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Alert Level: UNASSIGNED, Color Code: UNASSIGNED
2014-05-29 21:14:00 UTC




(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued: (20140529/2114Z)
(3) Volcano: Ahyi (VNUM #284141)
(4) Current Color Code: UNASSIGNED
(5) Previous Color Code: YELLOW
(6) Source: U.S. Geological Survey
(7) Notice Number: 2014/N2
(8) Volcano Location: N 20 deg 25 min E 145 deg 1 min
(9) Area: Northern Mariana Islands
(10) Summit Elevation: -449 ft (-137 m)
(11) Volcanic Activity Summary: Seismic activity indicative of submarine eruptions near Ahyi seamount has ended. The last signal from the Ahyi area received on distant seismometers was recorded on May 17. NOAA scientists working in the vicinity of Ahyi on the research vessel Hi'ialakai in mid-May reported no significant signs of ongoing submarine venting.

Based on the apparent cessation of activity, we are returning Ahyi seamount to UNASSIGNED.

The exact location of the April-May 2014 activity in the northern Mariana Islands remains uncertain. Additional investigations will be required to further constrain the source vent and details of the type of submarine volcanic activity. Submarine vents from active Farallon de Pajaros (Uracas) Island 18 km (11 mi) northwest of Ahyi seamount is one potential candidate.

At no time during the period of unrest was anything observed in satellite imagery that suggested activity had reached the surface. A single shipboard sighting of possible floating debris near the southern shoreline of Farallon de Pajaros (Uracas) Island in mid-May may have been related to the unrest, but this remains uncertain.
(12) Volcanic cloud height: No cloud produced.
(13) Other volcanic cloud information: Nil.
(14) Remarks: Ahyi seamount is a large conical submarine volcano that rises to within 137 m (450 ft) of the sea surface about 18 km (11 mi) southeast of Farallon de Pajaros (Uracas) Island in the northern Marianas, about 600 km (370 mi) north of the island of Saipan. In the past, discolored water has been observed over the submarine volcano. In 1979, the crew of a fishing boat felt shocks over the summit area and then observed 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 or 9 miles) at a location near the southern base of Ahyi.

(15) Contacts: USGS Northern Marianas Duty Scientist (808) 967-8815
http://volcano.wr.usgs.gov/cnmistatus.php


CNMI Emergency Management Office (670) 322-9274
http://www.cnmiemo.gov.mp/
(16) Next Notice: A new VAN will be issued if conditions change significantly or alert levels are modified.



NMI/USGS Volcanic Activity Notice

Volcano: Ahyi (VNUM #284141)

Current Volcano Alert Level: UNASSIGNED
Previous Volcano Alert Level: ADVISORY

Current Aviation Color Code: UNASSIGNED
Previous Aviation Color Code: YELLOW

Issued: Friday, May 30, 2014, 7:14 AM ChST
Source: U.S. Geological Survey
Notice Number: 2014/N2
Location: N 20 deg 25 min E 145 deg 1 min
Elevation: -449 ft (-137 m)
Area: Northern Mariana Islands

Volcanic Activity Summary: Seismic activity indicative of submarine eruptions near Ahyi seamount has ended. The last signal from the Ahyi area received on distant seismometers was recorded on May 17. NOAA scientists working in the vicinity of Ahyi on the research vessel Hi'ialakai in mid-May reported no significant signs of ongoing submarine venting.

Based on the apparent cessation of activity, we are returning Ahyi seamount to UNASSIGNED.

The exact location of the April-May 2014 activity in the northern Mariana Islands remains uncertain. Additional investigations will be required to further constrain the source vent and details of the type of submarine volcanic activity. Submarine vents from active Farallon de Pajaros (Uracas) Island 18 km (11 mi) northwest of Ahyi seamount is one potential candidate.

At no time during the period of unrest was anything observed in satellite imagery that suggested activity had reached the surface. A single shipboard sighting of possible floating debris near the southern shoreline of Farallon de Pajaros (Uracas) Island in mid-May may have been related to the unrest, but this remains uncertain.


Recent Observations:
[Volcanic cloud height] No cloud produced.
[Other volcanic cloud information] Nil.

Remarks: Ahyi seamount is a large conical submarine volcano that rises to within 137 m (450 ft) of the sea surface about 18 km (11 mi) southeast of Farallon de Pajaros (Uracas) Island in the northern Marianas, about 600 km (370 mi) north of the island of Saipan. In the past, discolored water has been observed over the submarine volcano. In 1979, the crew of a fishing boat felt shocks over the summit area and then observed 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 or 9 miles) at a location near the southern base of Ahyi.



Contacts: USGS Northern Marianas Duty Scientist (808) 967-8815
http://volcano.wr.usgs.gov/cnmistatus.php


CNMI Emergency Management Office (670) 322-9274
http://www.cnmiemo.gov.mp/

Next Notice: A new VAN will be issued if conditions change significantly or alert levels are modified.