Late Holocene tectonic implications deduced from tidal notches in Leukas and Meganisi islands (Ionian Sea)

In this paper the tectonic behavior of Leukas and Meganisi islands (Ionian Sea) is examined through underwater research carried out in both islands. A possible Late Holocene correlation between coseismic subsidences is attempted and evidenced by submerged tidal notches in both islands. These subsidence events probably occurred after the uplift that affected the northernmost part of Leukas around 4 to 5ka BP. In conclusion, although the whole area was affected by a similar tectonic strain, certain coseismic events were only recorded in one of the two islands and in some cases they affected only part of the study are

Late Holocene shorelines deduced from tidal notches on both sides of the Ionian Thrust (Greece): Fiscardo Peninsula (Cephalonia) and Ithaca Island.

Fossil shorelines produced by recent co-seismic movements were identified throughasubmarine survey along the coasts of Ithaca and Fiscardo (Greece).In both areas a tidal notch-slightly submerged below present Mean Sea Level (MSL) was observed at various sites. This “modern” notch is known to have been submerged by the global sea-level rise during the 19th and 20th centuries. The depth after tide and air-pressure correction of the vertex of the “modern” notch (that owes its submergence to the current rapid sea level rise) was measured between -20 and -30±5cm at Fiscardo and between -36 and -45±6cm at Ithaca. This “modern” notch at the same depth on east and west sides of the Ionian Thrust suggests that both areas were not affected by the co-seismic vertical movements that occurred in 1953 (in the wider area). On the other hand, a greater depth in Ithaca could be an effect of co-seismic subsidence. Over the long term, the tectonic behavior of Ithaca differs from Fiscardo. At Ithaca no evidence of emergence was found and Holocene vertical movements have been only of subsidence: submerged fossil tidal notches were distinguished below MSL at about -40 (modern), -60, -75, -95, -106, -126, -150 and -220±6cm. On the East coast of Fiscardo peninsula impacts of ancient earthquakes have left some marks of emergence at about +18 and +44±5cm, and of submergence at about -25 (modern), -45, -60, -75, -82, -100 and -230cm, with even some evidence of past uplift and subsidence at the same sites

Multiple submerged tidal notches: A witness of sequences of coseismic subsidence in the aegean sea, greece

In some islands of the Aegean, there is evidence of the occurrence of repeated rapid subsidences during the Late Holocene. In this paper, the shape of tidal notches that may be well-preserved underwater is recalled in order to reconstruct sequences of coseismic subsidences and other relative sea-level changes, which occurred during, at least, the last few millennia. A reanalysis of the published measurements of submerged tidal notches in several islands reveals that subsidence trends in many areas of the Aegean are not continuous with gradual movement but, also, are the result of repeated coseismic vertical subsidences of some decimetres at each time. The estimated average return times are of the order of approximately some centuries to one millennium. Although the results cannot be used for short-term predictions of earthquakes, they may provide useful indications on the long-term tectonic trends that are active in the Aegean region. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Late Holocene tectonic implications deduced from tidal notches in Leukas and Meganisi islands (Ionian Sea)

In this paper the tectonic behavior of Leukas and Meganisi islands (Ionian Sea) is examined through underwater research carried out in both islands. A possible Late Holocene correlation between coseismic subsidences is attempted and evidenced by submerged tidal notches in both islands. These subsidence events probably occurred after the uplift that affected the northernmost part of Leukas around 4 to 5ka BP. In conclusion, although the whole area was affected by a similar tectonic strain, certain coseismic events were only recorded in one of the two islands and in some cases they affected only part of the study area

Relative sea level changes and morphotectonic implications triggered by the samos earthquake of 30th october 2020

On 30th October 2020, the eastern Aegean Sea was shaken by a Mw = 7.0 earthquake. The epicenter was located near the northern coasts of Samos island. This tectonic event produced an uplift of the whole island as well as several cases of infrastructure damage, while a small tsunami followed the mainshock. Underwater and coastal geological, geomorphological, biological observations and measurements were performed at the entire coast revealing a complex character for the uplift. At the northwestern part of the island, maximum vertical displacements of +35 ± 5 cm were recorded at the northwestern tip, at Agios Isidoros. Conversely, the southeastern part was known for its subsidence through submerged archaeological remains and former sea level standstills. The 2020 underwater survey unveiled uplifted but still drowned sea level indicators. The vertical displacement at the south and southeastern part ranges between +23 ± 5 and +8 ± 5 cm suggesting a gradual fading of the uplift towards the east. The crucial value of tidal notches, as markers of co-seismic events, was validated from the outcome of this study. The co-seismic response of Samos coastal zone to the 30th October earthquake provides a basis for understanding the complex tectonics of this area. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Coastal geomorphological study of St. George bay, Western Naxos, Greece

In order to study the geomorphological and environmental characteristics of St. George bay, in western Naxos, Greece, a series of beachrock samples were examined. Special attention was given to the cement, to obtain information about the formation conditions of the beachrocks. In order to examine the cement of the beachrock samples, the methods of optical microscopy, secondary electron microscopy (SEM) and Raman Spectroscopy were used. The results of the beachrock samples analyses indicate that their formation took place under meteoric and marine vadose zone conditions. Certain characteristics relating to the composition and structure of the cement, sug-gest that the development of the beachrocks took place during sea level rise. © 2021 Gebr. Borntraeger Verlagsbuchhandlung, Stuttgart, Germany

Virtual field trips as a tool for indirect geomorphological experience: A case study from the southeastern part of the Gulf of Corinth, Greece

Field trips are an essential part for geoscience students, as the field is intrinsic for understanding what they are taught in the classroom. Yet, distance learning has never been more necessary than today. Despite their significance in the students' education, field trips cannot be performed under the present conditions with the COVID-19 pandemic. Educators are called to find, use and evolve various tools in order to offer students quality education, with an effort to eliminate the drawbacks of the lack of physical contact and "live"field work. Virtual field trips are one such tool through which one can virtually see any place on the globe by means of a computer, tablet, or even mobile phone, without physically visiting it. In this paper, we present the results of a virtual field trip developed for students following the Geomorphology course of the Faculty of Geology and Geoenvironment, National and Kapodistrian University of Athens; it can, however, be used from other universities with similar courses not only in Greece but also in other countries as well. The purpose of this study is the evaluation of virtual field trips, both as an alternative to and/or substitute for in situ field work and as a means of preparation for live field trips, by taking into consideration the students' views through an anonymous questionnaire. Our findings suggest that virtual field trips are useful for geoscience students, and they provide a good alternative during restriction periods, and although they can under no circumstances substitute real field trips, they can be a valuable additional tool when preparing for a live field trip. © 2021 Niki Evelpidou et al