# Presentation: 919216

**  **

- Forecasting Earthquakes

-  ・ Difference between Predictions and Forecasts
-  ・ Earlier Efforts in Earthquake Prediction
-  ・ Long-term Probability Estimates

## Earthquake Predictions versus Forecasts

- Predictions have specific times, locations, and magnitudes
-    for future earthquakes.
- Forecasts are more long-term estimates of earthquake
-    occurences. Often they include probability information.

## What is needed in an earthquake prediction ?

-        	1. Time window
-        	2. Location window
-     	3. Magnitude window
- 	4. Indication of confidence
-    	5. Chances earthquake occurs anyways as a
-        random event
-        	6. Prediction must be presented in accessible
-        form for later evaluation

*What is needed in an earthquake prediction ?*

- Allen, 1996

## Optimism in the 1960’s and 1970’s

*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)

## Earthquake Prediction Research in the 1970’s

- Distance Measurements on the
- San Andreas fault

- Matsushiro strainmeter

- Earthquake Prediction Research in the 1970’s

## ‘Dilatancy’

- <date/time>

- ‘Dilatancy’

## <footer>

- <date/time>

## Prediction of the 1975 Haicheng, China

- Earthquake (M7.3)

- Prediction based on foreshocks
- and animal behavior saved many
- lives

## Scholz et al., 1973

## Short-Term Crustal Deformation Precursor

- Mogi, 1984

## Short-Term Electromagnetic Precursor

- Fraser-Smith, et al., 1990

## For short-term precursors, there are currently 

- more ‘negative’ results than ‘positive’results.

- Kanamori et al., 1996

- Johnston and Linde, 2002

## ‘Not Predicted’

-      ・1973 Blue Mountain Lake (M2.5)
-      ・1975 Haicheng, China (M7.3)
-      ・1978 Oaxaca, Mexico (M7.7)
-      ・1978  Izu, Japan (6.7)
*‘**Not Predicted’*
-      ・1976 Tangshan, China
-          (M7.7 650,000 casualties)
-      ・2003 Tokachi-oki, Japan (M7.9)
-      ・2004 Parkfield, California (M6.0)

- Successes and Failures

*Periodic             Time-predicatable      Slip-predicatable*

- Shimazaki and Nakata, 1980

- Earthquake Cycle

## History of Nankai Earthquakes

## Trenching faults to find 

- Trenching faults to find
- geological evidence of
- past earthquakes

- Pallet Creek site on the San Andreas fault

## 100 years

- Conditional Probability

- Probability

## Variability in Repeating Earthquakes

- Well defined recurrence interval

- Wide range of recurrence intervals
-     (Large variability)

- (Small variability)

## Probabilistic Earthquake Forecasting for California

## “... the Earthquake Research Committee announced on May 24, 2003, 

- there was 10-20 percent chance of occurrence of a M8-class Off-shore
- Tokachi Earthquake over the next 10 years starting from January 1, 2003,
- and a 60 percent chance over the next 30 years”

- Tokachi-oki earthquake
- September 26, 2004
- M8.0

## Probabilistic Hazard Maps

- Attenuation Relations

- Proabilistic Earthquake
- Occurence

## Japan National Seismic Hazard Maps 

- Probabilty of exceedence
- 10% in 50 years

- Japan National Seismic Hazard Maps

## USGS National Hazard Maps

## For an earthquake on the southern San Andreas it would take about 30 sec 

- <date/time>

- For an earthquake on the southern San Andreas it would take about 30 sec
- for the S wave to reach Los Angeles. (The S wave travels at about
- 18,000 km/h.)  This is enough time to issue an Early Warning.

## JR ‘500 series’ bullet train

- can reach peak speed of
- 300 km/hr

## Existing Early Warning Systems

- 	UrEDAS
- 	SAS (Mexico)
- 	Taiwan (EWS)
- 	REIS (NIED, JMA)
- 	Istanbul, Italy, Greece, Romania
- 		plus many other design concepts
- 		 ElarmS, California