Seismic Waves NOTES.notebook

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January 05, 2016

Dec 10­8:10 AM

Seismic Waves

Dec 10­8:10 AM

Earthquake

Earthquake: Release of the built‐up stress in the ________________

once the ____________ __________ is passed

Release of this energy is called ___________ ____________

Most earthquakes occur along a ____________

__________: crack in the Earth’s crust where _____________can occur.

Energy is released at a _________ in the form of

_____________ ____________.

lithosphereelastic limit

elastic rebound

faultFault movement

faultseismic waves

Dec 10­8:10 AM

Earthquake

________________ ______________ originate at the ___________

of the earthquake.

_____________________: the location on Earth’s surface directly

above the ______________.

Seismic waves focus

focusEpicenter

Dec 10­8:10 AM

Seismic Waves

Move in _________ directions from the ___________.

Carry the energy of an earthquake away from the focus,

through the Earth’s ____________, and across its ____________.

all focus

interior surface

Dec 10­8:10 AM

Seismic Waves

Felt the ___________________ at the epicenter.

Two categories of seismic waves:

1. ________________________________

2. ________________________________

strongest

Body wavesSurface waves

Dec 10­8:10 AM

Body Waves

Travel through the ground in __________ directions.

______________ Waves (P‐Waves)

First waves to arrive

Produce __________________ waves

Travel from one end to the other and back in astraight line

all

Primary

compression

Seismic Waves NOTES.notebook

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January 05, 2016

Dec 10­8:10 AM

P‐Waves

Series of ___________________ & ___________________ waves

Also known as “ _________ ‐ _________” waves

Travel through _____________, ______________, and __________

expanding contracting

Push Pullsolids liquids gases

Dec 10­8:10 AM

Body Waves

______________________ Waves (S‐Waves)

Second waves to arrive

Produce ________________ waves

Move ________ and ___________

Travel through _________________ only

Secondary

shearup down

solids

Dec 10­8:10 AM

Body Waves

Primary Waves Secondary Waves

Fast, Arrive 1st Slow, Arrive 2nd

Push - Pull Wave(Compression) Shear Wave

Solids ONLYSolids, Liquids & Gases

Dec 10­8:10 AM

Surface Waves

Travel along ____________________ only

_________________ than body waves

While P and S‐waves are generated by the ____________________,

surface waves are made by _______________________.

surface

Slower

earthquake (focus)

P-Waves

Dec 10­8:10 AM

Surface Waves

Produce the____________ ________________ ground movements.

____________ wave actions at the same time:

_________________ waves: causes ground to _________ like ocean waves

_________________ waves: shake ground from _________

to __________

most severe

TwoRayleigh roll

Love sideside

Dec 10­8:10 AM

Surface Waves

Rayleigh

Love

Seismic Waves NOTES.notebook

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January 05, 2016

Dec 10­8:10 AM

Earthquake Strength

Seismograph: Records __________________ movements

caused by _______________ ______________ .

groundseismic waves

Dec 10­8:10 AM

Earthquake Strength

Richter Scale: Measure of earthquake _____________________ (released energy from earthquake)

Logarithm of the maximum wave amplitude

No _________________ limit

Reported using ________________ numbers

2.0 – 3.0 : Felt by people (minor) 6.0 : Strong4.0 : Light 7.0 : Major (18/yr)5.0 : Moderate (800/yr) 8.0 – 9.0: Great 10.0+ : Epic (Never)

MAGNITUDE

upper

decimal

Dec 10­8:10 AM

Earthquake Strength

Moment Magnitude Scale: _________________ version of the Richter scale.

In addition to the amplitude of the seismic waves, it also considers:

1. Amount of _______________ ________________ along the fault

2. Strength of ____________ that were broken

(Also uses _________________ numbers)

Modern

surface movement

rocksdecimal

Dec 10­8:10 AM

Earthquake Strength

Mercalli Scale: Measure of _____________________

Not a precise measurement using instruments, but based

on __________________ _____________________

Scale of 1 to 12 using _____________ numerals:

_______ to ________

INTENSITY

human observationsroman

I XII

Dec 10­8:10 AM

Earthquake Strength

Dec 10­8:10 AM

Determining Distance to Epicenter

Seismograph records the arrival of P and S‐waves on a24‐hour clock using Greenwich Mean Time (GMT)

May also be called Universal Coordinated Time (UTC)

The prime meridian runs through Greenwich, England

Greenwich, England is 5 hours ahead of New York State.

Seismic Waves NOTES.notebook

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January 05, 2016

Dec 10­8:10 AM

Determining Distance to Epicenter

Seismograph records the arrival of P and S‐waves on a24‐hour clock using Greenwich Mean Time (GMT)

May also be called Universal Coordinated Time (UTC)

The prime meridian runs through Greenwich, England

Greenwich, England is 5 hours ahead of New York State.

Dec 10­8:10 AM

Determining Distance to Epicenter

Seismograph records the arrival of P and S‐waves on a24‐hour clock using Greenwich Mean Time (GMT)

Times reported as hh:mm:ss (uses a 'military time' format)

Ex: 09:14:32

14:52:17

9:14:32 in the morning

2:52:17 in the afternoon

Dec 10­12:29 PM

New York is GMT -5 (UTC -5):

If it is 4:00:00 pm in New York, whatis GMT?

4:00:00 pm + 5 hours = 9:00:00 pm

or, 21:00:00 GMT

Dec 10­12:29 PM

If it is 4:00:00 pm in New York, whatis the time in Chicago (central time zone)?

3:00:00 pm

Dec 10­12:29 PM

Chicago is GMT -6 (UTC -6):

If it is 3:00:00 pm in Chicago, whatis GMT?

3:00:00 pm + 6 hours = 9:00:00 pm

or, 21:00:00 GMT

Jan 5­2:26 PM

If a seismograph location records the arrival of a P-wave at 10:21:30 am (hours : minutes : seconds) ...and the earthquake occurred 8,000 km away, what time did the earthquake originate?

Seismic Waves NOTES.notebook

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January 05, 2016

Dec 14­7:25 AM Dec 14­7:25 AM

Dec 14­7:25 AM Dec 10­8:10 AM

Determining Distance to Epicenter

Must determine the difference between the P and S‐wave arrival times, then use ESRT (Page 11) to determine the distance.

Determine the Difference to get the Distance

between P and S-Wavearrival times

to the Epicenter

Dec 10­8:10 AM

Determining Distance to Epicenter

Say what?

Dec 10­8:10 AM

Determining Distance to Epicenter

In class example:

P(arrival) = 17:43:32 GMT

S(arrival) = 17:45:21 GMT

Seismic Waves NOTES.notebook

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January 05, 2016

Dec 10­8:10 AM

Determining Distance to Epicenter

Step 1: Determine the Difference between the P and S-Wave arrival times.

Subract the P-Wave arrival (the lower number) from the S-Wave arrival

17:45:2117:43:3200:

Dec 10­8:10 AM

Determining Distance to Epicenter

Step 1: Determine the Difference between the P and S-Wave arrival times.

Subract the P-Wave arrival (the lower number) from the S-Wave arrival

17:45:2117:43:3200: 02:

Dec 10­8:10 AM

Determining Distance to Epicenter

Step 1: Determine the Difference between the P and S-Wave arrival times.

Subract the P-Wave arrival (the lower number) from the S-Wave arrival

17:45:2117:43:3200:02: -11

The negative value means we need to borrow 60 seconds (one minute) from the minutes.

Dec 10­8:10 AM

Determining Distance to Epicenter

Subract the P-Wave arrival (the lower number) from the S-Wave arrival

17:45:2117:43:3200: -1102:

Reduce the minutes by 1 minute and then subtract the negative value from 60 seconds:

17:45:2117:43:3200: (60-11)01:

Dec 10­8:10 AM

Determining Distance to Epicenter

Subract the P-Wave arrival (the lower number) from the S-Wave arrival

17:45:2117:43:3200: -1102:

Reduce the minutes by 1 minute and then subtract the negative value from 60 seconds:

17:45:2117:43:3200: (60-11)01: = 00:01:49

Dec 16­7:46 AM

Find the difference between the following P and S-wave arrival times:

1. Parrival: 07:30:24 GMT Sarrival: 07:35:42 GMT

2. PA: 19:24:46 UTC SA: 19:27:02 UTC

Use some paper to supplement your notes:

Seismic Waves NOTES.notebook

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January 05, 2016

Dec 16­7:54 AM Dec 16­7:54 AM

Dec 16­7:54 AM Dec 16­7:55 AM

Dec 16­7:55 AM Dec 16­7:55 AM

Seismic Waves NOTES.notebook

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January 05, 2016

Dec 16­7:55 AM Dec 16­7:55 AM

Dec 10­8:10 AM

Determining Distance to Epicenter

Now what?

Dec 10­8:10 AM

Determining Distance to Epicenter

Now what?Take a piece of scrap paper (with a straight edge) and make a 'tic' mark at one minute and 49 seconds as read against the y-axis

Dec 10­8:10 AM

Determining Distance to Epicenter

Now what?Take a piece of scrap paper (with a straight edge) and make a 'tic' mark at one minute and 49 seconds as read against the y-axis

Dec 10­8:10 AM

Determining Distance to Epicenter

Now what?Take a piece of scrap paper (with a straight edge) and make a 'tic' mark at one minute and 49 seconds as read against the y-axis

one minute

Seismic Waves NOTES.notebook

9

January 05, 2016

Dec 10­8:10 AM

Determining Distance to Epicenter

Now what?Take a piece of scrap paper (with a straight edge) and make a 'tic' mark at one minute and 49 seconds as read against the y-axis

one minute;20 seconds

Dec 10­8:10 AM

Determining Distance to Epicenter

Now what?Take a piece of scrap paper (with a straight edge) and make a 'tic' mark at one minute and 49 seconds as read against the y-axis

one minute;40 seconds

Dec 10­8:10 AM

Determining Distance to Epicenter

Now what?Take a piece of scrap paper (with a straight edge) and make a 'tic' mark at one minute and 49 seconds as read against the y-axis

one minute;49 seconds

Dec 10­8:10 AM

Determining Distance to Epicenter

Now what?Take a piece of scrap paper (with a straight edge) and make a 'tic' mark at one minute and 49 seconds as read against the y-axis

one minute;49 seconds

'tic' mark

Dec 10­8:10 AM

Determining Distance to Epicenter

Step 2: Determine the Distance to the Epicenter.

Use the ESRT (page 11) and the

"Slip and Slide" method

Dec 10­8:10 AM

Determining Distance to Epicenter

Use the ESRT (page 11) and the

"Slip and Slide" method:Slide the scrap paper with the 'tic' mark on it up and between the "P" and "S" curves (keeping it verticle) until the bottom of the paper is touching the "P" curve at the same time the "S" curve is touching the 'tic' mark.

Seismic Waves NOTES.notebook

10

January 05, 2016

Dec 10­8:10 AM

Determining Distance to Epicenter'tic' mark

Slip andSlide toget the distance

Epicenter Distance (x103 km)

Dec 10­8:10 AM

Determining Distance to Epicenter

The greaterthe difference between the P and S-Wave arrival, the greater the distance to the Epicenter

Dec 10­10:35 AM

What is the time difference between these arrival times?

Dec 10­10:35 AM

What is the distance to the epicenter?

Jan 5­8:51 AM

Let's Practice......