Overview of lectureOverview of lecture

• Acquisition of Data• Measures of ground motion• Processing of Data• Properties of Data from Observations

– Data distribution in M-D space– Path dependence of ground motion– Magnitude dependence of ground motion– Site dependence of ground motion

The first known instrument for earthquakes measurement is the Chang seismoscope built in China in 132 B.C.

Balls were held in the dragons’ mouths by lever devices connected to an internal pendulum. The direction of the epicenter was reputed to be indicated by the first ball released.

MEASURING EARTHQUAKES

Jargon

seismoscope – an instrument that documents the occurrence of ground motion (but does not record it over time)

seismometer – an instrument that senses ground motion and converts the motion into some form of signal

accelerometer – a seismometer that records acceleration, also known as strong ground motion

geophone – another name for a seismometer, commonly used in active source seismology

More Jargon

seismograph – a system of instruments that detects and records ground motion as a function of time

seismogram – the actual record of ground motion produce by a seismograph

seismometry – the design and development of seismic recording systems

data logger – device that converts analog to digital signal and stores the signal

How Seismometers Work

Fundamental Idea: To record ground motion a seismometer must be decoupled from the ground. If the seismometer moves with the ground then no motion will be recorded.

Principles of seismographs

Strong-Motion Accelerographs

Analog

Magnification curves

Not shown: broadband (0.02—DC sec)

The nature of the seismogram and the waves shown depends directly on the type

of seismograph

It is easier to make a stable, small short-period oscillator than a long-period oscillator. Note that modern strong-motion sensors use force-balance accelerometers with resonant frequencies near 50 Hz, where the quantity being measured is the current in a coil required to keep the mass centered. This current is proportional to the force on the mass.

“Broadband” seismometers (velocity sensors, using electronics to extend the frequency to low values) are starting to be used in engineering seismology: the boundary between traditional strong-motion and weak-motion seismology is becoming blurred.

Digital strong-motion recording

• Broadband: nominally flat response from dc to at least 40 Hz– But noise/ baseline problems can limit low-frequency

information– High-frequency limit generally not a problem because these

frequencies are generally filtered out of the motion by natural processes (exception: very hard rock sites)

• High dynamic range (ADC 16 bits or higher)• Pre-event data usually available

Trifunac &

Todorovska (2001)

Many networks of instruments, both traditional “strong-motion” and, more

recently, very broad-band, high dynamic-range sensors and dataloggers

http://www.k-net.bosai.go.jp

• 1000 digital instruments installed after the Kobe earthquake of 1995

• free field stations with an average spacing of 25 km

• velocity profile of each station up to 20 m by downhole measurement

• data are transmitted to the Control Center and released on Internet in 3-4 hours after the event

INSTRUMENTATION

Kyoshin Net: Japanese strong motion network

Reminder: Play Chuettsu and Tottori movies

A number of web sites provide data from instrument networks

• But no single web site containing data from all over the world.

• An effort is still need to add broad-band data into the more traditional data sets.

WEB SITES

COSMOS Consortium of Organizations for Strong - Motion Observation Systems

http://www.cosmos-eq.org/

Measures of ground-motion intensity for Measures of ground-motion intensity for engineering purposesengineering purposes

• PGA, PGV• Response spectra (elastic, inelastic)• Others (avg. spectra over freq., power

spectra, Fourier amplitude spectra)• Time series

Peak ground acceleration (pga)• easy to measure because the response of most

instruments is proportional to ground acceleration

• liked by many engineers because it can be related to the force on a short-period building

• convenient single number to enable rough evaluation of importance of records

• BUT it is not a measure of the force on most buildings

• and it is controlled by the high frequency content in the ground motion (i.e., it is not associated with a narrow range of frequencies); records can show isolated short-duration, high-amplitude spikes with little engineering significance

Peak ground velocity (pgv)

• Many think it is better correlated with damage than other measures

• It is sensitive to longer periods than pga (making it potentially more predictable using deterministic models)

• BUT it requires digital processing (no longer an important issue)

Peak ground displacement (pgd)

• The best parameter for displacement-based design?• BUT highly sensitive to the low-cut (high-pass) filter that

needs to be applied to most records (in which case the derived pgd might not represent the true pgd, unlike pga, for which the Earth imposes a natural limit to the frequency content). For this reason I recommend against the use of pgd.

Äug

Elastic response spectra (many structures Elastic response spectra (many structures can be idealized as SDOF oscillators)can be idealized as SDOF oscillators)

10 20 30 40 50 60

-100

1020

Time (sec)

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0.1 1 10 100

10-4

0.001

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0.1

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Period (sec)

Rel

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acem

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(cm

)

1999 Hector Mine Earthquake (M 7.1)

station 596 (r= 172 km), transverse component

Ground acceleration (cm/sec2)

Ground displacement (cm)

10 20 30 40 50 60

-100

1020

Time (sec)

-5

0

5

0.1 1 10 100

10-4

0.001

0.01

0.1

1

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Period (sec)

Rel

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ispl

acem

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(cm

)

1999 Hector Mine Earthquake (M 7.1)

station 596 (r= 172 km), transverse component

10 20 30 40 50 60

-2*10 -4

0

2*10 -4

Time (sec)

Tosc = 0.025 sec

Ground acceleration (cm/sec2)

Ground displacement (cm)

At short periods, oscillator response proportional to base acceleration

10 20 30 40 50 60

-100

1020

Time (sec)

-5

0

5

-0.001

0

0.001

0.1 1 10 100

10-4

0.001

0.01

0.1

1

10

100

Period (sec)

Rel

ativ

eD

ispl

acem

ent

(cm

)

1999 Hector Mine Earthquake (M 7.1)

station 596 (r= 172 km), transverse component

10 20 30 40 50 60

-2*10 -4

0

2*10 -4

Time (sec)

Tosc = 0.025 sec

Tosc = 0.050 sec

Ground acceleration (cm/sec2)

Ground displacement (cm)

10 20 30 40 50 60

-100

1020

Time (sec)

-5

0

5

-0.001

0

0.001

-1

0

1

0.1 1 10 100

10-4

0.001

0.01

0.1

1

10

100

Period (sec)

Rel

ativ

eD

ispl

acem

ent

(cm

)

1999 Hector Mine Earthquake (M 7.1)

station 596 (r= 172 km), transverse component

10 20 30 40 50 60

-2*10 -4

0

2*10 -4

Time (sec)

Tosc = 0.025 sec

Tosc = 0.050 sec

Tosc = 1.0 sec

Ground acceleration (cm/sec2)

Ground displacement (cm)

10 20 30 40 50 60

-100

1020

Time (sec)

-5

0

5

-0.001

0

0.001

-1

0

1

-10

0

10

0.1 1 10 100

10-4

0.001

0.01

0.1

1

10

100

Period (sec)

Rel

ativ

eD

ispl

acem

ent

(cm

)

1999 Hector Mine Earthquake (M 7.1)

station 596 (r= 172 km), transverse component

10 20 30 40 50 60

-2*10 -4

0

2*10 -4

Time (sec)

Tosc = 0.025 sec

Tosc = 0.050 sec

Tosc = 1.0 sec

Tosc = 10 sec

Ground acceleration (cm/sec2)

Ground displacement (cm)

10 20 30 40 50 60

-100

1020

Time (sec)

-5

0

5

-0.001

0

0.001

-1

0

1

-10

0

10

-5

0

5

0.1 1 10 100

10-4

0.001

0.01

0.1

1

10

100

Period (sec)

Rel

ativ

eD

ispl

acem

ent

(cm

)

1999 Hector Mine Earthquake (M 7.1)

station 596 (r= 172 km), transverse component

10 20 30 40 50 60

-2*10 -4

0

2*10 -4

Time (sec)

Tosc = 0.025 sec

Tosc = 0.050 sec

Tosc = 1.0 sec

Tosc = 10 sec

Tosc = 40 sec

Ground acceleration (cm/sec2)

Ground displacement (cm)

10 20 30 40 50 60

-100

1020

Time (sec)

-5

0

5

-0.001

0

0.001

-1

0

1

-10

0

10

-5

0

5

0.1 1 10 100

10-4

0.001

0.01

0.1

1

10

100

Period (sec)

Rel

ativ

eD

ispl

acem

ent

(cm

)

1999 Hector Mine Earthquake (M 7.1)

station 596 (r= 172 km), transverse component

10 20 30 40 50 60

-2*10 -4

0

2*10 -4

Time (sec)

-5

0

5

Tosc = 0.025 sec

Tosc = 0.050 sec

Tosc = 1.0 sec

Tosc = 10 sec

Tosc = 40 sec

Tosc = 80 sec

Ground acceleration (cm/sec2)

Ground displacement (cm)

At long periods, oscillator response proportional to base displacement

0.1 1 10 100

0.01

0.1

1

10

100

Period (sec)

Acc

eler

atio

n(c

m/s

2)

0.1 1 10 100

10-4

0.001

0.01

0.1

1

10

100

Period (sec)

Rel

ativ

eD

ispl

acem

ent

(cm

)

1999 Hector Mine Earthquake (M 7.1)

station 596 (r= 172 km), transverse component

convert displacement spectrum into acceleration spectrum (multiply by (2π/T)2)

Acceleration spectrum usually used in engineering

0.1 1 10 1000.001

0.01

0.1

1

10

100

Period (sec)

2% damping5% damping10% damping20% damping F

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2% damping5% damping10% damping20% damping

1999 Hector Mine Earthquake (M 7.1)station 596 (r= 172 km), transverse component

At short and very long periods, damping not significantAt short and very long periods, damping not significant

PGA generally a poor measure of ground-motion intensity. All of these time series have the same PGA:

0 50 100 150-0.2

-0.1

0

0.1

0.2

Acc

eler

atio

n(g

) Peru, 5 Jan 1974, Transverse Comp., Zarate

M = 6.6, rhyp = 118 km

0 50 100 150-0.2

-0.1

0

0.1

0.2

Acc

eler

atio

n(g

) Montenegro, 15 April 1979, NS Component, Ulcinj

M = 6.9, rhyp = 29 km

0 50 100 150-0.2

-0.1

0

0.1

0.2A

ccel

erat

ion

(g) Mexico, 19 Sept. 1985, EW Component, SCT1

M = 8.0, rhyp = 399 km

0 50 100 150-0.2

-0.1

0

0.1

0.2

Time (sec)

Acc

eler

atio

n(g

) Romania, 4 March 1977 EW Component, INCERC-1M = 7.5, rhyp = 183 km

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Period (sec)

Peru (M=6.6,rhyp=118km)

Montenegro (M=6.9,rhyp=29km)

Mexico (M=8.0,rhyp=399km)

Romania (M=7.5,rhyp=183km)

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Period (sec)

5%-D

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Acc

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)

Peru (M=6.6,rhyp=118km)

Montenegro (M=6.9,rhyp=29km)

Mexico (M=8.0,rhyp=399km)

Romania (M=7.5,rhyp=183km)

But the response spectra (and consequences for structures) are quite different (lin-lin and log-log plots to emphasize different periods of motion):

Data Processing

• Data processing = removing long-period noise• Processing at high frequencies of much less concern

Baseline problems are common

• Even for digitally recorded records• There can be many reasons for the shifts, and as a

result it is not possible to design a single correction scheme to remove the long-period noise without affecting the long-period signal.

-300

0

300

cm/s

ec2 Acceleration

-50

0

cm/s

ec

Velocity

0 20 40 60

-500

0

Time (s)

cm

Displacement

1999 Hector Mine (M=7.1), HEC, E-W (rjb=8.2 km)

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Many possible causes

• Mechanical:– Hysteresis (mechanical/ electrical)– “Popcorn” noise– Other

• Ground deformation– Tilt near earthquakes– Differential settlement– Other

• Analog-Digital Conversion (ADC)

• Seismologists may want residual displacements. Schemes have been tailored that claim to produce these. Although OK in some cases of large signal to noise, in general I am pessimistic about being to remove long-period noise and retain long-period signal.

A possible correction scheme

• Modification of one proposed by Iwan et al. (1985)

• Guarantees that velocity will have a value around 0.0 in the later part of the record (a physical constraint)

• Choice of critical parameters is arbitrary unless they can be associated with a physical mechanism (as for the specific instrument studied by Iwan et al.)

20 40 60 80

-50

0

50

Time (sec)

Vel

ocity

(cm

/sec

)

TCU129, E-W

t1

t2=30 sec

t2=50 sec

t2=70 sec

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0 20 40 60 80 100-200

0

200

400

Time (sec)

Dis

pla

cem

en

t(c

m)

TCU129, E-W

t2 = 30 sec

t2 = 50 sec

t2 = 70 sec

GPS, station AF11

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Although the results look physically plausible, the residual displacements can be sensitive to

t1, t2

• But response spectra at periods of engineering interest can be insensitive to the baseline correction, which says that the “noise” is very long period

• If abandon desire to recover residual displacements, then many methods are available for removing long-period noise, in addition to baseline correction: filtering, polynomial fits, combinations of above.

0 20 40 60 80 100-200

0

200

400

Time (sec)

Dis

pla

cem

en

t(c

m)

TCU129, E-W

remove mean only

t2 = 30 sec

t2 = 50 sec

t2 = 70 sec

quadratic fit to velocity

low-cut filter only, fc=0.02 Hz

GPS, station AF11

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Although the results look physically plausible, the residual displacements can be sensitive to

t1, t2

Quadratic fit to velocity gives best fit to GPS residual displacement in this casein this case

1 101 102101

102

period (s)

5%-d

ampe

dre

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resp

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(cm

)

no adjustmentst2 = 70 st2 = 50 st2 = 30 sno bl; acausal flc=0.02

TCU129, EW

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• In spite of large differences in waveforms, the response spectra at periods of engineering interest are similar. Two general conclusions to be made here:– Filtering alone is often all that is needed– Response spectra at periods of engineering interest are often

insensitive to filter cutoff periods for modern digital records

• More examples, comparing displacements and SD from accelerograms and “high-rate” (1 sps) gps

From Wang et al.

From Guoquan Wang

• Still have many analog records, for which choosing the filter corner can be very important if want long-period response spectra (e.g., project in Italy to determine regression equation for T=10 s SD)

Choosing Filter Corners

• Choosing filter corners often guided by – Shape of Fourier acceleration spectrum (look for f^2 slope)– Appearance of displacement waveforms (do they “look

reasonable”?)

Choosing Filter Corners

• near- and intermediate-field contributions to ground displacement can fool our ideas of what is “normal” or “reasonable”

Note very different shape for EW, NS components, and peculiar shape for NS waveform until fc=0.16

Data from C. Di’Alessandro

Data from C. Di’Alessandro

But data from a nearby station (2 km) shows that the “peculiar” features are real, and suggest that a filter somewhere between 0.04 and 0.08 is appropriate

To convince you that differences are independent of acausal filter transients:

In spite of the resemblance of the displacement traces, the response spectra are less similar than I would have expected, demonstrating that the spatial variation in ground motions can be large

CharacteristicsCharacteristics of Data

• Magnitude-Distance depends on region• Change of amplitude with distance for fixed magnitude• Change of amplitude with magnitude after removing

distance dependence• Site dependence• Scatter

Observed data adequate for regression exceptclose to large ‘quakes(the recently developed NGA database contains such records, primarily from Taiwan and Turkey)

Observed data not adequate for regression, use simulated data

1 10 100 1000

5

6

7

8

Mom

ent

Mag

nitu

de

Used by BJF93 for pga

Western North America

1 10 100 1000

5

6

7

8

Distance (km)

Mom

ent

Mag

nitu

de

AccelerographsSeismographic Stations

Eastern North America

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Path effects

• Wave types– Body (P, S)– Surface (Love, Rayleigh)

• Amplitude changes due to wave propagation– Geometrical spreading (1/r in uniform media, more rapid

decay for velocity increasing with depth)– Critical angle reflections– Waveguide effects

• Amplitude changes due to intrinsic attenuation (conversion to heat) and scattering attenuation

How does the motion depend on distance?

• Generally, it will decrease (attenuate) with distance• But wave propagation in a layered earth predicts more

complicated behavior (e.g., increase at some distances due to critical angle reflections (“Moho-bounce”)

• Equations assume average over various crustal structures

More distant data show limitations of function fit to closer data (but ground motions at greater distances are of little engineering interest)

From V. Graizer

Scaling with magnitudeScaling with magnitude

0.1 1 10 100

10

100

1000

10000

Rjb (set values less than 0.1 to 0.1 km)

PS

A(c

m/s

ec2)

Chi-Chi (M 7.6)Loma Prieta (M 6.9)Northridge (M 6.7)

T = 0.1 sec

0.1 1 10 100

Rjb (set values less than 0.1 to 0.1 km)

Chi-Chi (M 7.6)Loma Prieta (M 6.9)Northridge (M 6.7)

T = 2 sec

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Chi-Chi data are low at short periods(note also scatter, distance dependence)

Illustrating distance and magnitude dependence

0.1 1 10 100

10

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10000

Rjb (set values less than 0.1 to 0.1 km)

PS

A(c

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Denali fault (M 7.9)Kocaeli (M 7.5)Northridge (M 6.7)

T = 0.1 sec

0.1 1 10 100

Rjb (set values less than 0.1 to 0.1 km)

Denali fault (M 7.9)Kocaeli (M 7.5)Northridge (M 6.7)

T = 2 sec

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And so are Denali and Kocaeli (or is Northridge high?)

4 5 6 7 81

2

3

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6

Me

ven

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rm

4 5 6 7 81

2

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4

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M

eve

nt_

term

4 5 6 7 81

2

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M

eve

nt_

term

4 5 6 7 80

1

2

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Me

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T=0.1, 0.3, 1.0, 2.0 secrjb _< 80: buried eventsrjb _< 80: events with surface slip

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Magnitude scaling

Note that each symbol represents the average of the strong-motion recordings for a single earthquake, correcting for the distance dependence.

(note strong correlation of events breaking to the surface with magnitude)

4 5 6 7 81

2

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Me

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2

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M

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term

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2

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4 5 6 7 80

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T=0.1, 0.3, 1.0, 2.0 secquadratic in Mrjb _< 80: buried eventsrjb _< 80: events with surface slip

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07Magnitude scaling

quadratic fit (used for empirical ground-motion prediction equations)

Note decrease of motion with increase of M for T = 0.1 and 0.3 sec

Site Effects, Basin Waves,Spatial Variability, Site Effects, Basin Waves,Spatial Variability, Azimuthal DependenceAzimuthal Dependence

People have known for a long time thatPeople have known for a long time thatmotions on soil are greater than on rockmotions on soil are greater than on rock

• e.g., Daniel Drake (1815) on the 1811-1812 New Madrid sequence:

•

– "The convulsion was greater along the Mississippi, as well as along the Ohio, than in the uplands. The strata in both valleys are loose. The more tenacious layers of clay and loam spread over the adjoining hills … suffered but little derangement."

Steidl

Steidl

2002 M 7.9 Denali Fault

K2-16

1741

K2-03

K2-06K2-09

K2-11K2-12

K2-14

K2-22

1744

1751

K2-02

K2-13

1734

1737

K2-01

K2-04

K2-05

K2-07

K2-19

1397

1731

1736

K2-08

K2-20K2-21

-150 -149.8

61.1

61.2

Longitude (oE)

La

titu

de

(oN

)

D

C/D C

Chu

gach

Mts

.

Site Classes are based on the average shear-wave velocity in the upper 30 m (discussed later).

pulses 1 & 2: subevent 1pulse 3: subevent 2pulse 4: subevent 3

0.1 1 100.001

0.01

0.1

1

10

100

Frequency (Hz)

Fou

rier

Acc

eler

atio

n(c

m/s

ec)

Denali: EWclass Dclass C/Dclass Cclass B (one site)

range of previous site response studies

0.1 1 100.1

0.2

1

2

Frequency (Hz)R

atio

(rel

ativ

eto

avg

C)

Denali: EWclass Dclass C/Dclass Cclass B (one site)

range of previous site response studies

File

:C

:\a

nc

ho

rag

e_

gm

\fa

s_

an

d_

ratio

_E

W_

av

g_

ref_

cc

_4

pp

t.d

raw

;Da

te:2

00

5-0

4-1

9;T

ime

:1

7:1

9:5

4

Basin Waves Basin Waves

time (sec)

0 20 40 60 80 100

1.6

-1.73.9

-4.76.0

-5.0

b) velocity (cm/s)UP90, S3EE

SF71, PV

SF71, CM

time (sec)

0 20 40 60 80 100

0.80

-0.973.2

-2.64.2

-5.0

c) displacement (cm) UP90, S3EE

SF71, PV

SF71, CM

-- Horizontal Components --

UP90, S3EE: component x

SF71, PV: component b

SF71, CM: component a

0 20 40 60 80 100

13

-1441

-2924

-20

a) acceleration (cm/s2)

1990 Upland (M=5.6,D=74)

1971 San Fernando (M=6.6)

Palos Verdes (D=66)

Costa Mesa (D=95)

S3EE

File

:C

:\s

em

s\p

ap

er2

\Up

cm

pv

_p

pt.

dra

w;Da

te:2

00

3-0

6-1

6;T

ime

:1

6:1

2:4

2

0.1 0.2 1 2 10 200.1

1

10

Period (sec)

PS

V(c

m/s

ec)

Upland (M 5.6), recorded on OBS, whole record used for PSVas above, but PSV from S-wave only.Regression: Boore etal, 1997, Vs = 216 m/sRegression: Abrahamson & Silva, 1997, corrected to 216 m/sStochastic-method simulation: AB98 model

File

:C

:\s

em

s\p

ap

er2

\SE

MS

_u

pla

nd

_p

pt.

dra

w;

Da

te:2

00

3-0

6-1

6;T

ime

:2

0:1

0:0

7

"Site" (path) effect

"It is an easy matter to select two stations within 1,000 feet of each other where the average range of horizontal motion at the one station shall be five times, and even ten times, greater than it is at the other”

John Milne, (1898, Seismology)

Spatial VariabilitySpatial Variability

Comparing the 1966 and 2004 Aftershocks

Both Earthquakes Ruptured the Same Segment

But with Some Important Differences

Most Extensively Observed Earthquake to Date in the Near-

Fault Region

-120.55 -120.5 -120.45 -120.4 -120.35

35.85

35.9

35.95

36

long

lat

digital (PKD, PHOB)

analog (CSMIP)

0.17g

0.28g

1.1g

2.5 g

1.3g0.3g

10 km

File

:C

:\pa

rkfie

ld_

04

\pa

rkfie

ld_

smst

as_

pg

a_

vari

atio

n.d

raw

;D

ate

:2

00

5-0

4-2

2;

Tim

e:

10

:20

:29

Potential Contributing Factors to the Observed Ground Motion

•Site conditions

•Rupture propagation

•Stopping phases

•Prestress (“Asperities”)

•Fault geometry

85 90 95-400

-200

0

200

400

Acc

el(c

m/s

2)

JFUDFU

vertical component

85 90 95

-500

0

500

NS component

0.05 Hz low-cut, nroll=2

85 90 95-600

-400

-200

0

200

400

600

EW component

85 90 95-10

-5

0

5

10

Vel

(cm

/s)

85 90 95-30

-20

-10

0

10

20

30

85 90 95-30

-20

-10

0

10

20

30

85 90 95-2

-1

0

1

2

Time (s)

Dis

(cm

)

85 90 95

-4

-2

0

2

Time (s)

85 90 95

-4

-2

0

2

4

Time (s)

File

:C

:\p

ark

field

_0

4\m

s\u

sgs\

dfu

_jfu

_lc

p0

5n

r2_

avd

_sa

me

_xs

cale

.dra

w;

Da

te:

20

05

-04

-18

;T

ime

:1

7:4

2:4

0

80 100 120 140

-6

-3

0

3

Time (sec)

Velocity (cm/s)

80 100 120 140

-10

-5

0

5

Time (sec)

Displacement (cm)

80 100 120 140-30

-20

-10

0

10

20

30

Time (sec)

Station 596Station 1099

Acceleration (cm/s2)

File: C:\procssng\working\596_1099_acausal_corr_avd_4ppt.draw;Date: 2005-04-18;Time: 17:31:43

0 2 4 6 8 10

0

0.1

0.2

0.3

Interstation Spacing (km)

ofd

iffe

ren

ceo

flo

g10

ph

a

Northridge 94 MS PHA (Boore, 1997)small arrays (Abrahamson & Sykora, 1993)SMART1, f = 3.3 Hz (Abrahamson, pers. commun.)SMART1, f = 10.0 Hz (Abrahamson, pers. commun.)

2 , San Fernando (McCann & Boore, 1983)Northridge aftershocks (Field & Hough, 1997)

0 2 4 6 8 10

0

0.1

0.2

0.3

Interstation Spacing (km)

ofd

iffe

ren

ceo

flo

g10

ph

a

2*0.188 ( 1, larger comp., M6.0-6.9: Joyner, pers. commun.)

log10 pha = 0.27*(1-exp(- (0.6* ))) (eyeball fit)Chiba (Kawakami & Mogi, 2003)SMART1 (Kawakami & Mogi, 2003)SIGNAL (Kawakami & Mogi, 2003)

File

:C

:\sp

atlv

ar\

corr

lstd

_d

mb

_e

van

s_ka

wa

kam

i_4

pp

t.dra

w;D

ate

:20

05

-05

-03

;Tim

e:

14

:52

:30

END

Azimuth-dependent amplification of weak and Azimuth-dependent amplification of weak and strong ground motions within a fault zone strong ground motions within a fault zone (Nocera Umbra, central Italy)(Nocera Umbra, central Italy)

G. Cultrera, A. Rovelli, G. Mele, R. Azzara, A. Caserta, and F. Marra (2003)

END

Magnitude scaling

Expected scaling for simplest self-similar model (to be discussed later)

4 5 6 7 81

2

3

4

5

6

Me

ven

t_te

rm

4 5 6 7 81

2

3

4

5

6

M

eve

nt_

term

4 5 6 7 81

2

3

4

5

6

M

eve

nt_

term

4 5 6 7 80

1

2

3

4

5

Me

ven

t_te

rm

T=0.1, 0.3, 1.0, 2.0 secrjb _< 80: buried eventsrjb _< 80: events with surface slip

File

:C

:\pe

er_n

ga\t

eam

x\st

age1

_eve

nt_t

erm

s_al

l_pe

r_no

bs_g

t_1_

rle_8

0_su

rfsl

ip_s

msi

m.d

raw

;D

ate:

2005

-05-

24;

Tim

e:10

:49:

37

-2 -1 0 1 2

-2

-1

0

1

2

Nor

th

Station K2-16 (filtered 0.02--0.08 Hz)

24--54 s to s.e. 1

-4 -2 0 2 4

-4

-2

0

2

4

East

Nor

th

94--124 s

to s.e. 2

-4 -2 0 2 4

-4

-2

0

2

4

East

Nor

th

154--194 s

to s.e. 3

-4 -2 0 2 4

-4

-2

0

2

4

Nor

th

54--84 s to s.e. 1

File

:C

:\anc

hora

ge_g

m\h

odog

ram

s_k2

16_b

az_f

bp_0

p02_

0p08

_4pp

t.dra

w;

Dat

e:20

05-0

4-19

;T

ime:

17:1

3:59

-2 -1 0 1 2

-2

-1

0

1

2

Nor

th

Station K2-20 (filtered 0.02--0.08 Hz)

24--54 s to s.e. 1

-4 -2 0 2 4

-4

-2

0

2

4

East

Nor

th

94--124 s

to s.e. 2

-4 -2 0 2 4

-4

-2

0

2

4

East

Nor

th

154--194 s

to s.e. 3

-4 -2 0 2 4

-4

-2

0

2

4

Nor

th

54--84 s to s.e. 1

File

:C

:\anc

hora

ge_g

m\h

odog

ram

s_k2

20_b

az_f

bp_0

p02_

0p08

_4pp

t.dra

w;

Dat

e:20

05-0

4-19

;T

ime:

17:1

2:50

0.5

1

1.5

2

2.5

PG

A(s

tatio

n)/P

GA

(K2-

16)

class Cclass C/Dclass D

0.5

1

1.5

2

2.5

PG

V(s

tatio

n)/P

GV

(K2-

16) class C

class C/Dclass D

0.5

1

1.5

2

2.5

PG

D(s

tatio

n)/P

GD

(K2-

16) class C

class C/Dclass D