The Gyra washover fan in the Lefkada Lagoon, NW Greece—possible evidence of the 365 AD Crete earthquake and tsunami

Napatree Point, an isolated barrier in southern Rhode Island, provides a case study of barrier spit migration via storm driven overwash and washover fan migration. Documented shoreline changes using historical surveys and vertical aerial photographs show that the barrier had little in the way of net change in position between 1883 and 1939, including the impact of the 1938 hurricane. The barrier retreated rapidly between 1945 and 1975, driven by both tropical and extra-tropical storms. The shoreline position has been largely static since 1975. The removal of the foredune during the 1938 hurricane facilitated landward shoreline migration in subsequent lower intensity storms. Dune recovery following the 1962 Ash Wednesday storm has been allowed due to limited overwash and barrier migration over the last several decades. Shoreline change rates during the period from 1945–1975 were more than double the rate of shoreline change between 1939 and 2014 and triple the rate between 1883 and 2014, exceeding the positional uncertainty of these shoreline pairs. The long-term shoreline change rates used to calculate coastal setbacks in Rhode Island likely underestimate the potential for rapid shoreline retreat over shorter time periods, particularly in a cluster of storm activity. While sea-level rise has increased since 1975, the barrier has not migrated, highlighting the importance of storms in barrier migration.

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Washover and washover fan

10.1007/springerreference_4799 ◽

2011 ◽

Keyword(s):

Washover Fan

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Impact of historical tsunamis on a sandy coastal barrier: an example from the northern Gargano coast, southern Italy

Natural Hazards and Earth System Science ◽

10.5194/nhess-1-213-2001 ◽

2001 ◽

Vol 1 (4) ◽

pp. 213-219 ◽

Cited By ~ 41

Author(s):

F. Gianfreda ◽

G. Mastronuzzi ◽

P. Sansò

Keyword(s):

Northern Coast ◽

Deep Trench ◽

Tsunami Waves ◽

Coastal Barrier ◽

Severe Erosion ◽

Gargano Promontory ◽

Historical Times ◽

Roman Age ◽

Washover Fan ◽

Radiometric Data

Abstract. The Lesina coastal barrier is characterized by the presence of three wide washover fans. They were formed by three distinct tsunamis which struck the northern coast of the Gargano Promontory (Apulia, Italy) during historical times. A model for their formation is presented. It takes into account the geomorphological data collected and some reports about the effect of recent tsunamis on coastal barriers and beaches. Washover fans were produced by tsunami waves which ran through coseismic cracks developed on dune ridges shaping a narrow, straight and relatively deep trench which constitutes the fan throat. Moreover, each tsunami event most likely caused severe erosion of the coastal barrier, shaping erosive grooves across the dune ridges, causing beach cliffs and causing the nourishment of submarine offshore bars. After the tsunami, a phase of coastal barrier recovery began, forming new dune ridges and closing washover fan throats. Morphological, archeological and radiometric data indicate a pre-Roman age for the oldest event, which was dated at 2430 years BP. The second tsunami struck the Lesina coastal barrier with similar magnitude 1550 years BP; it was caused by the strong earthquake that occurred at Gargano Promontory in the year 493 AD as reported by a medieval sacred legend. The smallest and more recent fan formed following the tsunami that hit the northern coast of Gargano on 30 July 1627.

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Washover Fan and Terrace Dynamics--A Stormy Year on Assateague Island, Virginia and Maryland: ABSTRACT

AAPG Bulletin ◽

10.1306/ad460ed6-16f7-11d7-8645000102c1865d ◽

1984 ◽

Vol 68 ◽

Author(s):

R. Craig Kochel, Jacob H. Kahn

Keyword(s):

Assateague Island ◽

Washover Fan

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Washover fan and brackish bay sedimentation in the Berriasian-Valanginian of Bornholm, Denmark

Sedimentology ◽

10.1111/j.1365-3091.1988.tb00945.x ◽

1988 ◽

Vol 35 (2) ◽

pp. 197-217 ◽

Cited By ~ 28

Author(s):

NANNA NOE-NYGAARD ◽

FINN SURLYK

Keyword(s):

Washover Fan

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Rupture model of the great AD 365 Crete earthquake in the southwestern part of the Hellenic Arc

Acta Geophysica ◽

10.2478/s11600-008-0001-6 ◽

2008 ◽

Vol 56 (2) ◽

pp. 293-312 ◽

Cited By ~ 25

Author(s):

Eleftheria E. Papadimitriou ◽

Vassilios G. Karakostas

Keyword(s):

Southwestern Part ◽

Hellenic Arc ◽

Rupture Model ◽

Crete Earthquake

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Integration of historical, archaeoseismic and paleoseismological data for the reconstruction of the early seismic history in Messina Strait (south Italy): the 1st and 4th centuries AD earthquakes

Annals of Geophysics ◽

10.4401/ag-6369 ◽

2014 ◽

Vol 57 (1) ◽

Author(s):

Maria Serafina Barbano ◽

Viviana Castelli ◽

Daniela Pantosti ◽

Claudia Pirrotta

Keyword(s):

Historical Data ◽

Seismic Source ◽

Seismic Sources ◽

Tsunami Deposits ◽

Damage Area ◽

South Italy ◽

Messina Strait ◽

Historical Accounts ◽

Crete Earthquake ◽

Northeastern Sicily

<p>Historical accounts, archaeoseismic and paleoseismological evidence allowed us to reappraise two earthquakes affecting northeastern Sicily and southern Calabria in the 1st (probably between 14 and 37) and 4th (likely between 361 and 363) centuries AD, to obtain a better reconstruction of their effects and to reconsider their sources.The 1st century event damaged the area from Oppido (Calabria) to Tindari (Sicily), roughly that of the February 6, 1783 Calabria earthquake. The similitude of these earthquakes is further stressed by the fact that they generated tsunamis, as recorded by historical data and by the tsunami deposits found at Capo Peloro, the oldest dated 0-125 AD, the youngest linked to the 1783 event. These earthquakes could be related to the same Calabria seismic source: the Scilla fault. Northeastern Sicily and southern Calabria were also damaged by one or more earthquakes in the 4th century AD and several towns were rebuilt/restored at that time. The hit area roughly coincides with that of the Messina 1908 earthquake suggesting similar seismic sources for the events. However, because close in time, historical descriptions of the 4th century Sicilian earthquake were mixed with those of the 365 Crete earthquake that generated a basin-wide tsunami most likely reaching also the Sicilian coasts. Reevaluating location, size, damage area and tsunamigenic potential of these two earthquakes of the 1st and 4th centuries AD is relevant for reassessing the seismogenic and tsunamigenic potential of the faults around the Messina Strait and the seismic hazard of the affected areas.</p>

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Spatial and temporal controls on overwash occurrence on a Great Lakes barrier spit

Canadian Journal of Earth Sciences ◽

10.1139/e92-011 ◽

1992 ◽

Vol 29 (1) ◽

pp. 102-117 ◽

Cited By ~ 24

Author(s):

Robin G. D. Davidson-Arnott ◽

John D. Fisher

Keyword(s):

Lake Level ◽

Field Measurements ◽

High Water ◽

Water Phase ◽

Storm Events ◽

North Shore ◽

The North ◽

High Lake Level ◽

Washover Fan

Field measurements from 1985 to 1990 and sequential aerial photography since 1945 show that overwash plays an extremely important role in the dynamics of Long Point, a large barrier spit on the north shore of Lake Erie. Overwash occurs primarily in the transgressive proximal and central zones of the spit, which together account for some 65% of the total shoreline length of 41 km. During periods of high lake level, over 50% of the shoreline in these zones may be overwashed. Washover morphology ranges from continuous washover terraces in areas of low foredunes to isolated washovers with narrow throats and distinct fans where breaching has occurred through high dunes. Individual overwash events commonly produce deposits on the fan surface 0.25–0.75 m or more in thickness. Washover-fan sediments are dominated by nearly horizontal planar bedding, with deposits near the fan margins often having foreset bedding, reflecting deposition in standing water of the bay or of interdune ponds.The frequency of overwash occurrence is strongly influenced by long-term lake-level fluctuations, which produce a distinct cycle of overwash activity. During the high-water phase more than 40% of the shoreline may consist of active washover fans or inlet breaches. Even storms with a return frequency of 1–2 per year can lead to significant overwash activity, and the washovers are generally reactivated several times in a 2 or 3 year period around the peak water level. During the low-water phase wider beaches offer protection against even extreme storm events, resulting in washover healing and restoration of a continuous foredune.

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