There was a M5.8 followed by a M5.9 quake offshore just east of Christchurch New Zealand. They look to be strike-slip, but not on vertical fault. Well, actually, each has multiple focal mechanism solutions, and the solutions seem very different. Certain include vertical N-S planes. The quakes were shallow.
John, Roger, can you supply more information on why the focal mechanisms are so different?

I'm interested because I work on some number of non-vertical strike-slip faults offshore California (Hosgri, Santa Monica-Dume, Carlsbad, Descanso, Cornado Bank (have not really demonstrated yet that last 2 are strike-slip: working on that), and North Anatolian northern strand SE of Istanbul.

We can see that some of the faults dip 45 to 55 deg in the upper couple or few km, but we don't know what they do much deeper. This non-vertical dip is due to the faults reactivating older faults of different type.

This matters to such places as San Diego downtown. If the en-echelon strands of the NE-dipping Coronado strands maintain their dips, and cut through the SW-dipping Descanso fault, then theie deep parts would be closer to or maybe directly beneath downtown San Diego.

Chris

• New Zleand M5.8 and 5.9