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The July–August 2000 seismic swarms at Campi Flegrei Volcanic Complex, Italy
Author(s) -
Saccorotti Gilberto,
Bianco Francesca,
Castellano Mario,
Del Pezzo Edoardo
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl013053
Subject(s) - geology , seismology , volcano , earthquake swarm , focal mechanism , fault (geology) , fault plane , geodetic datum , shear (geology) , induced seismicity , geodesy , petrology
Two swarms of microearthquakes ( M L ≤ 2.2), occurred on July 2–7 and August 22, 2000 at Campi Flegrei, accompained by a ground uplift episode (4 cm) which interrupted on early March 2000 the descending trend started on 1985. Spectral analysis indicates a direct involvement of magmatic/hydrothermal fluids in the source process of the July swarm, while the August events are typical of shear failure, similar to most of the earthquakes that occurred during the last (1982–1984) bradyseismic crisis. Precise 3‐D relative location applied to similar earthquakes allows for the recognition of two parallel alignments trending NE‐SW at depths of 1.7 and 3.2 Km. This trend is consistent with the direction of the main focal plane obtained from fault plane solutions and evidences tensile failure in close proximity to the zone of maximum uplift as depicted by geodetic measurements. A fault weakening mechanism triggered by increasing pore pressure is invoked as the cause of these earthquakes.