微少量の海岸砂に含まれる重鉱物によるSEM-EDXを用いた法科学的な異同識別に必要な分析点数とその手法| 微少量の海岸砂に含まれる重鉱物によるSEM-EDXを用いた法科学的な異同識別に必要な分析点数とその手法 |
| 杉田律子 |
| Number of grains required to examine heavy minerals by SEM-EDX for forensic discrimination of small quantity of coast sand and proposal of its analytical method |
| Ritsuko SUGITA |
| Keywords: coast sand, heavy minerals, forensic geology, SEM- EDX |
| Abstract Sediments recovered from crime scenes, suspects, and victims are crucial evidence in linking individuals to a crime. Coastal sand is one such type of evidence but presents unique challenges compared to soil. The grains of coastal sand are constantly moved and rubbed against each other by waves. This movement also sorts the grains by size and weight, and removes surface coatings like organic matter and iron oxide. As a result, some common forensic soil comparison methods, such as color examination and the ratio of light to heavy minerals, are less applicable to coastal sand samples. However, heavy mineral assemblages may serve as a useful indicator for distinguishing these sand samples, despite the effects of mineral sorting. This study examines the necessary sample sizes to estimate the ratios of minerals in the pyroxene group. The coastal sand samples analyzed predominantly contain heavy minerals from the pyroxene group. Using SEM-EDX analysis, the minerals are classified as orthopyroxene (Opx), clinopyroxene (Cpx), ilmenite, and magnetite. The ratio of Opx to Cpx in 50 to 70 pyroxene grains is sufficient to characterize the sampling sites. SEM-EDX provides more objective and reliable results in mineral identification than traditional microscope observations, reducing examiner bias and dependence on skill level. |
| Geopol. Sci., Med. Geol. and Urban Geol. 2024 Vol.20, p. 9-14 Article: Received 17 Oct. 2024; Accepted 19 Dec. 2024 |
微少量の海岸砂に含まれる重鉱物によるSEM-EDXを用いた法科学的な異同識別に必要な分析点数とその手法
| 2024年能登半島自然災害の形跡 |
| 福山厚子・福山建一 |
| Traces of the 2024 Noto Peninsula earthquake and heavy rains |
| Atsuko FUKUYAMA and Kenichi FUKUYAMA |
| はじめに 2024年1月1日，石川県能登半島に発生した地震はM7.6を観測し，震源断層は北東から南西方向に150 kmの範囲の逆断層型で，家屋の倒壊や火災，津波などにより多くの死傷者を出した（鈴木2024；平松2024；平松ほか2024）．続いて9月21日から22日にかけ，能登半島北部を中心に発生した豪雨は河川の氾らん，山林等の土砂崩れなど地震災害で脆弱になった一帯にさらなる甚大な被害を与えた（国土交通省，2024）．特に被害の大きかった輪島市は21日から22日午前10時までに478mmの記録的大雨を観測した（気象庁2024）． 能登半島豪雨から数日後の2024年9月28日（曇り，気温22℃）に石川県金沢市から“のと里山海道”を通り，鳳至郡穴水から輪島市内（図1）までの状況を確認したので報告する． |
| Geo-pol. Sci., Med. Geol. and Urban Geol. 2024 Vol.20, p.1-8 Photo: Received 15, Nov. 2024 |
2024年能登半島自然災害の形跡