10,820 research outputs found
Resurvey of site stability quadrilaterals, Otay Mountain and Quincy, California
Trilateration quadrilaterals established across two faults near the San Andreas Fault Experiment laser/satellite ranging sites were resurveyed after four years. No evidence of significant tectonic motion was found
Surface deformation and elasticity studies in the Virgin Islands
The report consists of four sections. The first section describes tilt and leveling measurements on Anegada, the most northerly of the British Virgin Islands; the second section contains a discussion of sea-level measurements that were initiated in the region and which played a significant role in the development of a network of sea-level monitors now telemetered via satellite from the Alaskan Shumagin Islands. The third part of the report is a brief description of surface deformation measurements in Iceland using equipment and techniques developed by the subject grant. The final part of the report describes the predicted effects of block surface fragmentation in tectonic areas on the measurement of tilt and strain
Theory of time-dependent rupture in the Earth
Fracture mechanics is used to develop a theory of earthquake mechanism which includes the phenomenon of subcritical crack growth. The following phenomena are predicted: slow earthquakes, multiple events, delayed multiple events (doublets), postseismic rupture growth and afterslip, foreshocks, and aftershocks. The theory predicts a nucleation stage prior to an earthquake, and suggests a physical mechanism by which one earthquake may 'trigger' another
Metamorphism, argon depletion, heat flow and stress on the Alpine fault
The Alpine fault of New Zealand is a major continental transform fault which was uplifted on its southeast side 4 to 11 km within the last 5 m.y. This uplift has exposed the Haast schists, which were metamorphosed from the adjacent Torlesse graywackes. The Haast schists increase in metamorphic grade from prehnite-pumpellyite facies 9-12 km from the fault through the chlorite and biotite zones of the greenschist facies to the garnet-oligoclase zone amphibolite facies within 4 km of the fault. These metamorphic zone boundaries are subparallel to the fault for 350 km along the strike. The K-Ar and Rb-Sr ages of the schists increase with distance from the fault: from 4 m.y. within 3 km of the fault to approximately 110 m.y. 20 km from the fault. Field relations show that the source of heat that produced the argon depletion aureole was the fault itself
Strain buildup and release, earthquake prediction and selection of VLB sites for the margins of the North Pacific
Projects studying different aspects of crustal deformation are discussed. The rifting process at the plate boundary in northern Iceland was investigated using combined seismic, tilt, and displacement measurements. Stresses acting on the Alpine fault, New Zealand, were modeled based on observations of regional variation in metamorphism and argon loss. The relationship between the stress pattern shown by intraplate seismicity and possible stresses on plates arising from litohspheric motion over the asthenosphere was investigated. Small earthquakes in Southern California were studied to determine if subregions of uniform strain release exist and if interaction occurs between faults
On the Predictability of Talk Attendance at Academic Conferences
This paper focuses on the prediction of real-world talk attendances at
academic conferences with respect to different influence factors. We study the
predictability of talk attendances using real-world tracked face-to-face
contacts. Furthermore, we investigate and discuss the predictive power of user
interests extracted from the users' previous publications. We apply Hybrid
Rooted PageRank, a state-of-the-art unsupervised machine learning method that
combines information from different sources. Using this method, we analyze and
discuss the predictive power of contact and interest networks separately and in
combination. We find that contact and similarity networks achieve comparable
results, and that combinations of different networks can only to a limited
extend help to improve the prediction quality. For our experiments, we analyze
the predictability of talk attendance at the ACM Conference on Hypertext and
Hypermedia 2011 collected using the conference management system Conferator
Substellar Objects in Nearby Young Clusters (SONYC) IX: The planetary-mass domain of Chamaeleon-I and updated mass function in Lupus-3
Substellar Objects in Nearby Young Clusters -- SONYC -- is a survey program
to investigate the frequency and properties of substellar objects in nearby
star-forming regions. We present new spectroscopic follow-up of candidate
members in Chamaeleon-I (~2 Myr, 160 pc) and Lupus 3 (~1 Myr, 200 pc),
identified in our earlier works. We obtained 34 new spectra (1.5 - 2.4 mum,
R~600), and identified two probable members in each of the two regions. These
include a new probable brown dwarf in Lupus 3 (NIR spectral type M7.5 and
Teff=2800 K), and an L3 (Teff=2200 K) brown dwarf in Cha-I, with the mass below
the deuterium-burning limit. Spectroscopic follow-up of our photometric and
proper motion candidates in Lupus 3 is almost complete (>90%), and we conclude
that there are very few new substellar objects left to be found in this region,
down to 0.01 - 0.02 MSun and Av \leq 5. The low-mass portion of the mass
function in the two clusters can be expressed in the power-law form dN/dM
\propto M^{-\alpha}, with \alpha~0.7, in agreement with surveys in other
regions. In Lupus 3 we observe a possible flattening of the power-law IMF in
the substellar regime: this region seems to produce fewer brown dwarfs relative
to other clusters. The IMF in Cha-I shows a monotonic behavior across the
deuterium-burning limit, consistent with the same power law extending down to 4
- 9 Jupiter masses. We estimate that objects below the deuterium-burning limit
contribute of the order 5 - 15% to the total number of Cha-I members.Comment: Accepted for publication by Astrophysical Journa
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