For Cathryn - "Normal"
Posted by Mike Williams in Arroyo Grande on October 15, 2006 at 20:12:01:

Cathryn, the word "normal," as Chris is using it, is a seismological term which means vertical slip on a fault. Specifically, it means slip in an extensional environment, where two blocks move apart and consequently one slips down relative to the other. A better term to have used here, where we don't know much about the fault that produced the quake, is "dip-slip," meaning vertical slip in general (slip in the direction of the dip of the fault plane), as opposed to strike-slip (meaning horizontal slip along the strike of the fault). He did accurately convey that the predominant motion was horizontal rather than vertical. The opposite of "normal" is "reverse" - also dip slip, but where the stress regime is compressional. As to what's "normal" for Hawaii, I dunno, but I suspect a hot-spot volcanic area tends to be somewhat extensional.

Mike Williams
Arroyo Grande, CA USA


Follow Ups:
     ● Re: For Cathryn - "Normal" - Cathryn  21:02:24 - 10/15/2006  (41698)  (1)
        ● Re: For Cathryn - "Normal" - heartland chris  06:46:40 - 10/16/2006  (41707)  (1)
           ● Second Quake-Harvard MT Solution - Glen  10:44:47 - 10/16/2006  (41709)  (2)
              ● Re: Second Quake-Harvard MT Solution - Glen  14:43:11 - 10/16/2006  (41712)  (1)
                 ● 1868 quakes 4 days apart - chris in suburbia  06:31:03 - 10/17/2006  (41721)  (1)
                    ● Hawaii flash flood - heartland chris  09:46:24 - 10/17/2006  (41723)  (1)
                       ● Re: Hawaii flash flood - Canie  11:43:30 - 10/17/2006  (41724)  (0)
              ● Re: Second Quake-Harvard MT Solution - heartland chris  13:04:03 - 10/16/2006  (41710)  (0)