In this paper, a new approach to the detection of anomalies in geophysical records is connected with a fuzzy mathematics application. The theory of discrete mathematical analysis and collection of algorithms for time series processing constructed on its basis represents the results of this research direction. These algorithms are the consequence of fuzzy modeling of the logic of an interpreter who visually recognizes anomalies in records. They allow analyzing large data sets that are not subjected to manual processing. The efficiency of these algorithms is demonstrated in several important geophysical applications. Plans for an extension of the Russian INTERMAGNET segment are presented

Summary. More than 1500 volcanoes can potentially enter into eruption but only some tens of them are equipped with monitoring networks. Most of volcanic erupti

The study analyzes electromagnetic data and plasma characteristics in the ionosphere recorded by DEMETER microsatellite over erupting volcanoes during the life of the mission: from August 2004 to December 2010. The time window in which anomalous changes are searched brackets the onset of the eruptive activity from 60 days before to 15 days after the period during which most pre- and posteruptive phenomena are amplified. 73 volcanoes have entered into eruption. For 58 of them, 269 anomalies were found in relation to 89 eruptions. They are distributed in 5 types, similarly to the ones observed above impeding earthquakes. The two main types are electrostatic turbulence (type 1, 23.4%) and electromagnetic emissions (type 2, 69.5%). The maximum number of types 1 and 2 anomalies is recorded between 30 and 15 days before the surface activity, corresponding to the period of accelerating phenomena. The amount of anomalies seems related to the powerfulness of the eruptions. The appearance seems dependant on the likelihood to release bursts of gases during the preparatory eruptive phase. For the huge centenary October 26, 2010, Merapi (Indonesia) eruption, 9 ionospheric type 2 anomalies appeared before the eruption. They mainly emerge during the mechanical fatigue stage during which microfracturing occurs.

Typical eruptions of Taal Volcano in the Philippines are frequent and violently explosive. The last devastating phreatomagmatic eruption from 1965 to 1977 resulted in the death of about 200 persons. For this and other earlier events, no warnings of impending eruptions were issued. Since this time, volcanic crises involving episodes of seismicity, deformation, gas release, temperature change, etc., have occurred frequently. Each of these did not, but possibly could have, evolved into an explosive eruption. One such event occurred between April 2010 and March 2011. This paper reports various types of geophysical data (electric/magnetic field, ground temperature, seismicity and ground deformation) taken during this period of activity together with the current state of geophysical knowledge about the volcano in order to throw light on activity evolution. While the 2010 seismovolcanic crisis was preceded by unusual changes in electric field, ground tilting and uplift, the major signals from all data were concomitant with the evolution of the crisis. On April 20, 2010, felt earthquakes first started to occur. The numbers increased sharply after April 29 with repeated pulses of seismicity that ended finally in March 2011. Overall, we can identify three periods of seismic activity, from April 20 to August 4–8, from August 4–8 to November 18, and from November 18 to March 28, 2011. Although only a single tiltmeter was in operation, it recorded three phases of deformation that correspond generally with the pulses in seismic activity. Phase 1 appears to correspond to inflation at a depth of about 5 km just to the NW of Main Crater Lake from April 20 to June 11, 2010. This resulted in an eastward tilting of the northern flank of the volcano. This apparently triggered rapid but shallower inflation (Phase 2) in the hydrothermal region of the volcano under the northern edge of Main Crater Lake from June 11 to July 13 just to the SE of the initial deeper source as indicated by northward tilting of the volcano’s northern flank. Progressive deflation began after July 13. By March 28, 2011, the deformation state recovered to the pre-crisis level and felt seismic activity ceased. Apparent related changes in seismicity, tilt, magnetic and electric fields occur during smaller NS inflations in the Phase 3 deflation—Phase 3a (July 13 to August 4–8), Phase 3b (August 4–8 to November 18) and Phase 3c (November 18 to March 28, 2011). These likely result from interrelated stress change, fluid/gas migration and thermal activity at depth and in the hydrothermal system. The rapidity of changes in the state of the volcano over a matter of hours during this entire process indicates rapid communication occurs between processes at depth and in the hydrothermal system and this could easily result in the dramatic evolution to violent phreatic explosions with little warning.