Earthquake country

April 1st lecture FINAL EXAM IS WORTH 40%
Professor goes by Abhi (Obi) like star wars

One required textbook Earthquakes science and society lecture will be on additional material not in book but will be guided by materials in the book. take notes (HE SAID IT ALOT!) his lecture slides will not be posted.

CH.1 for this lecture

Why Learn Earthquakes?

Plate Tectonics they are not static they always move. they are moving in a limited space it will cause friction when it moves moves very slowly a few centimeters a year. slides past each other and radiated seismic energy. as it travels it causes shaking. seismic waves from epicenter cause a lot of shaking

Continental drift pangea moved and separated into different continents.
SF 1906 the plate moved 400 km past each other creating 8.2 earthquake he shows a lot of examples of massive earthquakes.

Myths and legends

Thousands of years ago it was believed animals caused earthquake

Mongolian belief believed that the earth was on a back of a big frog and when it moves so does earth.

Japanese folklore catfish was the reason behind earthquakes when it shakes japanese gods were in charge of taming the catfish.

Greek God: poseidon earth shaker he is short tempered and when he gets mad he stomps his foot causes earthquakes.

Aztec calendar cyclical massive earthquake causing the end of the world.
Indian myth they believe the earth on a snake, turtle and elephants when they moved the earth shaked.
Tremor in Hollywood movie about raboids causing an earthquake

Logic (Elastic rebound theory) noticed that the land moved as the ground shook

Our Place in Earthquake Country

The goal is to be prepared for an upcoming earthquake by understanding it better.

April 3rd:

OUTLINE:

Earth’s Interior
Plate Tectonics (Read Chapter 6)
Plates
Continental Drift
Sea Floor spreading
Driving Mechanisms
Plate Boundaries

lithosphere- Solid is very hard. if you apply pressure it breaks (rock)
Asthenosphere- solid but not as hard as lithosphere.(soft plastic) if you apply pressure it flows.

Mesosphere- “stiff plastic” he said we wont go over this too much in this class.

outer core- Liquid. It can flow. Acts as a dynamic for Earth’s magnetic field. Remember that. Made up of Iron and Metal. very dense liquid.

Inner core- Solid because the pressure is high. Pressure increases with increasing depth.

the lower you get the more dense the material becomes.

the lithosphere can flow on top of the asthenosphere which is very important to know when it comes of earthquakes.

Plate tectonics (what is it)

the placement of volcanoes and earthquakes are directly linked there is a pattern.

there is more in the middle east and volcanoes are in the same locations as earthquakes.

the boundaries from the plates above are creating volcanoes and earthquakes.

we know that plates move because plumes (molten rock) under volcanoes that want to come up stays in the same place over geologic time. so based on the plume we can find out how fast plate tectonics are moving. the closest volcano to the plume is the youngest volcano.

Plate tectonics Continental drift

the continents are like a jigsaw puzzle- you also see similar rock types in south america and africa. seeing the same plants and animal fossils suggests that the continents drifted away from each other previously being connected. the continents are in a very different configuration along time ago and if put in the right position they fit together. Think Pangea.

Ill look for an explanation later- don't feel like taking good notes lol
Sea floor spreading

conveyor belt theory.

seafloor bathymetry

earths magnetic field- every few million years the magnetic field swaps so north and south will switch. magnetic reversals. rocks also show the reverse in the magnetic field. rocks are polarized in a normal position right now the last time it reversed was around 1 million years ago. new rock is created and is oriented the way earths magnetic field is then it is moved from the center

reverse polarity-.

why are earthquakes and volcanoes in the same areas. volcanoes are created by plate boundaries that also create earthquakes

seafloor spreading there is volcanoes in the middle of the ocean the volcanoes create new crust and the lithosphere expands on both directions. its like a conveyor built. seafloor spreading

reversed poles reversed polarity the poles switch/reverse over geologic time the magnetic field switches it reverses instantly not gradually.

rocks can record earths magnetic field by aligning itself towards the direction the magnetic field is set. stripes of rock that alternate in polarization parallel to the mid-ocean ridge

important concepts continental drift- since the seafloor is spreading the continents a drifting apart. sea-floor spreading convection how heat is spreading… heat is the main source of energy driving this conveyor belt.

earth’s core makes the heated material go up which drives the plates along with gravity. the heat that goes up is heated magma that drives the plate tectonics to move.

volcanoes are the driving force for divergent plates… the following are all under the sea divergent - moving away from each other like mid ocean ridges. convergent- moving towards each other like subduction zones transform- slide past each other

Iceland is the only land that sits on the mid oceanic ridge system on land.

the red sea is a new mid-oceanic ridge forming there. in millions of years the middle east will be a sea.

Important to know
Cross section
Spreading rate - two people walk away from each other at 50 steps per minute spreading rate = 100 steps/Min half spreading rate- two people walk away from each other at 50 steps per minute spreading rate/ 2 = 50 steps/Min so cut the spreading rate in half the spreading rates are for mid oceanic ridges.

a special case like two continents colliding we have high mounts that are formed like India and china with very big mountains.. the continents are subducting but very slowly

the ridge is high because the cooled magma is still high in temperature but as it cools its density increases and it goes lower. thats why there is a ridge.

we live on the pacific plate and we can drive 50 mins and reach north american plated. san andreas fault is a transform boundary the plates slide past each other. san andreas fault is on the plate boundary… there are other faults but they are within the plate.
Lecture April 10
Fault, Earthquake and Elastic rebound theory

1. Plate Boundaries and fault
2. Types of fault
3. Complexity in faults and EQ’s

Ch.3 Fault and Earthquakes review subduction zones and lithosphere crust that heats up and goes out to the volcano

plate boundaries is where the majority of earthquakes are occurring. mid oceanic ridges are always at plate boundaries

Types of faults

stick- slip motion plates do not move smoothly. they move in a jerky motion everytime it moves it creates an earthquake before it moves it accumulates stress then releases the stress by slipping.

Force
Force = mass * acceleration ( * = multiplication) units of force - newtons unit of mass - Kilograms acceleration m/s^2 stress = Force / Area (/ = division)
KG * M / S^2 M^2 = KG/S^2 M = Pa (pascal) compressional stress vs extensional force vs stress you are applying an equal amount of force but the smaller the area of the force being applied the higher the stress example force = 5 area equals 5 vs 1 stress = force / area
Strain
strain = change / original (L- L0 / L0) shortening and extension
Divergent plates extension and gets gets longer convergent plates shorten and compress
Transform
neither is occurring

Fault surface or narrow zone with shear displacement along the zone shear displacement is displacement across the surface (along the plate never across) strike is where the fault meets the surface (horizontal surface) fault will always be acute (based on 180 degree angle)

foot wall = below plane hanging wall = above plane

Normal Fault when hanging wall moves down

Reverse/ Thrust fault the hanging wall must move up in order for this to happen

Transform fault move along each other

Oblique fault

fault scarp is shown above

there is a system of faults not just one fault

to find out what lateral it is is stand on one block turn toward the fault and see what direction the other block is moving.

April 15
What defines the fault linear shocks crossing the two walls on the fault.

picture above is showing a pop up hill being created by asperity fault in california is not straight right lateral movement there is also a zone of compression along a transform fault. (compression is a reverse fault)
Asperity on fault there are bumps when it slips across the bump it creates earthquakes.

Heterogeneous slip indonesia in 2004 subduction zone slipped causing a 9.2 earthquake entire fault did not slip uniformly. parts of a fault slip more than others. this is because asperity because there is bumps and some are more stuck than others. the earthquake started south and propagated north. this earthquake lasted 10 minutes
1300 kilometer fault.

2. Earthquake definitions

focus = hypocenter

epicenter is the point where it started or hypocenter (focus)

epicenter is NOT where the earthquake is felt the most.

3.Friction

Friction- is the force that resists relative movement (for the test).

Elastic rebound theory the rock deforms away from the fault

how do we measure when measuring an earthquake

earthquakes are measured in waves they ripple sort of like water up and down ripples on land.

we measure three things measured by a seismometer
Displacement
Velocity
Acceleration

Seismic waves

seismic network we need alot of seismometers in order to find out how much ground is shaking through out the world. used to detect and record earthquakes throughout the world.

Continental seismic network created a dense network of seismometers within the continent.

Regional seismic network dense regional network. california is the most dense than the rest of the world. seismic array to do analyses transportable array

Quick digression

Fault vs Plate Boundaries

all plate boundaries are faults but not all faults are plate boundaries

Waves---types

Frequency

Crest to crest is a full cycle or trough to trough.

frequency is number of full cycles per second. the unit of frequency is Hertz (Hz) per second

Period: length of time for one full cycle.

Wavelength: distance between the wave crests (or troughs).

wavelength = velocity * period → λ = V * T

λ = V/F ……. F is frequency

T = 1/F

Wave Types

there are different types of waves that travel differently through earth.

seismic waves body waves - travel through earth surface waves - travel through the surface of the earth

Body waves
Primary waves (P wave) (compressional or longitudinal) secondary waves (S wave) (Shear or transverse waves)

Surface waves love waves
Rayleigh waves

Primary Waves

like a slinky’s wave. the compression moves through the ground. the original position and the final position is the same after this. goes through liquid.

S waves there is shear movement between the particles. This cannot go through liquid. does not change original and final position it stays the same. cannot go through outer core because it is liquid

no vertical motion. movement is horizontal. only goes through the surface same movement as S wave but not vertical

Rayleigh Waves
Surface wave

How to Identify waves

3 Components seismograms

1. vertical horizontal ones
2.East west Radial (parallel to the propagation of the earthquake)

3. North South Transverse (tangential (perpendicular to the propagation of the earthquake)

April 24 2014

seismic waves the way seismic waves as they travel they bend as seismic waves propagate it loses amplitude

Picture above shows that P waves have a higher velocity than S waves… there are four types of waves but the other two are surface waves so it doesn't matter.. for S waves there is zero velocity at the outer core because it is liquid and S waves cannot go through liquids. seismic waves bend when they touch the outer core.

the waves below are organized by velocity… the fastest waves are P waves while the rayleigh wave is the slowest. based on the waves the first ones to appear in a seismogram is based on this order…

P waves can be seen well in vertical channels… because particle movement is vertical.

S waves can be seen well in horizontal channel.. because particle movement is horizontal.

Love waves can be seen better in horizontal channels because of particle movement is horizontal. it will be sensed the best in transverse component.

Rayleigh wave.. slowest wave speed. most complicated with particle movement

Attenuation (go search youtube for help) geometrical spreading- body waves 1/ distance …. surface waves 1/√(Distance) inelastic attenuation-

Midterm 1
Emphasize these topics… there will be other stuff as well.. it will be 45 mins long 3:40PM- 4:25

what is covered textbook chapters 1,2,3,6

Activity 1,2,3,4

all class lectures (including today)

Format multiple choice
25 questions
Answer on scantron different ecam forms

every person will have a different set of exam forms

Policy
Late
not allowed to take the exam as soon as the first person left the examination area.
The items that will be on tables
Exam form scantron pencil eraser calculator nothing else

what kind of scantron its light blue not green

whats on the exam plate tectonics cross section through earth (velocity and how it relates to the density and structure of the layers) structure of the shallow part (lithosphere and asthenosphere plate movements so the massive plates like pacific plate. earthquakes and volcanoes on plate boundaries evidence that plates do move based on the chains of volcanoes. good evidence on the volcanic islands chained in hawaii. magnetic reversals and how they are imprinted in the rock. sea floor age. near mid oceanic ridge the rocks are young. older rocks further away from these ridges. seafloor spreading caused by convection from mid oceanic ridges from the heat source and the subduction zones. the heat is the energy and driving source of it.
Types of plate boundaries. divergent, transform and convergent. wadati-benioff zone has earthquakes and one is near japan and one by southamerica. both are subduction zones. subduction zones causing the deepest earthquakes. can be very deep. it gets deeper the further in the plate you go.
Faults and Earthquakes hanging wall and footwall fault plane
Normal fault ,reverse fault and transform (strike slip) fault. oblique stress regime extensional and compressional getting different types of faulting. geometrical complexities near faults pull apart (sag-pond) usually has a lake or a pop up hill whether its right lateral or left lateral will decide if it has a pond or a hill the step over also decides left or right elastic rebound theory seismic stations waves three component ground motion

Waves can only exist with movement of particles.

P waves parallel to propagation. fastest wave body wave compressional waves.
S waves perpendicular to propagation body wave sheering up and down from the particles
Love waves
Horizontal particle movement surface wave perpendicular to propagation the particles sheer past each other
Rayleigh waves slowest wave elliptical patterns surface wave shearing and compressional waves retrograde/elliptical movement. counter clockwise movement

Chapter summaries

Chapter 1
History of Earthquakes
Prehistoric explanations of Earthquake occurrences legends (mythical animals & what not) (and gods) powerful forces
Greek: vapors trapped in caverns popular belief ‘til’ 1758
Modern Study of Earthquakes late medieval period experimentation based on observations realized that were there were faults there was earthquakes and where there was volcanoes there is earthquakes
Great lisbon Earthquake of 1755
John Mitchell
Earthquake waves
Estimating velocities
Location techniques (not clearly understood until 19th century)
Formation of fault scarp
Observed by mino-owari 1891
Relation
B. Koto (observer)
1906 San fran provided data on EQ’s
Reid commission established rebound theory ground deformation around and across a fault before, during & after an EQ.
Chapter 2 notes

Measuring Earthquakes
Different types of data are collected from earthquakes:
-Description of ground shaking
-Damage caused
-Effects on structures (cracking or swaying buildings)

Domenico Pignataro (1783) created the first scale to to determine the strength of an earthquake
P.N.C Egen (1828) Created a more detailed scale
Joham Noggerath (1847) created a map for the Rhenish earthquake to trace areas with similar intensities.

Focus or hypocenter -- point of initiation of an earthquake
Epicenter -- point on surface or a map directly above the focus
Intensity -- ground shaking determined by the manner and amount of energy released at the source , distance from the source (including depth of the source), and the material and topography at the site experiencing movement.
Wave Attenuation -- a portion of a wave energy that is absorbed by the material through which it passes. This results in the decrease of amplitude and therefore ground shaking intensity.
Geometrical spreading -- the farther the wave travels, the more energy is lost by absorption

Wave attenuation + Geometrical spreading = the farther from the site of an earthquake is less intense shaking and deeper depths = less intensity
Local geological conditions such as materials like fill and mud determine intensity (the Bay Area fill amplified shaking).

Azimuth (direction) -- direction determines intensity as well. A site close to the direction of rupture along a fault will be greater in intensity.
9
Modified Mercalli Scale -- 12 levels of intensity in (Roman Numerals) is used in the USA and Western Europe as of now

Chapter 6 Plate tectonics
Acceptance of mobile earth crust
Distribution of ancient fauna,. matching continental coastlines, ancient glacial patterns, and truncated mountain systems.
Alfred Wegener & continental drift
Problem: what is source of energy? previous explanations: tidal forces of the sun and moon and centrifugal force and continental buoyancy.
Continental drift revived after WWII concept of plate tectonics
Plate tectonics mobile seafloor energy comes from within
Thermal convection of heat earths interior seafloor spreading
Volcanic activity concept supported by oceanographic studies and study of Earth’s magnetic.

Chapter 3 Faults and Earthquakes faults are fractures in which the blocks of rock move parallel to the fault surface
San Andreas fault is a strike slip
2 blocks of Earths crust slip past one another thrust or reverse fault creep or stable sliding smooth movement instead stress building up water lowers friction which leads to more frequent movement.

people struggled on the midterm with these topics
What plate are you on?
Fault stepovers
West Coast of South AMerica
Spreading Center
An epicenter is marked on a map
The core

the deepest mine is 2.3 km deep
Deepest drill hole is 12 km we have only discovered the shallowest .19%

Hollow earth theory people still believe in this the earth is hollow and there is a sun in it. what is density dont need to know this. mass/volume Emil Wiechert germany believes there is an outer core of rock and inner core of something nobody believed him

Richard Oldham 1906
14 earthquakes
Seismographs recorded around the world

Snells law law of refraction and works with waves.
S wave velocity look at the formula come back and explain later.
Formula: n1(sin(theta1)) = n2(sin(theta2))

Waves that go deeper will come back quicker than waves that stay in a straight path on the surface. makes sense because surface waves are slower.
Seismic shadow zones when earthquake occurs, there will be locations on the globe where seismometers won’t record anything. why is that? the core is important allows for life on earth. also rotates at a different speed than the outer core. its almost floating they noticed the waves passed differently through the inner core and outer core.

Earthquake Ch.4 Size and Location

Professor goes over midterm
Distance = Velocity * Time

2. elastic rebound theory, where are the rocks that are undergoing the most strain the ones that are the close to the fault are
3.you are traveling right lateral stirke-slip
4. the epicenter of an earthquake is marked on a map. This point is where none of the above
5. which type of fault does not have vertical movement strike slip
6. math problem again about plate boundary movement.

7. which plate are you sitting on right now? pacific South america convergent plate boundary and it has compression since it is compressional it is a reverse plate boundary
San andreas fault is a right lateral strike slip fault

Ch.4

Earthquake waves don’t travel the same speed
P-waves are faster and they will reach the place first.
S-waves lag behind… S waves have higher amplitude.

as you get further away from the epicenter of the earthquake the distance between P and S waves is increasing because P waves are traveling faster for a certain period of time.

the top seismogram is closer to the epicenter. notice how the distance between p waves and s waves increases the further it goes out. (because of wave attentuation & geop

you have to use 3 seismograms draw circles around them and as soon as all three circles cross at a point. that point is the epicenter. when plotting an epicenter we are ignoring depth and that creates uncertainty with our calculations.

Moment Magnitude: some big equation that I dont understand

Mo = 10^((3/2)(Mw+9))
Mo: Seismic moment
Mo = (mu)Sd
(mu): rigidity around the fault zone
Big S: surface of rupture d: length of slip along the fault plane
A = Lw
L: along-strike length w: fault width
L = (Mo/((mu)*s*w)) little s: average slip
Mo2/Mo1 = 10^((3/2)(Mo-M1))
D = [VpVs / (Vp – Vs)]*(ts – tp)
Vp: Velocity of P-wave
Vs: Velocity of S-wave tp: time of arrival for P-wave ts: time of arrival for S-wave
(equations given by my TA. If your TA already explained the new activity then I would use that as a reference, if not you can message me and I can try the explain the equations and how they were used on the activity)
Mo = (mu)Au
(mu): shearing strength of rock
A: Area of the fault rupture u: average displacement on the fault
Watch this video to understand moment magnitude watch later

It is physically impossible to get a 10.5 earthquake because earth is not a big enough planet.. other planets can actually have big earthquakes.

Earthquake shaking if you are close to the hypocenter or epicenter the shaking is a lot when you go further the shaking is less. DUHHHHH

What controls ground shaking
Magnitude
Distance (including depth)
Local Geology rupture direction

loose sediments equals more shaking it will shake violently. the sediments are sturdy and we get less shaking. so amplitude is amplified when sediments are loose like LA.

Midterm 2

Starts thursday 3:40-4:25

midterm is cumiliative

includes activities 1,2,3,4,5,6,7

Textbook Ch 1,2,3,4,5,6,7

no use of cellphones in the room.. switch off cellphone before you walk in the room

when you stand up you are not allowed to modify anything so make sure everything is on exam.

scantron SC882-E

what to study
Body waves vs surface waves waves and wave length, amplitude, cycles. geometric spreading A1*R1 = A2*R2 ray bends seismic velocity structure
How to locate earthquake the distance between P-waves and S Waves grow the further away you go from the epicenter. three circles give you earthquake location

Types of Eq magnitude moment magnitude the most important and scientifically correct magnitude is more accurate when calculating bigger earthquakes it has a straight line and does not saturate compared to the others. thats why they always use this magnitude local magnitude Log ( A/Ao)
ML = log (A/Ao)
ML for local earthquakes (Richter magnitude adapted to local structure)
Mb, Ms: measured on P waves or surface waves for distant earthquakes
Moment magnitude Mw related to the seismic moment M0: a more accurate measurement which tells something about the total energy of the earthquake understand the difference between the magnitude
Wave amplitude decay

(Kris’ Notes)
Book Notes
Chapter 7 Journey to the Center of the Earth
*Hollow concept of Earth
“This can be seen in Dante’s Inferno where evildoers are sent to the dark caverns below to be at Satan’s whim.”
- I just wanted to say that this was the most inaccurate description of Dante’s Inferno that I have ever had the misfortune to encounter. Sorry, had to rant about it.
The Earth’s interior was always thought of as a mystery until the beginning of the 20th century
Study of earthquake waves helped us to understand the complex nature of Earth’s interior
Earliest studies relied on the analysis of wave properties reflection refraction velocity Properties seen on seismograms
Lead to the discovery of the subdivisions of the interior crust mantle outer core inner core
Development of high speed computers in the 1960s-1970s allowed data analysis of thousands of wave oaths to map out areas of velocity change in Earth in both two dimensions and three dimensions.
Termed as tomography provided researchers images of the interior analogous to X-ray pictures in medicine studies of both body waves and surface waves large-scale global research problems provides strong support for plate tectonics
“The surface to core study of velocity changes has outlined a gross pattern that could represent the convective heat flow pattern of plate tectonics” subducted slabs revealed beneath oceanic trenches
Study of volcano hazards
Long Valley caldera in California large shallow magma body
Chapter 4 Earthquake Size and Location successful seismograph systems led to accurate estimates of location and size of earthquakes
Pendulum seismograph stations first 20 years of operation
John Milne design systems sufficient to begin to locate earthquakes
Steps in earthquake location construction of travel time chart
Chart of travel time of the P-, S-, and surface waves against distance (think about the activity due this week) accomplished by 1900 due to different velocities, the difference in arrival time for P- and S- waves could be used to estimate distance
Location obtained by drawing arcs, based on distance, around at least 3 stations
Arcs intersect at epicenter called arc or circle intersect technique
Problems in seismology, such as earthquake location, are inverse problems interpretation of the result
Result could be earthquake arrival times interpretation would be the unique source location which would be the unique source location which would give the arrival times
The opposite problem is the direct or forward modeling problem given a source location arrival times can be calculated or predicted
Depth of focus is the hardest to estimate
Factors
variations in rock type affect the seismic velocity and location estimates
Classical approach use P-waves from deep focus earthquakes reflect from the underside of Earth’s surface in the epicenter region (pP).
Earliest instrumental approach for EQ size developed by K. Wadati and Charles Richter
Richter scale based on the maximum S-wave amplitudes for Southern California EQs later extended to surface waves (Ms) for large distance EQs and P-waves (mb) for deep focus EQs
Best description of EQ size is based on the size of the source
Moment magnitude - estimate of source size through seismic moment (Mo) and gives much better estimates of the size of the largest EQs
Alaska EQ (1964) larger moment magnitude (9.2) than surface wave magnitude (8.4) difference in estimates for smaller EQs is generally much less.
Chapter 5 The Earthquake Process
“Understanding of the earthquake source process has its roots in the discovery of the cause and effect link between faults and earthquakes.” elastic rebound theory provided basis upon which focal mechanism theory could be built. provided by Nakano’s analysis of focus couples at an EQ focus
Agreed well with motion ground patterns from EQs plotted on maps by early Japanese and Italian seismologists
First motion plot of P-waves was the first tool to be applied to analysis of the EQ source mechanism plots called fault plane solutions and indicate type of faulting at the focus and the orientation of two perpendicular planes, one of them the fault plane
Fault plane solution - stereographic projection of a hemisphere centered at the focus upon which the potential fault planes appear as great circle traces limitation for P-waves: it doesn’t unambiguously allow one to choose which pane is the fault plane
Choices are inferred by comparing the results to regional fault trends and by looking at aftershock distributions or by examining long-term geographic distribution of microearthquakes
Analysis of the whole earthquake signature reveals much greater information about the EQ process. using computers has allowed detailed analysis of EQ source mechanisms
Synthetic EQ signatures has been successful in revealing depth of focus, rupture velocity and direction, area and distribution of slip on the fault surface, and resolution of multiple slip events (EQs) spaced closely together in space and time.
EQ Source mechanism is no longer a complete mystery and the results of source modeling efforts are being widely applied to studies of crustal deformation, EQ hazards, and structural engineering.

Slow Earthquakes (This is a new field of research) occur over a period of a months…. so the earthquake lasts a month but is very slow. releases the energy through a long period of time.. very slow release so ground shaking at one period of time is not much. tremor is that slow earthquake release which comes after a long period of being stuck and accumulation of stress

the red lines above is the accumulation of stress then the dip is the tremor (or slow earthquake) slowly releasing that stress within a few months.
One slow earthquake is one earthquake closer to a massive one. a slow earthquake may have triggered the big earthquake in japan 2011 earthquake magnitude 9.

solo seismic array uses an array method to capture the tremor. slow earthquakes can be complex with the way it moves… professor figured out a way to track earthquakes minute by minute. he scans the seismogram and locates it using GPS.. you need to know just this.

the picture above is actually professors picture its under his name online! that is the seismic array method talked about above. to scan and so on

Earthquake Hazard (focus on the first 3 for this class)
1.Earthquake Shaking (is primary hazard and the ones below are secondary hazards)
2.Tsunami
3. Liquefaction
4.Landslides
5.Flooding (dam collapse)
6.Fire

Ground shaking being close to the fault line is very dangerous structure will be damaged. expect LA to continue shaking for a long time because of the sediment type it is sitting on. new island was created close to pakistan because of massive earthquake.. seafloor rose.

Tsunami occurs at subduction zones big vertical displacement of water big block of rock shifts up creating a tsunami its hard to tell if a tsunami is coming because of a low amplitude and large wavelength. it hits the hardest on the shore.

california does have a subduction zone but to the north cascadia has produced a 9.0 earthquake which could cause a tsunami.

tsunami ripples that hit japan reached the shores of california and south america… the waves got smaller but still dangerous. other places can have a big tsunami and hit us hard.. if its nearby like alaska. it would cause a lot of damage its a global hazard it can cause tsunamis and earthquakes in multiple locations.

Liquefaction

the shaking causes the ground to liquify… that is ground the car went through in the picture above not water. it becomes water saturated and loose especially if it has water.. the volume decreases and the soil begins to act like a liquid.

buildings sunk into the soil because of liquefaction.

%G = acceleration due to gravity 9.8 m/s2

we need to understand the Earthquake hazard map using %G

PGA = Peak Ground Acceleration which is at a rate of 2% in 50 years.

in california we have a 2% chance of having the earthquake size inidicated on the hazard map in next 50 years..

convergent plate boundaries tend to cause massive earthquakes.

riverside is in the highest level of shaking zone.

Largest Earthquakes since 1900

the number in the circle is the rank of earthquake size… number 1 being the most. some areas have more deaths because of their dense population and others may be densely populated but they are well prepared for the earthquakes.

ring of fire is called that because of the volcanoes associated with it. the ring of fire has many subduction zones that are producing the largest earthquakes known to man. ring of fire is the highlighted area above.

these subduction zones are stuck and is accumulating stress… once the stress is released a massive earthquake will occur. cascadia (close to alaska) has been accumulating stress for a very long time. this accumulation of stress is based on the elastic rebound theory.

Basin and range is slowly extending and it has normal faulting if you look at the basin and range area on the hazard map you see red blobs because of its slow normal faulting.

New madrid seismic zone two large earthquakes occurred in early 1800’s (1810-1812) a fault that has produced a big earthquake. around magnitude 8 earthquake thats why it has a red blob

strands of San Andreas faults a lot of them there are many other faults but these are the major ones capable of doing serious damage. professor suggested to remember the name of these faults in the picture above. on average every 150 years a large earthquake occurs on the San Andreas fault. san francisco is blue because it has had an earthquake recently 1906. the southern segment (california) had an earthquake along time ago it is overdue is about to rupture.

riverside has the highest intensity because a strand of the San Andreas fault is right next to us called San Jacinto its 8.5 kilometers from the bell tower… we are surrounded by 3 main faults that can produce large earthquakes.

Beach Balls (also known as Focal Mechanism) three types

these beach balls go over the three types of faults. as seen in the picture above. remember normal faults are divergent reverse/thrust faults are convergent the black shaded areas on the balls are areas experiencing compression. you can also figure out what type of lateral the fault is the red line is the fault line on the balls. the closer the fault is to the edge of the ball the more shallow it is. shallow as in a shallow angle.. if its in the middle of the ball the angle of the fault is more vertical. week 10

Earthquake predictions no such thing you cannot predict an earthquake. in china government predicts earthquakes using animal signals… that is not true however animals cannot sense an earthquake before it occurs.

California EQ probability we can use physics and mathematics and come up with a probability of it occurring during a specific time or space. the probability of an earthquake occurring in the next few years. doesn’t mean it will occur within those years it just means the chance it might occur within the years. anything above 10% probability means it will eventually occur

Parkfield Prediction experiment this location had a 90% chance of having an earthquake after plotting the cities earthquakes we found out that it is linear and the earthquake occurred every 22 years or so. the data was wrong. so with the present state of knowledge its not possible to predict an earthquake.

Seismic gap a zone of low seismic activity is called a seismic gap these seismic gaps are stuck and produce massive earthquakes with the elastic rebound theory we know which areas of the fault can produce these big earthquakes. not a prediction but an understanding that the location will produce one in california we have a very large seismic gap its called anza gap.. close to hemet its on the san jacinto fault. that portion is locked and stuck and is ready to produce a big earthquake. in the picture above the black dots are locations that have experienced seismic activity… the gap along the san jacinto fault is the anza fault its stuck and accumulating stress.

the map above is the percent chance of having that magnitude earthquake in the region… so we are going to have a big earthquake soon.

don’t memorize equations but he wants us to know what the equations are used for and when we need them.

I wrote the equation notes on paper.
M0 = PV

moment magnitude is a logarithmic scale every 1 unit is 30 times bigger just know that so from 5 to 6 magnitude earthquake it is 30 times bigger

Last Class

FInal Exam he will go over what may be on the exam

Saturday 11:30 AM- 2:30PM

Place: UNLH 1000

everything is covered accumulative (all class lectures)

Format multiple choice
75 choices
3 hours answer on scantron different exam forms

not allowed to take exam as soon as first student left the hall not allowed to go outside the hall before submission

No Cellphones turn it off until you leave.

Final counts 40% of our grade

Final Exam review a study guide only

Go over

plate tectonics

cross section of earth

movement of plates convincing evidence comes from the volcanic chains. the plume is static but the plate moves and it creates new volcanoes. the youngest volcano is the activated one.

magnetic reversals. width of the strip is due to the velocity.

step overs and pop hills and sag ponds
Elastic rebound theory

seismometers basic principles

waves

body waves vs surface wave

the channels or components the waves appear in.

seismic wave velocity

geometric spreading A1R1 =A2R2

how to locate earthquake

know the equations for earthquake location

know local and moment magnitude….. if he puts just M assume its moment magnitude because it is the most important.

look over all these notes you should do good