2024年04月16日(火)1 tweet 14時間前 USGS@USGS #DYK the USGS operates five #volcano observatories throughout the U.S.? 🌋 With approximately 170 potentially active volcanoes in the U.S., this is important work! Learn more about what they do and where they are located➡️ ow.ly/Qab950Rfugu @USGSVolcanoes #MagmaMonday pic.twitter.com/sjYomHpsSr Retweeted by Ryusuke IMURA retweeted at 08:35:37 2024年04月15日(月)3 t