if I read the focal mechanism correctly, this quake is unusual-one nodal plane is dipping about 10 deg, and one is dipping 80 deg. The quake was on one of these. It was pure normal slip. Normal earthquakes generally are on 30 to 60 deg dipping planes-with most large ones being 45 deg. So, if the focal mechanism is accurate, it requires high fluid pressures to hold the fault apart to allow it to slip (e.g., Sibson). My post as part of this thread does not imply that I believe the relationships posted at the start of this thread.
Chris

• focal mechanism