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Strong submarine earthquake swarms but no surface changes
An earthquake swarm occurred at the W tip of the island 24-31 August, including a M 5.2 shock at 9 km depth on 24 August (figure 3). A total of 24 earthquakes was detected at Iriomote-jima Weather Station, on the NW coast of the island.
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Figure 3. Epicenters of earthquakes near Iriomote-jima (filled circles), September-November, 1992. Diagonal lines mark the area of the August 1992 swarm. Courtesy of JMA. |
A second, more severe swarm began on 17 September, centered a few kilometers N of the island and about 20 km NE of the August swarm. Epicenters migrated towards the island, and by November, the source area encompassed the northern coast. Depths ranged from 0 to 10 km, concentrated at around 5 km.
Seismicity gradually declined toward the end of 1992, after a peak in mid-October when 112 earthquakes were recorded on the 14th (figure 4). The swarm's largest shock was M 5.2 on 20 October. A total of 1316 earthquakes occurred from 17 September to 31 December. A network of ten seismometers recorded no volcanic tremors, and no anomalies were observed on the land or sea surface.
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Figure 4. Daily number of earthquakes at Iriomote-jima, 1 August-31 December 1992. Courtesy of JMA. |
The most recent seismic activity had occurred in the same area from January-May 1991, when 676 earthquakes were recorded, the largest M 4.3 (16:3-4).
Information Contacts: JMA.
The Global Volcanism Program has no Weekly Reports available for Submarine Volcano NNE of Iriomotejima.
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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High-frequency earthquake swarm; many felt shocks; no surface activity
A swarm of high-frequency earthquakes . . . began 23 January, peaked in February, and continued at high levels through mid-April. The press reported that more than 940 earthquakes had been recorded by 14 April. Epicenters were on the W coast (at shallow depth) where many shocks were felt daily. Tremor episodes were not recorded and surface activity was not observed on the island or the surrounding sea.
Information Contacts: JMA.
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Strong felt seismicity but no surface changes
High levels of seismicity . . . suddenly declined in late April (figure 1). A total of 670 high-frequency earthquakes were felt by the end of April, including nine of JMA intensity IV, and a M 4.3 event on 31 March. The swarm was centered on the NW coast of the island (figure 2) at 0-10 km depth (the majority at ~5 km). No surface phenomena (steaming, bubbling, or water discoloration) were found despite frequent patrolling over the island and adjacent sea area by JMSA aircraft.
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Figure 1. Daily number of recorded earthquakes at Iriomote-jima island, 23 January-10 May 1991. Solid columns represent felt events. Courtesy of JMA. |
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Figure 2. Epicenter map of earthquakes at Iriomote-jima island, 23 January-10 May 1991. A solid square marks the JMA weather station. Courtesy of JMA. |
Information Contacts: JMA.
Cite this Report
Strong submarine earthquake swarms but no surface changes
An earthquake swarm occurred at the W tip of the island 24-31 August, including a M 5.2 shock at 9 km depth on 24 August (figure 3). A total of 24 earthquakes was detected at Iriomote-jima Weather Station, on the NW coast of the island.
|
Figure 3. Epicenters of earthquakes near Iriomote-jima (filled circles), September-November, 1992. Diagonal lines mark the area of the August 1992 swarm. Courtesy of JMA. |
A second, more severe swarm began on 17 September, centered a few kilometers N of the island and about 20 km NE of the August swarm. Epicenters migrated towards the island, and by November, the source area encompassed the northern coast. Depths ranged from 0 to 10 km, concentrated at around 5 km.
Seismicity gradually declined toward the end of 1992, after a peak in mid-October when 112 earthquakes were recorded on the 14th (figure 4). The swarm's largest shock was M 5.2 on 20 October. A total of 1316 earthquakes occurred from 17 September to 31 December. A network of ten seismometers recorded no volcanic tremors, and no anomalies were observed on the land or sea surface.
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Figure 4. Daily number of earthquakes at Iriomote-jima, 1 August-31 December 1992. Courtesy of JMA. |
The most recent seismic activity had occurred in the same area from January-May 1991, when 676 earthquakes were recorded, the largest M 4.3 (16:3-4).
Information Contacts: JMA.
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 |
| Iriomotezima | Iriomote-jima |
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There is data available for 1 confirmed Holocene eruptive periods.
1924 Oct 31 Confirmed Eruption VEI: 5 (?)
| Episode 1 | Eruption | ||||||||||||||||||||||||||||||
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| 1924 Oct 31 - Unknown | Evidence from Observations: Reported | |||||||||||||||||||||||||||||
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List of 4 Events for Episode 1
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There is no Deformation History data available for Submarine Volcano NNE of Iriomotejima.
There is no Emissions History data available for Submarine Volcano NNE of Iriomotejima.
An "X" marks the approximate location of Iriomote-jima submarine volcano, the southernmost Ryukyu Islands volcano. The submarine volcano is located north of the NE tip of 30-km-wide Iriomote-jima island (lower left) and WSW of the northern tip of the island of Ishigaki-shima (right-center). A major submarine eruption that was volumetrically one of the largest in Japan during historical time took place at this volcano on October 31, 1924. It produced pumice rafts that were carried by currents along both coasts of Japan as far north as Hokkaido. 
A submarine volcano is located approximately 20 km offshore NNE of Iriomotejima, shown in this bathymetric map by the Japan Coast Guard. On 31 October 1924 an eruption produced a pumice raft that eventually reached Japan.Maps are not currently available due to technical issues.
There are no samples for Submarine Volcano NNE of Iriomotejima in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.
| 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. |
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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 Submarine Volcano NNE of Iriomotejima. 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 Submarine Volcano NNE of Iriomotejima. 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 Submarine Volcano NNE of Iriomotejima | 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). |
