-The Cocos plate subducts beneath North America at the Mexico trench. The northernmost segment of this trench, between the Orozco and Rivera fracture zones, has ruptured in a sequence of five large earthquakes from 1973 to 1985: the Jan. 30, 1973 Colima event (M, 7.5) at the northern end of the segment near Rivera fracture zone; the Mar. 14, 1979 Petatlan event (M s 7.6) at the southern end of ...

The morphology of the tarsal attachment system of the running spider Philodromus dispar Walckenaer 1826 (Araneae, Philodomidae) was studied using scanning electron microscopy and its performance was experimentally tested in traction force measurements. Each pretarsus bears a hierarchically built hairy adhesive pad that consists of a dense array of flattened setae covered with numerous microtric...

Vertical vibrations at the slider leading edge exited by a disk asperity were investigated in a drive level system, using laser Doppler vibrometry and acoustic emission (AE) sensors. The flying height change at the leading edge of a thermal flying-height control slider was measured for different power inputs to the heater element. The maximum spacing change at the slider leading edge was found ...

Synthesis of geodetic and seismological results for the 1979 Imperial Valley earthquake is approached using three-dimensional finite element modeling techniques. The displacements and stresses are calculated elastically throughout the modeled region. The vertical elastic structure in the model is derived from compressional and shear wave velocities as used in the seismic data analysis (Fuis et ...

Understanding contact between rough surfaces is of critical importance to the design of many engineering applications. Contact models rely on material properties and surface topography of the contacting surfaces as input parameters. Hence, the relevance of the contact models is dependent on their inherent assumptions and the accuracy with which the input parameters are determined. We have evalu...

Superlubricity of graphite and graphene has aroused increasing interest in recent years. Yet how to obtain a long-lasting superlubricity between graphene layers, under high applied normal load in ambient atmosphere still remains a challenge but is highly desirable. Here, we report a direct measurement of sliding friction between graphene and graphene, and graphene and hexagonal boron nitride (h...

Phosphorus L-edge and oxygen K-edge X-ray PhotoEmission Electron Microscopy (XPEEM) have been used to characterize the chemical nature of the cation present in tribochemical films via comparison with model Fe and Zn compounds. The results are contrasted to the P L-edge, P K-edge and S K-edge XANES data. The findings suggest that antiwear pads containing long chain zinc polyphosphate glass are f...

Friction is a complicated phenomenon involving nonlinear dynamics at different length and time scales. Understanding its microscopic origin requires methods for measuring force on nanometer-scale asperities sliding at velocities reaching centimetres per second. Despite enormous advances in experimental technique, this combination of small length scale and high velocity remain elusive. We presen...