Computer assisted quality control in tree ring dating and measurement

09 Jul

Etna when investigating how the magma feeding systems works.The eruption of January–March 1974 represents a petrological transition between two eruptive periods during which different types of magma were emitted: a phenocryst-charged basalt type, which was observed coming from the central vent until 1974, and a more glassy basalt type, free of plagioclase that has been observed in many occasions since 1974 with up to 150 events per day detected at the Mt. In the summer-autumn 1973, a seismic event triggered the deployment of a seismic network on Mt. Unfortunately, due to technical issues, the locations of the October events, could not be determined with certainty.Vetore station (20 events per day at the Catania station; Fig. For reference, during the 1971 crisis, the daily seismic rate did not exceed 10 events per day at the Catania station and afterwards is often associated with magma intrusions. The temporal coincidence of the October 1973 seismic crisis with both renewed activity at the Voragine and the NIR signal, raises the question of the presence of an early intrusion into the western flank in the vicinity of Monte de Fiore.Seismic activity as detected by seismic sensors deployed on the flanks of Mt.Until now, it has been unclear when this signal started, whether it was sustained and which process(es) could have caused it.By analyzing tree-ring width time-series, we show that the reduced near-infrared precursory signal cannot be linked to a reduction in annual tree growth in the area.Such an impact is not visible in the tree-ring width time-series of MFs trees. 4 the detrended ring-width data for trees in MFn (a), MFs (b), both parts of Monte de Fiore (c) and the control site (d) are shown.A zoom image for the eruptive period of this figure is available in the Supplementary Materials (Supplementary Fig. After detrending the low-frequency variability of the raw time series is eliminated but high-frequency variability, such as the reduced growth of MFn trees during 1974–1975, is preserved. 3 after applying detrending to samples from MFn (a), MFs (b), all of Monte de Fiore (c) and the control site (d).

If not recorded because of their unconventional or too tenuous appearance, precursors of volcanic activity are lost forever.

The vertical green line indicates the time of the eruption.

For most MFn trees, which were closest to the vent, growth stopped for two consecutive years following the 1974 eruption.

As tree growth largely depends on environmental conditions (i.e., on the local availability of water and nutrients, and temperature during the vegetation season) tree rings have been widely used in the environmental sciences as proxies to assess both local and regional past climate variations.

As trees form one growth ring each year, tree-ring chronologies may be used as annually resolved, long-term records of past eruptive events. These observations were not the first satellite observables of this kind. In this case, the start and duration of the NIR signal could not be determined nor was the cause of the signal identified as the eruptive activity started months later.