Title: A 125 Kyr‐long geological record of seismic source repeatability: the Messina Straits (southern Italy) and the 1908 earthquake (M<sub>s</sub> 71/<sub>2</sub>)
Abstract: ABSTRACT The occurrence of characteristic earthquakes along segments of major active belts has been described as early as the beginning of the century. The large 1908, Messina Straits, blind normal faulting earthquake provides an opportunity to investigate the repetition of characteristic earthquakes and the persistency of the main features of the fault zone over a time‐scale in the order of 100 Kyr. We have compared seismological and geodetic descriptions of the 1908 rupture process with long‐term crustal deformation recorded at different stratigraphic levels by marine terraces, marine sedimentary units, and landscape features. The wealth of elevated coastal features in and around a region affected by large normal faulting earthquakes indicates that coseismic strain is superimposed on much faster uplift on a regional scale. We investigated in detail the pattern of deformation of the 125 Kyr‐old, lowest emergent terrace, and found that it mimics the pattern of elevation changes observed following the earthquake. This suggests (1) that the 1908 earthquake is characteristic, (2) that its segment boundaries have been stationary during the past 125 Kyr, and (3) that even the locations of the regions of largest coseismic release do not change through many seismic cycles. Based on a comparison between observed heights of the 125 Kyr terrace and 1908 displacements, we estimated an average repeat time of 1000± yr for a 1908‐type earthquake. We also investigated the height, position, age and state of deformation of older terraces, and found (1) that uplift of the region started about 1 Ma and has since continued rather uniformly at 0.9–1.4 mm yr ‐1 , (2) that during this time the Straits have narrowed at a rate of 10–20 mm yr ‐1 , and (3) that all the main geomorphic features of the Messina Straits result from the interaction of fast regional uplift, 1908‐type coseismic subsidence, and global sea‐level fluctuations.
Publication Year: 1992
Publication Date: 1992-04-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 176
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