OK Mike,

I was thinking in terms of "Anza Seismic Gap" or "Shumagin Gap" up in the Aleutian subduction. I take your previous comment to mean that a gap in seismicity that is geographical in nature should not be a rational pretext for a prediction scheme. (At least short term forcast) In this regard you are absolutely correct. However, one can look at the historic pattern and make some judgements thusly;

After lengthy study of the historic record of 3+ magnitudes in the Anza area, I see that these quakes are very deviated up until 1999, and then the depths become much more uniform at 12 to 16 Km. One example was in 1975, when I think the gap came very close to rupture;

PDE 1975 08 01 114212.60 33.65 -116.75 5 4.90 mb GS .. . ....... 14+++
PDE 1975 08 02 001407.70 33.52 -116.55 13 4.70 MLPAS .F . ....... 9+++

These two quake were only 12 hours apart, and the 4.9 was north of Anza at 5 Km and the second south of Anza at 13 Km. The distance between the quakes was 23.5245 Km, suggesting that a large area of locked ground was brought close to rupture. The depth difference is what I noticed.

Here is 1976, another year of various depth hits;

PDE 1976 01 01 014754.70 33.52 -116.60 11 3.40 MLPAS .. . ....... 7
PDE 1976 01 02 093214.30 33.57 -116.68 8 3.00 MLPAS .. . ....... 6
PDE 1976 03 28 072236.90 33.52 -116.48 5 3.90 mb GS .. . ....... 1
PDE 1976 05 23 133020.50 33.68 -116.82 19 3.20 MLPAS .. . ....... 21
PDE 1976 07 14 201959.30 33.48 -116.52 17 3.00 MLPAS .. . ....... 14
PDE 1976 08 11 152455.50 33.48 -116.52 15 4.30 MLPAS 6D . ....... 14+++
PDE 1976 08 20 051403 33.43 -116.52 8 3.20 MLPAS .. . ....... 19
PDE 1976 09 19 111142.10 33.48 -116.78 16 3.30 MLPAS .. . ....... 18
PDE 1976 09 30 160546.90 33.47 -116.53 8 3.10 MLPAS .. . ....... 15
PDE 1976 10 22 231913.60 33.48 -116.58 15 4.50 mb GS .F . ....... 11+++
PDE 1976 11 27 152342.20 33.53 -116.50 2 3.30 MLPAS .F . ....... 12

And 1995 record of 3+ quakes in Anza;

PDE 1995 01 31 193133.85 33.46 -116.58 5 2.70 MLGS .. . ....... 14
PDE 1995 02 02 075116.71 33.47 -116.46 10 2.40 MLPAS .. . ....... 19
PDE 1995 03 17 115856.34 33.62 -116.72 11 2.40 MLPAS .. . ....... 9
PDE 1995 05 30 014456.12 33.50 -116.82 13 3.10 MLPAS .F . ....... 21
PDE 1995 06 10 113735.54 33.70 -116.82 15 2.70 MLGS .. . ....... 22
PDE 1995 07 28 070730.39 33.54 -116.69 8 3.60 MLGS .F . ....... 8
PDE 1995 12 24 191623.59 33.59 -116.64 10 2.80 MLGS .. . ....... 1
PDE 1995 12 26 054411 33.70 -116.77 14 3.20 MLPAS .F . ....... 18

All of the quakes from 1973 to 1998 were at various depths, north and south. In 1999, a change in the depth pattern then occurs. The quakes become situated at the 14 to 16 km depth. There are a few oddballs though. Also within this newer quake trend are the two 5+ magnitude quakes for the 25 Km circular and PDE file used.

PDE 1999 06 24 124528.23 33.50 -116.51 14 2.90 MLPAS .. . ....... 13
PDE 1999 07 19 220927.49 33.63 -116.72 14 4.20 MLPAS .F . ....... 10+++
PDE 1999 08 26 121431.95 33.49 -116.51 8 2.90 MLPAS .. . ....... 15

PDE 2000 01 27 092154.90 33.70 -116.77 16 2.90 MLPAS .. . ....... 18
PDE 2000 01 27 094822.37 33.70 -116.77 14 2.80 MLPAS .. . ....... 19
PDE 2000 11 23 004523.18 33.49 -116.84 11 2.80 MLPAS .. . ....... 22

PDE 2001 02 18 060932.16 33.67 -116.81 16 3.30 MLPAS 4F . ....... 20
PDE 2001 02 20 103647.85 33.71 -116.78 16 3.10 MLPAS 3F . ....... 19
PDE 2001 04 20 095212.27 33.71 -116.78 16 3.40 MLPAS 3F . ....... 19
PDE 2001 06 05 093846.08 33.68 -116.76 16 3.10 MLPAS .. . ....... 16
PDE 2001 06 12 120823.81 33.69 -116.82 15 3.10 MLPAS .F . ....... 21
PDE 2001 07 16 032139.57 33.46 -116.42 14 3.00 MLPAS .. . ....... 23
PDE 2001 08 28 213012.22 33.65 -116.74 14 3.40 MLPAS 4F . ....... 13
PDE 2001 09 06 043422.74 33.46 -116.44 5 2.80 MLPAS .. . ....... 21
PDE 2001 09 10 174008.59 33.45 -116.63 9 3.00 MLPAS .F . ....... 14
PDE 2001 09 23 224432.96 33.51 -116.51 15 3.00 MLPAS .F . ....... 13
PDE 2001 10 12 160840.46 33.50 -116.52 12 3.10 MLPAS .. . ....... 13
PDE 2001 10 17 200251.38 33.51 -116.46 6 2.80 MLPAS .. . ....... 16
PDE 2001 10 31 075616.63 33.51 -116.51 15 5.20 mb GS 5F . ....... 13***
PDE 2001 10 31 094105.48 33.50 -116.51 15 2.80 MLPAS .. . ....... 14
PDE 2001 10 31 102725.78 33.50 -116.51 14 2.90 MLPAS .. . ....... 13
PDE 2001 11 01 060608.71 33.51 -116.51 15 2.80 MLPAS .. . ....... 13

PDE 2002 09 04 144417.68 33.62 -116.70 14 2.80 MLPAS .. . ....... 8
PDE 2002 09 17 150005.17 33.50 -116.78 16 3.70 MLPAS 4F . ....... 17
PDE 2002 09 17 170701.40 33.51 -116.78 16 2.80 MLPAS .F . ....... 17
PDE 2002 10 17 032634.52 33.48 -116.50 14 3.10 MLPAS .. . ....... 15
PDE 2002 10 24 171832.91 33.51 -116.58 14 3.80 MLPAS 3F . ....... 9
PDE 2002 12 14 014633.97 33.45 -116.55 9 2.80 MLPAS .. . ....... 16

PDE 2003 02 24 230644.60 33.44 -116.44 13 3.20 MLPAS .F . ....... 23

PDE 2004 01 16 213149.74 33.47 -116.47 14 2.80 MLPAS .. . ....... 19
PDE 2004 03 20 045537.41 33.51 -116.57 14 3.10 MLPAS 3F . ....... 9
PDE 2004 05 13 060428.90 33.65 -116.73 16 3.10 MLPAS 3F . ....... 12
PDE 2004 10 19 021209.05 33.50 -116.51 14 3.20 MLPAS 3F . ....... 13

PDE 2005 05 15 132956.34 33.46 -116.63 7 3.20 MLPAS .. . ....... 14
PDE 2005 06 09 230207.32 33.50 -116.52 14 3.10 MLPAS .. . ....... 13
PDE 2005 06 12 154146.54 33.53 -116.57 14 5.20 MwHRV 6D M ......S 7***
PDE 2005 06 12 204747.73 33.50 -116.57 12 3.10 MLPAS .F . ....... 10
PDE 2005 06 17 032428.12 33.49 -116.53 12 3.30 MLPAS 3F . ....... 13
PDE 2005 07 15 021251.32 33.54 -116.61 12 2.80 MLPAS .. . ....... 5
PDE-W 2005 11 08 220346.22 33.53 -116.68 12 3.30 MLPAS 3F . ....... 8

PDE-W 2006 05 03 162249.11 33.52 -116.58 12 3.20 MLPAS .F . ....... 7
PDE-W 2006 07 30 133253.49 33.69 -116.79 15 3.20 MLPAS 3F . ....... 19
PDE-W 2006 10 05 195409.53 33.44 -116.60 11 3.00 MLPAS .. . ....... 15

Now the quakes are beginning to run at a shallower depth. Mean something? I don't know. But the ams are watching. Don't subtract us from the overall endeavor. We just might catch somemthing the professional stargazers don't see. Get my drift?

Glen