Subsurface fluid distribution and possible seismic precursory signal at the Salse di Nirano mud volcanic field, Italy
| Autor: | Tullio Ricci, Matteo Lupi, Barbara Suski Ricci, Johannes Kenkel, Florian Fuchs, Andreas Kemna, Stephen A. Miller |
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| Rok vydání: | 2015 |
| Předmět: |
geography
geography.geographical_feature_category 010504 meteorology & atmospheric sciences Field (physics) Geophysics Forcing (mathematics) 010502 geochemistry & geophysics 01 natural sciences Signal Natural (archaeology) law.invention Amplitude Volcano Geochemistry and Petrology law ddc:550 Hydrostatic equilibrium Seismology Geology 0105 earth and related environmental sciences Mud volcano |
| Zdroj: | Geophysical Journal International, Vol. 204, No 2 (2016) pp. 907-917 |
| ISSN: | 1365-246X 0956-540X |
| DOI: | 10.1093/gji/ggv454 |
| Popis: | Mud volcanoes are geological systems often characterized by elevated fluid pressures at depth deviating from hydrostatic conditions. This near-critical state makes mud volcanoes particularly sensitive to external forcing induced by natural or man-made perturbations. We used the Nirano mud volcanic field as a natural laboratory to test pre- and post-seismic effects generated by distant earthquakes. We first characterized the subsurface structure of the Nirano mud volcanic field with a geoelectrical study. Next, we deployed a broad-band seismic station in the area to understand the typical seismic signal generated by the mud volcano. Seismic records show a background noise below 2 s, sometimes interrupted by pulses of drumbeat-like high-frequency signals lasting from several minutes to hours. To date this is the first observation of drumbeat signal observed in mud volcanoes. In 2013 June we recorded a M4.7 earthquake, that occurred approximately 60 km far from our seismic station. According to empirical estimations the Nirano mud volcanic field should not have been affected by the M4.7 earthquake. Yet, before the seismic event we recorded an increasing amplitude of the signal in the 10–20 Hz frequency band. The signal emerged approximately two hours before the earthquake and lasted for about three hours. Our statistical analysis suggests the presence of a possible precursory signal about 10 min before the earthquake. |
| Databáze: | OpenAIRE |
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