Japan Geoscience Union Meeting 2016

Presentation information

International Session (Poster)

Symbol H (Human Geosciences) » H-TT Technology & Techniques

[H-TT08] Geoscientific applications of high-definition topography and geophysical measurements

Sun. May 22, 2016 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Yuichi S. Hayakawa(Center for Spatial Information Science, The University of Tokyo), Hiroshi, P. Sato(College of Humanities and Sciences, Nihon University), Shoichiro Uchiyama(National Research Institute for Earth Science and Disaster Prevention), Shigekazu Kusumoto(Graduate School of Science and Engineering for Research, University of Toyama), Thad Wasklewicz(East Carolina University), Daniele Giordan(National Research Council, Rome), Hiroyuki Obanawa(Center for Environmental Remote Sensing, Chiba University)

5:15 PM - 6:30 PM

[HTT08-P08] Spatial pattern analysis of wall surface modification by weathering in Yoshimi-Hyakuana cave using terrestrial laser scanning

*Yuichi S. Hayakawa1, Chiaki T. Oguchi2, Hisashi Aoki3, Natsuki Ariga3 (1.Center for Spatial Information Science, The University of Tokyo, 2.Graduate School of Science and Engineering, Saitama University, 3.Graduate School of Education, Tokyo Gakugei University)

Keywords:terrestrial laser scanning, weathering, point cloud, digital elevation model

Detection and quantitative evaluation of actual changes in rock surface morphology are crucial for understanding weathering processes. Repeated measurements by terrestrial laser scanning (TLS) were performed at test sites in the Yoshimi-Hyakuana cave in Saitama Prefecture, central Japan. Six time series of point clouds were obtained in 3 years, and those point clouds were finely aligned to each other at millimeter-scale accuracies applying the ICP algorithm for unchanged domains. Digital elevation models (DEMs) were then produced by projecting the point cloud on a vertical plane at a resolution of millimeters. Centimeter-scale changes in the wall surface were successfully detected. Such changes are particularly active at a wall close to the outlet of the cave, and are found to be concentrated on a certain height above ground. This indicates that the rock surface modification is actively induced by salt weathering where groundwater evaporation is favorable. In contrast, walls located more inside of the cave show less or almost no changes in their surface. The air temperature and humidity monitoring at the wall surfaces supports this fact, suggesting the decreasing effects of environmental fluctuations which are higher around the cave entrance but lower in the inner side. This study is supported by JSPS KAKENHI Grants (20312803, 25702014).