Hi All. Here are the criteria I use to determine the accuracy of my earthquake forecasts. As the "Richter Scale" is used to measure the magnitude of the quake I use it also, but with a slight difference. I use the description based on how it is felt and how if affects the area which uses the "Modified Mercalli Scale" It may not be the perfect method for everyone, but it works for me. Also I'm the one who must be satisfied with the forecast and as I want it to be as accurate as I can get it so I'm my own worst critic.

Let's say I forecast a 6.1 to 6.9 quake to center at 28.00N/122.00W. Radius 100Km. The area of past quakes of this size determined the radius.

I always use a window no large then 5 days. I use this window on the bases of what would be considered practical for an evacuation.

On the day of the quake it is 101Km north of the forecasted epicenter. My score would be a "D" because the quake didn't occur within the area I specified. If it occurred 80 Km from the specified epicenter the score would be a "C" If it occurred 60Km from the specified epicenter it would be a "B" and 40Km would be "A".

If the quake occurs on the day or 1 day before the forecasted day the score is a "A" 2 days a "B" 3 days a "C" 4 days a "D". If it occurs 1 day after the forecasted date it's a "A" 2 days a "B" 3 days a "C" and 4 days a "D"

For the magnitude of the quake if it is within the specified range it's an "A". If it's a 7.0 –7.2 it's an "A" for 7.3-7.5 it's a "B" 7.6-7.9 it's a "C". Anything above 6.9 would be a "D".

For quakes larger then 7.0 the grade becomes tighter and this is because the larger the expected quake the more sever the damage and a larger area would be involved. Take Care...Don in creepy town.

Mercalli Intensity/ Richter Scale

I 1 to 2 Felt by very few people; barely noticeable

II 2 to 3 Felt by a few people, especially on upper floors.

III 3 to 4 Noticeable indoors, especially on upper floors, but may not be recognized as
an earthquake.
IV 4 Felt by many indoors, few outdoors. May feel like heavy truck passing by.

V 4 to 5 Felt by almost everyone, some people awakened. Small objects moved. Trees and poles may shake.

VI 5 to 6 Felt by everyone. Difficult to stand. Some heavy furniture moved, some plaster falls. Chimneys may be slightly damaged.

VII 6 Slight to moderate damage in well built, ordinary structures. Considerable damage to poorly built structures. Some walls may fall.

VIII 6 to 7 Little damage in specially built structures. Considerable damage to ordinary buildings, severe damage to poorly built structures. Some walls collapse.

IX 7 Considerable damage to specially built structures, buildings shifted off foundations. Ground cracked noticeably. Wholesale destruction. Landslides.

X 7 to 8 Most masonry and frame structures and their foundations destroyed. Ground badly cracked. Landslides. Wholesale destruction.

XI 8 Total damage. Few, if any, structures standing. Bridges destroyed. Wide cracks in ground. Waves seen on ground.

XII 8 or greater Total damage. Waves seen on ground. Objects thrown up into air.