment 360

Swiss Re website

"2018 should have been an unremarkable year for natural catastrophes. There was no single major disaster that caused massive destruction, such as Hurricane Katrina in 2005, the Japanese tsunami in 2011 or Hurricanes Harvey, Irma and Maria in 2017. But a larger number of smaller disasters took an immense toll. 13,500 lives were lost. According to the Swiss Re Institute, economic losses from natural catastrophes amounted to USD155 billion, triggering USD 76 billion in insurance pay-outs and contributing to the fourth highest ever". "One of the driving factors behind this trend is climate change. 2018 was the fourth warmest year on record, and the past five years have been the five hottest. Although the link between global warming and major events like hurricanes is uncertain, there is much clearer evidence for the link with heatwaves, droughts, wildfires and floods. These can cause significant damage - the single biggest insurance loss event of 2018 was Camp Fire in California, which cost USD 12 billion". These people (reinsurers) really closely study disasters. They know a ton about climate change

Prediction vs. Forecasting

"Prediction" •Statement of specification that a particular earthquake either will or will not occur - at a given location, during a given time window, within a given magnitude range •Validation requires a single observation. •It is "inherently" impossible -due to so many variables involved. "Forecasting" •Statement of probability regarding a particular earthquake occurring - at a given location, during a given time window, within a given magnitude range •Validation requires many observations. •Regularly performed .

Ground fissures

(cracks that are not the fault itself) due to lateral spreading and liquefaction -Lateral spreading in the soil beneath embankment causes the embankment to be pulled apart, producing the large crack down the center of the road.

California earthquake October 17, 1989

(magnitude 7.0) struck the SF Bay Area (pop. 10 million) and killed 63 people

Reinforced Concrete

(with steel reinforcing bars) Increases ductility and tensile strength

Worlds costliest natural disasters since 1965

-2011 Japan tsunami and earthquake was the costliest natural disaster in the world since 1965 -Then Kobe earthquake in Japan 1995 -Hurricane Katrina in 2005 -only very small portions of these losses were covered by insurance -Floods are very pervasive and frequent. The single events might not be as extreme as a hurricane, but they happen so much, its a lot of accumulated damage

Flood insurance:

-Communities (towns and cities) must designate floodplain zones and enforce regulations, to be eligible for NFIP federal flood insurance -Flood insurance is a good deal for those in flood-prone areas -Not such a good deal for US taxpayer, paying cost of losses -NDIP was $23 billion in debt in 2016, premiums not high enough to pay it off -Participants in 2003 paid only 38% of actuarial risk rates (statistical calculation of actual risk of lesses from floods)

NFIP is governed by legislation, subject to various interests

-Community government often opposes too much regulation, especially by federal government -NFIP legislation had good intentions of not encouraging development or subsidizing poor choices, but ... -For example: by law, NFIP can only require that property not be reconstructed in the same place if losses total 50% or more of the value.

Can we predict catastrophes? (the truly massive disasters causing great loss of life and property?

-Difficult to extrapolate the curve of flood size versus how often that size happen -Often see linear relations between the frequency of events versus their magnitude when using logarithms

Detection and warning for tornadoes

-Doppler radar, wind profilers, and automatic surface observing systems do a good job of predicting possible tornado formation and detecting ones on the ground -Psychological research has shown that 15-20 minutes' warning is best: less, and people don't have time to seek shelter; more, and people tend to think the danger has passed!

Flood Insurance

-Few people even bother to purchase flood insurance -Before the 1993 Mississippi river flood, only 5.2% of households in flood hazard area had purchased flood insurance (average price $400/year at the time) -Flood insurance could be required before purchasing property or developing land (NFIP requirement in 100 year zone not consistently enforced) -Insurance funds could be received only when building higher or relocating structure -Added: 2008 Senate regulation requires homeowners to buy flood insurance if levee breach will flood their home

Flooding is among the deadliest and costliest of disasters

-Flooding is the most common natural disaster, affecting virtually all regions of the country -Average in US of 84 deaths per year, 4 billion dollars in losses. Globally, much much greater -Not typically because of large single events, but because floods are relatively common and occur in many areas. -Costs are rising over time - why?

Tornado warning signs

-Green sky before a hailstorm or tornado -Cause is unclear -Particles in air (including water droplets) normally scatter blue light to create a blue sky -Most thunderstorms happen later in the day, when light is tinted red but light under a tall thundercloud is blue because of water droplets -Blue objects illuminated by red light appear green -Green color = Tall storm, and tall storms typically produce hail and tornadoes

Land Use on Floodplains

-Historically, land was settled along rivers useful for transportation and access to fertile soil (nowadays, even for the view) -People tend to underestimate their risk: -Forget major floods quickly -- maybe never happened to them or their parents -Believe that flooding unlikely if it has not occurred lately

Enhanced Fujita Scale

-In 1953 Tatsuya Fujita left Japan to study U.S. tornadoes -ranges from EF-0 to EF-5 Fujita scale: F0- little damage, under 72 mph, 32 m/sec F1- Roof damage, 73-112 mph, 33-50 m/sec F2- Roof gone, 113-157 mph, 51-70 m/sec F3- Wall collapse, 158-206 mph, 71-92 m/sec F4- House blown down, 207-260 mph, 93-116 m/sec Enhanced Fujita scale: EF0- Siding and shingle damage, 68-85 mph, 29-38 m/sec EF1- uprooted trees and overturned single wides (trailer homes), 86-110 mph, 38-49 m/sec EF2- Permanent houses off foundations, 111-135 mph, 50-60 m/sec EF3- Severe damage, houses mostly destroyed, 136-165 mph, 61-74 m/sec EF4- Devastating. Large sections of school buildings destroyed. 166-200 mph, 74-89 m/sec EF5- Incredible damage. Deformation of mid and high rise buildings. Over 200 mph winds, 89+ m/sec

Two houses in Louisiana: which one offers more flood protection?

-Modern suburban ranch house: built on concrete slab -200 year old house in Baton Rouge: elevated to protect against the frequent floods -Houses that are elevated are better protected against floods

How do tornados move

-Most U.S. tornadoes travel towards northeast -Localized but extreme damage can result (ex: Greensboro, Kansas May 4, 2007)

Major Disaster Declarations during 1953- 2014

-Most disaster declarations are for severe storms, flooding, hurricanes, and tornadoes - 37.1 percent of the top ten major disaster declarations by type of incident from 1953-2014 were from severe storms -32.8 percent from floods -9.3 percent from hurricane -6.5 percent from tornado and so on -Texas and Oklahoma have a very high rate of disaster declarations -For deaths due to severe weather in the US from 1977-2013, there were 161 from heat -102 from winter storm/cold -96 from floods -72 from tornado -63 from hurricanes -55 from lightning -53 from wind 602 total fatalities per average year

Flood insurance

-Normal homeowner insurance only covers water damage from inside (ex: burst pipe) not natural flood - extra insurance required for that -In flood-prone regions, private insurance companies often dont offer policies at all, or only at high rates -National flood insurance program (NFIP) established in 1978 makes insurance available to those living on floodplains, at modest cost -insurance provided by federal government, but purchased through private insurance companies (subsidized and guaranteed by govt., like some student loans)

"Predicted (yubao)" 1975 Mw 7.3 Haicheng Earthquake, China

-Officials had distributed educational brochures to the public about earthquakes and reporting unusual/precursory phenomena. -Early afternoon, February 4, 1975: officials in Haicheng issued warning to expect large earthquake in next two days , asking people to remain outside -Prediction based on - Increase in small earthquakes - Increase in elevation and ground tilting - Changes in groundwater levels and magnetic field - Strange animal behavior Mw 7.3 earthquake struck at 7:36 PM on February 4, 1975 -90% of buildings damaged or destroyed -2,014 deaths, 27,500 injuries, out of 3 million people -Preparedness and public education were the key factors that kept the death toll relatively low.

Federal Disaster Declaration

-State-level declaration of a "disaster area" can trigger federal disaster relief -Regular Federal Emergency Management Agency (FEMA) funds -Special appropriations (like Harvey, Irma bills) -Pays for immediate emergency costs, and then post- event recovery -Public level -Individual level (apply for funds) -Supplemental to insurance ... but does that create an incentive not to carry insurance?

Insurance Companies buy Insurance Policies Too

-The reinsurance industry insures the insurers against catastrophic losses -Example: Hurricane Andrew caused $15.5 billion in damage in Florida in 1992. Seven U.S. insurance companies became insolvent because they were unable to pay the claims resulting from the disaster. Reinsurers (SwissRe, MunichRe, Lloyds of London, etc.) are ones worrying most about: -Underestimates of how often disasters will occur -Change in the rate that disasters are occurring -The unlikely but truly catastrophic events

Tornado Protection

-Tornado shelter or safe room in basement away from windows is best -if no basement, interior rooms beneath heavy furniture or in bathtub beneath mattress

Longevity

-Tornadoes can last from seconds to over an hour, but typically minutes. -Tornado moves forward at 50-80 km/h (30 -50 mph) but rotating winds can be over 500 km/h (>300 mph) -Up to 2x maximum speed of hurricane winds! but force is proportional to square of speed, so 4x maximum hurricane force - Fw = p A = 0.5 ρ V squared A , where: Fw = wind force (Newton = kg m/s squared) A = surface area (m sqaured) p = pressure (Pascal = 1 Newton/m squared) ρ = density of air (kg/m cubed) V= wind speed (m/s)

tornado formation (the process)

-Wall cloud forms as rotating cell drops below cloud base from condensation, it forms a wall cloud -as wall cloud descends, a smaller, more rapidly rotating funnel cloud (mesocyclone) may form within or next to wall cloud -Funnel cloud of moist warm air reaches down towards ground as droplets condense - if it reaches ground -> tornado -often forms at back of storm, so can catch people unaware -As tornado matures, it widens and becomes more intense see pics on slides

tornado damage

-obviously, EF-5 is most dangerous but also rarer most deaths due to lower intensity tornados -Even for extreme EF5 events, tornadoes are still very localized which greatly helps recovery

April 25-28 2011 "Super Outbreak"

-the most catastrophic tornado swarm in U.S. history -349 tornadoes in 3 days - > 300 lives lost, $11 billion in damage -Extreme instability over a wide region: warm, humid air near the surface overlaid by cold, dry air aloft

Other ground failure: (besides cracking along the fault, displacement from transform faults, fault scarp etc) Landslides

... caused by disturbances in the natural stability of a slope 2001 Mag 7.6 El Salvador Earthquake ~1,000 killed; more than half due to landslides -Earthquakes create stresses that make weak slopes fail -Earthquakes of magnitude 4.0 and greater have been known to trigger landslides

Dont drive thru a flood.

1 ft of water exerts 500 lbs of lateral force, dangerous 2 ft can float ur car (1500 lb buoyancy force), and also exerts 1,000 pounds of lateral force, possibly fatal -dont turn around ex: Madison, Wisconsin flood August 21, 2018 Odana Road near Grand Canyon Drive (see pic on slide)

Plate speed

1-20 cm/yr: the rate at which your fingernails grow PLates are about 100 km thick, all of them are moving relative to one another

Earthquake Forecasting

1. Earthquake Precursors for Earthquake Prediction 1) Ground movement 2) Foreshocks 3) Increased groundwater radiation 4) Others Earthquake Prediction and Its Consequences 2.Earthquake Forecasting and Probability 1) Paleoseismology (looking at geologic sediments and rocks, for signs of ancient earthquakes.) 2) Earthquake probability and seismic hazard map

Internal Energy of the Earth

1. Primordial (original) Heat: Converted from impact (kinetic) energy through collision/accretion and gravitational energy as Earth pulled to smaller/denser mass, generating heat 2. Radiogenic heat Small amounts of Radioactive Uranium (U), Thorium (Th), and Potassium (K) are unstable; radioactive decay of these elements releases heat These things help heat up the earths mantle I think

FEMA's definitions for flood insurance purposes

100 year floodplain is separated into: floodway carries deeper water at higher velocities during floods and most (but not al) new building is prohibited in this area Fringe is further from the stream, but will still be underwater during a 100 yr flood How about the 500 yr flood plain? Probably not covered by government subsidized insurance

What if there is no historical record of earthquakes at all?

1700 Cascadia (Pacific Northwest) Earthquake Excerpted from a story told by a Cowichan elder to James Hill-Tout in the early 1900's and included in his Report on the southeastern tribes of Vancouver Island (Maud, R. (1978) The Salish People, Volume IV) "In the days before the white man there was a great earthquake. It began about the middle of one night and continued about 20 hours... " This region has been known to geologists to be a plate subduction zone since the 1970s ... but there have been no major earthquakes in recorded (means European colonial) history Cascadia subduction zone threat not recognized until early 1990s

Shaking Amplification and Liquefaction

2 factors affect damage during earthquake: 1) intensity of shaking (felt motion, not magnitude) 2) Engineering

Collapse of unreinforced masonry (brick building)

2010 Mw 7.0 Haiti Earthquake •Combination of reverse and left -lateral strike slip faulting 10 miles west of the capital of Haiti, Port-au-Prince •No construction standards; little or no reinforcing steel •100,000-316,000 killed; $11 billion in damage •Compare with 2010 Mw8.8 Chile Earthquake that killed < 1,000; enforced construction standards

For Tall Buildings: "Base Isolation"

2011 Mw9.0 Tohoku Earthquake, Japan 30-story Apple Towers Sendai proved the effectiveness of seismic isolation construction. Laminated rubber bearing made of alternating layers of rubber and steel plate; sways sideways to isolate the building from the ground Sliding seismic isolator; a laminated rubber bearing on resins that allow smooth sliding; absorbs strong tremors

Tuned Mass Dampers (TMD): Harmonic Absorber

A mass mounted within the structure to reduce the amplitude of vibration Taipei Financial Center, Taiwan (101 stories, 1670.6 ft)

Waves - Reminders

ALL waves have: Wavelength Period Frequency, and Amplitude Period: Time for one complete cycle between wave peaks Frequency: Number of peaks per second (Hertz, Hz) (= 1/Period) Wave velocity =Frequency × Wavelength Typical seismic waves: Wavelength: 0.5km < λ < 100 km Frequency: f= 0.05-20 Hz (s to the negative one) Amplitudes: 10 to the negative 7-10m

Ground shaking

Amplification: Seismic shaking/intensity is affected by rock type at different locations -The less consolidated and more saturated the sediment is, the more amplified the shaking

Three Little Pigs: Which was the best house to keep the wolf from getting in?

And in an earthquake...? Unreinfored masonry and adobe (mud brick) are is the deadliest. Wood frame is much better because it is less rigid. (straw wouldn't be too bad either!)

Societal Responses to Flood Hazards

Approaches to minimize flood hazards: 1. Engineering approaches to control flooding 2. Regulatory approach designed to decrease vulnerability to flooding

The Earthquake Cycle: Elastic Rebound Theory

As tectonic plates are slowly moving, their edges are locked into place, causing bending of the crust along plate edges

What produces earthquakes?

Big picture: motion of tectonic plates exerts stress at the edges •Elastic Rebound Theory -Slow accumulation of strain in rocks around a locked fault -Sudden release of stored elastic energy as fault ruptures - slips up to meters in seconds -Aftershocks -Cycle of strain accumulation begins again Stick-Slip Behavior

1993 mississippi river flood

Caused flooding in ND, SD, MN, WI, NB, IA, IL, KS, MO Why did it happen? Maps on slides Low pressure in northwest, High pressure in southeast, combine by the jet stream It rained for weeks Was almost 50 feet above flood stage It lasted for weeks above flood stage for a full month Satellite images on slide The floodplains were totally filled except for in like one area, the channelized St. Louis reach.

Engineering approaches to control flooding

Channel modifications- Straightening, widening, deepening and clearing channel to increase water-carrying ability Dams and retention ponds- Water can be trapped in a retention pond and then released at a controlled discharge to prevent flooding downstream. Levees, dikes, sandbagging, floodwalls, etc- Structures built along side the channel to increase the stage at which the stream floods. Floodways-Areas built to provide an outlet to a stream and to be flooded to reduce river flood level Dams have finite lifetimes so we really don't know how good they are

Dendrochronology (tree-ring dating)

Dead trees in a tidal mash (Copalis River, Washington Coast) Trees killed during subsidence accompanying the 1700 earthquake.

Disasters on the rise

Different types of disasters have different trends •Increasing human population modulates rising $ impacts

3 types of plate boundaries

Divergent- plates move apart Mid ocean ridges and rifts Convergent-plates move toward each other Subduction zones and collision zones Transform- plates move side by side Strike slip faults and oceanic transform faults •Earthquakes •Volcanoes •Formation of major mountain ranges Magma rises to the surface because its so hot compared to the surface around it , just like a hot air balloon. It buoyant

Earthquake Probability and Seismic Hazard Maps

Earthquake Probability Forecasting -Based on the past earthquake records and knowledge of fault movement •Probability of an earthquake of a certain magnitude (range) occurring in a certain region over a certain span of time •Probability of a certain level of ground shaking ("peak acceleration") occurring in a certain region over a certain span of time

Effect of Geology on Earthquake Intensity

Earthquakes are less frequent in the eastern US, but their damaging effects can extend over a larger area than the western US because of the stronger crust with fewer faults that transmit seismic waves more efficiently

What is driving plate tectonics?

Energy sources and hazards Earth's internal energy (thermal energy) - HEAT! Drives plate tectonics; volcanic eruptions, earthquakes Sun (thermal energy) - HEAT! Produces weather, lightning, tornadoes and hurricanes The earth has an energy budget I think

Locating Earthquakes

Epicenter Location: Based on the difference in arrival times (ts-tp; "travel time delay") of compressional (P) and shear (S) waves, we can calculate the distance (d) to the earthquake epicenter equation and example on slide

FEMA

Federal Emergency Management Agency (FEMA)'s Mission "to build, sustain and improve our capability to prepare for, protect against, respond to, recover from and mitigate all hazards." -This runs under the US dept of homeland security

Regulatory Approaches

Floodplain zoning: Restrict construction and habitation of floodplains Floodplain building codes: Restricted to those that can withstand high velocity of flood waters and are high enough off the ground to reduce risk of contact with water. Floodplain buyout programs: Government buying the rights to the land Mortgage limitations: Lending institutions could refuse to give loans Evacuation planning and public education

2008 Mw7.9 Wenchuan (Sichuan) Earthquake, China

Ground Shaking ex •Tibetan Plateau moved over the Sichuan Basin •Strict building codes, but not enforced properly •Rural villages in narrow steep- sided valleys lived in brick and unreinforced building, some with heavy tile roofs •School buildings with insufficient support collapsed, killing children •>87,000 killed, ~140 billion US dollar in damage

From Probabilities to Hazard Maps

Hazard Maps show distribution of earthquake shaking levels that have a certain probability of occurring

NFIP Flood insurance policies

High risk areas: In high risk areas, there is at least a 1 in 4 chance of flooding during a 30 year mortgage. All home and business owners in these areas with mortgages from federally regulated or insured lenders are required to buy flood insurance. They are shown on the flood maps as zones beginning with the letters A or V. So basically, in a 100 year flood zone, insurance is required. Moderate to low risk areas: In these areas, the risk of flooding is reduced but not completely removed. These areas submit more than 20 percent of NFIP claims and receive one third of federal disaster assistance for flooding. Flood insurance isn't federally required in these areas, but it is recommended for all property owners and renters. They are shown on flood maps as zones beginning with the letters B, C or X. So, in a 500 year flood zone, insurance is not required, which is a problem. Those are the most catastrophic floods and would require the most insurance dollars

Warning allows...

If S and surface waves travel at 4 km/s from >100 km away, warning can give >25 seconds. Human Responses • Public: drop, cover, and hold on; turn off stoves, safely stop vehicles. • Businesses: Personnel move to safe locations. • Medical services: Surgeons, dentists stop delicate procedures. • Emergency responders: Open firehouse doors, personnel prepare and prioritize response decisions. Automated responses • Businesses: Open elevator doors, shut down production lines, secure chemicals, place sensitive equipment in a safe mode. • Transportation: Automatically slow or stop trains to prevent derailment. • Power infrastructure: Protect power stations and grid facilities from strong shaking.

How do Insurance Companies Determine Costs for Coverage?

Insurance costs are actuarial -> they depend on past experience They are based on: Probability of occurence X cost of the probable loss from the event For insurance, a hazard is a condition that increases the severity of frequency of a loss Living with 100 yr flood plain is a hazard. Actuarial risk is the above equation

How do we measure earthquake size?

Intensity •Describes effects/experience of shaking •One quake, many values •Magnitude •Depends on the size of fault rupture itself •One quake, one value (in theory)

Human Population

Just before WWII, the population was about 1.2 billion Before the beginning of settled agricultural societies, the population basically didn't grow, and even for a while after that, but then it shot up and was almost perpendicular on the graph

Geologic factors

Location of the fault scarp Ground shaking & amplification Resonance (which is the number of seconds it takes for the building to naturally vibrate back and forth.) Liquefaction

What can be learned from seismic recordings?

Location, depth, and time of earthquake •Magnitude of earthquake •Type of faulting (motions) causing earthquake

Can earthquakes be predicted?

Long-term forecasting: -A qualified yes, based on probability and past events, BUT recent earthquakes have humbled us •Short term warnings in advance of the quake: -Not now -Maybe never...? -Precursory signals might exist, but we don't really know enough about what is going on deep underground -Need for samples and measurements from inside the faults •Earthquake Early Warning (EEW) -Seconds to minutes of warning after the quake has happened but before the strong shaking arrives at a particular location - Yes!

How do tornadoes form

Main way tornadoes form: Supercell thunderstorms a) Single cell thunderstorm (common) b) Supercell storm: accompanied by wind shear, heavy rain, updraft, tilting and occasionally tornado formation How do tornadoes form? Two key components •Thermal updrafts of warm moist (gulf) air into supercell reaching to jet stream •Wind shears due to rapid movement of 3 distinctive air masses: •Low altitude warm moist air •Mid-altitude cold fast wind •Polar front jet stream see pic on phone

Emergency Management Plan

Mitigation- Efforts to reduce the effects or risks associated with hazards Preparedness- actions taken prior to an emergency to facilitate response and promote readiness Response- actions taken during an emergency to save lives, property, and the environment Recovery-actions taken after an emergency to restore and resume normal operations

Major Disaster Declarations during 1953-2014

Most disaster declarations are for severe storms (37.1%) , flooding (32.8%) , hurricanes (9.3%), and tornadoes (6.5%) The number of disaster declarations has been increasing with time from 1953-2014 Human population has also increased exponentially

Injections

New USGS assessment of earthquake hazard released in March 2016 •Based on induced earthquakes in the central US in regions of active oil and gas drilling •Induced earthquakes are generally not directly from fracking - but are from wastewater injection into the ground -class II wells are used to inject fluids associated with oil and gas production deep into the ground. They are put into rock formations isolated from drinking water -Number of magnitude 2.5+ earthquakes SHOT up in 2014 because of injection

10 largest quakes since 1900

ON phone

Mercalli Scale

On phone Why is intensity useful? •Engineering and earthquake hazard •Effects of local geology •Earthquakes from before there were seismographs Why isn't intensity enough? Subjective •How to compare quakes? •Not fundamentally associated with the size of the earthquake or the type of faulting

Epicenter Location

One station gives infinite possible epicentral locations •Two stations give two psssible locations •Three stations give one I think because they can find the distance between them and the epicenter they just dont know which way. That distance is the radius of the circle, with three circles, you can find where they all meet

What's driving plate tectonics?

Our old friend convection in a totally new setting! Earth's Internal heat energy and gravity Mantle convection: very slow creeping motion of Earth's solid mantle, carrying heat from Earth's interior ex: lava video convection: when the hotter, less dense stuff rises Convection means movement, relative motion of materials Think of hot air balloon: the hot air in the balloon makes it rise In boiling water, the hot water is rising Rocks can flow, given enough time and thermal energy. That leads to convection of the upper part of the mantle

Where do earthquakes occur?

Plate Boundaries and Hazards Earthquakes are at plate boundaries. "young" volcanoes on earth are mostly at subduction zones or mid ocean ridges (these also might be plate boundaries) But, some are located in the middle of plates see "plates on earth" map on phone

fault vs plate boundary

Plate boundaries are always faults, but not all faultsare plate boundaries. The movement of the platesrelative to each other distorts the crust in the region of the boundaries creating systems of earthquake faults. ... Meanwhile, the fault is held together by the force of friction.

Land use on floodplains

Policies changed after 1993 mississippi river floods -Federal began buying up floodplain land -Provided disaster relief funds only if moved out of floodplain -Prohibited new structures on flood plains, but many exceptions being made -People feel that floodplain regulations infringe on personal rights -Individual's choice to build on floodplain can infringe on many other individuals' rights, and can be extremely costly to public

Three types of disaster declarations that can be made

Robert T. Stafford Disaster Relief and Emergency Assistance Act Three types of declarations that can be declared under the Stafford Act (1) Fire Management Assistance Grants declarations (2) Emergency declarations (3) Major disaster declarations FEMA activates the program

Digital Seismograms

Samples ground motion at a specified interval. The motion of the ground is continuous, but we can pick only certain positions and reconstruct the motion (within certain limits).

Liquefaction

Saturated sediment turns to fluid when shaken. Loses internal cohesion and strength. •Occurs in water-saturated (i.e., pores filled with water) unconsolidated sediment. •Ground shaking causes the grains to lose grain-to-grain contact, and thus the material tends to flow. When water just filled in the pore space between grains, friction held the sediment together. but when water stops the grains from touching each other at all, then friction cannot hold them When liquefaction occurs, the strength of the soil decreases and the soil can no longer support the foundation of buildings and bridges. Mexico City, 1985: liquefaction toppled many buildings that actually withstood the shaking itself Cali freeway built on bay mud example

What causes ground motion?

Seismic waves •Compressional waves (Primary, or P-waves) •Fastest waves, small amplitude •Travel at kilometers per second! (about 2 to 8 km/s - how fast is that in miles per hour?) move like a slinky P=waves travel fastest, but are small in amplitude - means they don't cause strong shaking •Shear waves (Secondary, or S-waves) •About 60% of P wave speed, but larger amplitude •Often the most destructive because they have large amplitude at relatively high frequency move up and down like a sideways snake S-waves travel more slowly, but are larger in amplitude - they move the ground a lot and cause a lot of the damage to structures •Surface waves •Slowest (still km/s) but largest amplitude •Sometimes very destructive

Recording Earthquakes & Seismic Waves

Seismoscope: Zhang Heng (132 A.D.) Each dragon has a ball balanced in its mouth. Earthquake causes a ball to fall into the mouth of the toad - the position of the toad which swallowed the ball was thought to indicate the direction of the earthquake. see pics of seismographs used to detects vertical and horizontal movement. When earth goes down, needle goes up An analog drum seismograph. The needle pen moves back and forth on a turning roll of paper. Now, all seismographs that are really being used are digital

West Coast ShakeAlert System (Testing Stage)

Sensors detect the early P wave and immediately transmit data to an earthquake alert center where the location and size of the quake are determined and updated as more data becomes available then basically you get a notification on your phone which calculates the estimated arrival time and intensity at your location

Hazard-risk

Some cities have high hazard (good chance of powerful earthquake happening) and also high risk (due to population density and poor construction practices)

Infrastructure Failure

Sometimes even if u are prepared, things dont go super well 1995 Mw6.9 Kobe Earthquake, Japan • Kobe, a city of 1.5 million, was the closest (20 km) to the epicenter. • Collapse of steel-reinforced Hanshin Expressway, which was built according to the building codes in force back in 1960's. • 6400 killed, 200 billion USD in damage

Rayleigh waves

Surface waves that travel in a backward-rotating, elliptical motion, causing both vertical and horizontal ground movement. Can travel through solid, liquid, and gas. Fourth to arrive. Dangerous.

Love waves

Surface waves: side to side

Poor countries tend to fare worse overall - but "Corruption kills"

The poorest countries are the most corrupt, but some are more corrupt than others. Named countries have lost citizens in building collapse caused by earthquakes since 1980. "Global construction industry is the most corrupt segment of world economy" -Ex. in 2016 Taiwan earthquake 2016, M6.4 Taiwan earthquake The apartment complex was supposed to withstand the earthquake. Replacement of structural concrete with empty cooking oil cans may have critically weakened the building - 115 deaths by this collapse, only 2 other deaths elsewhere.

What is an Earthquake?

The shaking is vibrations of the Earth (seismic waves) produced by energy released during rapid slip on a fault. •(or also by volcanic events and even explosions) -Shaking spreads over a broad area of the surface, but is produced by a specific fault rupture (breaking) at depth in the Earth.

When/Where do tornados occur

U.S. ~1,200/year Canada ~100 -United States leads world in number of tornadoes but they can occur almost anywhere -alaska has 0 yearly tornados on average, Hawaii has one, Texas has the most, so do the other states in tornado alley -North America extends from tropics to arctic without any east-west mountain ranges to block air flow -see tornado risk map -tornado alley has the highest average number of tornados per year per 10,000 square miles -Most tornadoes occur in summer (may has the highest occurence, then June) -Most tornadoes occur in afternoon (5, then 4, then 6 pm is most common)

passive continental margin

a continental margin that is not a plate boundary Is the east coast of the USA on a plate boundary? No! It is in the middle of the North American plate. The place the continent and oceanic crust meet is called this

Another way tornadoes form: Mesocyclones

a) Colliding masses of air generate horizontal spinning tube of air, a vortex b) Rising air with an updraft tilts rotating vortex stretching it upward c) As vortex is stretched upward, spin velocity increases see pic on phone

Inaccurate warnings

china is clamping down on these because they cause panic and can be bad for the economy because they cause crowding and mass evacuation

Transform plate boundaries

continental transform fault-two plates slip past each other (ex: San Andreas fault, pacific and North American plate) Transform faults on continents can generate large earthquakes. north Anatolian fault in turkey

protecting buildings against earthquakes

diagonal construction something about too many windows Many useful and relatively inexpensive measures can make houses much more earthquake-safe -bolt furniture to walls/floor -etc

Terminology

fault- a fracture in rock where there has been movement and displacement. fault scarp- a small step or offset on the ground surface where one side of a fault has moved vertically with respect to the other. -Focus (also called hypocenter)- the point of origin of an earthquake -Epicenter- the point on the earth's surface vertically above the focus of an earthquake.

Number of lives lost due to floods and flash floods (1995-2014)

graph on phone In U.S. •Floods among deadliest and costliest weather-related hazards • Annual costs of flood damage increased tenfold from 1929 to 2003, from $400 million to about $4 billion (unrelated) - mendota is really high rn which increases the possibility of flooding

3 main types of faults

just like the 3 types of plate boundaries: -NORMAL faults cause DIVERGENCE cause extension - crust pulling apart Like divergent plate boundaries: mid-ocean ridges and rifts IN these normal, or dip-slip faults, the block above the fault (the hanging wall) moves down relative to the block below the fault (the foot wall). This fault motion is caused by tensional forces and results in extension -REVERSE or thrust faults cause CONVERGENCE: crust pushing together Like convergent plate boundaries: subduction zones and collisions In a reverse fault, the block above the fault ( the hanging wall) moves up relative to the block below the fault ( the foot wall). This motion is cause by compressional forces and results in shortening. It is called a thrust fault if the dip (slope) of the fault plane is small -STRIKE SLIP faults cause SIDE BY SIDE motion - crust moves laterally Like transform plate boundaries A vertical or near vertical fracture on the earth where the ground has shifted horizontally. If you stand on one side of the fault and the block opposite from you shifts left, the motion is termed left lateral, if it moves right, it is termed a right lateral fault

2010 Port-au-Prince, Haiti earthquake

magnitude 7.0 - killed > 220,000 people

Tornado season

most tornados in WI happen in June, then July, then may, then august. There was actually a tornado on October 17, 2017 in Madison which is pretty late season

Tornadoes

narrow funnels of rapidly rotating wind. Most often form from powerful thunderstorms or hurricane systems.

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need to listen to this tornado lecture to fill out the notes and also read the chapter and put in the notes

Subduction Zones cause the largest earthquakes and tsunami

plates are stuck and build up strain until the earthquake The uplift of the sea bed during the earthquake is the cause of the tsunami

Zoning

restricting use of flood prone areas is remarkably effective, but not practical in all areas And is often fought for political or economic reasons

2 types of convergent plate boundaries:

subduction zones- Ocean-continent convergence When oceanic lithosphere meets continental lithosphere, the oceanic lithosphere is subjected (goes under), and a volcanic mountain belt is formed at the continental margin Subduction Zones are the location of most non-ridge volcanoes and of the largest earthquakes and tsunamis Where oceanic lithosphere meets oceanic lithosphere, one plate is subducted under the other, and a deep sea trench and a volcanic island arc are formed. (ex: Mariana islands and Marianas trench) continental collision zones- Continent-continent convergence: where 2 continents converge, the crust crumples and thickens, creating high mountains and a wide plateau . (ex: Himalayas) April 2015 Nepal earthquake killed over 8,000 people and injured more than 21,000 (Himalayas) India/asia plates hitting Long history of earthquakes along the edge of the Himalayan mountains April 25, 2015 Mw =7.8 Katmandu earthquake Stick-slip accommodation of India-Eurasia plate convergence across the Himalayan frontal thrust fault M7.8 earthquake was a low-angle thrust earthquake along the shallow-dipping fault beneath the High Himalayas.

Evidence of Subsidence and Tsunami (dated 1700 AD)

subsidence: the gradual caving in or sinking of an area of land.

Amplitude

the height of a wave's crest

Amazingly, the geologic & tree evidence of something big having happened ... could be linked to a tsunami puzzle from Japan!

• Documented historical records indicate tsunami with no known earthquake to go with it hit Japan around 12 AM on 27 Jan 1700 • Travel time ~10 hours from Cascadia -Earthquake occurred about 9:30 PM on Jan 26, 1700 in Pacific coast time -Consistent with Native American legends that EQ occurred on a winter night

SF Bay Area Earthquake Probability

• Overall probability of Mw 6.7 or greater in the Greater Bay Area during 2014-2043 is 72%. • Probability is highest for the Hayward-Rodgers Creek Fault system, 33%; last damaging earthquake was in 1868. • Probability of a large earthquake on the San Andreas Fault in the next 30 years is 22%. This fault was responsible for the 1906 M 7.8 San Francisco and M 6.9 Loma Prieta earthquake. "The most dangerous fault in America" The Hayward fault runs through a densely populated urban area including Oakland, Berkeley, and Hayward, California California is almost certain (>99% probability) to have a major earthquake in the next 30 years. Los Angeles region (63%) San Francisco region (67%) the 1906 San Fran earthquake was pretty bad

Earthquake Forecasting and Probability

• Based on the frequency, magnitude, intensity and spatial distribution of past earthquakes •Can be used for Establishing construction standards based on risk Evaluating risk for insurance purposes (rates higher in high- risk areas). Risk-based site selection (e.g., for nuclear power plants)

Prediction Consequences

•A number of failed predictions. •With current state of knowledge, earthquakes are inherently unpredictable in short term •Predictions raise complex political issues (1) Announcing predictions can cause hysterical public reaction and major physical and economic damage (2) Not announcing predictions can lead to accountability issues

Japanese Early Earthquake Warning System

•In 2007, Japan introduced the world's most sophisticated early warning system using a network of ~1000 seismic stations . •The system estimates the source and magnitude of an event and sends out alerts via TV, radio, and cell phones. •2011 Mw9.0 Japan EQ began at 2:46 p.m. ~ 150 km offshore; 31 sec later, residents of the Tohoku region received the first warning with a lead time of 10-30 sec.

How do we measure earthquake size?

•Intensity (old way, but still useful) •Describes effects/experience of shaking •One quake, many values •Works something like the Fujita Scale for tornadoes - based on observations of effects Magnitude (Richter Scale, etc.) •Depends on the size of fault rupture itself •Uses the amplitude of the waves scaled by the distance - calculate the energy released by the fault breaking •One quake, one value

What factors cause damage from earthquakes?

•Magnitude -Bigger earthquakes are likely to be more damaging, all other things being equal, BUT: •Depth -Earthquake hypocenters range from 1 to 600 kilometers in depth - deeper ones generally produce less strong shaking at the surface. •Distance -How far away from the site where you are experiencing it? Farther mostly means less strong, BUT •Local "Site Effects" -Every spot on the ground has a different way it responds to the seismic waves that are shaking it - some amplify, some damp it out. -Buildings have a response to the waves too - higher floors in tall buildings will sway a lot, for example, like upside down pendulum.

USGS ShakeMaps

•Maps of ground motion and shaking intensity for significant events and potential earthquakes •Used by federal, state, and local organizations, both public and private, for post- earthquake response and recovery, public and scientific information, preparedness exercises and disaster planning. 30 Shaking intensities expected for a hypothetical scenario earthquake (M6.7) on the southern Hayward Fault, which last ruptured in 1868 in an event of magnitude about 6.9.

Increased Background Radiation in Well Water

•Radon (rare gas) forms as part of uranium decay •Remains trapped in rock until it escapes along fractures •Formation of new fractures before large earthquakes may allow radon to escape, increasing radioactivity of groundwater •Earthquakes often occur at > several km depth, long distance from the surface where radon measurements are made; unreliable

Earthquake Magnitude

•Richter Magnitude Scale -Amplitude of largest waves is measured, normalized by distance to epicenter -Logarithmic scale: one point is a factor of 10 bigger Moment Magnitude Scale -Modern replacement: uses various measures to compute the energy released -Slip amount x Slip area x rock shear strength

Earthquake Magnitude

•Richter Magnitude Scale -Amplitude of largest waves is measured, normalized by distance to epicenter -Logarithmic scale: one point is a factor of 10 bigger •Moment Magnitude Scale -Modern replacement: uses various measures to compute the energy released -Slip amount x Slip area x rock shear strength •Mercalli Intensity Scale -Subjective , based on reports of experiences and damage -Useful for historic earthquakes before there were good seismograph recordings

Seismic Moment Magnitude (Mw)

•Seismic Moment (M0): Measure of the size of an earthquake (seismic energy expended during an earthquake) •M0 determined by examining seismic waveforms, not just the maximum amplitude, at many stations around the globe M0= Seismic moment (Newton-m) =μ ×A×D μ= rock strength (stress required to make it break and slip) A= Area of fault rupture (L×W) D= Average amount it slipped on the fault Seismic Moment Magnitude Moment magnitude is based on seismic moment (the area of faulting and the fault slip)

What makes earthquakes hazardous?

•Seismic waves are the shaking of the ground -accelerations of the surface and anything on it -Depend on magnitude of the earthquake and distance ... BUT •Site effects: -Local at any point affected by the earthquake -Mean that level of shaking can be vastly different from place to place for the same earthquake -Liquefaction, when the soil turns to mush •Construction practices and engineering -Can build earthquake-resistant structures -Poor construction practices kill people! •Other societal factors: -Time of day! -Preparedness of the population for emergency -Emergency response by authorities

Accountability for Earthquake Predictions: 2009 Mw 6.3 L'Aquila Earthquake, Italy

•Seven large earthquakes had damaged region in past 700 years •Small earthquakes began in central Apennines in January 2009 •Italian technician warned of an imminent major earthquake on TV •National Commission for the Forecast and Prevention of Major Risks met on March 31 to evaluate earthquake risks and concluded that there was no threat. •Mw 6.3 earthquake struck on April 6 •Medieval city of 70,000 people with buildings dating back to 1200s, lying on lake bed with sediments which amplified shaking •297 people killed, ~1,500 injured •6 scientists at the March 31 meeting were convicted of manslaughter and sentenced to 6 years in jail in 2012; acquitted in 2014; the deputy head of Italy's Civil Protection Department at the time is serving 2 years in prison since 2014 •Question remains of how to handle "predictions"

Fire

•Tipped over wood or coal stoves •Broken gas lines and power lines in Japan earthquake: Oil refinery on fire Leaked gases and gasoline from fuel tanks in automobiles, ships, houses etc. were ignited by sparks from metals colliding with each other by tsunami

Learning from Mistakes?

•collapsed in 1971 San Fernando Valley EQ •Rebuilt using same construction techniques - no additional earthquake engineering •Collapsed again in 1994 Northridge Quake