Download Seismic Waves NOTES.notebook

Seismic Waves NOTES.notebook
January 05, 2016
Earthquake
Seismic Waves
lithosphere
Earthquake: Release of the built‐up stress in the ________________
limit
elastic
once the ____________ __________ is passed
elastic rebound
Release of this energy is called ___________ ____________
fault
Most earthquakes occur along a ____________
movement
Fault
__________: crack in the Earth’s crust where _____________
can occur.
fault
Energy is released at a _________ in the form of seismic waves
_____________ ____________.
Dec 10­8:10 AM
Dec 10­8:10 AM
Earthquake
Seismic Waves
Seismic
waves
focus
________________ ______________ originate at the ___________
all
focus
Move in _________ directions from the ___________.
of the earthquake.
Carry the energy of an earthquake away from the focus,
Epicenter
_____________________: the location on Earth’s surface directly interior
surface
through the Earth’s ____________, and across its ____________.
focus
above the ______________.
Dec 10­8:10 AM
Dec 10­8:10 AM
Body Waves
Seismic Waves
strongest
Felt the ___________________ at the epicenter.
all
Travel through the ground in __________ directions.
Two categories of seismic waves:
Primary
______________ Waves (P‐Waves)
Body waves
1. ________________________________
First waves to arrive
Surface waves
2. ________________________________
Produce __________________ waves
compression
Travel from one end to the other and back in a
straight line
Dec 10­8:10 AM
Dec 10­8:10 AM
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Seismic Waves NOTES.notebook
January 05, 2016
Body Waves
P‐Waves
expanding
contracting
Series of ___________________ & ___________________ waves
Push
Pull
Also known as “ _________ ‐ _________” waves
solids
liquids
gases
Travel through _____________, ______________, and __________
Secondary
______________________ Waves (S‐Waves)
Second waves to arrive
shear
Produce ________________ waves
up
down
Move ________ and ___________
solids
Travel through _________________ only
Dec 10­8:10 AM
Dec 10­8:10 AM
Body Waves
Surface Waves
surface
Travel along ____________________ only
Primary Waves
Secondary Waves
Fast, Arrive 1st
Slow, Arrive 2nd
Push - Pull Wave
(Compression)
Shear Wave
Solids, Liquids & Gases
Solids ONLY
Slower
_________________ than body waves
earthquake (focus)
While P and S‐waves are generated by the ____________________,
P-Waves
surface waves are made by _______________________.
Dec 10­8:10 AM
Dec 10­8:10 AM
Surface Waves
Surface Waves
most
severe
Produce the____________ ________________ ground movements.
Two
____________ wave actions at the same time:
Rayleigh
_________________ waves: causes ground to _________
roll
like ocean waves
Rayleigh
side
_________________ waves: shake ground from _________
Love
Love
side
to __________
Dec 10­8:10 AM
Dec 10­8:10 AM
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Seismic Waves NOTES.notebook
Earthquake Strength
Seismograph: Records __________________ movements
ground
waves
caused by _______________ ______________ .
seismic
January 05, 2016
Earthquake Strength
MAGNITUDE
Richter Scale: Measure of earthquake _____________________
(released energy from earthquake)
Logarithm of the maximum wave amplitude
upper
No _________________ limit
decimal
Reported using ________________ numbers
2.0 – 3.0 : Felt by people (minor) 4.0 : Light 5.0 : Moderate (800/yr) Dec 10­8:10 AM
Earthquake Strength
Modern
Moment Magnitude Scale: _________________ version of the Richter scale.
In addition to the amplitude of the seismic waves, it also considers:
surface movement
1. Amount of _______________ ________________ along the fault
rocks
2. Strength of ____________ that were broken
6.0 : Strong
7.0 : Major (18/yr)
8.0 – 9.0: Great
10.0+ : Epic (Never)
Dec 10­8:10 AM
Earthquake Strength
INTENSITY
Mercalli Scale: Measure of _____________________
Not a precise measurement using instruments, but based
on __________________ _____________________
human
observations
roman
Scale of 1 to 12 using _____________ numerals:
XII
I
_______ to ________
decimal
(Also uses _________________ numbers)
Dec 10­8:10 AM
Earthquake Strength
Dec 10­8:10 AM
Determining Distance to Epicenter
Seismograph records the arrival of P and S‐waves on a
24‐hour clock using Greenwich Mean Time (GMT)
The prime meridian runs through Greenwich, England
Greenwich, England is 5 hours ahead
of New York State.
May also be called Universal Coordinated Time (UTC)
Dec 10­8:10 AM
Dec 10­8:10 AM
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Seismic Waves NOTES.notebook
Determining Distance to Epicenter
Seismograph records the arrival of P and S‐waves on a
24‐hour clock using Greenwich Mean Time (GMT)
The prime meridian runs through Greenwich, England
Greenwich, England is 5 hours ahead
of New York State.
January 05, 2016
Determining Distance to Epicenter
Seismograph records the arrival of P and S‐waves on a
24‐hour clock using Greenwich Mean Time (GMT)
Times reported as hh:mm:ss (uses a 'military time' format)
Ex: 09:14:32
9:14:32 in the morning
14:52:17
2:52:17 in the afternoon
May also be called Universal Coordinated Time (UTC)
Dec 10­8:10 AM
Dec 10­8:10 AM
New York is GMT -5 (UTC -5):
If it is 4:00:00 pm in New York, what
is GMT?
4:00:00 pm + 5 hours = 9:00:00 pm
If it is 4:00:00 pm in New York, what
is the time in Chicago (central time zone)?
3:00:00 pm
or, 21:00:00 GMT
Dec 10­12:29 PM
Chicago is GMT -6 (UTC -6):
If it is 3:00:00 pm in Chicago, what
is GMT?
Dec 10­12:29 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?
3:00:00 pm + 6 hours = 9:00:00 pm
or, 21:00:00 GMT
Dec 10­12:29 PM
Jan 5­2:26 PM
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Seismic Waves NOTES.notebook
Dec 14­7:25 AM
January 05, 2016
Dec 14­7:25 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
Dec 14­7:25 AM
between P and S-Wave
arrival times
to the Epicenter
Dec 10­8:10 AM
Determining Distance to Epicenter
Determining Distance to Epicenter
In class example:
Say what?
P(arrival) = 17:43:32 GMT
S(arrival) = 17:45:21 GMT
Dec 10­8:10 AM
Dec 10­8:10 AM
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Seismic Waves NOTES.notebook
Determining Distance to Epicenter
January 05, 2016
Determining Distance to Epicenter
Step 1: Determine the Difference between
the P and S-Wave arrival times.
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
Subract the P-Wave arrival (the lower number) from the S-Wave arrival
17:45:21
17:43:32
17:45:21
17:43:32
00:
00: 02:
Dec 10­8:10 AM
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
The negative value means we need to borrow 60
seconds (one minute) from the minutes.
Dec 10­8:10 AM
00: 02: -11
00:01: (60-11)
Dec 10­8:10 AM
Determining Distance to Epicenter
Subract the P-Wave arrival (the lower number) from the S-Wave arrival
17:45:21
17:43:32
00: 02: -11
Reduce the minutes by 1 minute and then subtract the
negative value from 60 seconds:
Dec 10­8:10 AM
17:45:21
17:43:32
17:45:21
17:43:32
00: 02: -11
00: 01: (60-11)
Subract the P-Wave arrival (the lower number) from the S-Wave arrival
Reduce the minutes by 1 minute and then subtract the
negative value from 60 seconds:
17:45:21
17:43:32
17:45:21
17:43:32
Determining Distance to Epicenter
Use some paper to supplement your notes:
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
= 00:01:49
Dec 16­7:46 AM
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Seismic Waves NOTES.notebook
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
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Seismic Waves NOTES.notebook
January 05, 2016
Dec 16­7:55 AM
Dec 16­7:55 AM
Determining Distance to Epicenter
Determining Distance to Epicenter
Now what?
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
Dec 10­8:10 AM
Determining Distance to Epicenter
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
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
Dec 10­8:10 AM
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Seismic Waves NOTES.notebook
January 05, 2016
Determining Distance to Epicenter
Now what?
one minute;
20 seconds
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
Determining Distance to Epicenter
Dec 10­8:10 AM
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
Step 2: Determine the Distance to the
Epicenter.
Use the ESRT (page 11) and the
"Slip and Slide" method
Dec 10­8:10 AM
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
one minute;
49 seconds
Now what?
one minute;
40 seconds
Determining Distance to Epicenter
one minute;
49 seconds
'tic' mark
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
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.
Dec 10­8:10 AM
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Seismic Waves NOTES.notebook
January 05, 2016
Determining Distance to Epicenter
'tic' mark
Determining Distance to Epicenter
The greater
the difference
between the P
and S-Wave
arrival, the
greater the
distance to the
Epicenter
Slip and
Slide to
get the
distance
Epicenter Distance (x103 km)
Dec 10­8:10 AM
What is the time difference between these arrival times?
Dec 10­10:35 AM
Dec 10­8:10 AM
What is the distance to the epicenter?
Dec 10­10:35 AM
Let's Practice......
Jan 5­8:51 AM
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