Éruption volcanique

The autonomous Model-based Volcano Sensor Web (MSW), based at JPL, proved its worth during a volcanic crisis at Nyamulagira, Democratic Republic of Congo, in 2006. The MSW facilitated the rapid acquisition of spacecraft data which allowed pinpointing the location of the volcanic vent. This was vital in predicting lava flow direction and extent. In 2007 a number of improvements have been made to the MSW. These include the deployment of in situ SO2 sensors on Kilaueavolcano, HI, capable not only of triggering requests by the EO-1 spacecraft in the event of anomalous SO2 detection, but also of being triggered autonomously by an anomalous thermal detection from advanced data processing software onboard EO-1, and the conversion of the sensor web to using Open Geospatial Consortium Web Services. The Sensor Web is monitoring volcanoes around the world. A number of interesting volcanic eruptions have been detected and monitored, including a carbonatite eruption at Oldoinyo…

The MODVOLC satellite monitoring system has revealed the first recorded eruption of Mount Belinda volcano, on Montagu Island in the remote South Sandwich Islands. Here we present some initial qualitative observations gleaned from a collection of satellite imagery covering the eruption, including MODIS, Landsat 7 ETM+, ASTER, and RADARSAT-1 data. MODVOLC thermal alerts indicate that the eruption started sometime between 12 September and 20 October 2001, with low-intensity subaerial explosive activity from the islands summit peak, Mount Belinda. By January 2002 a small lava flow had been emplaced near the summit, and activity subsequently increased to some of the highest observed levels in August 2002. Observations from passing ships in February and March 2003 provided the first visual confirmation of the eruption. ASTER images obtained in August 2003 show that the eruption at Mount Belinda entered a new phase around this time, with fresh lava effusion into the…

Automatic interval recording of volcanic clouds at Mt. Mayon, Philippines started in June 2003 as joint work of PHILOVOLCS and the Kagoshima University group, and evolved into a real time monitoring system accessible from Quezon and Kogoshima in April 2004. In this system, a conventional visible camera is used in tandem with a near-infrared camera, which is less sensitive to atmospheric haze and able to detect hot anomalies. It is intended to eventually provide live access to imagery of the volcanic cloud on the World Wide Web/ The necessity of the ground-based system in conjunction with satellite-based volcanic cloud from the Mayon eruptions of 29 February 2000. The performance of the system until November 2006 is reported including the summer 2006 eruptions with lava flows from the summit crater.

The use of satellite remote sensing to monitor active geological processes is described. Specifically, threats posed by volcanic eruptions are briefly outlined, and essential monitoring requirements are discussed. As an application example, a collaborative, multi-agency operational volcano monitoring system in the north Pacific is highlighted with a focus on the 2007 eruption of Kliuchevskoi volcano, Russia. The data from this system have been user since 2004 to detect the onset of volcanic activity, support the emergency response to large eruptions, and asses the volcanic products produced following the eruption. The overall utility of such integrative assessments is also summarized.

Rapid response to the onset of volcanic activity allows for the early assessment ofhazard and risk [Tilling, 1989]. Data from remote volcanoes and volcanoes in countries with poor communication infrastructure can only be obtained via remote sensing [Harris et al., 2000]. By linking notifications of activity from ground-based and spacebased systems, these volcanoes can be monitored when they erupt. Over the last 18 months, NASA’s Jet Propulsion Laboratory (JPL) has implemented a Volcano Sensor Web (VSW) in which data from ground-based and space-based sensors that detect current volcanic activity are used to automatically trigger the NASA Earth Observing 1 (EO-1) spacecraft to make high-spatial-resolution observations of these volcanoes.The fully-automated process allows for rapid acquisition and transmission—typically within 48 hours, though theoretically possible within 2–3 hours—of data products containing the most useful data content, namely…

Thermal data are directly available from the Geostationary Operational Environmental Satellites (GOES) every 15 minutes at existing or inexpensively installed receiving stations. This data stream is ideal for monitoring high temperature features such as active lava flows and fires. To provide a near-real-time hot spot monitoring tool, we have developed, tested and installed software to analyse GOES data on-reception and then make results available in a timely fashion via the web. Our software automatically: (1) produces hot spot images and movies; (2) uses a thresholding procedure to generate a hot spot map; (3) updates hot spot radiance and cloud index time series; and (4) issues a threshold-based e-mail alert. Results are added to http://volcano1.pgd.hawaii.edu/goes/ within ~12 minutes of image acquisition and are updated every 15 minutes. Analysis of GOES data acquired for eVusive activity at Kilauea volcano (Hawai’i ) during 1997-98 show that short (<1…

Satellite data were the primary source of information for the eruption of Mt. Cleveland, Alaska on 19 February, and 11 and 19 March 2001. Multiple data sets were used pre-, syn- and post-eruption to mitigate the hazard and determine an eruption chronology. The 19 February eruption was the largest of the three, resulting in a volcanic cloud that formed an arc over 1000 km long, moved to the NE across Alaska and was tracked using satellite data over more than a 50-h period. The volcanic cloud was “concurrently” detected on the GOES, AVHRR and MODIS data at various times and their respective signals compared. All three sensors detected a cloud that had a very similar shape and position but there were differences in their areal extent and internal structural detail. GOES data showed the largest volcanic cloud in terms of area, probably due to its oblique geometry. MODIS bands 31 and 32, which are comparable to GOES and AVHRR thermal infrared wavelengths, were…

Volcanic ash is dangerous to aircraft. In response to this, a warning system has been created: the International Airways Volcano Watch. Many of the world's active volcanoes are in relatively underresourced regions of the southwest Pacific and eastern Indian Ocean. We show here examples of recent eruptions in the southwest Pacific and Indonesia, including major eruptions at Rabaul (NewBritain, Papua New Guinea), Merapi (Java, Indonesia), and Ruang (Sangihe Islands, Indonesia). We examine the effectiveness of satellite, air, and ground observations. There is a great variation in reported eruption heights between different observations, and we explore some of the reasons for this. There are particular difficulties with the under-reporting of eruption heights from the ground. More funding and development of ground-based observations will improve the overall effectiveness of the warning system.

Within the projects SACS (Support to Aviation Control Service) and Exupéry (the mobile volcano fast response system, VFRS) SO2 total columns are retrieved from different space-borne instruments such as GOME-2, SCIAMACHY and OMI. The backward trajectory matching technique is applied to relate exceptional SO2 values to particular sources and volcanic regions. Additionally, the moment of the eruption as well as the emission and the plume height can be estimated. Dispersion modeling is applied to forecast the motion of the plume and to estimate the SO2emissions.

MODVOLC is a non-interactive algorithm developed at the Hawaii Institute of Geophysics and Planetology (HIGP) that uses low spatial resolution (1-km pixel-size) infrared satellite data acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) to map the global distribution of volcanic thermal anomalies in near-real-time. MODVOLC scans the Level-1B MODIS data stream, on a pixel-by-pixel basis, for evidence of pixel and sub-pixel-sized high-temperature radiators. Once a hot spot has been identified its details (location, emitted spectral radiance, time, satellite observation geometry) are written to ASCII text files and transferred via FTP to HIGP, from where the results are disseminated via the internet http://modis.higp.hawaii.edu). In this paper, we review the underlying principles upon which the algorithm is based before presenting some of the results and data that have been obtained since its inception. We show how MODVOLC reliably detects thermal…