Thailand Training Program in Seismology and Tsunami Warnings, May 2006

Forecasting Earthquakes

Forecasting Earthquakes

  ・  Difference between Predictions and Forecasts

  ・  Early Efforts in Earthquake Prediction

  ・  Long-term Forecasting

 

Earthquake Predictions versus Forecasts

Predictions have specific times, locations, and magnitudes for future earthquakes.

Forecasts are more long-term estimates of earthquake occurrences with probability information.

Short-term (minutes to weeks)

Intermediate (months to 10 years )

Long-term (> 10 years)

Forecast Loading Cycle

Interseismic

Preseismic

Coseismic

Postseismic

1. Time 2. Location 3. Magnitude

What is needed in an earthquake prediction ?

Allen, 1996

Frequency of Occurrence of Earthquakes

Descriptor Magnitude

Average Annually

Great 8 and higher

1

Major 7 - 7.9 17

Strong 6 - 6.9 134

Moderate 5 - 5.9 1319

Light 4 - 4.9 13,000

(estimated)

Minor 3 - 3.9 130,000

(estimated)

Very Minor 2 - 2.9 1,300,000(estimated)

        1. Time        2. Location     3. Magnitude

4. Indication of confidence (window)　　  5. Prediction must be presented in accessible 　　　　　　　 form for later evaluation 　　 6. Chance earthquake occurs anyway as a 　　　　　　　 random event

What is needed in an earthquake prediction ?

Allen, 1996

‘Now, when will earthquake prediction be possible and an efficient Forewarning 　 service available ? …if we start the project presented here we should be able to 　 answer the question with sufficient certainty within ten years.’ The Japanese Blueprint (Tsuboi et al, 1962)

‘Based on an assessment of worldwide observations and findings over the past few years, it is the panel’s unanimous opinion that the development of an effective earthquake prediction capability is an achievable goal. …with appropriate commitment and level of effort, the routine announcement of reliable predictions may be possible within ten years…’

Panel of the US National Research Council (Allen et al., 1976)

Optimism in the 1960’s and 1970’s

In actuality: Can only forecast earthquakes and mitigate hazard

‘Predicted’      ・ 1973 Blue Mountain Lake              ・ 1975 Haicheng, China      ・ 1978 Oaxaca, Mexico      ・ 1978  Izu, Japan

‘Not Predicted’      ・ 1976 Tangshan, China         (M7.7 650,000 est. casualties)       ・ 2004 Parkfield, California

Successes and Failures

Blue Mountain Lake, NY

‘Dilatancy’

Scholz et al., 1973Dilatancyhardening

Prediction of the 1975 Haicheng, ChinaEarthquake (M7.3)

Prediction based on foreshocksand animal behavior saved many lives

Short-Term Crustal Deformation Precursor(M 8.1 Tonankai Earthquake 1944)

Mogi, 1984

Short-Term Electromagnetic Precursor1989 Loma Prieta Earthquake

Fraser-Smith, et al., 1990

1978 Oaxaca, Mexico (Ohtake et al., 1981)

Intermediate-Term:Seismicity Patterns

‘Mogi Doughnut’

Dilatancy Hardening

Mogi, 1985

Intermediate-Term:Crustal Deformation

1964 Niigata earthquake

Wakita, 1981

Intermediate-Term:Water and Chemical

M 7.0 Izu earthquake 1978

‘Successfully’ Predicted

     ・ 1973 Blue Mountain Lake        

      ・ 1975 Haicheng, China

      ・ 1978 Oaxaca, Mexico

      ・ 1978  Izu, Japan

Parkfield Earthquake Prediction Experiment

95% probability thatM5.5 to 6 will occur1985-1993.

Based on •Recurrence pattern•Characteristic waveforms

Bakun and McEvilly, 1979

- Repeating Characteristic Earthquakes- M5 foreshock 17 minutes before 1934 and 1966 events

Not Predicted      ・ 1976 Tangshan, China         (M7.7 650,000 est. casualties)       ・ 2004 Parkfield, California  

For short-term prediction, there have been more negative results than positive results:

Other precursors have not been consistently seen

Why has there been lack of continued success in observing precursors?

•Animal experiments have failed•Original observations were hindsight• Instrumentation •Geology dependent (including lights and piezoelectric effects)• Predictive algorithms have not worked (at least short-term)•Earthquakes may be non-characteristic• No connection to tides or planetary alignment• No psychics have made consistent predictions

Short-term minutes to weeks

Intermediate-term months to 10 years

Long-term > 10 years

Earthquake Forecasting

Recurrence times of earthquakes to forecast future earthquakes

• Using historic data• Using geologic data

Shimazaki and Nakata, 1980

Earthquake Cycle

Periodic Time-predictable Slip-predictable

History of Nankai Earthquakes

PALEOSEISMOLOGY

Trenching faults to find geological evidence of past earthquakes

Pallet Creek site on the San Andreas fault

Periodic Time-predictable Slip-predictable

Shimazaki and Nakata, 1980

Earthquake Cycle

100 years

Conditional Probability

Probability

Well defined recurrence interval

Wide range of recurrence intervals (Large variability)

(Small variability)

Variability in Repeating Earthquakes

Probabilistic Earthquake Forecasting for California

Hector Mines Landers 1992

Parkfield 2004

Loma Prieta 1989

http://geohazards.cr.usgs.gov/eq/

USGS National Hazard Maps

Earthquake Hazards

• Ground Shaking

• Surface Faulting

• Landslides and Liquefaction

• Avalanches and soil (mud flows)

NEIC Catalog Seismicity (M>4.5) 1964-2005

What about Thailand?

・ Low Seismicity・ No Historical Earthquakes・ Active Faults (?)

・  Probability is low for    future earthquakes

   But earthquakes can happen   in low probability regions   and offshore

 

Will we be able to predict earthquakes in the future ? Long-term: Probably Intermediate term: Maybe Short-term: Maybe

Future Outlook

Don’t forget that the precursorto a tsunami is the earthquake.

Parkfield Earthquake Prediction Experiment

Loading or deformation cycle

– Four phases• Interseismic• Preseismic• Coseismic• Postseismic

For short-term precursors, there are currently more ‘negative’ results than ‘positive’results.

Kanamori et al., 1996Johnston and Linde, 2002

Distance Measurements on theSan Andreas fault

Matsushiro strainmeter

Earthquake Prediction Research 　 in the 1970’s

Laser Distance Measurements

M 6.8 Nisqually 2001Ground Shaking

Surface faulting

Bei-Fung Bridge near Fung-Yan city, 1999 Chi-Chi, Taiwan earthquake

1964 Niigata EarthquakeLiquefaction