This paper develops a set of quantitative variables to characterise urban forms at the metropolitan level and, in particular, to distinguish compactness from 'sprawl'. It first reviews and analyses past research on the definitions of urban form, compactness and sprawl, and corresponding quantitative variables. Four quantitative variables are developed to measure four dimensions of urban form at the metropolitan level: metropolitan size, activity intensity, the degree that activities are evenly distributed, and the extent that high-density sub-areas are clustered. Through a series of simulation analyses, the global Moran coefficient, which characterises the fourth dimension, distinguishes compactness from sprawl. It is high, intermediate and close to zero for monocentric, polycentric and decentralised sprawling forms respectively. In addition, the more there is more local sprawl, composed of discontinuity and strip development, the lower is the Moran coefficient.

Two years into the introduction of City CarShare in San Francisco, California, nearly 30% of members have gotten rid of one or more cars, and two-thirds stated that they opted not to purchase another car. By City CarShare's second anniversary, 6.5% of members' trips and 10% of their vehicle miles traveled were in carshare vehicles. Matched-pair comparisons with a statistical control group suggest that, over time, members have reduced their total vehicular travel. Because carshare vehicles tended to be small and fuel-efficient, per capita gasoline consumption and greenhouse gas emissions among members also appeared to go down. Suppressed travel likely reflected a combination of influences: reduced car ownership, more judicious and selective use of cars for particular trip purposes, and multiple-occupant carshare trips. Carsharing, however, has also enhanced mobility and allowed members to reach more destinations in and around San Francisco conveniently and to do so more quickly. Because it widens mobility choices and offers a resourceful form of automobility, carsharing is a welcome addition to the urban transportation sector in cities such as San Francisco.

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Abstract:Mt. Baekdu is a volcano near the North Korea-Chinese border that experienced a few destructive eruptions over the course of its history, including the well-known 1702 A.D eruption. However, signals of unrest, including seismic activity, gas emission and intense geothermal activity, have been occurring with increasing frequency over the last few years. Due to its close vicinity to a densely populated area and the high magnitude of historical volcanic eruptions, its potential for destructive volcanic activity has drawn wide public attention. However, direct field surveying in the area is limited due to logistic challenges. In order to compensate for the limited coverage of ground observations, comprehensive measurements using remote sensing techniques are required. Among these techniques, Differential Interferometric SAR (DInSAR) analysis is the most effective method for monitoring surface deformation and is employed in this study. Through advanced atmospheric error correction and time series analysis, the accuracy of the detected displacements was improved. As a result, clear uplift up to 20 mm/year was identified around Mt. Baekdu and was further used to estimate the possible deformation source, which is considered as a consequence of magma and fault interaction. Since the method for tracing deformation was proved feasible, continuous DInSAR monitoring employing upcoming SAR missions and advanced error regulation algorithms will be of great value in monitoring comprehensive surface deformation over Mt. Baekdu and in general world-wide active volcanoes.