Major Holocene glacio-isostatically-induced earthquakes triggered mass-transport deposits and seabed displacements in Lake Melville

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology Pub Date : 2025-01-21 DOI:10.1016/j.margeo.2025.107482

Jaia Syvitski , Alexandre Normandeau , Patrick Lajeunesse

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引用次数: 0

Abstract

The character and history of post-depositional structures within Lake Melville, Labrador, Canada, is investigated from a geohazard and sedimentary process perspective. Large Holocene earthquakes during glacio-isostatic recovery generated large (up to 3.1 km³) contemporaneous failures across up to 7 separated basins, and earthquake-related markers including vents, pockmarks, diapirs, stratigraphic offsets, and massive liquefaction fronts. Epicenter locations within Lake Melville are identified for three ∼7 ± M_L magnitude Holocene earthquakes. Deposits include a massive 3.1 km³ turbidite MT event at ∼7 ± 0.3 kyr BP, the up to 1.1 km³ mega debris flow DF1 event at ∼6 ± 0.2 kyr BP, and the equally large 1750 ± 50 CE DF2 event. Mega-debris flow theory is revised to include seafloor liquefaction beneath the path of the mass flow, debris-flow bulking by incorporating underlying sediments, and shock-front compression for failures with large drop heights. During the DF1 event, 68 km² of the seafloor collapsed forming fault-strike mega-pockmarks or vents, with 40 % contemporaneously buried by mega debris flows. The collapse volume is associated with ∼5000 large sand or mud diapirs (∼0.2 Gt) at a spatial density of 5 ± per km² across well-separated basins. The DF2 event created a 0.11 km³ prodelta channel that since 1750 CE serves largely as a bypass zone for a growing 0.01 km³ sandy turbidite fan. Lake Melville's tendency towards thixotropic sediment failure reflects high basin-filling accumulation rates (3+ cm per yr) and the presence of buried and over-pressured low-cohesion sandy-silt layers. Mega debris flows in Lake Melville remobilized and entrained substrate during transport, more than doubling their original failure volume. Tsunami wave amplitude predictions may be over-estimated by up to 75 %, if incorrectly based on deposit volume rather than the originating slope failure. Maximum tsunamis amplitude estimates for Lake Melville fall between ∼23 m and ∼ 69 m.

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来源期刊

Marine Geology 地学-地球科学综合

CiteScore

6.10

自引率

6.90%

发文量

175

审稿时长

21.9 weeks

期刊介绍： Marine Geology is the premier international journal on marine geological processes in the broadest sense. We seek papers that are comprehensive, interdisciplinary and synthetic that will be lasting contributions to the field. Although most papers are based on regional studies, they must demonstrate new findings of international significance. We accept papers on subjects as diverse as seafloor hydrothermal systems, beach dynamics, early diagenesis, microbiological studies in sediments, palaeoclimate studies and geophysical studies of the seabed. We encourage papers that address emerging new fields, for example the influence of anthropogenic processes on coastal/marine geology and coastal/marine geoarchaeology. We insist that the papers are concerned with the marine realm and that they deal with geology: with rocks, sediments, and physical and chemical processes affecting them. Papers should address scientific hypotheses: highly descriptive data compilations or papers that deal only with marine management and risk assessment should be submitted to other journals. Papers on laboratory or modelling studies must demonstrate direct relevance to marine processes or deposits. The primary criteria for acceptance of papers is that the science is of high quality, novel, significant, and of broad international interest.