Operational volcano monitoring for decision support demonstration Daniel Carrasco (1), José Fernández (2), Rosana Romero, Antonio Martínez (1), Victoriano Moreno (1), Vicente Araña (3) (1) Indra Espacio. Remote Sensing Dept. Calle Mar Egeo, 4. Pol. Ind. Nº 1. 28850 San Fernando de Henares. Madrid. SPAIN. E-mail: dcar@mdr.indra-espacio.es (2) Universidad Complutense de Madrid. Facultad de Ciencias Matemáticas. Instituto de Astronomía y Geodesia. Red de Investigación Volcanólogica - CSIC. (3) Departamento de Volcanología. Museo de Ciencias Naturales. Red de Investigación Volcanológica - CSIC. Madrid. ABSTRACT: Indra Espacio, in close cooperation with the Spanish Volcanic Research Network and Civil Protection, has started a project for volcano monitoring in the Canary Islands in the frame of an ESA contract using ERS interferometry. Within 12-18 months, an operational SAR interferometric processing system will be set up by Indra, based on its comercial INSAR processor. The information provided by this new system will be added to that collected from ground deployed instrumentation for decission making. The project has a second stage where the tecnology and the lessons learned will be ported to a Southamerican scenerio for volcanic risk monitorig in Ecuador. Introduction The application of space technologies for the management of emergency situations has a huge development potential. However, there is still a real need to bridge the gap between the space data service providers and the end users civil and governmental authoritiesinvolved in risk management. The advantages of using satellite systems to facilitate Decision Making for emergency or natural hazard management can readily be demonstrated using existing satellites. Such a demonstration could possibly also pave the way for the development of dedicated satellite systems for emergency management. Eight years after the launch of the first ERS satellite, the scientific achievement has reached maturity and many applications are ready to go to the operational market. SAR interferometry has become one of the more eye-catching and promising applications and a precise knowledge of its performance and limitations has been achieved (Massonnet, 1993). In particular, the differential interferometry is a straightforward application, and one of the best suited for its operational application. Within this context, ESA has launched a project named PROMOTION OF SPACE TECHNOLOGIES FOR SUPPORTING THE MANAGEMENT OF NATURAL DISASTERS: EARTH OBSERVATION TECHNOLOGIES FOR DECISION SUPPORT DEMONSTRATION. In this frame, Indra Espacio in collaboration with the RIV (Spanish Volcanic Research Network) was awarded the DECIDE- VOLCANO project which will try to demonstrate the feasibility of using Earth
Observation technologies (DInSAR) for operational decision support demonstration at a volcanic risk scenario like the Canary Islands. In a second stage of the project, a Southamerican project extension will be started in Ecuador in collaboration with CLIRSEN (Centro de Levantamientos Integrados de Recursos Naturales mediante Sensores Remotos) for the monitoring of Pichincha and Tungurahua volcanos (currently active). DECIDE-VOLCANO project was started in September 1999 an it is a currently ongoing project. Along this article we shall summarise the key issues of the project and the expected outcome. Rationale of DECIDE-VOLCANO DECIDE-VOLCANO project is expected to bridge the gap between the Satellite technology users group (the satellite ground segment and the value added companies dedicated to EO) and the potential end user of this technology in the frame of decision making upon the management of natural disasters (Civil Protection Authorities). The project consortium includes two branches. By one side, Indra Espacio (the prime contractor and value added company) which provides its expertise in Earth Observation technology and by the other side the Spanish Volcanologic Network,RIV, as the end user, responsible (by law) for the monitoring of the Canarian volcanoes, in close cooperation with the Civil Protection Authorities, which has not used EO technology up to date. The goal of the project is to commit the end user, the volcano specialist, to use the EO technology on an operational basis for decision making. INDRA s role will be to transfer the SAR technology to the end user, customising it to his needs, and supporting him during the execution of the project. For this purpose, INDRA will set up a customised version of its INSAR commercial software EPSIE 2000 at the RIV facilities and take care of the training so that RIV s personnel are able to operate the system on their own. After the completion of the project, the end user is willing to operate the EO system on its own on a regular basis. After the implementation of the DECIDE project, the EO technology is at the reach of the end user who takes advantage of it on an operational basis as illustrated in figure 1. The image processing is carried out directly by the end user with the support of INDRA. End user clearly benefits from the new source of information and satellite technology finds an highly demanding operational application. The scenario and the current monitoring system The Canary Islands with a population about 1.6 million people -are a well known volcanic area, i.e. there is a high probability of future volcanic eruptions over their territory. In historical times, there have been reported a dozen eruptions in the Islands of La Palma, Tenerife and Lanzarote. In the other Islands save for La Gomera there have been many recent eruptions although beyond the short 500 years historical time of the Islands. The type and location of these eruptions yields that the expected future eruptions are of basalt outpouring with a dominant lava flow. However, the explosive eruptions in Mt. Teide slopes are close enough in time (under 2000
years) as to take also in consideration these kind of eruptions. Usually, any kind of volcanic eruption is preceded (weeks, days) by some precursors (Earth tremors, ground deformations, gravimetry and electromagnetic variations, chemical modifications in smoke emissions, etc.) which can be detected by specially on-site deployed equipment. The interpretation of the data from these instruments requires a deep knowledge of the volcanism mechanism of the area under study along with the knowledge of the instrument response in previous eruptions or crisis (a sort of calibration). This later fact is not the case of the Canary Islands, since all the measuring equipment has been deployed much later than the last eruption (Teneguía eruption, La Palma, 1971). However, the deep knowledge of the Canarian volcanism is expected to allow the monitoring of any future eruptions as soon as they arise. One of the main tasks that faces vulcanologists who are researching an active volcano area instrumentally observed, is to define the most suitable monitoring system, a task that is particularly difficult in the absence of recent activity. The task not only takes into account the technical optimisation of the monitoring systems, but also their economic and scientific profitability. Traditionally, observations of seismic, hydrologic, or fumarolic activity have proven useful. Yet, in the light of the IAVCEI s recommendations regarding routine monitoring, geodetic measurements are being used more and more extensively in active volcanoes and have been shown to be a reliable eruption precursor. It becomes harder to predict future eruptions when their likelihood is not limited to a specific volcano but to a wide active volcanic region. This is the situation in the Canary Islands, where there is an active stratovolcano, the Teide (Tenerife), and monogenetic historic volcanism scattered over several islands. This is a typical case in which the volcanic monitoring system must be carefully designed. The system must be efficient, but must also make full use of existing facilities and have acceptable installation and running costs, in line with the current inactivity. These facts makes the volcano monitoring in the Canary Islands a very demanding issue which requires the collaboration of all the institutions (scientific and political at all levels central, regional and municipal government-). Furthermore, the monitoring of a volcanic area cannot be limited to a single warning factor but it has to take into consideration the data from different origins; in particular, it should be considered: a) Seismic activity (Earth tremors). b) Ground deformation. c) Geomagnetic field. d) Fumarolic activity. Present volcano monitoring in the Canary Islands relies on the seismic and geodetic networks, which cover the whole archipelago, but with a higher density over the most probable eruption scenarios. An eruption may take place at any island, although Lanzarote, Tenerife, La Palma and El Hierro do have a higher probability. Furthermore, an explosive eruption is feasible in Mt. Teide in Tenerife.
RIV s reporting to Civil Protection Authorities is based upon the analysis of the data extracted from the volcanic precursors measurement. Present deployed equipment includes dense seismic networks, water tube clinometers, magnetometers, etc. This equipment is networked with a high reliability telemetry, which guarantees operation despite of failure in telephone lines or power supply networks (some stations are starting to use satellite low-bit-rate telemetry provided by INDRA SANARIS project). Besides of the permanent deployed equipment, extra information is generated from periodic and expensive- surveying campaigns over the geodetic networks (precision levelling and GPS). Figure 2 shows an artist view of the present deployed equipment. The Earth Observation approach advantage Present monitoring systems do not include any EO technology. So, what could be the benefits of SAR interferometry for volcano monitoring in the Canary Islands? Next item list describes the advantages of the new technique over the selected scenario: a) SAR differential interferometry delivers information on ground deformation. This is a well-known volcanic precursor, which up to date is monitored with geodetic measurements. Observed cases over the calderas in Rabaul, Campi Flegrei, Long Valley and Yellowstone proof that the observation of ground deformation allows the detection of re-activation at mid and long term and can be used as a clue in order to predict future eruptions. b) Remote sensing allows monitoring of areas during eruption, when using field deployed instrumentation becomes unfeasible or hazardous. c) Whereas geodetic surveying measurements provide information only over some selected points, SAR interferometry provides wide area images (100x100 km) showing the deformation field trends along all the area of interest allowing the extrapolation of the field measurements. d) SAR imaging allows continuos monitoring of the areas of interest. Present ERS-2 configuration allows 35-day revisit time. Furthermore, if ascending and descending passes are considered, the periodicity can be doubled. e) SAR imaging allows the monitoring of sparse volcanism scenarios like the Canary Island. Furthermore, the island s dimensions perfectly match the ERS frame structure as shown in the coverage image. f) DINSAR can be a very costeffective tool to monitor active volcano in remote areas without deployed instrumentation and difficult access. g) DINSAR allows long-term stability analysis, which is one of the recommended techniques for volcano monitoring. Weather and land cover (scarce vegetation) of the area a most suitable for long time baseline DINSAR. h) DINSAR should not be intended as a replacement to traditional geodetic methods but as a most powerful complementary tool. i) Finally, we must state that the yearly operation cost of an INSAR system is quite under an order of
magnitude of the cost of a traditional field based instrumentation monitoring system (not to say of the initial cost!) The utilisation of SAR interferometry for volcano monitoring and therefore the wide area analysis, will require an adequate data interfacing for the geocoded information. A total amount of 30 ERS images are expected to be purchased for the Canary Islands scenario. Three islands are under consideration: Tenerife, Lanzarote and La Palma, In order to maximise the success of the project, we shall order most of them over the most interesting scenario, Tenerife. A third of the images will be ordered over Lanzarote, the following in interest. 10 to 15% of the images will be ordered over La Palma. The initial ERS data collecting will be carried out over Tenerife. Concerning the data selection, we are not only interested in near-real time image acquisition but also in the historical series since 1991 since the long term phase stability allows multiyear deformation analysis. Future image acquisition will be arranged with Eurimage. The funding available for the project does not allow the acquisition of all the visible images over the three areas. However, in the near future these images would probably be acquired in the frame of research projects and once the autonomous (in terms of funding) and sustained operation had been achieved (within 18 months). This is why we would like this area to be defined as a privileged site in terms of image planning and acquisition by ERS mission control, despite of not all the images being acquired in the frame of DECIDE- VOLCANO project. Phases towards a self-sustainable service and success criteria The phases required for a self-sustainable service are fully coincident with the project schedule as follows: a) Specification, development and set up [T0,T0+6]. During this phase, Indra should customize its interferometric processor EPSIE based upon the requirements agreed with the RIV. Training on the system operation will be provided to RIV personnel. The evaluation plan for the system will be defined. The success of this stage will be judged upon the installation of an equipment at the RIV and the kick off of the operations with the first data from the Islands. b) Pre-operational service demonstration and validation [T0+6,T0+12]. During this phase the RIV will start the operation of the system with the support from INDRA. The success of this stage will be based upon the completion of the system evaluation plan. c) First phase exploitation [T0+12,T0+18]. At T0+12 the service must have achieved its maturity and RIV should be able to operate it on its own. However, INDRA will continue providing its support although its contribution is not expected to be significative. During this phase, the processing chain should be handled on an operational basis achieving a sustained data throughput (this will be the success criteria). In parallel with these three stages, there will be a background work aiming to the continuation of the project. Once the system functionality had been assessed (during phase 2) efforts should be
addressed to get funding for the service operation beyond T0+18, once ESA/INDRA funding is over. This will also be considered a key to the project success. During phase c), a twin system will be set up in Ecuador in collaboration with CLIRSEN. A key point in the project will be to spread the results achieved by the system and the system implementation itself. This will be achieved, for example, through the participation in national/international conference (both SAR and Geophysics) and the distribution of promotion material. Acknowledgement This project is being developed under ESA contract nº 13661/99/I-CD) in the frame of PROMOTION OF SPACE TECHNOLOGIES FOR SUPPORTING THE MANAGEMENT OF NATURAL DISASTERS: EARTH OBSERVATION TECHNOLOGIES FOR DECISION SUPPORT DEMONSTRATION. References Massonet D., Rossi M., Carmona C. Adragna F., Peltzer G., Feigl K., Rabaute T., 1993: The displacement field for the Landers eartquake monitored by spacebone radar interferometry. Nature, 364,138-142. Future scenario after DECIDE INDRA Value adding EO company Satellite ground segment: Acquisition Processing Archiving Satellite data Know-how Support Ready to go technolgy Volcanic network Research Field measurements EO data processing Information based on ground collected data enhanced with EO data Civil Protection Authorities Decission making Action! END USER Non EO data Figure 1. Future scenario after the DECIDE project: the decision making chain has adopted EO technology on an operational basis.
Figure 2. Present volcano monitoring equipment at the Canary Islands, including satellite telemetry. LANZAROTE LA PALMA TENERIFE Figure 3. This image shows an example of ERS coverage (from ESA s DESC software) over the Canary Islands. Some descending ERS frames have been highlighted over Lanzarote, La Palma and Tenerife the areas of interest- which can be fully covered with a single SAR image.