Volcano Update from Archive



NORTHERN MARIANA ISLANDS WEEKLY UPDATE
Friday, May 2, 2014 9:52 AM PDT (Friday, May 2, 2014 16:52 UTC)


Report prepared by the U.S. Geological Survey.

AHYI VOLCANO (VNUM #284141)
20°25'12" N 145°1'48" E, Summit Elevation -449 ft (-137 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

The submarine activity that began on 24 April ChST (23 April UTC), and was detected by seismic stations on Pagan, Sarigan, Anatahan and Saipan is continuing. The location of the unrest has not been confirmed, but available data indicates that a likely source of the seismic activity is at or near Ahyi seamount. Since we are unable to precisely locate the source of the activity, it is possible that the vent is one of the other volcanic seamounts in the area.



Seismic activity has changed little over the past week. Satellite images show nothing out of the ordinary and we have received no reports of activity at the ocean's surface.

Ahyi seamount is a large conical submarine volcano that rises to within 137 m of the sea surface about 18 km SE of the island of Farallon de Pajaros (Uracas) in the northern Marianas. Water discoloration has been observed over the submarine volcano, and in 1979 the crew of a fishing boat felt shocks over the summit area followed by upwelling of sulfur-bearing water. On April 24-25, 2001 an explosive submarine eruption was detected seismically from a seismic station on Rangiroa Atoll, Tuamotu Archipelago. The event was well constrained (+/- 15 km) at a location near the southern base of Ahyi; the summit of the seamount lies within the location uncertainty.

PAGAN VOLCANO (VNUM #284170)
18°7'48" N 145°48' E, Summit Elevation 1870 ft (570 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Low-level unrest continued at Pagan Volcano throughout the past week. Seismic activity remains above background. A vapor plume was visible in web camera and satellite images during clear periods this week. This level of unrest is typical of the past several months.



Volcanic gas from Pagan may be noticed downwind of the volcano as distinctive sulfurous odors. Additional information about volcanic gas and vog can be found on the web at this address: http://hvo.wr.usgs.gov/hazards/FAQ_SO2-Vog-Ash/main.html



Access to the island may be restricted by the CNMI government. Contact the EMO for the latest information.





OTHER NORTHERN MARIANA ISLAND VOLCANOES



Other Northern Mariana Island volcanoes volcanoes show no signs of significant unrest.

USGS conduct daily checks of earthquake activity at Pagan, Sarigan, and Anatahan volcanoes.



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/



CONTACT INFORMATION:

USGS Northern Mariana Duty Scientist (808) 967-8815

http://volcano.wr.usgs.gov/cnmistatus.php



CNMI Homeland Security and Emergency Management Office (670) 664-2216

http://www.cnmihsem.gov.mp/