- Current Update, last updated May 30, 2014 07:14 :
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.
- Volcanic History Overview: 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 of the seamount 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. From the Smithsonian Global Volcanism Program.
- Location: Mariana Islands, Mariana Islands
Elevation: -137 m
Recent Eruption: 2001
- Hazard Assessments: Sako, M. K.; Trusdell, F. A.; Koyanagi, R. Y.; Kojima, George; Moore, R. B., 1995, Volcanic investigations in the Commonwealth of the Northern Mariana Islands, April to May 1994, USGS Open-File Report 94-705.
- Link to monitoring data: NMI Web Site
Volcanic Alert Level: UNASSIGNED Aviation Color Code: UNASSIGNED