Hi All. The following is by Andrea Donnellan and Greg Lyzenga and I found it to be interesting in that it started me to thinking, which I don’t very often as it gives me a headache.

“Global Positioning System (GPS) observations indicate that significant aseismic deformation occurred in the year following the January 17, 1994, Northridge earthquake.

The postseismic observations show the same sense of motion as the coseismic. Compared with the coseismic displacements, the far-field postseismic motions (1-2 fault dimensions away) are proportionally larger than those seen in the near field. The postseismic data are best modeled with two faults: one on the rupture plane and one located in the shallow crust. The upper crustal fault may represent an actual fault or may be indicative of viscous relaxation occurring in the upper crust. The inferred afterslip and/or relaxation moment is approximately 2.9 x 1018 N-m or 22% of the mainshock moment release.

We expect that the moment release due to the afterslip and relaxation effectively reduce the earthquake hazard locally. It is not clear from this study how the postseismic deformation loads the surrounding faults or alters the state of stress on those faults.”

The reason I found this interesting is this.

If this occurs in the immediate area of the quake I wonder what happens to areas far removed the quakes epicenter. We know the waves, pulses, ripples (or what ever you want to call them) from a quake move outwards from that quake. We know this because a seismograph halfway around the world will record that quake.

Lets say that an area under great stress and is near the breaking point has a wave, or waves move through the area. Could this be enough to trigger a quake that is located 1000s of miles from another large quake? Do these waves last for only a couple of days, or can they last for a number of years? What would happen if these waves do last for years and they merge onto an area under great stress at the same time? What kind of affect would they have on an area that is under stress and is ready to break?

Would these waves have a greater affect moving up the fault, or across it?

There have been some instances in the past where I have observed s curious pattern on the tensor strain data at Parkfield. There are times when there will be a pattern similar to someone giving the tensor data a sharp rap. There will be other times it appears as if someone lifted the trace line and held there for an hour or so. It will raise up at a sharp angel continue at a different level, but still flat for the most part then drops back to its original level and continues as if nothing happened.

A lot of questions, but no answers. Take Care…Don in creepy town.