U-Pb dating was known as a tool to date the oldest rocks on the earth and was applicable to ages as old as 0.1-1 billion years range. However, the method can now be used to date even Quaternary materials using easily-accessible equipment. Therefore it may be true that U-Pb dating can now be applicable to engineering geology.

This paper deals with a brief introduction to U-Pb dating, showing its principle, experimental procedures using zircon, and some notes on interpreting the age data. It also deals with how the zircon U-Pb method has been used for Quaternary tephras, Quaternary granites, and geothermal exploitations. Finally, this paper shows a new application dealing with landslide. A core drilling was performed at Matsushima, Miyagi Prefecture, where a large landslide is supposed to have happened, creating picturesque small islands in the Matsushima Bay. Zircon U-Pb dating was performed at three points, namely, upper block of the supposed landslide, the supposed landslide layer, and lower block of the supposed landslide, using tuffs and tuffaceous sandstone. All of them yielded ～15 Ma, which indicates there is no geochronological evidence for the supposed landslide.

In conclusion, zircon U-Pb method can now be applicable to a variety of engineering geological aspects（landslide, active faults, etc.）and are expected to be used widely.

In this study, we introduce some applicable results to the geophysical exploration of the cosmic rays muons as a technique to visualize internal density structure for underground and large structures. We have investigated the applicability of the exploration to a cavity in the ground, an internal structure of the nuclear reactor, a fractured zone and water level change of the reservoirs etc. in which have been applied to the depth from several meters to 300 meters. We investigate the measurement time by numerical computations and case study for cosmic ray muons exploration because the measurement time greatly varies by condition of the engineering geological application.

We estimated the measurement time when the covering depth, density of the soil and the zenith angle by the coincident measurement method of the conventional detector of 24.5cm in diameter and distance 140cm between the two detectors. As a result, for example, five days are approximately necessarily to detect the significant difference of the muons counting with density differences 0.2g/cm³ and the zenith angle less than 30 degrees with covering depth of 50m with the cavity of 5m in diameters.

In addition, we show the required measurement time is only 10 minutes per one measurement point by the omnidirectional measurement by the spherical detector of 24.5cm in diameter with the covering depth of 11m and cavity thickness of 3m.

Airborne laser measurement has been widely known as a surveying technique for acquiring topographic data with a high accuracy, and it has been lately utilized as a differential analysis for evaluating the amount of the sediment caused by a large-scale landslide. However, it is impossible to detect landslide behavior at speed of a few centimeters using aerial laser measurement. In this study, we have developed the analytic method to evaluate landslide variation amount with a high accuracy by discriminating characteristic land features from digital elevation model, which is called S-DEM or Substratum Digital Elevation Model, using laser point clouds at the position shifted from the ground with an arbitrary distance. We also describe the result that it is possible to predict the movement of debris slide occurred in the area of landslide using the method we developed.

Recently, surface displacement monitoring using interferometric synthetic aperture radar （InSAR） analysis has been investigated by many researchers. InSAR analysis has a great advantage to observe spatial distribution of surface displacement by utilizing data acquired with radar installment on a satellite. In this study, we detected landslide surface displacements around Jinnosuke-dani, Bettou-dani, and Yuno-tani in Mt. Haku using InSAR analysis of ALOS-2 imageries. As a result of the analysis, we found landslide displacement with the amount of 5-10 cm in line of sight direction. The displacement areas detected by the analysis correspond to the landslide blocks interpreted by geological and geographical analysis, and our results identify the active landslide blocks of the region. These results demonstrate the effectiveness of InSAR analysis to monitor landslide displacements.

In this study, a set of adequate mapping methods for landform analysis in steep rock walls has been proposed and its efficiency has been confirmed. Two rock walls were selected in Fukuoka Castle ruins. Recently, the DEM has been easily calculated via photogrammetry using SfM with coordinated control points. The map image of the steep slopes calculated from the DEM is not always available to show sufficient landform because of the small horizontal extension comparing to the vertical one.

To convert the coordinates of the three control points on a wall, the geometrical meaning has been recognized and calculation formulas using spreadsheet software for the parallel and rotational movements have been created. They are converted from their original coordinates to new ones．They are at the origin, on the X-axis and on the XY plane. The converted DEM of the wall was calculated via photogrammetry using SfM with the converted coordinate data of these points. In addition, landform analysis of the contour and relief maps were conducted using GIS with the DEM.

Consequently, the roughness or relief due to piled stones from the maps is easier to be recognized than those on maps using the general DEM before conversion. In addition, averaging of the DEM on some unit area was conducted using a spatial-filtering GIS function. Therefore, it can be concluded that if the averaged DEM can represent an ideal landform of the wall, the degree and extent of its deformation can be estimated.

This study explains the significance of the coordinate conversion of the control points before the DEM analysis in SfM and the importance of the DEM-scale adjustment before the landform analysis via GIS. Consequently, the proposed set of methods could be used for solving steep slope problems in engineering geology.