# History and Future of Operational Earthquake Forecasting - PowerPoint Presentation

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at the USGS Andrew J Michael What Is Operational Earthquake Forecasting aka OEF Currently OEF Earthquake Clustering aka Foreshocks and Aftershocks Earthquakes trigger other earthquakes ID: 804409 Download

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Slide1

History and Future of

Operational Earthquake Forecasting

at the USGS

Andrew J. Michael

Slide2

What Is Operational Earthquake Forecasting?

a.k.a. OEF

Currently OEF = Earthquake Clustering

a.k.a. Foreshocks and Aftershocks

Earthquakes trigger other earthquakes.

When you have one earthquake,

the probabilities for other earthquakes go up.

Slide3

Semantics

When earthquake happens without obvious ancestors, it is a

mainshock

.

If smaller earthquakes follow, they are aftershocks.

If an aftershock occurs that is bigger than the

mainshock

, then we rename all previous events foreshocks, and the biggest aftershock is now the mainshock.If smaller earthquakes follow, they are aftershocks.……

The Physics Fine Print: all earthquakes are the same, we can’t tell foreshocks,

mainshocks

and aftershocks apart.

Slide4

Standard Aftershock Warning

Issued after M>=5 Earthquakes in California

PROBABILITY REPORT Published on May 24, 2009 @ 16:58:34 GMT

MAINSHOCK Magnitude : 4.6 Mw (A light quake) Time : 23 May 2009 03:58:32 PM, PDT : 23 May 2009 22:58:32 GMT Coordinates : 36 deg. 25.28 min. N, 117 deg. 46.24 min. W : 36.4213 N, 117.7707 W Depth : 0.0 miles ( 0.1 km) Quality : Fair Location : 7 mi. ( 11 km) SE from Keeler, CA : 20 mi. ( 32 km) SE from Lone Pine, CA Event ID : NC 66099

STRONG AFTERSHOCKS (Magnitude 5 and larger) -

At this time (18 hours after the

mainshock) the probability of a strong and possibly damaging aftershock IN THE NEXT 7 DAYS is less than 10 PERCENTEARTHQUAKES LARGER THAN THE MAINSHOCK -Most likely, the recent

mainshock

will be the largest in the sequence. However, there is a small chance (APPROXIMATELY 5 TO 10 PERCENT) of an earthquake equal to or larger than this

mainshock

in the next 7 days.

WEAK AFTERSHOCKS (Magnitude 3 to 5) -

In addition, up to approximately 5 SMALL AFTERSHOCKS are expected in the same 7-DAY PERIOD and may be felt locally.

This probability report is based on the statistics of aftershocks typical for California. This is not an exact prediction, but only a rough guide to expected aftershock activity. This probability report may be revised as more information becomes available

.

Slide5

Standard Aftershock Warning

Issued after M>=5 Earthquakes in California

Background

Like most earthquakes, the recent earthquake is expected to be followed by numerous aftershocks. Aftershocks are additional earthquakes that occur after the

mainshock

and in the same geographic area. Usually, aftershocks are smaller than the

mainshock, but occasionally an aftershock may be strong enough to be felt widely throughout the area and may cause additional damage, particularly to structures already weakened in the mainshock. As a rule of thumb, aftershocks of magnitude 5 and larger are considered potentially damaging.Aftershocks are most common immediately after the mainshock; their average number per day decreases rapidly as time passes. Aftershocks are most likely to be felt in the first few days after the mainshock

, but may be felt weeks, months, or even years afterwards. In general, the larger the

mainshock

, the longer its aftershocks will be felt.

Aftershocks tend to occur near the

mainshock

, but the exact geographic pattern of the aftershocks varies from earthquake to earthquake and is not predictable. The larger the

mainshock

, the larger the area of aftershocks. While there is no "hard" cutoff distance beyond which an earthquake is totally incapable of triggering an aftershock, the vast majority of aftershocks are located close to the

mainshock

. As a rule of thumb, a magnitude 6

mainshock

may have aftershocks up to 10 to 20 miles away, while a magnitude 7

mainshock

may have aftershocks as far as 30 to 50 miles away.

Slide6

Standard Aftershock Warning

Issued after M>=5 Earthquakes in California

STRONG

AFTERSHOCKS (Magnitude 5 and larger)

-

At this time (18 hours after the

mainshock

) the probability of a strong and possibly damaging aftershock IN THE NEXT 7 DAYS is less than 10 PERCENTEARTHQUAKES LARGER THAN THE MAINSHOCK -Most likely, the recent mainshock will be the largest in the sequence. However, there is a small chance (APPROXIMATELY 5 TO 10 PERCENT) of an earthquake equal to or larger than this mainshock in the next 7 days.WEAK AFTERSHOCKS (Magnitude 3 to 5) -

In addition, up to approximately 5 SMALL AFTERSHOCKS are expected in the same 7-DAY PERIOD and may be felt locally

.

Slide7

Slide8

Haiti

Slide9

Haiti

Slide10

Mineral, VA

Slide11

STEP

Gerstenberger

et al.

Nature, 2005

USGS OFR 2004

Slide12

Reasenberg

and Jones, Science, 1989

Probability of earthquakes

during an aftershock sequence

as a function of time and

magnitude.

Initial estimates are based on

parameters for a “generic”

California earthquake sequence.

Sequence specific parameters

are used once they can be

determined.

Slide13

Spatial Clustering

Aftershocks occur in the general region of the

mainshock

.

Up to about 1 – 2 fault lengths away.

In the case of a large aftershock at the edge of the zone, the zone will get larger.

The people we are warning, felt the

mainshock or should be aware of it.

Slide14

How Many Aftershocks?

Bigger

Mainshocks

Produce More Aftershocks

Magnitude of

Mainshock

Expected number of aftershocks

Magnitude 3 or largerIn

the first week

5

6.7

6

67

7

670

8

6700

Slide15

The Sizes of Aftershocks

(including bigger ones)

Minimum

Magnitude

Observed Number

Expected Number

3

310

340

4

42

34

5

6

3.4

6

0

0.34

7

0

0.034

Most Aftershocks Are Smaller

1994 Northridge Earthquake Magnitude 6.7

Number of Aftershocks within 30 km of

Mainshock

In the first week

Slide16

The Times of Aftershocks

When

Observed Number

Expected Number

First Day (½ – 1½)

420

733

Tenth Day

44

70

100

th

Day

4

7.1

1000

th

Day

0

0.71

10000

th

Day

? until

2021

0.071

The Rate of Aftershocks Decays at About 1/time

1994 Northridge Earthquake Magnitude 6.7

Number of Aftershocks in 1 day

Magnitude

2

or

larger, within 30 km of

Mainshock

Slide17

Forecast After a Magnitude 7

Minimum

Magnitude

Expected Number

Probability

of

1 or more events

3670

>99%

4

67

>99%

5

6.7

99%

6

0.67

50%

7

0.067

6.5%

8

0.0067

0.66%

Magnitude 7

Mainshock

Forecast for the First Week

Slide18

Forecast After a Magnitude 5

Minimum

Magnitude

Expected Number

Probability

of

1 or more events

36.7

99%

4

0.67

49%

5

0.067

6.5%

6

0.0067

0.67%

7

0.00067

0.067%

8

0.000067

0.0067%

Magnitude 5

Mainshock

Forecast for the First Week

Wide Range of

Probabilities

Slide19

Forecast After a Magnitude 5

Minimum

Magnitude

Expected Number

Probability

of

1 or more events

30.31

27%

4

0.031

3.1%

5

0.0031

0.31%

6

0.00031

0.031%

7

0.000031

0.0031%

8

0.0000031

0.00031%

Magnitude 5

Mainshock

Forecast for the Fifth Week

Slide20

The Long Lives of Aftershocks

Aftershocks of the Magnitude 8¼

Nobi

Earthquake of 1891

Slide21

Forecasts With Respect to

Urban Planning for Recovery

Stage

Emergency Response

(search and rescue, fire fighting, shelters, damage assessment)

2. Restoration

(restore utilities, debris removal, temporary repairs)

3. Reconstruction

(structures replaced to pre-disaster levels)

4. Betterment

(major projects improve community to a new standard)

5. Long-Term

(life with a new normal)

Forecast for a Magnitude 7

Mainshock

Slide22

Forecasts With Respect to

Urban Planning for Recovery

Stage

Dominant

Time Period

(Kobe, Northridge, Christchurch)

Emergency Response

(search and rescue, fire fighting, shelters, damage assessment)

0

to

14

days

2. Restoration

(restore utilities, debris removal, temporary repairs)

14 days to 1 year

3. Reconstruction

(structures replaced to pre-disaster levels)

1 to 3 years

4. Betterment

(major projects improve community to a new standard)

3 to 10 years

5. Long-Term

(life with a new normal)

10 to 50 years

Forecast for a Magnitude 7

Mainshock

Slide23

Forecasts With Respect to

Urban Planning for Recovery

Stage

Dominant Time Period

(Kobe, Northridge, Christchurch)

Probability of an Aftershock with Magnitude 6 or larger

Emergency Response

(search and rescue, fire fighting, shelters, damage assessment)

0

to

14

days

61%

2. Restoration

(restore utilities, debris removal, temporary repairs)

14 days to 1 year

33%

3. Reconstruction

(structures replaced to pre-disaster levels)

1 to 3 years

11%

4. Betterment

(major projects improve community to a new standard)

3 to 10 years

11%

5. Long-Term

(life with a new normal)

10 to 50 years

13%

Forecast for a Magnitude 7

Mainshock

Slide24

Uncertainties

Variability from sequence to sequence by at least a factor of 10. Our forecasts will adapt to each sequence as we collect data.

Slide25

Agnew and Jones, JGR, 1991:

“But it ought to be possible to do better:

Should we say the same thing

after every event?

the probability of a very large earthquake should be higher if the candidate foreshock were to occur near a fault capable of producing that

mainshock

than if it were located in an area where we believe such a

mainshock to be unlikely.Moreover, the chance of a candidate earthquake actually being a foreshock should be higher if the rate of background (nonforeshock) activity were low.”

Foreshock Model

to a

Specific

Mainshock

Slide26

M4.8 Event At Bombay Beach On March 24, 2009

Could It Be A Foreshock To A Larger Earthquake In The Next 3 Days?

Slide27

Mainshock

:

SAF, Coachella

Seg

.

UCERF2:

Length = 69 km

M 75-yr Prob. = 5%3-day Prob.= 0.009%M4.8 Event At Bombay Beach On March 24, 2009Could It Be A Foreshock To A Larger Earthquake In The Next 3 Days?

Slide28

Mainshock

:

SAF, Coachella

Seg

.

UCERF2:

Length = 69 km

M 75-yr Prob. = 5%3-day Prob.= 0.009%Reasenberg &Jones, 1989:Probabilityof M4.8 beingfollowed by

an M≥7 event

PF = 0.05%

M4.8 Event At Bombay Beach On March 24, 2009

Could It Be A Foreshock To A Larger Earthquake In The Next 3 Days?

Slide29

Mainshock

:

SAF, Coachella

Seg

.

UCERF2:

Length = 69 km

M 75-yr Prob. = 5%3-day Prob.= 0.009%R&J 1991:PF= 0.05%Agnew and

Jones, 1991:

PF = 4%

M4.8 Event At Bombay Beach On March 24, 2009

Could It Be A Foreshock To A Larger Earthquake In The Next 3 Days?

Slide30

Past Efforts -

Parkfield

Slide31

Past Efforts -

Parkfield

Status

Slide32

Slide33

Forecast After a Magnitude 5

Minimum

Magnitude

Probability

of

1 or more events

Probability

of 1 or more events if M≥7 occur 100xmore frequently

3

>99%

>99%

4

49%

52%

5

6.5%

12%

6

0.67%

7%

7

0.067%

6.4%

Magnitude 5

Mainshock

Forecast for the First Week

Integrated Aftershock

and Foreshock Forecast

Slide34

Uncertainties

The probabilities for the largest events could be underestimated by a factor of 10 to 100.

Slide35

Future USGS Plans

Expand the standard aftershock warnings nationally and internationally (for internal government use) with updated messaging. This will start as a

Reasenberg

and Jones calculation.

Develop the UCERF3 clustering model and associated products. This will combine

Reasenberg

and Jones type calculations with Agnew and Jones type calculations.

1-year hazard assessments for induced seismicity.Test models and products, develop new methods.

Slide36

Are these statements worth saying?

They are

true, everyone

knows

New Zealand and Italy

experiences

When probabilities are high enough then public warnings have been issued in conjunction with the State of California. "During the August 8, 1989 advisory, all our departments ran drills to prepare for an imminent earthquake. This made a tremendous difference in the city's response when the earthquake struck," said Henry Renteria, Emergency Services Manager, Oakland, California"The probability of aftershocks given by the U.S. Geological Survey was one of the factors we used in deciding how many firefighters to keep on duty after the 1989 San Francisco Bay area earthquake," said Greg Abell

, Battalion Chief in the San Francisco Fire Department

.

The

important thing is what you want to do with them.

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