Premium
Pre‐seismic slip on the 26 September 1997, Umbria‐Marche Earthquake fault? Unexpected clues from the analysis of 1951–1992 elevation changes
Author(s) -
De Martini P. M.,
Valensise G.
Publication year - 1999
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 - 10.1029/1999gl900386
Subject(s) - geology , seismology , slip (aerodynamics) , geodesy , amplitude , elevation (ballistics) , fault (geology) , geometry , mathematics , quantum mechanics , thermodynamics , physics
We studied 1951–1992 elevation changes recorded by a first order leveling line that intercepts the surface projection of the 26 Sep. 1997, M w 6.0, Umbria‐Marche earthquake causative fault. The line documents 1951–1992 localized subsidence along a 12 km section above the fault. We calculated the expected 1997 coseismic elevation changes along the line using standard dislocation modeling and found that their trend has an amplitude three times larger than the trend of the observed pre‐1997 signal but with a similar shape. We suggest that this signal is the result of 10 cm of pre‐1992 slip along the northernmost 5 km of the 1997 earthquake fault, where coseismic slip was found to be less than the average estimated for the entire fault. This result implies unusually fast slip along this section of the fault and may suggest slip acceleration in preparation for the impending failure.