59 research outputs found
The 2015 Illapel earthquake: a comprehensive assessment
No full textOn September 16, 2015, the convergent Chilean margin again experienced a great subduction megathrust earthquake.
The MW=8.2 Illapel earthquake occurred in the Metropolitan segment north of where the Juan-Fernandez
ridge meets the Chile trench and subduction style and geometry change over a short distance. Combining GPS
displacement measurements, InSAR interferograms, strong motion data, broadband seismological waveforms and
backprojection of high frequency teleseismic signals we derive a comprehensive description of the coseismic rupture.
Further, we determine accurate depths for the mostly offshore aftershock sequence by careful observations of
teleseismic depth phases and derive moment tensors for the larger earthquakes from waveform modelling of bodyand
surface waves. The rupture nucleated near the coast but then propagated to the north and updip. The resulting
simple rupture geometry is approximately circular with a peak slip of 6 m, and a diameter of approximately 100
km, centered below the middle slope of the forearc. Forward modelling of tsunami propagation for this model
successfully predicts approximate tsunami wave heights measured at 3 tide gauges along the North Central Chile
coast, confirming that the rupture diminished towards the trench. Similar to previous observations, high frequency
seismic radiation is mostly emitted downdip of the region of most intense slip, but unlike in most previous events,
the high frequency emitters do not track the whole rupture along-strike but are confined to a small region within
∼ 50 km of the epicenter. The time evolution of high frequency seismic radiation also peaks earlier than the long
period rupture evolution, indicating that the final phase of the rupture progressed smoothly. The aftershocks extend
significantly beyond the limits of the main rupture in both north and south direction; their pattern of propagation
suggests triggering by coseismic changes to the Coulomb failure stress. Plate interface events dominate the aftershock
sequence but there are also some thrust events in the forearc crust and some shallow normal faulting events
in the oceanic crust below the trench. In 1943, an earthquake of comparable along-strike extent occurred in the
Illapel area. The similar extent of the aftershock zone and tsunami heights therefore make this part of the margin
a candidate site for generating characteristic earthquakes, in particular as the 1943 event was itself preceded by
an event in 1880, again with apparently the same part of the margin affected. The approximate match of peak slip
and accumulated slip deficit in the 72 years since the 1943 event also support this interpretation. However, the
1943 Illapel event appears to have had a shorter source time function and probably a smaller magnitude than the
2015 event, pointing to differences in the detailed rupture evolution. The coupling is mostly close to fully locked
in this area at least along the coast line but nevertheless the coseismic rupture is associated with a local peak in the
locking pattern, whereas a distinct narrow partially interseismically creeping area is found just to the south of the
main rupture. The northern transition to lower locking is more gradual but also here the rupture can be said to have
terminated against a zone of reduced locking. Although locally the recent Illapel earthquake has relieved much of
the accumulated stress, the segment immediately adjacent to the north remains unbroken since 1922, and presents
a serious earthquake and tsunami hazard
The 2015 Illapel earthquake, Central Chile, a case of characteristic earthquake?
No full textOn September 16, 2015, the Chilean margin experienced a great subduction megathrust earthquake. The MW=8.2 Illapel earthquake occurred in the Metropolitan segment north of where the Juan-Fernandez ridge meets the Chile trench and subduction style and geometry change. Combining GPS displacement measurements, InSAR interferograms, strong motion and broadband seismological waveforms, and high frequency (HF) teleseismic backprojection we derive a comprehensive description of the coseismic rupture. We further determine moment tensors and obtain accurate depth estimates for mostly offshore aftershock sequence by careful observations of teleseismic depth phases. The rupture nucleated near the coast but then propagated to the north and updip, with a circular geometry of diameter 100 km and a peak slip of ~6 m below the forearc. HF seismic radiation is mostly emitted downdip of the region of most intense slip, but unlike in most previous events the high frequency emitters do not track the whole rupture but are confined to a small region. The time evolution of HF seismic radiation also arrests earlier than the long period rupture evolution, indicating that the final phase of the rupture progressed more smoothly. The aftershocks, mostly plate interface events, extend significantly beyond the limits of the main rupture in both directions. In 1943, a comparable event struck the Illapel area. The similar extent of the aftershock zone and tsunami heights therefore make this part of the margin a candidate site for generating characteristic earthquakes. The approximate match of peak slip and accumulated slip deficit in the 72 years since the 1943 event also support this interpretation. However, the 1943 event appears to have had a shorter source time function and probably a smaller magnitude, pointing to differences in the detailed rupture evolution. The coupling is mostly close to fully locked in this area at least along the coast line but nevertheless the coseismic rupture is associated with a local peak in the locking pattern, whereas a narrow partially creeping area is found just to the south of the main rupture. Although locally the recent Illaped earthquake has relieved much of the accumulated stress, the segment immediately adjacent to the north remains unbroken since 1922, and presents a serious earthquake and tsunami hazard
The 2015 Illapel earthquake, central Chile: A type case for a characteristic earthquake?
No full textOn 16 September 2015, the MW = 8.2 Illapel megathrust earthquake ruptured the Central Chilean margin. Combining inversions of displacement measurements and seismic waveforms with high frequency (HF) teleseismic backprojection, we derive a comprehensive description of the rupture, which also predicts deep ocean tsunami wave heights. We further determine moment tensors and obtain accurate depth estimates for the aftershock sequence. The earthquake nucleated near the coast but then propagated to the north and updip, attaining a peak slip of 5–6 m. In contrast, HF seismic radiation is mostly emitted downdip of the region of intense slip and arrests earlier than the long period rupture, indicating smooth slip along the shallow plate interface in the final phase. A superficially similar earthquake in 1943 with a similar aftershock zone had a much shorter source time function, which matches the duration of HF seismic radiation in the recent event, indicating that the 1943 event lacked the shallow slip
Eckelmann, Mary E. (Death, 1891-11-03)
No full textAddress: 33 Bellevue AvenueAge at death: 6986/Pg 123/1891/F W W/Germany/Dr. Samuel Nickles/Meyer & Son/Walnut Hills Cem.Original record filed in drawer labeled 'DYER-EDWARDS, J'
Experimentelle Untersuchungen in einer turbulenten Kanalströmung mit starken viskosen Wandschichten
No full text
Cooperative engineer. Vol. 31 No. 4 (June 1954)
No full textContents:
Cover - Cincinnati drawing by Robert Martin
Frontispiece - City Manager C. A. Harrell
City Manager: C. A. Harrell, by Ronald R. Eckelmann
Red Tape Can Be Useful...magnetic tape recording, by John T. Heizer
Senior Personalities, by John T. Price and F. Richard Folkerth
Annual Industrial Scholarships in the College of Engineering
Pulse Columns...for extraction, by Carl Bahme
Atomic Battery, by Richard Hunt
Tall Totem...new staff, by Jim Stockert
Quadrangle NewsPublished quarterly from 1921-1975 by the students and alumni of the College of Engineering, University of Cincinnati
Hopf bifurcation in wakes behind a rotating and translating circular cylinder
No full textA low-dimensional Galerkin method, initiated by Noack and Eckelmann [Physica D 56, 151 (1992)], for the prediction of the flow field around a stationary two-dimensional circular cylinder in a uniform stream at low Reynolds number is generalized to the case of a rotating and translating cylinder. The Hopf bifurcation describing the transition from steady to time-periodic solution is investigated. A curve indicating the transitional boundary is given in the two-dimensional parameter plane of Reynolds number Re and rotating parameter alpha. Our results show that rotation may delay the onset of vortex street and decrease the vortex-shedding frequency. (C) 1996 American Institute of Physics
- …
