Archaeology of disaster in Indonesia: where are we now?

Natural disasters are a phenomenon that shaped the Indonesian Archipelago. Earthquakes and volcanic activities have become periodic experiences in the lives of people in this region. The geographical characteristics of Indonesia which are located at the confluence of active plates and part of the global volcanic chain are natural factors that make these islands vulnerable to disasters. Cultural historical studies have recorded various phenomena of past natural disasters in the archipelago. Some have had minimal impact, but others have resulted in the loss of civilization. Although the issue has become the important part of the civilization and profile of Indonesia, the archaeological study of disasters has not well developed. The existing studies so far are still very partial with the fragmentary results. Characterized with this complex character, the study of archaeological disaster requires a multidisciplinary approach. This paper attempts to discuss the archaeology of disasters in Indonesia including the background, current conditions and the prospects of future development. Particularly in discussing the role of local wisdoms in dealing with disasters as part of the civilization of the archipelago.

Multiple melt source origin of the Line Islands (Pacific Ocean)

The Line Islands volcanic chain in the central Pacific Ocean exhibits many characteristics of a hotspot-generated seamount chain; however, the lack of a predictable age progression has stymied previous models for the origin of this feature. We combined plate-tectonic reconstructions with seamount age dates and available geochemistry to develop a new model that involves multiple melt regions and multiple melt delivery styles to explain the spatial and temporal history of the Line Islands system. Our model identifies a new melt source region (Larson melt region at ~17°S, ~125°W) that contributed to the formation of the Line Islands, as well as the Mid-Pacific Mountains and possibly the Pukapuka Ridge.

A Globally Significant Potential Megascale Geopark: The Eastern Australian Mantle Hotspot Interacting with a North-Migrating Heterogeneous Continental Plate Creating a Variety of Volcano Types, Magmas, Xenoliths, and Xenocrysts

Australia commenced separating from Antarctica some 85 million years ago, finally separating about 33 million years ago, and has been migrating northwards towards the Eurasian plate during that time. In the process, Australia, on its eastern side, progressively passed over a mantle hotspot. A magma plume intersected a variable lithocrust with various lithologic packages such as Phanerozoic sedimentary basins, fold belts and metamorphic terranes, and Precambrian rocks. As such, there was scope for compositional evolution of magmas through melting and assimilation, as well as plucking of host rocks to include xenoliths, and xenocrysts. The volcanic chain, volcanoes, and lava fields that are spread latitudinally along 2000 km of eastern Australia present a globally-significant volcanic system that provides insights into magma and crust interactions, into the variability of xenoliths and xenocrysts, into magma evolution dependent on setting, and into the mantle story of the Earth. The Cosgrove Volcano Chain is an example of this, and stands as a globally-unique potential megascale geopark.

Critical Tectonic Limits for Geothermal Aquifer Use: Case Study from the East Slovakian Basin Rim

The Pannonian basin is a major geothermal heat system in Central Europe. Its peripheral basin, the East Slovakian basin, is an example of a geothermal structure with a linear, directed heat flow ranging from 90 to 100 mW/m2 from west to east. However, the use of the geothermal source is limited by several critical tectono-geologic factors: (a) Tectonics, and the associated disintegration of the aquifer block by multiple deformations during the pre-Paleogene, mainly Miocene, period. The main discontinuities of NW-SE and N-S direction negatively affect the permeability of the aquifer environment. For utilization, minor NE-SW dilatation open fractures are important, which have been developed by sinistral transtension on N–S faults and accelerated normal movements to the southeast. (b) Hydrogeologically, the geothermal structure is accommodated by three water types, namely, Na-HCO3 with 10.9 g·L−1 mineralization (in the north), the Ca-Mg-HCO3 with 0.5–4.5 g·L−1 mineralization (in the west), and Na-Cl water type containing 26.8–33.4 g·L−1 mineralization (in the southwest). The chemical composition of the water is influenced by the Middle Triassic dolomite aquifer, as well as by infiltration of saline solutions and meteoric waters along with open fractures/faults. (c) Geothermally anomalous heat flow of 123–129 °C with 170 L/s total flow near the Slanské vchy volcanic chain seems to be the perspective for heat production.

Critical Tectonic Limits for Geothermal Aquifer Use: Case Study from the East Slovakian Basin Rim

The Pannonian basin major heat system in Central Europe. Their peripheral basins like the East Slovakian basin is a example of a geothermal structure with a linear directed heat flow ranging from 90 to 100 mW /m2 from west to east. However, the use of the geothermal source is limited by several critical tectono-geologic factors: (a) tectonics, and the associated disintegration of the aquifer block by multiple deformations during the pre-Paleogene mainly Miocene period. The main discontinuities of NW-SE and N-S direction negatively affect the permeability of the environment. On the contrary, for utilization are important the secondary minor NE-SW dilatation open fractures which have developed by sinistral transtension on N–S faults and accelerated normal movements to the southeast in the present. (b) hydrogeological conditions, the geothermal structure accommodated three water types, namely Na-HCO3 with 10.9 g.l-1 mineralization (in the north), the Ca-Mg-HCO3 with 0.5 – 4.5 g.l-1 mineralization (in the west), and Na-Cl water type containing 26.8-33.4 g.l-1 (in the southwest) mineralization. The chemical composition is influenced by the Middle Triassic dolomites aquifer as well as by infiltration of saline solutions and meteoric waters along open fractures/faults. (c) geothermally anomalous heat 123 – 129 °C close to volcanic chain with 170 l/s total flow seems to be the perspective for heat production.

Conduit processes of the Sf. Ana (TGS) sub-Plinian-Vulcanian eruption sequence of the Ciomadul volcano (SE Carpathians)

<p>The Sf. Ana crater is the young volcanic crater of the dacitic Ciomadul volcano located at the SE end of the Călimani-Gurghiu-Harghita volcanic chain in the Eastern Carpathians. The crater was formed at ~60-30 kyr-s ago probably by several eruptions. The Sf. Ana also called as TGS eruption sequence was the main event that shaped the crater to the present form. The eruption produced fall and PDC deposits, but it is unclear what caused the change in the eruption style. The stratigraphically controlled analyses of the Mohos Layered Pyrolcalstic Sequence (MLPS) provide deep insight into the evolution of the eruption. Assuming that juvenile clast density is primarily controlled by the magma vesiculation within the conduit, the processes close to the fragmentation level can be studied. The vesicularity, vesicle texture, microlite texture, and glass H2O content of the juvenile pyroclasts were studied to reveal the conduit processes. The juvenile clasts show textural evidence for different stages of the vesiculation from bubble nucleation to collapse indicating degassing and outgassing processes in the conduit. The increase of the juvenile clast density upward in the MLPS and the sharp increase of the dense clasts in the PDC deposits indicate the effect of magma column heterogeneity on the eruption style. The conduit heterogeneity was induced by the effective outgassing of the slowly ascending magma portion due to the evolution of vesicle textures together with localized shearing. The eruption column collapse was preceded by a vent failure event which caused densification in the conduit. Banded pumices suggest that the observed conduit heterogeneity was small scale.</p><p> </p><p>The study is supported by the PD130214 project National Research, Development, and Innovation Fund of Hungary.</p>

Insights from fumarole gas geochemistry on the recent volcanic unrest of Pico do Fogo, Cape Verde

<p>The Cape Verde islands are located about 800 km west of Senegal, at 14°-17° latitude and 21°-25° longitude. The archipelago consists of a volcanic chain of 10 major islands and eight minor islands The only currently active volcano in the Cape Verde archipelago is Pico do Fogo, which is located on the island of Fogo. Rising to 2829 m a.s.l., it is the most active volcano of the Cabo Verde Island. We report the results of the geochemical monitoring of the fumarolic discharges at the Pico do Fogo volcano in Cape Verde from 2007 to 2016. During this period Pico do Fogo experienced a volcanic eruption (November 23, 2014) that lasted 77 days. Two fumaroles were sampled, a low (F1~100ºC) and a medium (F2~300ºC) temperature. The variations observed in the δ<sup>18</sup>O and δ<sup>2</sup>H in F1 and F2 suggest different fluid source contributions and/or fractionation processes. Although no significant changes were observed in the outlet fumarole temperatures, two clear increases were observed in the vapor fraction of fumarolic discharges during the periods 2008-2009 and 2013-2014. Also, two sharp peaks were observed in CO<sub>2</sub>/CH<sub>4</sub> ratios at both fumaroles, in November 2008 and November 2013, coinciding with significant increases in the emission rate of diffuse CO<sub>2</sub> and He, and heat flow measured in the crater of Pico do Fogo volcano. This confirms that gases with a strong magmatic component rose towards the surface within the Pico do Fogo system during 2008 and 2013. Further, F2 showed two CO<sub>2</sub>/St peaks, the first in late 2010 and the second after eruption onset, suggesting the occurrence of magmatic pulses into the volcanic system. Time series of He/CO<sub>2</sub>, H<sub>2</sub>/CO<sub>2</sub> and CO/CO<sub>2</sub> ratios are low in 2008-2009, and high in 2013-2014 period, supporting the hypothesis of fluid input from a deeper magmatic source. Regarding to the isotopic composition, increases in <sup>3</sup>He/<sup>4</sup>He (R/R<sub>A</sub>)<sub>cor</sub> are observed in both fumaroles; F1 showed a peak in 2010 from a minima in 2009 during the first magmatic reactivation onset and another in late 2013, while F2 displayed a slower rise to its maximum in late 2013. The high <sup>3</sup>He/<sup>4</sup>He ratios in both fumaroles are close to the magmatic end-member, indicating that He is predominantly of upper mantle origin. This work supports that monitoring of the chemical and isotopic composition of the fumaroles of the Pico do Fogo volcano is a very important tool to understand the processes that take place in the magmatic-hydrothermal system and to be able to predict future episodes of volcanic unrest and to mitigate volcanic risk.</p>

An investigation approach of the volcanic geomorphology in the Călimani – Gurghiu – Harghita volcanic chain, Romania

<p><span><span>In poorly-exposed forest-covered volcanic areas, the main challenge in classical geological and geomorphological studies is the interpretations of landforms and volcanic structures. The usage of 3D models provides modern opportunities in visualization of volcanic landforms in volcanological studies in areas with dense vegetation cover</span></span><span><span>. </span></span></p><p><span><span>Geological mapping of the Neogene Călimani-Gurghiu-Harghita (CGH) volcanic chain is challenging due poor exposure of area. The Călimani-Gurghiu-Harghita volcanic chain exhibits ~10 My age range spanning from North (> 10 Ma) to South (< 0.03 Ma) linked to the evolution of the adjacent intra-mountain sedimentary basins (</span></span><span>Bilbor, Borsec, Gheorgheni, Upper Ciuc, Lower Ciuc, Brașov </span><span><span>and </span></span><span>Baraolt </span><span><span>basins</span></span><span>)</span><span><span>. The geomorphological analysis of the CGH volcanic chain is currently performed using SRTM data. However, the SRTM data are affected by the vegetation cover. Instead, we used a digital elevation models (DEM) built from topographic maps in combinations with volcanological field observations.</span></span></p><p><span>Our method uses a DEM 3D spatial view with overlay standard geological maps, shaded relief complemented with terrain analysis and landform recognition. Then, the study integrates field-based observations and geomorphological mapping results in a new general overview of the complex volcanic topography of the CGH volcanic chain. </span></p><p><span><span>Using </span></span><span><span>digital</span></span><span><span> elevation models (DEM) allows the general identification of volcanic facies distribution (proximal, medial and distal) belonging to </span></span><span><span>an individual</span></span><span><span> volcanic structures as well as the regional assemblages of the whole volcanic chain. DEM studies also permit to reconstruct the erosion level of volcanic edifices in conjunctions with field-based volcanological studies. This approach may also help identifying volcanological formations and various types of volcanic facies resulting from both construction and destructions of the edifices in poorly exposed areas.</span></span></p><p><span><span>By using this methodology a broad range of volcanic morphological features have been observed along the CGH volcanic range including the </span></span><span>Călimani</span><span><span> caldera morphology, features of the old and young debris avalanche deposits of various volcanic edifices and the youngest lava-dome morphology of </span></span><span>Ciomadul</span><span><span> volcano. Our DEM approach provides better results than those obtained by previous studies pointing out, for instance, that the volcanic edifices are highly to moderately eroded in the north and progressively better preserved toward the south. </span></span></p><p><span>Acknowledgements. The research was funded through CNCS – UEFISCDI, project number PN-III-P4-ID-PCCF-2016-4-0014, within PNCDI III.</span></p>