322,853 research outputs found
Large rock slides in impact craters on the Moon and Mercury
No full textImpact craters are the most common surface features on the Moon and Mercury. On these two bodies, we recognized and mapped large landslides on the walls of impact craters. Through visual inspection of high-resolution imagery, we compiled an inventory of 60 landslides on the Moon and a second inventory of 58 landslides on Mercury. Adopting categories used to catalog terrestrial mass movements, we classified the landslides on the Moon and Mercury as rock slides. We determined the probability density distribution of their planimetric area, and we compared the distributions with similar distributions for terrestrial and martian landslides using data from the literature. We found that rock slides mapped in impact craters on the Moon are, on average, larger than analogous rock slides on Mercury. The relationship between the area of the individual rock slides and the area of the hosting crater suggests that rock slides on Mercury initiate in smaller craters. We hypothesize that the above findings are an effect of the weaker surface gravity of the Moon compared to that of Mercury and/or an effect of the rock material properties
Statistical approaches for the definition of landslide rainfall thresholds and their uncertainty using rain gauge and satellite data
No full textModels for forecasting rainfall-induced landslides are mostly based on the identification of empirical rainfall thresholds obtained exploiting rain gauge data. Despite their increased availability, satellite rainfall estimates are scarcely used for this purpose. Satellite data should be useful in ungauged and remote areas, or should provide a significant spatial and temporal reference in gauged areas. In this paper, the analysis of the reliability of rainfall thresholds based on rainfall remote sensed and rain gauge data for the prediction of landslide occurrence is carried out. To date, the estimation of the uncertainty associated with the empirical rainfall thresholds is mostly based on a bootstrap resampling of the rainfall duration and the cumulated event rainfall pairs (D,E) characterizing rainfall events responsible for past failures. This estimation does not consider the measurement uncertainty associated with D and E. In the paper, we propose (i) a new automated procedure to reconstruct ED conditions responsible for the landslide triggering and their uncertainties, and (ii) three new methods to identify rainfall threshold for the possible landslide occurrence, exploiting rain gauge and satellite data. In particular, the proposed methods are based on Least Square (LS), Quantile Regression (QR) and Nonlinear Least Square (NLS) statistical approaches. We applied the new procedure and methods to define empirical rainfall thresholds and their associated uncertainties in the Umbria region (central Italy) using both rain-gauge measurements and satellite estimates. We finally validated the thresholds and tested the effectiveness of the different threshold definition methods with independent landslide information. The NLS method among the others performed better in calculating thresholds in the full range of rainfall durations. We found that the thresholds obtained from satellite data are lower than those obtained from rain gauge measurements. This is in agreement with the literature, where satellite rainfall data underestimate the “ground” rainfall registered by rain gauges
Methods and tools for landslide forecasting and risk mitigation, and adaptation strategies
No full textThere is worldwide a mounting interest towards the operational forecasting of landslides, with particular regard to rainfall induced landslides. The main reason for this is the fact that landslides represent a serious hazard in many areas, and cause significant and repeated damage and economic losses to the society, posing substantial risks to people and infrastructure. Starting from these considerations, we recently started a IPL project initiative (IPL‐206) on rainfall induced landslides and their consequences, (i) to review past and existing operational landslide forecasting and warning systems, (ii) to propose recommendations for the design, the implementation, and the validation of operational landslide forecasting and warning systems, and (iii) to identify the best procedure for decision making when information from different source are available. Past and existing operational landslide forecasting and warning systems are being examined with these aims, highlighting their distribution in the different countries/continents, their level of accuracy during past events, the effective adoption of the systems by local authorities and the forensic aspects during the operation phase. Follow this first analysis, recommendations for the design, the implementation, and the validation of operational landslide forecasting and warning systems will be proposed. The project is addressed to all those governmental and administrative bodies in charge of the land management and dealing with civil protection issues. These could use the project outcomes, in direct cooperation with scientific bodies, to design, implement, and validate landslide early warning systems, personalized in function of the main physical and meteorological characters of their own areas of study/interest, aimed at attempting to mitigate the risk related to landslides through the adoption of the most suitable strategies
Automated reconstruction of rainfall events responsible for shallow landslides
No full textOver the last 40 years, many contributions have
identified empirical rainfall thresholds (e.g. rainfall intensity
(I ) vs. rainfall duration (D), cumulated rainfall vs. rainfall
duration (ED), cumulated rainfall vs. rainfall intensity (EI))
for the possible initiation of shallow landslides, based on
local and global inventories. Although different methods to
trace the threshold curves have been proposed and discussed
in literature, a systematic study to develop an automated procedure
to select the rainfall event responsible for the landslide
occurrence has only rarely been addressed. Objective
criteria for estimating the rainfall responsible for the landslide
occurrence play a prominent role on the threshold values.
In this paper, two criteria for the identification of the
effective rainfall events are presented. The first criterion is
based on the analysis of the time series of rainfall mean intensity
values over 1 month preceding the landslide occurrence.
The second criterion is based on the analysis of the trend
in the time function of the cumulated mean intensity series
calculated from the rainfall records measured through rain
gauges. The two criteria have been implemented in an automated
procedure that is written in the R language. A sample
of 100 shallow landslides collected in Italy from 2002
to 2012 was used to calibrate the procedure. The cumulated
event rainfall (E) and duration (D) of rainfall events that triggered
the documented landslides are calculated through the
new procedure and are fitted with power law in the D, E diagram.
The results are discussed by comparing the D, E pairs
calculated by the automated procedure and the ones by the
expert method
Automated reconstruction of rainfall events responsible for shallow landslides
No full textOver the last 40 years, many contributions have
identified empirical rainfall thresholds (e.g. rainfall intensity
(I ) vs. rainfall duration (D), cumulated rainfall vs. rainfall
duration (ED), cumulated rainfall vs. rainfall intensity (EI))
for the possible initiation of shallow landslides, based on
local and global inventories. Although different methods to
trace the threshold curves have been proposed and discussed
in literature, a systematic study to develop an automated procedure
to select the rainfall event responsible for the landslide
occurrence has only rarely been addressed. Objective
criteria for estimating the rainfall responsible for the landslide
occurrence play a prominent role on the threshold values.
In this paper, two criteria for the identification of the
effective rainfall events are presented. The first criterion is
based on the analysis of the time series of rainfall mean intensity
values over 1 month preceding the landslide occurrence.
The second criterion is based on the analysis of the trend
in the time function of the cumulated mean intensity series
calculated from the rainfall records measured through rain
gauges. The two criteria have been implemented in an automated
procedure that is written in the R language. A sample
of 100 shallow landslides collected in Italy from 2002
to 2012 was used to calibrate the procedure. The cumulated
event rainfall (E) and duration (D) of rainfall events that triggered
the documented landslides are calculated through the
new procedure and are fitted with power law in the D, E diagram.
The results are discussed by comparing the D, E pairs
calculated by the automated procedure and the ones by the
expert method
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Author's address:
No full textCan archives of audiovisual TV interviews be used to make authors more visible to students, and thereby reduce the learning gap between native and non-native language speakers in college classes? We examined students in a college course who learned about one scholar's ideas through watching an audiovisual TV interview (i.e., visible author format) and about another scholar's ideas through reading a formal text description (i.e., invisible author format). For the invisible author, native language speakers scored significantly higher than the non-native language speakers on a corresponding exam question (i.e., a cognitive measure), generated more words on the exam question (i.e., a motivational measure), and mentioned the author's name more often in answering the exam question (i.e., an affective measure). For the visible author, the groups did not differ on any of these measures. These findings provide evidence for the idea that making the author visible through audiovisual TV interviews can eliminate the learning gap between native and non-native language speakers. 3 Universities around the world serve students who are non-native speakers of th
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