Wikipedia is (uncharacteristically for engineering/science) not very talkative. All it says is that the rupture propagation speed exceeds the S-wave velocity, creating an analogy to a sonic boom.
So does that imply one has a propagating "shock wave" ? Which confuses me, what are the relevant state variables for the ground, which would suffer a discontinuity -- and how would the "shock" differ from the ordinary S and P waves?
Color me overdosed on chocolate bunny ears too.
Cheers!
Here’s one discussing Supershear in the 2002 Alaskan Denali Earthquake.
http://pangea.stanford.edu/~edunham/publications/Dunham_Archuleta_Denali_BSSA04.pdf
Warning: I read a lot of seismology papers and this one gets way too technical for me faster than normal.
Sweethearts jelly beans.
Chocolate eggs.
Ugh.
Turning green bout now. Poor choice of quake food.
Friend a few mi from here (Palm Springs area) is saying a few things fell, but no damage.
This one has the best abstract, but is not available free full-text online.
Science 6 June 2008:
Vol. 320. no. 5881, pp. 1323 - 1325
DOI: 10.1126/science.1155030
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Reports
The Aftershock Signature of Supershear Earthquakes
Michel Bouchon1* and Hayrullah Karabulut2
Recent studies show that earthquake faults may rupture at speeds exceeding the shear wave velocity of rocks. This supershear rupture produces in the ground a seismic shock wave similar to the sonic boom produced by a supersonic airplane. This shock wave may increase the destruction caused by the earthquake. We report that supershear earthquakes are characterized by a specific pattern of aftershocks: The fault plane itself is remarkably quiet whereas aftershocks cluster off the fault, on secondary structures that are activated by the supershear rupture. The post-earthquake quiescence of the fault shows that friction is relatively uniform over supershear segments, whereas the activation of off-fault structures is explained by the shock wave radiation, which produces high stresses over a wide zone surrounding the fault.
that is as probably non-technical as it can be presented. The ‘shock wave’ are the seismic waves passing through the earth. If the fault ruptures faster than wave promulgation is what is being spoken about.