Earthquake bigger than at first thought, CO2 increases suggest eruption imminent
IGN increases the magnitude of the quake this morning to 4.3
The Volcanological Institute of the Canaries (INVOLCAN) confirmed information from the Civil Protection Planning Organisation for Volcanic Risk (PEVOLCA) of an increase in the diffuse emission of carbon dioxide (CO2) into the atmosphere by the volcano island of El Hierro after their tenth scientific field campaign and evaluation of the results of their volcanic surveillance.
The measured emission rate has reached 1044 ± 31 tons per day, the highest value observed during the eruptive phenomenon that has been developing on El Hierro. For its part, the National Geographic Institute (IGN) has increased its detected earthquake magnitude to 4.3 on Wednesday at 07.56 (GMT) northwest of Frontera. This is the second quake of such a large magnitude recorded since the seismic crisis began in El Hierro this summer. The first CO2 diffusive flux took place at the time of the underwater eruption on the island .
Since last July 21, 2011 the INVOLCAN has materialized over 6,500 diffuse flux measurements of carbon dioxide (CO2) through 10 scientific field surveys each covering the entire subaerial volcano island of El Hierro (278 km2) in order to contribute to the improvement and optimization of volcano monitoring. Note that in this task have collaborated with a significant group of volunteers based in the Canary Islands. The record of the diffuse emission of carbon dioxide (CO2) by the volcano island of El Hierro since last July 21 runs from 331 ± 16 to 1044 ± 31 tonnes per day. Following the work on diffuse emission of carbon dioxide (CO2) made on El Hierro for the ITER volcanological group since 1997, now within the INVOLCAN, it has been established that the average value of the diffuse emission CO2 by the volcano island of El Hierro is 340 tons daily, and whose normal value range goes from 140 to 885 tons per day.
Prior to the submarine eruption occurred southwest of La Restinga diffuse emission rate of carbon dioxide (CO2) exceeded the normal range of values considered registering a 990 ± 49 tons per day last October 6, 2011. Additional geochemistry instruments to the INVOLCAN network's permanent instrumentation for monitoring volcanic features of El Hierro, has produced complementary information that can not be obtained from the permanent network that operates 24 hours a day, 365 days a year.
This type of equipment is designed to assess the rate of diffuse emission of CO2 into the atmosphere by the volcanic systems of El Hierro and to record their spatial distribution. The reasons for such methods reside in the realisatoin of the importance of carbon dioxide in volcano monitoring programs, because it is the second major component of volcanic gases after water vapor, and its low solubility in silicate melts - magma - helps this gas escape with ease from deep within volcanic systems.
The Directorate of the Civil Protection Special Planning and Emergency Response Organisation to Volcanic Risk in the Canary Islands (PEVOLCA) notes that the diffuse emission of CO2 is one of the precursor parameters to a volcanic eruption but has to be assessed jointly with other parameters, such as deformation and seismicity depth.
It should be remembered that we are immersed in an eruptive process underway in the south of the island, which generates greenhouse gas emissions in the Earth's surface. Also, the directorate of PEVOLCA reiterated that the current volcanic alert level is still red for La Restinga and yellow for the rest of the island, the population of the island have been asked to focus on the messages offered by the competent authorities assisting the Scientific Committee of PEVOLCA. The Plan has set the devices and means to cope with a change in the current situation with the media, at the right time, with precise instructions prepared for the population.