Tsunami deposits preserved in coastal karst pockets on Malta (Central Mediterranean Sea)

Document Type

Article

Source of Publication

Sedimentology

Publication Date

6-23-2025

Abstract

Triggered by earthquakes along the Hellenic and Calabrian arcs, submarine landslides and eruptions of active volcanoes in Italy and Greece, the Mediterranean Sea has experienced significant tsunamis in the past. Nonetheless, the patterns of these tsunamis in terms of timing, frequency, intensities and the dominant triggering mechanisms remain poorly understood. The unique position of the Maltese Islands in the Central Mediterranean makes Malta vulnerable to tsunami risks from various directions in the surrounding seascape. However, in contrast to many other Mediterranean coastlines, no onshore sediments associated with tsunamis have yet been reported in the Maltese archipelago, except for boulder deposits that face limitations with age-dating and correlation with known historical events. This study reveals hitherto unrecognized sand-grade sediments deposited within karst pockets (solution hollows), typical of exposed limestone terrain on the L-Aħrax Peninsula (northern Malta Island). These karst pockets (>10 m above sea-level) are ideal repositories for the preservation of tsunami deposits because, once washed in, sediments are protected from removal by natural forces. The sediments comprise shelly sands overlying terra rossa lining the base of the hollows. Through their retrieval, examination and interpretation, this study presents the first detailed description of tsunami sediments in Malta, characterizing their granulometric properties, sedimentary structures and micro-faunal assemblages that together indicate a marine origin for the sands. Relative age-dating was achievable from the detection of Amphistegina lobifera, locally an alien foraminifer species, but which is known to have invaded the Mediterranean Sea with the opening of the Suez Canal in 1869. The frequent occurrence of karst pocket sand deposits in juxtaposition with boulder deposits atop steep cliffs suggests a probable palaeotsunami origin, shedding new light on the coastal hazard exposure of the Central Mediterranean.

ISSN

0037-0746

Publisher

Wiley

Disciplines

Earth Sciences

Keywords

Foraminifera, grain-size analysis, Malta, Mediterranean, palaeotsunami research, tsunami

Scopus ID

105008524355

Indexed in Scopus

yes

Open Access

yes

Open Access Type

Bronze: This publication is openly available on the publisher’s website but without an open license

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