Considerations to Damage Patterns in the Marina District During the Loma Prieta Earthquake Based on Rayleigh Wave Investigation

Rayleigh wave investigation is made in the Marina District to study geotechnical factors controlling the damage patterns in the Loma Prieta earthquake. A portable system has been developed for determining a Rayleigh wave dispersion curve based on the measurements of artificially induced ground vibration or microtremor. Five sites are selected along a line crossing the hydraulic fill zone in which structures and/or buried utilities were significantly damaged. An inverse analysis on the measured dispersion curves results in a cross section of shear wave velocity profiles in the District. Site amplification and liquefaction potential of each site are estimated and discussed based on the Vs-profiles. It is shown that soil liquefaction is likely to have occurred throughout the fill zone, and that the predominant period of ground motions in the zone of structural damage is longer than and closer to the natural period of structures with soft first story than that in the non-damaged zone. These results appear to be consistent with the damage patterns in the District, indicating that the proposed investigation is effective for seismic zonation

Sodium temperature lidar based on injection seeded Nd:YAG pulse lasers using a sum-frequency generation technique

We report on a sodium (Na) temperature lidar based on two injection seeded Nd:YAG pulse lasers using single-pass sum-frequency generation. The laser power at 589 nm is 400 mW (40 mJ per pulse at a repetition rate of 10 Hz) and the pulse width is 22 nsec FWHM. The narrowband laser tuned to the Doppler broadened Na D(2) spectrum enables us to measure the temperature of the mesopause region (80-115 km). This solid-state transportable system demonstrated high performance and capability at Syowa Station in Antarctica for 3 years and at Uji in Japan for an additional year without any major operational troubles. (C) 2011 Optical Society of AmericaArticleOPTICS EXPRESS. 19(4):3553-3561 (2011)journal articl

Sodium temperature lidar observation at Syowa Station: Summary of three-year observations and unusually high temperature in 2002

Total 223 nights (2002 hours) of temperature measurement in the mesopause region (80-105 km) was successfully done in wintertime at Syowa Station (69ºS, 39ºE) starting from 2000 through 2002. Monthly mean temperatures were calculated using nightly mean temperatures and year-to-year variation was examined. The monthly temperature of 2002 shows unusually higher (25 K and 20 K) in June and July compared with previous 2 years. Variations of individual nights showed the temperatures at 80 km, 85 km and 110 km are in good agreement among three years through the observation period. The temperature of 2002 began to increase from the middle of May and was back to normal around the end of July in the limited altitude range of 90-105 km