Empirical Green's Functions Modified by Attenuation for Sources Located at Intermediate and Far Distances from the Original Source

We present a scheme to modify empirical Green's functions by attenuation considering: (1) geometrical spreading; (2) decay in high frequency; (3) regional attenuation; and (4) phase of the signal. The accelerograms computed with the proposed simulation method are compared, in time and frequency domains, with strong ground motions from subduction and intermediate-depth earthquakes recorded in Mexico. It is shown that this simple empirical Green's functions technique can synthesize both the shape and amplitude of the response spectra in the site, considering a postulated seismic source located at different distances from the original one.     

Technology and ocean‐scape: Defining the deep sea in mid‐nineteenth century

The ocean's profound inaccessibility makes it impossible to comprehend except through the mediation of technology. The first investigators to explore the great depths were hydrographers whose work was animated by mid‐nineteenth century growth of political, economic, and cultural interest in the oceans. While submarine telegraphy certainly boosted ocean science, interest in this field derived first from commercial concerns related to whaling and shipping as well as the intellectual pursuits of physical geography and questions about the existence of life at great depths. Hydrographers’ developing conception of the oceanic environment never represented a clear translation from technology. Dramatic changes in the understanding of the shape of the deep‐sea floor testified to the complexity of interaction between sounding machines, methods, and interpretations of depth. The shifting image of the sea floor not only reflected increasingly accurate measurements, but also mirrored shifting human motivations for studying this unexplored territory.     

Pollen-Analytical Results from Lake Katajajärvi – Aspects of the History of Settlement in the Finnish Inland Regions

Abstract

The Early Metal Period (1800 cal BC–AD 300) of the Finnish inland regions is characterized by a scarcity of archaeological remains. Its latest stages, in particular, have proved to be difficult to interpret. This paper discusses the continuity of settlement in the Early Metal Period as indicated by archaeological survey and pollen-analytical data. The study area is situated in Repovesi National Park in southeastern Finland. The pollen analysis was constructed from a sediment sequence taken from Lake Katajajärvi. The archaeological survey data from Repovesi National Park supports earlier hypotheses of the small number of Early Metal Period sites. In the pollen data, the first anthropogenic impact is recorded from about 2600 BC onwards, with weak signs of cultivation around 2370 BC. From around 1900 BC onwards a clear change in tree, shrub and herb pollen percentages indicates anthropogenic impact, possibly grazing, in the area. The pollen-analytical results also revealed a cultivation period of about 900 years at the end of the Early Metal Period, providing proof of continuity in settlement during a period characterized by a scarcity of archaeological material. A new beginning of cultivation from cal AD 1160 to 1250 onwards can be considered as indicating population growth, developing settlements and the colonization of new areas. The results from Repovesi are challenging from an archaeological point of view, because they represent slash-and-burn cultivation that appears to have been practised in total wilderness conditions. Comparison of the Lake Katajajärvi results with other areas raises new questions that call for a discussion of early slash-and-burn cultivation in new perspective.     

Development and Verification of a New Site Classification System and Site Coefficients for Regions of Shallow Bedrock in Korea

In this article, site response analyses for 124 sites collected in Korea were performed to evaluate earthquake ground motions in regions of shallow bedrock in Korea. Based on the results, a new two-parameter site classification system was developed for use in regions of shallow bedrock. The system incorporates depth to bedrock and mean V_S of soil above bedrock as parameters for site classification instead of V_S30. Soil sites were divided into seven site classes and the corresponding site coefficients were proposed for each site category. Some verification work demonstrates the superiority of the proposed system over the current seismic codes.     

Field Measurements and Numerical Simulation of Debris Flows from Dolomite Slopes Destabilized during the 2005 Kashmir Earthquake,Pakistan

A devastating earthquake occurred in Kashmir, Pakistan on October 8, 2005. This earthquake resulted from reactivation of a known active fault later defined as the Balakot–Bagh fault, which caused widespread slope failure throughout its stretch, particularly around Muzaffarabad, the provincial capital of Azad Jammu and Kashmir. This slope failure resulted in a huge amount of debris material which flows in deeply incised creeks during monsoon and hits the inhabitants along the valley in Muzaffarabad. Two GPS measurements are carried out along with channel morphometric parameters and observed changes to investigate the effect of debris flows along these creeks during monsoon. Other than the physical measurements, actual debris flow is simulated using the Depth Average Material Point Method (DAMPM) after carrying out parametric study and calibrating the model for subject topographical and geological settings. The generalized effect of different input parameters of the model on debris flow runout features is studied and discussed in detail. After ensuring validation of the numerical tool, the contribution of a single closed-type check dam to decrease runout intensity to its downstream reach is also investigated for different locations to obtain optimized selection.     

Sedimentary logics and the Rohingya refugee camps in Bangladesh

This paper adopts a geosocial approach to sociopolitical research by thinking with sediment as a forceful mode of terraqueous mobility driven by interactions between dynamic earth systems inflected by social processes. It demonstrates that sediment is an active and vital state of matter, with the potential to erupt into and disrupt human politics. Unpacking sediment as a form of movement challenges assumptions of the earth as a stable platform on which socio-political processes play out. The paper develops its argument through analyses of the Rohingya refugee camps in southeast Bangladesh and a char (sediment) island in the Meghna Estuary to which Bangladesh proposes to relocate the refugees. In the first situation, the sedimentary logics of anticline geology, deforestation and monsoon rains push back against political agendas directed towards constraining refugee movement. In the second, fluvial and oceanic sedimentary dynamics and the post-Holocene volatility of the monsoon throw into doubt the engineering solution proposed by Bangladesh to the political problems the refugee presence poses. Through these examples, the paper adds to literature on how states of matter inflect, exceed, undercut or in other ways interfere with matters of state through their unique, dynamic environmental properties.     

Optically stimulated luminescence dating of Southern High Plains archaeological sites

The Southern High Plains of North America is rich in archaeological sites, but many are not well constrained chronologically, owing to a lack of material for radiocarbon dating. A program of optically stimulated luminescence (OSL) dating, applying mainly single-grain analyses, was therefore initiated. Many samples have independent age estimates from radiocarbon to check the OSL results, but OSL age estimates are also provided for those sites that otherwise lack secure chronological control. Sediment samples for OSL were obtained primarily from Paleoindian and Archaic localities, though include deposits of more recent age. Through the analysis of single grains, equivalent dose—the numerator of the age equation—is evaluated independently on numerous grains. The distribution of these values is relatively broad for some samples, and this is attributed to post-depositional mixing. Mixing is also evident in some samples with more narrow distributions. Selecting portions of the mixed distributions for age determination allows more accurate dating for some samples, but the nature of the distributions limits the resolution on others, conclusions that cannot be as easily drawn from multi-grain analysis. Where independent age control is available, most OSL results broadly conform; however, some samples show discrepancies that are not readily explained, but may relate to association or dose rate problems. This underscores the desirability of obtaining where possible suites of chronological evidence.     

Seismic Response of the Central Part of Indo-Gangetic Plain

In spite of high seismic risk, there is no numerical model of Indo-Gangetic Plain. In this paper, seismic response of the central part of Indo-Gangetic Plain, i.e., Ganga Plain is studied using a two-dimensional plane strain finite element model. Seismic source is assumed to be located beneath the Himalayas near Himalayan Frontal Thrust. Basin response is simulated for a hypothetical M_w 8.0 Himalayan earthquake. Ground motion amplification and sensitive frequency band of the basin, obtained from the numerical simulation, show that the sediment depth and epicentral distance at a site play significant role in the seismic response of the site.     

Analysis of rock samples collected from rock hewn churches of Lalibela,Ethiopia using laser-induced breakdown spectroscopy

With the aim to study alteration processes of the rock hewn churches from Lalibela (Ethiopia), we applied Laser Induced Breakdown Spectroscopy (LIBS) technique to measure the elemental composition both of the bulk rock materials and their external layers, exposed to the environmental factors. The analytical plasma was generated by nanosecond pulses of an Nd: YAG laser emitting at 1064 nm. Different major and minor sample constituents were detected, including Ca, Mg, Na, Fe, Ti, Al and K. The detected O emission originates both from air surrounding and the sample, while the intensity of N lines, coming exclusively from air, was used for the LIBS signal normalization. By depth profiling of the weathered basalt rock, we observed a lower presence of K in the external layers, corresponding to the first 5 laser shots. The emission from this element is anti-correlated with the line intensities from O, and this was attributed to the variations in relative abundances of clay minerals and K-feldspar. The analogue measurements were performed on the tuff rock, and compared to the spectra from powder samples containing only the external soft material, scratched from the rocks. These analyses show an abundance of H in the weathered, wetted layers and suggest that cations are lost from the constituent primary minerals and replaced by H⁺; this process disrupts the lattice structure and causes a marked loss of strength. The studies presented here demonstrate that LIBS is a useful technique for studying the alteration processes in the rocks, caused by environmental factors.     

Revisiting Key Sedimentary Archives Yields Evidence Of A Rapid Onset Of Mining In The Mid‐13th Century At The Great Copper Mountain,Falun, Sweden

Mining in Falun, Sweden, was first mentioned in a deed from ad 1288, but previous studies of peat and lake sediments inferred that mining began during the fifth to eighth centuries. In order to reassess these findings, we performed new geochemical analyses on new samples from three key sites: Tisksjöbergets myr, a buried mire alongside the mine; Tisken, a small lake in Falun; and Runn, the main recipient for waters draining through Falun. At Tisksjöbergets myr, the peat contains up to 6% copper, giving it the characteristics of a cupriferous bog. Hence, this record is not useful for tracing early mining. The sediments of Tisken—upon which many of the old interpretations have relied—contain numerous cut wood fragments, and two of those gave young and reversed radiocarbon dates (19th and 16th centuries for 192 and 187 cm, respectively). This indicates that the sediment was derived from infilling and, thus, has little value as a historical record. Runn's sediment—the only reliable record—provides clear evidence of a rapid onset of large‐scale mining from c. ad 1245, with abrupt increases in ore‐related elements—for example, a 34‐fold increase in copper—this increase is consistent with the mid‐13th century burial of the mire at Tisksjöberget.