Pre-Conference Field Trip COV 11

Methana volcanic peninsula

2 DAYS

Field Leaders

Date
10-11 June 2022

Duration
2 days

Number of participants
from 35 to 40

Cost
170 euros

The peninsula is located in the area of the Saronic Gulf, which is characterized by E-W normal faults and by NE-SW strike-slip faults and cross-cut by a myriad of smaller faults. The vents have usually developed along these tectonic lines. 

According to scientists, at least 14 distinct eruptions can be identified, mostly effusive. Explosive activity is rare and emplaced at least 3 distinct pumice deposits. The erupted volumes are moderate, generally <0.9 km3. 

The volcanic stratigraphy of Methana has been documented on the “Geological Map 1:25000 of Methana” (Dietrich et al. 1996) and revised by Pe-Piper and Piper (2013). 

The ages of the volcanic activity are poorly constrained. For simplicity, the eruptions can be separated in 4 phases and numbered from I to XIV, after the model of Popa et al. (in press): 

Events I and II: the so-called “volcanic socle”, dated at 3.5 ± 0.9 Ma, covers the Mesozoic basement and Lower Pliocene marine marls (nannoplankton NN15 ∼ 4.2 Ma). It is marked by an explosive eruption and by a series of domes and lava flows extruded all over the peninsula. Events III – XI (with random dates between 1.4±0.3 and 0.6 ± 0.2 Ma): marked by two explosive eruptions (VI and VIII) and by a series of lava flows and domes. Limited hydrothermal activity is associated with this stage of volcanic activity. Events XII-XIII with ages of 0.34 and 0.29 Ma: lava flows and domes extruded from vents developed on N-S (XII) and E-W (XIII) directions. The eruptions are probably closely related to tectonic activity and the development of faults/fractures. Event XIV: the youngest eruption, the Mavri Petra lava flow complex, which has erupted in historical times ~ 250 BP in the NW corner of the peninsula. 

An extensive geochemical survey on the fluids released by the volcanic/geothermal system of Methana was undertaken. Characterization of the gases was made on the basis of the chemical and isotopic (He and C) analysis. CO2 soil gas concentration and fluxes were measured on the whole peninsula at more than 100 sampling sites. 

Today, Methana is well situated for family, religious and health tourism. It is ideal for hiking trips in beautiful paths between the hills, interesting for the unique flora and fauna and offers plenty of Byzantine churches and small chapels. It is a traditional site for hot baths and health spas.

Nisyros Field Trip

4 DAYS

Field Leader

Date
8-11 June 2022

Duration
4 days

Number of participants
from 25 to 30

Cost
430 euros

It lies above a basement of Mesozoic limestone and a thinned crust of the Alpine orogen, with a mantle-crust transition at ~ 27 km depth. The volcanic edifice of Nisyros comprises a succession of calc-alkaline lavas and pyroclastic rocks, with a summit caldera of an average diameter of 4 km. Although the last magmatic volcanic activity on Nisyros dates back at least 18,000 years, the present geodynamic activity encompasses high seismic unrest and widespread fumarolic activity with surface temperatures of ~ 100°C and 350°C at a depth of 1’500m. Violent earthquakes and steam blasts accompanied the most recent hydrothermal eruptions in 1871–1873 and 1887 and left large hydrothermal explosion craters behind. Mud and hydrothermal vapor rich in CO2 and H2S were emitted from fracture zones which cut the caldera and extend towards the NNW through the vicinity of the village of Mandraki, into the island of Yali, and even towards Kos. In 1996 and 1997 seismic activity started with earthquakes of magnitudes up to 5.5 and with hypocenters down to 10 km depth around inferred magna reservoirs between 5 -12 km. The discharge of all hydrothermal craters in the caldera releases 68 tons of hydrothermal-volcanic derived CO2 and around 42 MW of thermal energy per day.

Nisyros Island has a long-standing colorful history since it is found at the crossroads between occidental and oriental cultures. Cycladic and Minoan relicts are spotted in the wild mountainous scenery of post-caldera domes, whereas witnesses from the Hellenistic epoch, Roman, Byzantine, Venetian and Ottoman times are represented in ancient caverns and spas, magnificent castles, churches and monasteries.

The Yali volcanic island with eruptive ages between approx. 40,000 and 20,000 years exhibits parts of a submerged caldera, dissected by a post-caldera N-S fault Yali is located north of the island of Nisyros, with max. length of 5km, max. widths of 1.5km and a max. altitude of 165m is by Two large pumice successions built up the southwestern part of the island, whereas the north-eastern part comprises obsidian-perlitic lava domes and flows covered by pumice deposits. Since 1952 pumice and perlite are quarried on the uninhabited volcanic island