I assume you may be talking pre-historical, before seismic monitoring which could yield some recent date connections.  You might look into dating the sediments from these areas, which may require coring, defining contacts of sediment layers, and such things as pollen counts, Chrysophytes, nuclear dating, tree rings for dating if you find buried trees intact, etc.  Sediment dating is not my expertise, but various techniques exist.  Geologists may be most accustomed with these techniques.  Landslides may follow other sequences of disturbance history that may or may not be present for your area, such as severe wildfires, storms or rain on snow events, etc.

Lakes due to dam effect of landslides are existing and most of the dams have been broached. Layers of sediment deposited in lakes, before landslide dam breach, along rivers  are also present. Old trees are rare to find.

Dear Ijaz,

I assume, as William does, that all six landslides date back a considerable time.  You mention lake sediments formed during a period of damming and that the dams have since been breached.  Could I suggest that these sediments are likely to have sections with varve type deposits in which summer and winter deposits differ giving a seasonal pattern.  This would provide a method for dating and for correlation to other similar deposits elsewhere.  It is unlikely that you would find complete sections, but if you can find organic material anywhere within deposits, there are possibilities for radio carbon dating.  Lichenometry carried out on surficial deposits could also provide a further dating method.  One of the major problems is that tectonic movements may not have been the trigger of any or all of the slides, though the likelihood is high that they would have been in such a tectonically active area as you are working in.

Hope that is helpful.  Feel free to come back to me if you want further explanation.

George 

Excellent discussion. Two important ways landslides can be incorporated into  studies of tectonic deformation: