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
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 (URL: https://www.pmel.noaa.gov/).
2001: April
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
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: CNN; NOAA Vents Program; Associated Press
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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).
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 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 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 (URL: https://www.pmel.noaa.gov/).
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 (URL: https://www.pmel.noaa.gov/).
The Global Volcanism Program has no synonyms or subfeatures listed for Jackson Segment.
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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 12,000 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).
There is no Deformation History data available for Jackson Segment.
There is no Emissions History data available for Jackson Segment.
The Global Volcanism Program has no photographs available for Jackson Segment.
Maps are not currently available due to technical issues.
There are no samples for Jackson Segment in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.
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MODVOLC Thermal Alerts | Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales. |
WOVOdat
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WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
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Volcanic Hazard Maps | The IAVCEI Commission on Volcanic Hazards and Risk has a Volcanic Hazard Maps database designed to serve as a resource for hazard mappers (or other interested parties) to explore how common issues in hazard map development have been addressed at different volcanoes, in different countries, for different hazards, and for different intended audiences. In addition to the comprehensive, searchable Volcanic Hazard Maps Database, this website contains information about diversity of volcanic hazard maps, illustrated using examples from the database. This site is for educational purposes related to volcanic hazard maps. Hazard maps found on this website should not be used for emergency purposes. For the most recent, official hazard map for a particular volcano, please seek out the proper institutional authorities on the matter. |
IRIS seismic stations/networks | Incorporated Research Institutions for Seismology (IRIS) Data Services map showing the location of seismic stations from all available networks (permanent or temporary) within a radius of 0.18° (about 20 km at mid-latitudes) from the given location of Jackson Segment. Users can customize a variety of filters and options in the left panel. Note that if there are no stations are known the map will default to show the entire world with a "No data matched request" error notice. |
UNAVCO GPS/GNSS stations | Geodetic Data Services map from UNAVCO showing the location of GPS/GNSS stations from all available networks (permanent or temporary) within a radius of 20 km from the given location of Jackson Segment. Users can customize the data search based on station or network names, location, and time window. Requires Adobe Flash Player. |
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EarthChem | EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS). |