Hi All. I was digging through some documents that I had obtained at the 2001 Fall AGU meeting and what do you know. I found a paper on remote trigger of earthquakes (FFA) and got to thinking that maybe, just maybe it might be on the Internet. Well sure enough it is.

There is some strong evidence that indicates this also occurred with some of the more recent quakes in Southern California and is also known to have occurred after the 1906 San Francisco earthquake.

Up until a couple of years ago there has been a question that has always nagged me. Why does this occur with some quakes and not others? Is it where the main event occurs, or is it where the triggered quakes occur, or a combination of both? To a certain degree the FFA ring map provided some answers, but not all of them. The following paper provides some answers, but somehow I think there is something else there that were not seeing.

I have to give credit where credit is due to Petra. If it weren¡¯t for her fear of driving over bridges I wouldn¡¯t have taken her to the AGU fall meeting. Anyway I think after ridding around with me the last couple years has made her think that her having to driving over a bridge isn¡¯t so bad after all. Sure beats letting me do the driving. Anyway I hope you enjoy. Take Care¡­Don in creepy town

We present evidence that at least two of the three principal1811-1812 New Madrid, mainshocks and the1886 Charleston, South Carolina, earthquake were associated
with remotely triggered earthquakes. In addition to previously published results showing that the New Madrid sequence triggered earthquakes in the northern Kentucky/southern Ohio region, we present evidence suggesting that triggered events might have occurred in the Wabash Valley, to the south of the New Madrid Seismic Zone, and possibly near Charleston, South Carolina region as well.

We also discuss evidence that earthquakes might have been triggered in northern Kentucky in the immediate wake of the strong ground motions associated with the 23 January 1812 New Madrid mainshock. After the 1886 Charleston earthquake, accounts suggest that triggered events occurred near Moodus, Connecticut, and in southern Indiana.

Thus at least three out of the four known M¡Ý7 earthquakes in the central and eastern United States seem to have triggered earthquakes outside their aftershock zones. We explore the possibility that remotely triggered earthquakes might be common in low strainrate regions. We suggest that in a low strain-rate environment, permanent, non-elastic deformation might play a relatively more important role in stress accumulation than it does in interplate crust. Using a simple model incorporating both elastic and anelastic strain release, we show that, for realistic parameter values, faults in intraplate crust might remain close to their failure stress for a longer part of the earthquake cycle
than faults in high strain-rate regions. Our results further more reveal that remotely triggered earthquakes occur preferentially in regions of recent and/or future seismic activity, which suggests that faults tend to be at a criticalstress state in only some areas. It is not surprising that triggered earthquakes would serve as beacons that identify regions that are approaching a criticalstress state. Their occurrence in regions that have experienced large earthquakes in the recent past (a few hundred years) provides evidence that, once developed, a critically stressed region of intraplate crust will persist for hundreds if not thousands of years and give rise to prolonged episodes of seismic unrest.

• Remotely Triggered Earthquakes