Radon and helium anomalies in mud volcanoes from northern Apennines(Italy). A tool for earthquake prediction.

Abstract

Rn-222 and total helium contained in saline waters and associated gaseous fluids from a series of mud volcanoes occurring along the northeastern border of the Apennine chain (northern Italy) have been determined as possible precursors of local earthquakes. Investigations spanned over about one year (May 1986-May 1987 during which a series of low to medium-magnitude (M = 3-4.5) local earth quakes occurred with distinct focus. Spike-like Rn anomalies were almost systematically observed a short time (hours to few days) before and after the main shocks. These anomalies were frequently accom panied by slight but significant short-term changes in water chemistry. A unique very strong He anomaly was recorded in coincidence with a shock in an area very close to the focus. The significance of the ob served short-term anomalies of Rn and hydrochemical parameters (chlorinity, alkaline earths content) is explained in terms of an upsetting of the equilibrium between two chemically distinct (pellicular and nor mal) connate waters in confined reservoirs. Pellicular water trapping radiogenic Rn would be abruptly liberated into normal connate water by a tectonic stress change. In most cases, helium seems to be insen sitive to seismic events, this probably being due to the shallowness of the foci. The data confirm that mud volcanoes represent very sensitive natural systems for predicting local earthquakes.

The SEISMOFAULTS project: First surveys and preliminary results for the Ionian Sea area, Southern Italy

“…Active mud volcanoes in the Ionian Sea and elsewhere could provide information on the seismic cycle of nearby faults [e.g. Bouleguè et al, 1985;Gorgoni et al, 1988;Martinelli et al, 1991Martinelli et al, , 1995Gulijev and Feizullayen, 1997;Milkov, 2000;Dimitrov, 2002;Kopf, 2002, Mazzini andEtiope, 2017] and could therefore be important targets for future geochemical monitoring [Cuffaro et al, 2019], as mentioned above.…”

Between history, work and passion: medieval castle, mud volcanoes and Ferrari

“…Santi, 1896; Pellegrini et al, 1982;Gorgoni et al, 1988). Other investigations (Gorgoni, 2003) have shown that the activity of the mud volcanoes is influenced by local seismicity, some days before the occurrence of rather strong earthquakes.…”

“…The mud volcanoes show the presence of permeable structures, tectonically active, and their study can provide useful "windows" on how fluids move through the upper crust and the sedimentary cover towards the surface. Water analysis emitted by salse highlighted connate origin of such fluids dominated by sodium-chloride component (Gorgoni et al, 1988). Extruded gas is chemically composed by 93% methane, 5% nitrogen, 2% oxygen, 1% carbon dioxide, and about 660 ppm of ethane (analysis carried out by the Authors at the mud volcano complex, Stop 1.6, in June 2013).…”

“…This have been known since ancient times and have been studied from historians, scientists and travelers (e.g. Stoppani, 1873;Coppi, 1875;Pantanelli & Santi, 1896;Biasutti, 1907;Barbieri, 1947;Mucchi, 1966Mucchi, , 1968Bertolani, 1980;Ferrari & Vianello, 1985;Gorgoni et al, 1988;Bertacchini et al, 1999;Castaldini et al, 2003 and2007;Gorgoni, 2003;Bonini 2008Bonini , 2009Bonini and 2012Carobene & Gasperi, 2008;Bertacchini, 2009;Castaldini et al, 2011), contributing to create an important documentation on its evolution. Since the roman period, the Nirano area was a dwelling place of organized groups that worked with ceramics and bricks, as testified by many historical sources and proved by the discovery of an ancient crockery furnace.…”

“…Also seismic events may control the activity of Salse di Nirano. Indeed, episodes of intense activity of the mud volcanoes have been often correlated to local earthquakes (Stohr, 1869;Pantanelli & Santi, 1896;Pellegrini et al, 1982;Gorgoni et al, 1988) some days before the occurrence of these (Gorgoni, 2003). Per example, couple of days before of the strongest earthquakes of the Emilian seismic sequence of 2012 (May 20 and 29, M L 5.9 and 5.8, respectively), an increased activity of Nirano mud volcanoes, that led to the morphology modification of the main volcanic apparatus, was visually recorded.…”