High slip rate for a low seismicity along the Palu‐Koro active fault in central Sulawesi (Indonesia)
Olivier BellierMichel SébrierThierry BeaudouinMichel VilleneuveRégis BraucherDidier BourlèsLionel SiaméEka PutrantoIndyo Pratomo
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Abstract:
In eastern Indonesia, the Central Sulawesi fault system consists of complex left‐lateral strike‐slip fault zones located within the triple junction area between the Pacific, Indo‐Australian and Eurasian plates. Seismicity in Central Sulawesi documents low‐magnitude shallow earthquakes related, from NW to SE, to the NNW‐trending Palu‐Koro (PKF) and WNW‐trending Matano fault zones. Study of the active fault traces indicates a northward growing complexity in the PKF segmentation. Left‐lateral displacement of 370 ± 10 m of streams incised within fans, whose deposition has been dated at 11 000 ± 2300 years, yields a calculated PKF horizontal slip rate of 35 ± 8 mm yr −1 . This geologically determined long‐term slip rate agrees with the far‐field strike‐slip rate of 32–45 mm yr −1 previously proposed from GPS measurements and confirms that the PKF is a fast slipping fault with a relatively low level of seismicity.Keywords:
Slipping
Triple junction
During tactile exploration, partial slips occur systematically at the periphery of fingertip-object contact prior to full slip. Although the mechanics of partial slips are well characterized, the perception of such events is unclear. Here, we performed psychophysical experiments to assess partial slip detection ability on smooth transparent surfaces. In these experiments, the index fingertip of human subjects was stroked passively by a smooth, transparent glass plate while we imaged the contact slipping against the glass. We found that subjects were able to detect fingertip slip before full slip occurred when, on average, only 48% of the contact area was slipping. Additionally, we showed that partial slips and plate displacement permitted slip detection, but that the subjects could not rely on tangential force to detect slipping of the plate. Finally, we observed that, keeping the normal contact force constant, slip detection was impeded when the plate was covered with a hydrophobic coating dramatically lowering the contact friction and therefore the amount of fingertip deformation. Together, these results demonstrate that partial slips play an important role in fingertip slip detection and support the hypothesis that the central nervous system relies on them to adjust grip force during object manipulation.
Slipping
Contact area
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