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Flow front advances into sea with no explosive venting
[The eruption] has continued without explosive venting visible from a distance. Observers on a boat that passed Marchena on 7 or 8 November reported vigorous steaming at the W coast. Water near the flow front was too hot to touch and numerous fumaroles were evident inland. Since David Day's 28-30 September visit, lava had formed a single broad front at the coast, closing the small bay where Day had landed.
Reports collected by Day provided additional information about the timing and characteristics of the early phases of the eruption. The first reported activity was a "suspicious" large cloud seen over Marchena on 25 September at 1840 from ~65 km S (at Bartolomé). An explosion was observed at 1905 from ~90 km SSE (Turtle Cove, Santa Cruz Island). A low white cloud near the coast was seen with infrared binoculars at about 2100. Witnesses at three sites ~65 km S reported 7-8 evenly spaced vents that remained active throughout the night. Incandescent ejecta appeared to rise roughly the equivalent of the island's elevation (~350 m), with height increases of ~25% during the strongest activity. A more vigorous vent, lying W of the others, was first seen at about 0300 on 26 September. Ejecta heights from the W vent appeared to exceed those from the other vents by ~50%.
Information Contacts: D. Day, Isla Santa Cruz.
The Global Volcanism Program has no Weekly Reports available for Marchena.
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.
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First historical eruption
Marchena . . . started erupting on 25 September. The TOMS instrument aboard the Nimbus-7 satellite passed at about 1100 and sensed no SO2, but the next pass, at the same time on 26 September, mapped a 300-km plume to the SW with an SO2 content estimated to be close to 100 kt. High SO2 values immediately over the volcano indicated that the eruption was still vigorous at that time. On the following day the plume was nearly twice as long, but had almost vanished by the same time on 28 September. Weather satellite images during this period showed low cloud cover, but no conclusive indication of the volcanic plume. . . .
Information Contacts: A. Carrasco, Charles Darwin Research Station; S. Doiron, GSFC; SAB.
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Lava from circumferential fissure flows into caldera and ocean
The eruption was first observed on 25 September at about 2100 from a ship ~ 75 km S of Marchena [but see 16:10], and glow remained visible through the night. A large black and white eruption cloud was reported the next day, but no glow was evident during cloudy weather that night from a nearby island. During an overflight around midday on 27 September, a dark plume was visible above low weather clouds.
When David Day and others arrived at the island's W coast on 28 September at about 2230, lava was flowing into the sea along a front ~1.5 km wide. Incandescence was evident at about 10 sites over a roughly 3 x 3 km area, but lava fountaining had apparently stopped. The next day, small quantities of Pele's hair were found on the beach near the fresh flows, along with substantial numbers of dead fish and other marine organisms. Scuba divers found glassy breccia near the shore, a zone of aa rubble extending seaward for several hundred meters, and, with gradual increase in slope from 25 to 35 m depth, a small lava flow that included pillow structures. A 30 September summit climb revealed new lava covering much of the caldera's SW floor, suggesting that a circumferential fissure several kilometers long had been active on the W to SW rim, supplying lava to both the caldera floor and the outer flank.
Information Contacts: D. Day, Isla Santa Cruz.
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Flow front advances into sea with no explosive venting
[The eruption] has continued without explosive venting visible from a distance. Observers on a boat that passed Marchena on 7 or 8 November reported vigorous steaming at the W coast. Water near the flow front was too hot to touch and numerous fumaroles were evident inland. Since David Day's 28-30 September visit, lava had formed a single broad front at the coast, closing the small bay where Day had landed.
Reports collected by Day provided additional information about the timing and characteristics of the early phases of the eruption. The first reported activity was a "suspicious" large cloud seen over Marchena on 25 September at 1840 from ~65 km S (at Bartolomé). An explosion was observed at 1905 from ~90 km SSE (Turtle Cove, Santa Cruz Island). A low white cloud near the coast was seen with infrared binoculars at about 2100. Witnesses at three sites ~65 km S reported 7-8 evenly spaced vents that remained active throughout the night. Incandescent ejecta appeared to rise roughly the equivalent of the island's elevation (~350 m), with height increases of ~25% during the strongest activity. A more vigorous vent, lying W of the others, was first seen at about 0300 on 26 September. Ejecta heights from the W vent appeared to exceed those from the other vents by ~50%.
Information Contacts: D. Day, Isla Santa Cruz.
This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.
Synonyms |
| Bindloe | Torres |
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There is data available for 1 confirmed Holocene eruptive periods.
1991 Sep 25 - 1991 Nov 16 (?) ± 15 days Confirmed Eruption VEI: 2
| Episode 1 | Eruption | West to SW caldera rim | ||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1991 Sep 25 - 1991 Nov 16 (?) ± 15 days | Evidence from Observations: Reported | ||||||||||||||||||||||||||||||||||
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List of 5 Events for Episode 1 at West to SW caldera rim
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There is no Deformation History data available for Marchena.
There is data available for 1 emission periods. Expand each entry for additional details.
| Start Date: 1991 Sep 26 | Stop Date: 1991 Sep 26 | Method: Satellite (Nimbus-7 TOMS) |
| SO2 Altitude Min: 2 km | SO2 Altitude Max: 2 km | Total SO2 Mass: 200 kt |
Data Details
| Date Start | Date End | Assumed SO2 Altitude | SO2 Algorithm | SO2 Mass |
| 19910926 | 2.0 | 200.000 |
The low shield volcano forming Marchena Island contains one of the largest calderas of the Galápagos Islands. A group of pyroclastic cones was constructed inside the caldera. Lava flows originating from the 6 x 7 km wide caldera have spilled through low points on the caldera rim and flowed down the flanks of the volcano, in some cases reaching the sea. The first historical eruption of Marchena occurred in 1991. 
A large tuff cone rises near Punta Calle on the southern coast of Marchena Island beyond fresh-looking lava flows west of the cone in the foreground. The low shield volcano forming Marchena Island contains one of the largest calderas of the Galápagos Islands. In contrast to other Galápagos volcanoes, the 6 x 7 km caldera and its outer flanks have been largely buried by a cluster of pyroclastic cones and associated lava flows. The first historical eruption of Marchena occurred in 1991. Maps are not currently available due to technical issues.
The following 57 samples associated with this volcano can be found in the Smithsonian's NMNH Department of Mineral Sciences collections, and may be availble for research (contact the Rock and Ore Collections Manager). Catalog number links will open a window with more information.
| Catalog Number | Sample Description | Lava Source | Collection Date |
|---|---|---|---|
| NMNH 118120-1 | Basalt | -- | 31 Jul 1970 |
| NMNH 118120-10 | Basalt | -- | 31 Jul 1970 |
| NMNH 118120-11 | Basalt | -- | 1 Aug 1970 |
| NMNH 118120-12 | Basalt | -- | 1 Aug 1970 |
| NMNH 118120-13 | Tuff | -- | 1 Aug 1970 |
| NMNH 118120-14 | Tuff | -- | 1 Aug 1970 |
| NMNH 118120-15 | Flow Rock | -- | 1 Aug 1970 |
| NMNH 118120-16 | Tuff | -- | 1 Aug 1970 |
| NMNH 118120-17 | Volcanic Rock | -- | 1 Aug 1970 |
| NMNH 118120-18 | Volcanic Rock | -- | 1 Aug 1970 |
| NMNH 118120-19 | Flow Rock | -- | 2 Aug 1970 |
| NMNH 118120-2 | Basalt | -- | 31 Jul 1970 |
| NMNH 118120-20 | Basalt | -- | 2 Aug 1970 |
| NMNH 118120-21 | Volcanic Rock | -- | 2 Aug 1970 |
| NMNH 118120-22 | Calcareous Sinter | -- | 2 Aug 1970 |
| NMNH 118120-23 | Tuff | -- | 2 Aug 1970 |
| NMNH 118120-24 | Lava | -- | 2 Aug 1970 |
| NMNH 118120-25 | Lava | -- | -- |
| NMNH 118120-26 | Tuff | -- | 2 Aug 1970 |
| NMNH 118120-27 | Plagioclase Basalt | -- | 2 Aug 1970 |
| NMNH 118120-28 | Basalt | -- | 2 Aug 1970 |
| NMNH 118120-29 | Basalt-Andesite | -- | 2 Aug 1970 |
| NMNH 118120-3 | Basaltic Spatter | -- | 31 Jul 1970 |
| NMNH 118120-30 | Plagioclase Basalt | -- | 2 Aug 1970 |
| NMNH 118120-31 | Picrite | -- | 2 Aug 1970 |
| NMNH 118120-32 | Basalt | -- | 2 Aug 1970 |
| NMNH 118120-33 | Basalt | -- | 2 Aug 1970 |
| NMNH 118120-34 | Basalt | -- | 2 Aug 1970 |
| NMNH 118120-35 | Basalt | -- | 2 Aug 1970 |
| NMNH 118120-36 | Igneous Rock | -- | -- |
| NMNH 118120-37 | Igneous Rock | -- | -- |
| NMNH 118120-38 | Igneous Rock | -- | -- |
| NMNH 118120-39 | Volcanic Rubble | -- | 17 Jun 1971 |
| NMNH 118120-4 | Tuff | -- | 31 Jul 1970 |
| NMNH 118120-40 | Volcanic Rubble | -- | 17 Jun 1971 |
| NMNH 118120-41 | Volcanic Rubble | -- | 17 Jun 1971 |
| NMNH 118120-42 | Tephra | -- | 17 Jun 1971 |
| NMNH 118120-43 | Tuff | -- | 17 Jun 1971 |
| NMNH 118120-44 | Volcanic Rubble | -- | 17 Jun 1971 |
| NMNH 118120-45 | Volcanic Ash | -- | 17 Jun 1971 |
| NMNH 118120-46 | Volcanic Ash | -- | 17 Jun 1971 |
| NMNH 118120-47 | Volcanic Cinder | -- | 17 Jun 1971 |
| NMNH 118120-48 | Tephra | -- | 17 Jun 1971 |
| NMNH 118120-49 | Tephra | -- | 18 Jun 1970 |
| NMNH 118120-5 | Basalt | -- | 31 Jul 1970 |
| NMNH 118120-50 | Tephra | -- | 18 Jun 1970 |
| NMNH 118120-51 | Tephra | -- | 18 Jun 1970 |
| NMNH 118120-52 | Basalt | -- | 18 Jun 1970 |
| NMNH 118120-53 | Tuff | -- | 18 Jun 1970 |
| NMNH 118120-54 | Tephra | -- | 18 Jun 1970 |
| NMNH 118120-55 | Tephra | -- | 18 Jun 1970 |
| NMNH 118120-56 | Scoria | -- | 18 Jun 1970 |
| NMNH 118120-57 | Accretionary Lapilli | -- | 17 Jun 1971 |
| NMNH 118120-6 | Dacite | -- | 31 Jul 1970 |
| NMNH 118120-7 | Volcanic Rock | -- | 31 Jul 1970 |
| NMNH 118120-8 | Volcanic Rock | -- | 31 Jul 1970 |
| NMNH 118120-9 | Volcanic Rock | -- | 31 Jul 1970 |
| Copernicus Browser | The Copernicus Browser replaced the Sentinel Hub Playground browser in 2023, to provide access to Earth observation archives from the Copernicus Data Space Ecosystem, the main distribution platform for data from the EU Copernicus missions. |
| MIROVA | Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity. |
| 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
Single Volcano View Temporal Evolution of Unrest Side by Side Volcanoes |
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.
GVMID Data on Volcano Monitoring Infrastructure The Global Volcano Monitoring Infrastructure Database GVMID, is aimed at documenting and improving capabilities of volcano monitoring from the ground and space. GVMID should provide a snapshot and baseline view of the techniques and instrumentation that are in place at various volcanoes, which can be use by volcano observatories as reference to setup new monitoring system or improving networks at a specific volcano. These data will allow identification of what monitoring gaps exist, which can be then targeted by remote sensing infrastructure and future instrument deployments. |
| 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 Marchena. 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 Marchena. Users can customize the data search based on station or network names, location, and time window. Requires Adobe Flash Player. |
| DECADE Data | The DECADE portal, still in the developmental stage, serves as an example of the proposed interoperability between The Smithsonian Institution's Global Volcanism Program, the Mapping Gas Emissions (MaGa) Database, and the EarthChem Geochemical Portal. The Deep Earth Carbon Degassing (DECADE) initiative seeks to use new and established technologies to determine accurate global fluxes of volcanic CO2 to the atmosphere, but installing CO2 monitoring networks on 20 of the world's 150 most actively degassing volcanoes. The group uses related laboratory-based studies (direct gas sampling and analysis, melt inclusions) to provide new data for direct degassing of deep earth carbon to the atmosphere. |
| Large Eruptions of Marchena | Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA). |
| 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). |
