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USGS Volcano Notice - DOI-USGS-NMI-2023-09-20T18:23:29-07:00


U.S. Geological Survey
Thursday, September 21, 2023, 11:28 AM ChST (Thursday, September 21, 2023, 01:28 UTC)

Report prepared by the U.S. Geological Survey.

RUBY (VNUM #284202)
15°37'12" N 145°34'12" E, Summit Elevation -755 ft (-230 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

No activity has been detected at Ruby in regional seismic and infrasound data or in satellite imagery over the past day. The plume of discolored water from the September 14-16 eruption has drifted slowly east and today was visible in satellite imagery in the ocean between Saipan and Anatahan. 

It is possible that further eruptive activity could occur at Ruby. There are no local monitoring stations at Ruby, which limits our ability to detect and characterize volcanic unrest there. The volcano is monitored by a regional geophysical monitoring network, including a station at Saipan (50 km away) as well as others in Guam, Japan, and an underwater pressure sensor at Wake Island.

Ruby is a submarine volcano that rises to within 230 m of the sea surface near the southern end of the Mariana arc northwest of the island of Saipan. The volcano was first detected in eruption in 1966 by sonar signals. In 1995, submarine explosions were heard, accompanied by a fish kill, sulfurous odors, bubbling water, and the detection of volcanic tremor.

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