Coseismic soft-sediment deformation has been studied by structural and tectononophysical methods in the Selenga Delta area shaken by the devastating M ∼ 7.5 Tsagan earthquake in 1862. Among the documented deformation structures (seismites), clastic dikes are the most reliable paleoseismic indicators. The dikes have their sizes and extent showing proximity to the primary coseismic rupture zone and are closely associated with faults of different hierarchic levels. The Tsagan event occurred under SW–NE extension as motion on a stepped system of normal faults dipping at 300°–350°, ∠45°–75°.
The amount of vertical motion measured against a reference layer in a trench reached 2.83 m, and the maximum dip displacement measured in a single fracture was 0.5 m. The earthquake was generated by the Delta Fault that dips at 60° on average to the northwest.
The distribution of quantitative parameters of brittle and brittle-plastic deformation has been analyzed along two profiles, and two new parameters were introduced: indices of mean intensity (I) of clastic dikes and microdikes; the new parameters were calculated by specially developed equations. Summation of significant peaks in all parameters (SUMspp) allowed contouring the zone of most intense soft-sediment deformation near Dubinino Village.
Deformation mostly propagated in the NE–SW and N–S directions. The location of the 1862 Tsagan earthquake at 52.35° N and 106.67° E was inferred from the SUMspp value taking into account the dip of the causative fault plane and the average origin depth of earthquakes in the Baikal rift. The approach we used is applicable to locating preinstrumental events.
The recurrence of large earthquakes in the area of Proval Bay (Lake Baikal) has been estimated to be 1120–1230 years proceeding from alternating deformed and undeformed sediments in the sections, their thicknesses and deposition rates according to radiocarbon dating. The seismic activity has been associated with the same fault which can generate M ≥ 7 events.
The forms and location patterns of geologic hazards induced by earthquakes in southern Siberia, Mongolia, and northern Kazakhstan in
1950 through 2008 have been investigated statistically, using a database of coseismic effects created as a GIS MapInfo application, with a handy input box for large data arrays. The database includes 689 cases of macroseismic effects from MS= 4.1–8.1 events at 398 sites. Statistical analysis of the data has revealed regional relationships between the magnitude of an earthquake and the maximum distance of its environmental effects (soil liquefaction and subsidence, secondary surface rupturing, and slope instability) to the epicenter and to the causative fault. Thus estimated limit distances to the fault for the MS= 8.1 largest event are 40 km for soil subsidence (sinkholes), 80 km for surface rupture, 100 km for slope instability (landslides etc.), and 130 km for soil liquefaction. These distances are 3.5–5.6 times as short as those to the epicenter, which are 150, 450, 350, and 450 km, respectively. Analysis of geohazard locations relative to nearest faults in southern East Siberia shows the distances to be within 2 km for sinkholes (60% within 1.5 km), 4.5 km for landslides (90% within 1.5 km), 8 km for liquefaction (69% within 1 km), and 35.5 km for surface rupture (86% within 2 km). The frequency of hazardous effects decreases exponentially away from both seismogenic and nearest faults. Cases of soil liquefaction and subsidence are analyzed in more detail in relation to rupture patterns. Equations have been suggested to relate the maximum sizes of secondary structures (sinkholes, dikes, etc.) with the earthquake magnitude and shaking intensity at the site. As a result, a predictive model has been created for locations of geohazard associated with reactivation of seismogenic faults, assuming an arbitrary fault pattern. The obtained results make basis for modeling the distribution of geohazards for the purposes of prediction and estimation of earthquake parameters from secondary deformation.
We have studied the response of YBa,Cu,O, step-edge junctions to low-intensity millimeter-wave radiation in the temperature range from 4 to 80 K. The linewidth of the Josephson oscillations derived from the resonant part of the response at voltages Va (h/2e j f is shown to be determined by thermal fluctuations at liquid nitrogen temperatures. At lower temperatures the observed linewidth increases indicating that low-frequency fluctuations become dominant in the junction as the temperature is reduced. Due to an inhomogeneous spatial distribution of the current the step-edge junction might be considered as a multijunction multiloop interferometer and the excess noise can be discussed in terms of spontaneous transitions between the different states of these interferometers.-One of the promising types of high-T,. superconducting weak links is the step-edge junction (SEJ) .1;2 These junctions are fabricated by epitaxial growth of a high-T, thin film on a steep step etched in the substrate prior to the film deposition. As follows from h
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