STA

STA (Expanded Format only): This field may contain either alphabetic or numeric characters. Numeric characters indicate the number of stations used in the computation. Alphabetic characters are quality indicators for earthquakes from the following sources:

G-R: Three-letter combination (epicenter, origin time, depth):

A = Very accurate.
B = Good.
C = Fair.
D = Poor.

MOS: Two-character combination (epicenter, depth):

A = Best accuracy.
B = Very good.
N = Good.
V = Fair.
* = Poor.

PAS: Single-letter designator:

A = Specially investigated.
B = Epicenter probably within 5 km; origin time to nearest second.
C = Epicenter probably within 15 km; origin time to a few seconds.
D = Epicenter not known within 15 km; rough location.

BRK: Single-letter designator:

A = Accurate epicenter.
B = Good.
C = Fair.
D = Poor.

WEL: Single-letter designator:

A = accurate epicenter.
B = Good.
C = Fair.
D = Poor.

SRA: Single-letter designator:

A = Epicenter accuracy estimated to be within 0.0 - 0.1 degrees.
B = Epicenter accuracy estimated to be within 0.1 - 0.2 degrees.
C = Epicenter accuracy estimated to be within 0.2 - 0.5 degrees.
D = Epicenter accuracy estimated to be within 0.5 - 1.0 degrees.
E = Epicenter accuracy estimated to be 1.0 or larger degrees.
F = Noninstrumental epicenter accuracy is estimated to be within 0.0 - 0.5 degrees.
G = Noninstrumental epicenter accuracy is estimated to be within 0.5 - 1.0 degrees.
H = Noninstrumental epicenter accuracy is estimated to be within 1.0 - 2.0 degrees.
I = Noninstrumental epicenter accuracy is estimated to be 2.0 - larger degrees.

EPB: Single-letter designator (1983 - 1984 data):

F = Solution of good quality.
O = Solution of fair quality.

CDMG: Single-letter designator (pre-1900 events only):

A - Epicentral uncertainty probably not more than 15 km, or the fault rupture is identified.
B - Epicentral uncertainty probably not more than 30 km.
C - Epicentral uncertainty probably not more than 60 km.
D - Epicentral uncertainty more than 60 km.
E - No epicenter is estimated; the coordinates given are of the reporting locality when only one locality reports the earthquake, or of a convenient intermediate point when the earthquake is reported from more than one locality.

SSR: Three-letter quality code represents the standard error in origin time, coordinates, and magnitude:

A - 1   sec        0.01 deg.       0.1 units   
B - 2   sec        0.02 deg.       0.2 units
C - 5   sec        0.05 deg.       0.3 units
D - 10  sec        0.1  deg.       0.5 units
E - 20  sec        0.2  deg.       0.7 units
F - 1   min        0.5  deg.       1.0 units
G - 10  min        1.0  deg.       2.0 units
H - 1   hr         2.0  deg.      
I - 6   hr         5.0  deg.
J - 1   day
K - 1   month
L - 1   year
M - 10  year
N - 100 year

EPRI: Single-letter quality code:

A - +/- = 5 km.
B - +/- = 10 km.
C - +/- = 25 km.
D - +/- = 50 km.
E - +/- = 100 km.