Warning and evacuation in response to sediment-related disasters

On July 19, 2006, several sediment-related disasters (debris flows and landslides) occurred in Okaya and Suwa, Nagano Prefecture, Japan. In Okaya, neither the municipal government nor the residents had expected such a disaster, and they were unprepared. No evacuation of the population took place prior to the disaster, and two debris flows killed eight people. Another debris flow struck a retirement home. Fortunately, the first-floor residents could be evacuated to the second floor. In contrast, the nearby town of Suwa was evacuated voluntarily before the debris flow struck, and no fatalities occurred. This paper describes the situation at the time of the disaster, the evacuations in Okaya and in Suwa, and their consequences from the point of view of disaster-prevention personnel and retirement-home staff. Factors that should be considered in formulating warning and evacuation systems in response to sediment-related disasters are discussed.     

A method for localizing seismic sources whose signals are separated by an order of difference from the background noise

Doklady Earth Sciences -     

Accumulation of gas hydrates at the bottom of the sea during sequential deposits of sediments with different transport properties

Doklady Earth Sciences -     

慕课在远程网络教师教育领域的应用探析

随着近年来慕课浪潮的兴起,我国现行远程网络教师教育所存在的授课思想落后、授课形式枯燥单一以及评价方式重量轻质等问题逐渐凸显。现阶段我国慕课平台虽然提供了许多国外高校开设的有关教师教育的课程,但对于我国慕课学习者而言,还存在着一定的学习障碍。未来我国远程网络教师教育可以吸取慕课先进经验,在课程平台、教师角色以及教学流程等方面进行有效变革,从而促进我国远程网络教师教育健康发展。     

Lava tube shatter rings and their correlation with lava flux increases at Kīlauea Volcano,Hawai‘i

Shatter rings are circular to elliptical volcanic features, typically tens of meters in diameter, which form over active lava tubes. They are typified by an upraised rim of blocky rubble and a central depression. Prior to this study, shatter rings had not been observed forming, and, thus, were interpreted in many ways. This paper describes the process of formation for shatter rings observed at Kīlauea Volcano during November 2005–July 2006. During this period, tilt data, time-lapse images, and field observations showed that episodic tilt changes at the nearby Pu‘u ‘Ō‘ō cone, the shallow magmatic source reservoir, were directly related to fluctuations in the level of lava in the active lava tube, with periods of deflation at Pu‘u ‘Ō‘ō correlating with increases in the level of the lava stream surface. Increases in lava level are interpreted as increases in lava flux, and were coincident with lava breakouts from shatter rings constructed over the lava tube. The repetitive behavior of the lava flux changes, inferred from the nearly continuous tilt oscillations, suggests that shatter rings form from the repeated rise and fall of a portion of a lava tube roof. The locations of shatter rings along the active lava tube suggest that they form where there is an abrupt decrease in flow velocity through the tube, e.g., large increase in tube width, abrupt decrease in tube slope, and (or) sudden change in tube direction. To conserve volume, this necessitates an abrupt increase in lava stream depth and causes over-pressurization of the tube. More than a hundred shatter rings have been identified on volcanoes on Hawai‘i and Maui, and dozens have been reported from basaltic lava fields in Iceland, Australia, Italy, Samoa, and the mainland United States. A quick study of other basaltic lava fields worldwide, using freely available satellite imagery, suggests that they might be even more common than previously thought. If so, this confirms that episodic fluctuation in lava effusion rate is a relatively common process at basaltic volcanoes, and that the presence of shatter rings in prehistoric lava flow fields can be used as evidence that such fluctuations have occurred.