[petuniasevan]

Here's some tidbits on the Great Rift:

4. The Rift Valley System of East Africa

1. rifting of the continental lithosphere is the very first stage in the splitting apart of a continent to form a new ocean basin

2. rift valley is basically a graben
3. Rift Valley system of Africa:

1. 3000 km/1900 mi long

2. earth’s crust is being lifted and spread apart in a long, ridgelike swell
3. major rivers and long, deep lakes occupy the valley floors
4. multiple fault scarps give the valley sides a stepped appearance
5. Mount Kilimanjaro and Mount Kenya, 2 great stratovolcanoes, have formed near the Rift Valley

[petuniasevan]

The overall rate of rifting is approximately 1 inch a year.
Sounds awfully slow but we're talking a HUGE volume of crustal rock here.
And as the pressure builds, volcanoes erupt along the margins.
New soil is thus created. This attracts human habitation - think of Pompeii.
The agricultural bounty makes it worth the risk - until the next eruption.

[Cvengr]

There was increased interest in the hot spots around the Salton Sea recently to possibly be a forewarning of an 8.0 magnitude event, but nothing else recently,,this was a couple of weeks ago. There do seem to be some new major streses being relieved in some seismic patterns over the last week in S. Ca, but nothing more substantial at present.