ALBERT

Description: An important question in geophysics is whether earthquakes (EQs) can be anticipated prior to their occurrence. Pre-seismic electromagnetic (EM) emissions provide a promising window through which the dynamics of EQ preparation can be investigated. However, the existence of precursory features in pre-seismic EM emissions is still debatable: in principle, it is difficult to prove associations between events separated in time, such as EQs and their EM precursors. The scope of this paper is the investigation of the pre-seismic EM activity in terms of complexity. A basic reason for our interest in complexity is the striking similarity in behavior close to irreversible phase transitions among systems that are otherwise quite different in nature. Interestingly, theoretical studies (Hopfield, 1994; Herz and Hopfield 1995; Rundle et al., 1995; Corral et al., 1997) suggest that the EQ dynamics at the final stage and neural seizure dynamics should have many similar features and can be analyzed within similar mathematical frameworks. Motivated by this hypothesis, we evaluate the capability of linear and non-linear techniques to extract common features from brain electrical activities and pre-seismic EM emissions predictive of epileptic seizures and EQs respectively. The results suggest that a unified theory may exist for the ways in which firing neurons and opening cracks organize themselves to produce a large crisis, while the preparation of an epileptic shock or a large EQ can be studied in terms of “Intermittent Criticality”.

Description: Numerous factors control the topographic evolution of mountain belts. Crustal thickening, rock uplift rate, and denudational forcing doubtlessly interact, but the feedback mechanisms amongst these are disputed, because they operate over entirely different time scales. Cosmogenically-derived denudation rates cover time-scales of 10(3) to 10(5) years, providing a denudational tool that allows us to shed light on interactions between long-term topography-forming processes and short-term factors destroying topography. Prerequisites for the application of this method in presently uplifting and fast-eroding mountain belts like the Central Alps are an investigation of appropriate watershed sizes for systematic sampling. Denudation rates in Maggia tributaries of various sizes reveal that the trunk stream yields statistically the same denudation rate (0.85 ± 0.14 mm/yr) as the tributaries (0.74 ± 0.14 mm/yr). Therefore, sampling of large watersheds is a feasible approach. Denudation rates of watersheds from the Central Alps are amongst the highest ever measured in similar complex settings, ranging in mean from 0.27 ± 0.05 mm/yr for the Alpine foreland to 1.42 ± 0.4 mm/yr for the high crystalline Central Alps. The measured cosmogenic denudation rates are in good agreement with post-LGM lake infill rates; they are significantly higher than recent denudation rates from river loads. We attribute this discrepancy to differences in methodology and integration time scale. We will show that denudation is high in areas of high altitude and high relief. Furthermore, our data shows that denudation rates are low in areas of low rock uplift, and are high in areas of high rock uplift, respectively. It appears that rock uplift and denudation are intimately linked. It follows that either crustal thickening is generating rock uplift; the mountain belt reacts with erosional unloading. Alternatively, high precipitation and glaciers, most pronounced at high altitude, result in high denudation rates at these sites. Topography then would respond by increasing rock uplift.

Description: The Aral Sea Basin is a critical area for studying the influence of climate and anthropogenic impact on the development of hydrographic conditions in an endorheic basin. We present organic-walled dinoflagellate cyst analyses with a sampling resolution of 15 to 20 years from a core retrieved at Chernyshov Bay in the NW Large Aral Sea (Kazakhstan). Cysts are present throughout, but species richness is low (seven taxa). The dominant morphotypes are Lingulodinium machaerophorum with varied process length and Impagidinium caspienense, a species recently described from the Caspian Sea. Subordinate species are Caspidinium rugosum, Romanodinium areolatum, Spiniferites cruciformis, cysts of Pentapharsodinium dalei, and round brownish protoperidiniacean cysts. The chlorococcalean algae Botryococcus and Pediastrum are taken to represent freshwater inflow into the Aral Sea. The data are used to reconstruct salinity as expressed in lake level changes during the past 2000 years. We quantify and date for the first time prominent salinity variations from the northern part of the Large Aral Sea. During high lake levels, I. caspienense, representing brackish conditions with salinities of about 10–15 g kg− 1 or less, prevails. Assemblages dominated by L. machaerophorum document lake lowstands during approximately 0–425 AD (or 100? BC–425 AD), 920–1230 AD, 1500 AD, 1600–1650 AD, 1800 AD and since the 1960s. Because salinity in the Aral Sea is mostly controlled by meltwater discharges from the Syr Darya and Amu Darya rivers, we interpret changes in salinity levels as a proxy for temperature fluctuations in the Tien Shan Mountains that control snow melt. Significant erosion of marine Palaeogene and Neogene deposits in the hinterland, evidenced between 1230 AD and 1400 AD, is regarded as sheet-wash from shore. This is controlled by the low pressure system that develops over the Eastern Mediterranean and brings moist air to the Middle East and Central Asia during late spring and summer. We propose that the recorded environmental changes are related primarily to climate, but perhaps to a lesser extent by human-controlled irrigation activities. Our results documenting climate change in western Central Asia are fairly consistent with reports elsewhere from Central Asia.