Jackson Segment

No photo available for this volcano
  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 42.15°N
  • 127.05°W

  • -3100 m
    -10168 ft

  • 331032
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

Most Recent Weekly Report: 11 April-17 April 2001 Citation IconCite this Report


Scientists from NOAA used the T-phase Monitoring System to search for megaplumes from a possible eruption of the Jackson Segment of the Gorda Ridge that began on 3 April. They did not find evidence of a plume after collecting 25 vertical hydrographic casts during 11-16 April. Two bottom camera tows were also collected, but the film had not been developed at the time of this report. By 11 April seismic activity was at very low levels, possibly below the detection threshold of the T-phase Monitoring System.

Source: NOAA Vents Program


Most Recent Bulletin Report: August 2001 (BGVN 26:08) Citation IconCite this Report


Additional investigations show no evidence of April eruption

After a 3-9 April 2001 seismic swarm that was traced to the Jackson Segment of the Gorda Ridge (BGVN 26:03), seismically inferred volcanism remained unconfirmed. The signals detected on 3 April 2001 were located on the S side of the segment, and continued through 9 April. During a six-day period instruments detected over 3,500 earthquakes; 548 epicenters were located. By 11 April seismic activity was at very low levels, possibly below the detection threshold of the T-phase monitoring system.

On 10 April, an NSF- and NOAA-funded response team departed on the ship RV New Horizon to search for mega-plumes from the event, but no plumes were detected. On 26 April the U.S. Coast Guard ship Healy conducted conductivity, temperature, and depth (CTD) probes and took dredge samples on the site. A report made available in late May indicated that investigations from the Healy also failed to find evidence of an eruption at the Jackson Segment and detected no significant thermal anomalies from hydrothermal plumes. Rocks recovered by dredge from the sea floor were clearly old. The entire segment was also resurveyed with multibeam sonar to compare with bathymetry collected before the earthquake swarm. The early April earthquake swarm may have indicated moving magma that never made it up to the sea floor to erupt.

Information Contacts: Bob Embley (NOAA/PMEL) and Jim Cowen (SOEST, Univ. of Hawaii), NOAA Pacific Marine Environmental Laboratory (PMEL), 2115 SE Osu Drive, Newport, OR 97365 USA (Email: embley@pmel.noaa.gov, jcowen@soest.hawaii.edu, URL: http://www.pmel.noaa.gov/vents/acoustics/seismicity/ seismicity.html).

Weekly Reports - Index


2001: April


11 April-17 April 2001 Citation IconCite this Report


Scientists from NOAA used the T-phase Monitoring System to search for megaplumes from a possible eruption of the Jackson Segment of the Gorda Ridge that began on 3 April. They did not find evidence of a plume after collecting 25 vertical hydrographic casts during 11-16 April. Two bottom camera tows were also collected, but the film had not been developed at the time of this report. By 11 April seismic activity was at very low levels, possibly below the detection threshold of the T-phase Monitoring System.

Source: NOAA Vents Program


4 April-10 April 2001 Citation IconCite this Report


At about 1800 on 3 April an underwater eruption may have occurred at the Gorda Ridge. Volcanic seismicity in the form of T-waves was detected coming from the Gorda Ridge ~200 m W of the S coast of Oregon. The signals were detected at seismometers maintained by NOAA's Pacific Marine Environmental Laboratory (PMEL). They inferred that the seismic events came from the ridge's Jackson segment at approximately 42.15°N, 127.05°W. This spot lies just S of the North Gorda segment, which was the site of an eruption in February 1996. The 3 April signals appeared analogous to those of the February 1996 event, and were located near the summit of the "narrowgate" on the S side and also showed indications of dike propagation. The seismic activity lacked any large main shock, but instead consisted of rapidly repeating earthquakes and intervals of continuous tremor. The activity continued at a moderate rate through at least 9 April, with nearly 2,500 earthquakes detected since activity began. A response effort is being planned by the combined event response team funded by NSF and NOAA using the ship RV Horizon.

Sources: Associated Press; CNN; NOAA Vents Program


Bulletin Reports - Index


Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

03/2001 (BGVN 26:03) Volcanic seismicity along the Jackson segment, early April 2001

08/2001 (BGVN 26:08) Additional investigations show no evidence of April eruption




Information is preliminary and subject to change. All times are local (unless otherwise noted)


March 2001 (BGVN 26:03) Citation IconCite this Report


Volcanic seismicity along the Jackson segment, early April 2001

Volcanic seismicity along the Jackson Segment of the Gorda Ridge (figure 1) was detected by the NOAA/PMEL T-Phase Monitoring System beginning at ~1750 on 3 April 2001. Data were recorded using the U.S. Navy's Sound Surveillance System (SOSUS) in the NE Pacific, and were similar to the seismicity produced by the February 1996 eruption along the North Gorda Ridge segment of the ridge (BGVN 21:02).

Figure (see Caption) Figure 1. Map of Gorda Ridge segments (index map in upper left corner), with arrows locating the 2001 eruption along the Jackson segment; this segment lies ~60 km SW of the site where the February 1996 eruption initiated, along the North Gorda segment. Courtesy of NOAA/PMEL.

For the current episode, epicenters were inferred from hydroacoustic analysis (figure 2). Multibeam bathymetry from the area indicated that the signal source came from within the central axial valley. The activity was located near the summit of the "narrowgate" on the S side of the ridge, and indicated possible dike propagation.

Figure (see Caption) Figure 2. Earthquake locations for the Gorda Ridge derived from hydroacoustic monitoring. The time interval for these events is undisclosed. Courtesy of NOAA/PMEL.

The source of the recorded signals was analogous to the 1996 event's relative location along the ridge. The nature of the seismic character was consistent with other examples of volcanic seismicity that were detected hydroacoustically. These events were characterized by low-magnitude earthquakes emergent from background ambient ocean noise without a large "mainshock" to initiate the sequence. These were then followed by over a week of elevated seismicity, with rapidly repeating (up to 100 events/hour) small earthquakes and nearly continuous volcanic tremor in the range of 2-30 Hz (figure 3). The events were heard on multiple SOSUS arrays without the benefit of beamforming, indicating that they were relatively loud. Recorded epicenter locations as of 4 April indicated lateral migration of events to the S, typical of dike injections. As of 14 April, no hydrothermal plumes had been successfully detected.

Figure (see Caption) Figure 3. Histogram showing seismic events per hour along the Gorda Ridge during 3-12 April 2001. After a figure of NOAA/PMEL.

Information Contacts: Chris Fox, Bob Dziak, and Paul Will, NOAA Pacific Marine Environmental Laboratory (PMEL), 2115 SE OSU Drive, Newport, OR 97365 USA (Email: fox@pmel. noaa.gov, dziak@pmel.noaa.gov, will@pmel.noaa.gov, URL: http://www.pmel.noaa.gov/).


August 2001 (BGVN 26:08) Citation IconCite this Report


Additional investigations show no evidence of April eruption

After a 3-9 April 2001 seismic swarm that was traced to the Jackson Segment of the Gorda Ridge (BGVN 26:03), seismically inferred volcanism remained unconfirmed. The signals detected on 3 April 2001 were located on the S side of the segment, and continued through 9 April. During a six-day period instruments detected over 3,500 earthquakes; 548 epicenters were located. By 11 April seismic activity was at very low levels, possibly below the detection threshold of the T-phase monitoring system.

On 10 April, an NSF- and NOAA-funded response team departed on the ship RV New Horizon to search for mega-plumes from the event, but no plumes were detected. On 26 April the U.S. Coast Guard ship Healy conducted conductivity, temperature, and depth (CTD) probes and took dredge samples on the site. A report made available in late May indicated that investigations from the Healy also failed to find evidence of an eruption at the Jackson Segment and detected no significant thermal anomalies from hydrothermal plumes. Rocks recovered by dredge from the sea floor were clearly old. The entire segment was also resurveyed with multibeam sonar to compare with bathymetry collected before the earthquake swarm. The early April earthquake swarm may have indicated moving magma that never made it up to the sea floor to erupt.

Information Contacts: Bob Embley (NOAA/PMEL) and Jim Cowen (SOEST, Univ. of Hawaii), NOAA Pacific Marine Environmental Laboratory (PMEL), 2115 SE Osu Drive, Newport, OR 97365 USA (Email: embley@pmel.noaa.gov, jcowen@soest.hawaii.edu, URL: http://www.pmel.noaa.gov/vents/acoustics/seismicity/ seismicity.html).

The Global Volcanism Program has no synonyms or subfeatures listed for Jackson Segment.

Eruptive History


The Global Volcanism Program is not aware of any Holocene eruptions from Jackson Segment. If this volcano has had large eruptions (VEI >= 4) prior to 10,000 years ago, information might be found on the Jackson Segment page in the LaMEVE (Large Magnitude Explosive Volcanic Eruptions) database, a part of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).

Deformation History


There is no Deformation History data available for Jackson Segment.

Emission History


There is no Emissions History data available for Jackson Segment.

The Global Volcanism Program has no photographs available for Jackson Segment.

Smithsonian Sample Collections Database


There are no samples for Jackson Segment in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

Affiliated Sites