A fractal approach to the temporal distribution of microseismicity at the low eastern flank of Mt. Etna during 1989–1994

Waters of Mt. Etna are the main source of drinking water for the local population and are also distributed in municipal supply systems to neighbouring areas. Radioactivity in underground waters and surrounding rocks from the eastern flank of Mt.Etnawas investigated on the basis of 9 water and 8 rocks samples from 12 localities altogether. Three samples were from water drainage galleries and six from water wells. All water intakes are used for consumption. Activity concentration of uranium isotopes 234,238U, radium isotopes 226,228Ra and radon 222Rn were determined with the use different nuclear spectrometry techniques. The determination of uranium isotopes was carried out with the use of alpha spectrometry. The measurements of radium and radon activity concentration in water were performed with the use of a liquid scintillation technique. Additionally, rocks surrounding the intakes were examined with gamma spectrometry. All water samples showed uranium concentration above Minimum Detectable Activity (MDA), with the highest total uranium (234U + 238U) activity concentration equal to 149.2±6 mBq/L. Conversely, all samples showed radium isotopes activity concentrations below MDA. Radon activity concentration was within the range from 2.91±0.36 to 21.21±1.10 Bq/L, hence these waters can be classified as low – radon waters. Gamma natural background of the rocks surrounding the water sampling sites was found on the same levels as other volcanic rocks of Italy.

Download Full-text

Time-dependent deformation of the eastern flank of Mt. Etna: After-slip or viscoelastic relaxation?

Tectonophysics ◽

10.1016/j.tecto.2009.02.047 ◽

2009 ◽

Vol 473 (3-4) ◽

pp. 300-311 ◽

Cited By ~ 26

Author(s):

M. Palano ◽

S. Gresta ◽

G. Puglisi

Keyword(s):

Time Dependent ◽

Viscoelastic Relaxation ◽

Eastern Flank ◽

Mt Etna

Download Full-text

Mapping and evaluating kinematics and the stress and strain field at active faults and fissures: a comparison between field and drone data at the NE rift, Mt Etna (Italy)

Solid Earth ◽

10.5194/se-12-801-2021 ◽

2021 ◽

Vol 12 (4) ◽

pp. 801-816

Author(s):

Alessandro Tibaldi ◽

Noemi Corti ◽

Emanuela De Beni ◽

Fabio Luca Bonali ◽

Susanna Falsaperla ◽

...

Keyword(s):

Stress Field ◽

Best Practice ◽

Ground Deformation ◽

Active Faults ◽

Fault System ◽

Normal Faults ◽

Extension Rate ◽

Eastern Flank ◽

Mt Etna ◽

Ne Rift

Abstract. We collected drone data to quantify the kinematics at extensional fractures and normal faults, integrated this information with seismological data to reconstruct the stress field, and critically compared the results with previous fieldwork to assess the best practice. As a key site, we analyzed a sector of the northeast rift of Mt Etna, an area affected by continuous ground deformation linked to gravity sliding of the volcano's eastern flank and dike injections. The studied sector is characterized also by the existence of eruptive craters and fissures and lava flows. This work shows that this rift segment is affected by a series of NNE- to NE-striking, parallel extensional fractures characterized by an opening mode along an average N105.7∘ vector. The stress field is characterized by a σHmin trending northwest–southeast. Normal faults strike parallel to the extensional fractures. The extensional strain obtained by cumulating the net offset at extensional fractures with the fault heave gives a stretching ratio of 1.003 in the northeastern part of the study area and 1.005 in the southwestern part. Given a maximum age of 1614 CE for the offset lavas, we obtained an extension rate of 1.9 cm yr−1 for the last 406 years. This value is consistent with the slip along the Pernicana Fault system, confirming that the NE rift structures accommodate the sliding of the eastern flank of the volcano.

Download Full-text

Features of seismic events and volcanic tremor during the preliminary stages of the 1991-1993 eruption of Mt. Etna

Annals of Geophysics ◽

10.4401/ag-3974 ◽

1996 ◽

Vol 39 (2) ◽

Author(s):

G. Lombardo ◽

G Coco ◽

M. Corrao ◽

S. Gresta

Keyword(s):

Low Frequency ◽

Volcanic Tremor ◽

Temporal Distribution ◽

Spectral Signature ◽

Seismic Events ◽

Spectral Features ◽

Eruptive Activity ◽

Eruptive Event ◽

Mt Etna ◽

Dominant Frequencies

The study of the spectral features of volcanic tremor and low frequency events (l.f.e.) recorded before and during the preliminary phases of the powerful 1991-1993 eruption of Mt. Etna is briefly described. Significant modifications were observed in the spectral signature of l.f.e. before the onset of the eruptive event, as well as in the temporal distribution of the volcanic tremor dominant frequencies. We interpret both l.f.e. and tremor changes in terms of a spatial modification of the source, as the paroxysmal eruptive activity is approaching. Such findings also appear quite interesting for the identification of markers of the modifications which some seismic events of the volcano undergo in the early stages heading the occurrence of an eruption.

Download Full-text