I just resubmitted my long-suffering paper on the Santa Monica-Dume fault 5 minutes ago to JGR. We'll see if this turns into a 5 year ordeal or if this version does the trick. I went on a walk in the woods in the park to the north of here...Harriman Park NY. It was a 20 minute drive on a beautiful Saturday morning. A parked in an out of the way, but official hiking trail parking lot...dead on top of the Ramapo fault. I then hiked up its 200+ m-high fault line scarp. This fault is one of the major Mesozoic ("age of dinosaurs") rift faults (normal fault).related to the opening of the Atlantic,..with preCambrian gneiss (freaking old) in the footwall to the NW and red sandstones and conglomerate from age of dinosaurs in hanging-wall to SE. This is a really major fault on the cross sections on the geologic map of New Jersey. Anyway, started hiking at 9:30 AM and did not see another person for 3 hours...although one time I heard hikers on another trail in the distance. I parked myself on a rock sticking out into a 1 kmx300 m lake...which I also had to myself. This is really a wonderful park...lots of variety over small distances....we read the comments in the book at a shelter on the Appalachian trail where it passes through the park and some of the through-hikers found it the nicest part of the trail ...and they had hiked it from Georgia.
There is some seismicity aligned more or less along the Ramapo fault, from Pennsylvania to New York. If the whole thing broke in a large piece it would probably be a M7 (+?). Seeing as they built the Indian Point nuclear power plant on or near this fault, and that buildings in New York City might have trouble with such an earthquake even at 40 km or so, it would be important to know if it is "dead as a doorknob" as a reviewer once comments about a California fault that I was working on (that reviewer would be wrong..). But, this is a bit of a frustrating fault...the 200 m fault-line scarp is consistent with differential erosion (more resistant rocks stand high) and not with thrust reactivation pushing the hanging-wall high (the footwall is high). But, that does not rule out, for example, strike-slip activity, or activity on other associated faults. In California, especially offshore, there is often sediment or sedimentary rock that is cut and offset by the fault...that is relatively young....so that you can study the relatively recent (10,000 years or 5,000,000 years or in between) activity of faults. Here, you have billion year old rocks on one side and 200 million year old rocks on the other....and some marsh/swamp deposits scattered around that must be younger than the last glaciers...about 15,000 years. So...it seems impossible to know if this fault has had large earthquakes in the last 1 million years (for example). I did notice that there was a lot of rock falls (landslides of a type) on the escarpment...I suppose you could map all of these by location and by what slope they are on, and rocktype...I'm not sure if it would mean much if there were more along the fault...it would have to be pretty clear-cut pattern (this would be for the last 15,000 years). The operators of Indian Point want to re-license it, so this fault may get looked at.....
Chris