NORTHERN MARIANA ISLANDS VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, April 28, 2023, 8:51 AM ChST (Thursday, April 27, 2023, 22:51 UTC)
Report prepared by the U.S. Geological Survey.
NORTHERN MARIANAS VOLCANOES
No eruptive activity or significant unrest was detected at the Northern Mariana Island volcanoes during the past week. No unrest or discolored water above Ahyi Seamount has been detected for the past several weeks. As a result, the volcano alert level and aviation color code were lowered to UNASSIGNED on April 26, 2023.
Monitoring of Northern Mariana Islands Volcanoes
Northern Mariana Island volcanoes are monitored remotely with satellite data, distant seismic stations in Guam and Chichijima, Japan, and hydroacoustic data from Wake Island. These observations might detect significant explosive activity in the CNMI, but because of the absence of functional local ground-based monitoring stations at the volcanoes, we cannot provide advanced warning of activity.
Ground-based geophysical monitoring data from stations on Anatahan and Sarigan islands have been unavailable since storm damage in August, 2017. In addition, data flow from an intermittently operational seismo-accoustic network on Saipan stopped completely on June 7, 2022. Current logistical challenges in the CNMI prevent visiting these sites to make repairs. A timeline for returning these stations to operation is uncertain. Due to a lack of direct geophysical monitoring on the islands, Anatahan and Sarigan volcano alert levels are designated UNASSIGNED.
Other volcanoes in the CNMI including Farallon de Pajaros, Supply Reef, Maug, Asuncion, Agrigan, Pagan, Almagan, and Guguan are not seismically monitored and are normally designated UNASSIGNED, absent other observations of activity.
For definitions of Aviation Color Codes and Volcano Alert Levels, see: http://volcanoes.usgs.gov/activity/alertsystem/index.php
SUBSCRIBE TO VOLCANO ALERT MESSAGES by email: http://volcanoes.usgs.gov/vns/
CNMI Homeland Security and Emergency Management
USGS Northern Mariana Duty Scientist (907) 786-7497
Satellite information, Washington VAAC