Earthquake forecasting

Question 1

What would prediction of an earthquake state?

Answer 1

A specific magnitude, in a stated place at a stated time

Question 2

What precursory phenomena might prediction be based off?

Answer 2

Animal behaviour
Changes in seismic velocity, groundwater levels or radon emissions
Electromagnetic varations
Foreshcoks

Question 3

What is the problem with precursory phenomena?

Answer 3

Non statistically valid (most in hindsight)

Question 4

What is an example of where good eq predictions occurred?

Answer 4

Haicheng 1975 - 7.5
Foreshocks
Good education and public involvement

following year nearby Tangshan killed ~250,000

Question 5

What problems were associated with L’Aquila 2009?

Answer 5

Poor communication of risk and by Radon lab technician which identified risk led to public distrust exacerbating damages

Question 6

What is needed to make earthquake prediction valid?

Answer 6

More than a few days in advance to be useful
Must predict the earthquake with an accuracy of a few days
If the prediction is wrong:
Loss of credibility for prediction
Possible lawsuits

Question 7

What is eq forecasting?

Answer 7

statistical probabiity or eq above a specified magnitude in agiven place for a specific period of time

Question 8

What is forecasting based on?

Answer 8

Recurrence time estimte
Geodetic monitoring

Question 9

What can go wrong with using recurrence time with example?

Answer 9

If data is cherry picked like parkfield california and ignores year which doesnt fit pattern it can affect the outcome like when quake from 85-93 didnt occur till 04.

Question 10

What can be do when we have a long history of eqs in an area?

Answer 10

can estimate avg recurrence but lots of scatter

Question 11

How is the recurrence time of large eqs estimated when there is only a short history?

Answer 11

Interval between small eqs (can be bias)

Question 12

How does fault and eqs being fractal allow estimate of recurrence?

Answer 12

Means there is a relationship between number of large and small eqs in a gievn interval

Question 13

How does statistics used affect the forecasting of recurrence time?

Answer 13

Time indepenent - constant
Time dependent - probability small after last event then grows (probability lower until 2/3 recurrence)

Question 14

What happens to velocity and strain as you move away fro the fault zone in interseismic?

Answer 14

Both increase

Question 15

What will strain be like at the fault during the intersesicmic period?

Answer 15

0

Question 16

What is the best moniroting method for eqs?

Answer 16

Monitoring interseismic strain using geodetics (gps)

Question 17

WHat are sesimic gaps?

Answer 17

segemnt of active fault that has not experienced a significnt eq in some time

Question 18

What is the idea behind seismic gaps?

Answer 18

Slip on surrounding faults increase stress onto part of fault segemnt which hasent ruptured increasing risk there over time

Question 19

What is an example of the seimsic gap theory?

Answer 19

Tohoku eq occured on segemnt with no major eq ruptures but extented beyond the gap

Worrying area is siemic gao near Tokyo

Question 20

What is mexicos example of a seismic gap?

Answer 20

Guerrero gap

Question 21

Why is there an empahsis with forecasted shake maps to look at 30 to 50 yr intervals?

Answer 21

Typical lifetime of mortages

Question 22

What is important for ground motion models?

Answer 22

The assumptions of the model as well as magnitude

Question 23

What are ground motion models for the new madrid seismic zone derived from?

Answer 23

Known geology, past events (laregley histroical)

Question 24

What is seismic risk a combinaiton of?

Answer 24

Hazard (probability, shaking intensity) X Consequence

Question 25

What is a New Madrid example of seismic risk from ground motion model?

Answer 25

Proabability upto 90% M6 by 2040
Consequence = building codes not quake consious (now upgraded)