RESUMO
Remote sensing observations of Searles Lake following the 2019 moment magnitude 7.1 Ridgecrest, California, earthquake reveal an area where surface ejecta is arranged in a repeating hexagonal pattern that is collocated with a solution-mining operation. By analyzing geologic and geotechnical data, here we show that the hexagonal surface ejecta is likely not a result of liquefaction. Instead, we propose dissolution cavity collapse (DCC) as an alternative driving mechanism. We support this theory with pre-event Interferometric Synthetic Aperture Radar data, which reveals differential subsidence patterns and the creation of subsurface void space. We also find that DCC is likely triggered at a lower shaking threshold than classical liquefaction. This and other unknown mechanisms can masquerade as liquefaction, introducing bias into liquefaction prediction models that rely on liquefaction inventories. This paper also highlights the opportunities and drawbacks of using remote sensing data to disentangle the complex factors that influence earthquake-triggered ground failure.
RESUMO
PURPOSE: To compare a standardized battery of biomechanical laboratory tests to assess the performance of popular foldable intraocular lenses (IOLs). SETTING: Biomedical testing facilities, Alcon Research, Ltd., Fort Worth, Texas, USA. METHODS: Using industry-standard biomechanical testing techniques, 1- and 3-piece foldable IOLs (Alcon AcrySof MA60BM, MA30BA, SA30AL, SA60AT; Allergan Sensar AR40, PhacoFlex II SI-40NB; Bausch & Lomb Soflex LI61U; Pharmacia & Upjohn CeeOn 920) and a 1-piece all-poly(methyl methacrylate) (PMMA) IOL (Alcon MZ30BD) were tested under identical conditions with regard to (1) tensile/elastic properties by comparing haptic pull strength and haptic elongation and (2) compression properties by comparing haptic compression forces, haptic compression force decay over time, and axial displacement. All tests were performed with the IOLs submersed in a controlled-temperature water bath (mean 35 degrees C +/- 2 degrees C [SD]). RESULTS: For all IOLs, the ultimate elongation and pull strength of the haptics before failure was highest with the Alcon SA30AL and SA60AT. Similarly, the force required to compress haptics to a prescribed 10.0 mm diameter was least with the SA30AL and the SA60AT lenses. These 1-piece lenses also showed the least decay of residual compression force as a function of time. Optic displacement along the optical axis with haptic compression to 10.0 mm was least with the Alcon 1-piece IOLs and the all-PMMA control IOL. CONCLUSION: AcrySof 1-piece SA30AL and SA60AT IOLs demonstrated superior biomechanical characteristics over other foldable IOL designs.
