Slip Sequences in Laboratory Experiments Resulting from Inhomogeneous Shear as Analogs of Earthquakes Associated with a Fault Edge |
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| Authors: | Shmuel M Rubinstein Itay Barel Ze’ev Reches Oleg M Braun Michael Urbakh Jay Fineberg |
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| Institution: | (1) The Racah Institute of Physics, The Hebrew University of Jerusalem, Givat Ram, 91904 Jerusalem, Israel;(2) The School of Chemistry, Tel Aviv University, 69978 Tel Aviv, Israel;(3) School of Geology and Geophysics, University of Oklahoma, Norman, OK 73019, USA;(4) Institute of Physics, National Academy of Sciences of Ukraine, Kiev, 03028, Ukraine; |
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| Abstract: | Faults are intrinsically heterogeneous with common occurrences of jogs, edges and steps. We therefore explore experimentally
and theoretically how fault edges may affect earthquake and slip dynamics. In the presented experiments and accompanying theoretical
model, shear loads are applied to the edge of one of two flat blocks in frictional contact that form a fault analog. We show
that slip occurs via a sequence of rapid rupture events that initiate from the loading edge and are arrested after propagating
a finite distance. Each successive event extends the slip size, transfers the applied shear across the block, and causes progressively
larger changes of the contact area along the contact surface. Resulting from this sequence of events, a hard asperity is dynamically
formed near the loaded edge. The contact area beyond this asperity is largely reduced. These sequences of rapid events culminate
in slow slip events that precede a major, unarrested slip event along the entire contact surface. We suggest that the 1998
M5.0 Sendai and 1995 off-Etorofu earthquake sequences may correspond to this scenario. Our work demonstrates, qualitatively,
how the simplest deviation from uniform shear loading may significantly affect both earthquake nucleation processes and how
fault complexity develops. |
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