scholarly journals Dynamics of the Oso-Steelhead landslide from broadband seismic analysis

2015 ◽  
Vol 15 (6) ◽  
pp. 1265-1273 ◽  
Author(s):  
C. Hibert ◽  
C. P. Stark ◽  
G. Ekström
Keyword(s):  
Surface Waves ◽  
Slope Failure ◽  
Seismic Analysis ◽  
Source Parameters ◽  
Seismic Energy ◽  
Period Analysis ◽  
Long Period ◽  
Landslide Volume ◽  
Short Period ◽  
Seismic Records

Abstract. We carry out a combined analysis of the short- and long-period seismic signals generated by the devastating Oso-Steelhead landslide that occurred on 22 March 2014. The seismic records show that the Oso-Steelhead landslide was not a single slope failure, but a succession of multiple failures distinguished by two major collapses that occurred approximately 3 min apart. The first generated long-period surface waves that were recorded at several proximal stations. We invert these long-period signals for the forces acting at the source, and obtain estimates of the first failure runout and kinematics, as well as its mass after calibration against the mass-centre displacement estimated from remote-sensing imagery. Short-period analysis of both events suggests that the source dynamics of the second event is more complex than the first. No distinct long-period surface waves were recorded for the second failure, which prevents inversion for its source parameters. However, by comparing the seismic energy of the short-period waves generated by both events we are able to estimate the volume of the second. Our analysis suggests that the volume of the second failure is about 15–30% of the total landslide volume, giving a total volume mobilized by the two events between 7 × 106 and 10 × 106 m3, in agreement with estimates from ground observations and lidar mapping.

scholarly journals Seismology of the Oso-Steelhead landslide

2014 ◽  
Vol 2 (12) ◽  
pp. 7309-7327 ◽  
Author(s):  
C. Hibert ◽  
C. P. Stark ◽  
G. Ekström
Keyword(s):  
Surface Waves ◽  
Slope Failure ◽  
Source Parameters ◽  
Seismic Energy ◽  
Seismic Signals ◽  
Period Analysis ◽  
Long Period ◽  
Landslide Volume ◽  
Short Period ◽  
Seismic Records

Abstract. We carry out a combined analysis of the short- and long-period seismic signals generated by the devastating Oso-Steelhead landslide that occurred on 22 March 2014. The seismic records show that the Oso-Steelhead landslide was not a single slope failure, but a succession of multiple failures distinguished by two major collapses that occurred approximately three minutes apart. The first generated long-period surface waves that were recorded at several proximal stations. We invert these long-period signals for the forces acting at the source, and obtain estimates of the first failure runout and kinematics, as well as its mass after calibration against the mass-center displacement estimated from remote-sensing imagery. Short-period analysis of both events suggests that the source dynamics of the second are more complex than the first. No distinct long-period surface waves were recorded for the second failure, which prevents inversion for its source parameters. However, by comparing the seismic energy of the short-period waves generated by both events we are able to estimate the volume of the second. Our analysis suggests that the volume of the second failure is about 15–30% of the total landslide volume, which is in agreement with ground observations.

ON THE NOTION OF PERMANENT AND TEMPORARY CAUSES: THE LEGACY OF RICARDO

2014 ◽  
Vol 36 (4) ◽  
pp. 421-434 ◽  
Author(s):  
Maria Cristina Marcuzzo
Keyword(s):  
Common Language ◽  
John Maynard Keynes ◽  
Period Analysis ◽  
Long Period ◽  
Short Period ◽  
The Common ◽  
David Ricardo ◽  
The Way

This paper considers the distinction made by David Ricardo between “permanent” and “temporary” causes, which he sometimes refers to also as “stable” and “accidental” causes (seeThe Works and Correspondence of David Ricardo [hereinafter Works]I: 86, 88, 92; VI: 154), to derive implications useful to distinguish his approach from subsequent developments of the notions of short-period and long-period equilibrium. In particular, I trace the change of focus in the concept of “permanent” forces brought about by Alfred Marshall—from whose insights Alfred Kahn and John Maynard Keynes drew inspiration for their short-period analysis—which paved the way to fundamental changes in the method and theory.It is argued that Ricardo’s distinction maintains an heuristic value, in particular vis-à-vis the distinction between short and long period, which is part of the common language in standard economics.

GULF COAST SURFACE WAVES

Geophysics ◽  
1953 ◽  
Vol 18 (1) ◽  
pp. 41-53 ◽  
Author(s):  
Lynn G. Howell ◽  
E. F. Neuenschwander ◽  
A. L. Pierson
Keyword(s):  
Rayleigh Wave ◽  
Surface Waves ◽  
Velocity Dispersion ◽  
Gulf Coast ◽  
Group Velocity Dispersion ◽  
Vertical Strain ◽  
Long Period ◽  
Short Period ◽  
Component Velocity ◽  
Wave Trains

Surface wave recordings were made with the following: a three‐component velocity seismometer, a long‐period displacement seismometer, six dynamic seismometers, an air‐actuated condenser microphone, and a vertical strain seismometer. Wave trains were recorded similar to those obtained by B. F. Howell in California. We have divided the surface waves into two trains instead of three. The early train seems to have properties of the M‐2 wave of Sezawa; the late train seems to be a Rayleigh wave. An air‐coupled wave is shown to be associated with the M‐2 wave. In the group velocity dispersion curve of the Rayleigh wave, the short‐period branch was found as predicted by theory as well as the usually observed long‐period branch. By making certain assumptions, the thickness of the top layer appears to be about 50 feet according to the theoretical curves of Kanai.

Surface-wave constraints on the August 1, 1975, Oroville earthquake

1977 ◽  
Vol 67 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Robert S. Hart ◽  
Rhett Butler ◽  
Hiroo Kanamori
Keyword(s):  
Surface Wave ◽  
Rayleigh Waves ◽  
Body Wave ◽  
Source Parameters ◽  
The Body ◽  
Wave Radiation ◽  
Spectral Amplitude ◽  
Surface Wave Magnitude ◽  
Long Period ◽  
Short Period

abstract Observations of Love and Rayleigh waves on WWSSN and Canadian Network seismograms have been used to place constraints upon the source parameters of the August 1, 1975, Oroville earthquake. The 20-sec surface-wave magnitude is 5.6. The surface-wave radiation pattern is consistent with the fault geometry determined by the body-wave study of Langston and Butler (1976). The seismic moment of this event was determined to be 1.9 × 1025 dyne-cm by both time-domain and long-period (T ≥ 50 sec) spectral amplitude determinations. This moment value is significantly greater than that determined by short-period studies. This difference, together with the low seismic efficiency of this earthquake, indicates that the character of the source is intrinsically different at long periods from those aspects which dominate the shorter-period spectrum.

scholarly journals Calving and rifting on the McMurdo Ice Shelf, Antarctica

2017 ◽  
Vol 58 (75pt1) ◽  
pp. 78-87 ◽  
Author(s):  
Alison F. Banwell ◽  
Ian C. Willis ◽  
Grant J. Macdonald ◽  
Becky Goodsell ◽  
David P. Mayer ◽  
...  
Keyword(s):  
Time Lapse ◽  
High Energy ◽  
Global Dimension ◽  
Far Field ◽  
Ice Shelf ◽  
Long Period ◽  
Short Period ◽  
Seismic Records ◽  
Fast Ice ◽  
Break Up

ABSTRACTOn 2 March 2016, several small en échelon tabular icebergs calved from the seaward front of the McMurdo Ice Shelf, and a previously inactive rift widened and propagated by ~3 km, ~25% of its previous length, setting the stage for the future calving of a ~14 km2 iceberg. Within 24 h of these events, all remaining land-fast sea ice that had been stabilizing the ice shelf broke-up. The events were witnessed by time-lapse cameras at nearby Scott Base, and put into context using nearby seismic and automatic weather station data, satellite imagery and subsequent ground observation. Although the exact trigger of calving and rifting cannot be identified definitively, seismic records reveal superimposed sets of both long-period (>10 s) sea swell propagating into McMurdo Sound from storm sources beyond Antarctica, and high-energy, locally-sourced, short-period (<10 s) sea swell, in the 4 days before the fast ice break-up and associated ice-shelf calving and rifting. This suggests that sea swell should be studied further as a proximal cause of ice-shelf calving and rifting; if proven, it suggests that ice-shelf stability is tele-connected with far-field storm conditions at lower latitudes, adding a global dimension to the physics of ice-shelf break-up.

Large Explosions at Sea

1971 ◽  
Vol 8 (2) ◽  
pp. 243-247
Author(s):  
Goetz G. R. Buchbinder
Keyword(s):  
Surface Wave ◽  
Continental Shelf ◽  
Surface Waves ◽  
Small Amplitude ◽  
Body Wave ◽  
Surface Wave Magnitude ◽  
Underwater Explosions ◽  
Long Period ◽  
Short Period ◽  
The Difference

Two large unannounced events occurred at sea in aseismic areas in the Atlantic. Comparison of these with the announced event Chase III shows them to be explosions.Large explosions at sea may be recognized by the relatively small amplitude of long period surface waves with periods up to 10 s. Energy of longer periods is absent for events mb ≤ 5.5. The surface wave magnitudes for the events are at least 1.5 smaller at 10 s than those of underground explosions of equal mb, at 20 s they are at least 0.9 smaller. At longer periods the difference between body wave and surface wave magnitude is larger than 0.9 but larger explosions are needed to determine the separation. Underwater explosions on or near the continental shelf are very efficient in the generation of higher mode short period waves.

Inversion of regional surface-wave spectra for source parameters of aftershocks from the Loma Prieta earthquake

1991 ◽  
Vol 81 (5) ◽  
pp. 1726-1736
Author(s):  
Susan L. Beck ◽  
Howard J. Patton
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Focal Mechanism ◽  
Source Parameters ◽  
Strike Slip ◽  
Focal Mechanisms ◽  
P Wave ◽  
Wave Spectra ◽  
Short Period ◽  
First Motion

Abstract Surface waves recorded at regional distances are used to study the source parameters for three of the larger aftershocks of the 18 October 1989, Loma Prieta, California, earthquake. The short-period P-wave first-motion focal mechanisms indicate a complex aftershock sequence with a wide variety of mechanisms. Many of these events are too small for teleseismic body-wave analysis; therefore, the regional surface-waves provide important long-period information on the source parameters. Intermediate-period Rayleigh- and Love-wave spectra are inverted for the seismic moment tensor elements at a fixed depth and repeated for different depths to find the source depth that gives the best fit to the observed spectra. For the aftershock on 19 October at 10:14:35 (md = 4.2), we find a strike-slip focal mechanism with right lateral motion on a NW-trending vertical fault consistent with the mapped trace of the local faults. For the aftershock on 18 October at 10:22:04 (md = 4.4), the surface waves indicate a pure reverse fault with the nodal planes striking WNW. For the aftershock on 19 October at 09:53:50 (md = 4.4), the surface waves indicate a strike-slip focal mechanism with a NW-trending vertical nodal plane consistent with the local strike of the San Andreas fault. Differences between the surface-wave focal mechanisms and the short-period P-wave first-motion mechanisms are observed for the aftershocks analyzed. This discrepancy may reflect the real variations due to differences in the band width of the two observations. However, the differences may also be due to (1) errors in the first-motion mechanism due to incorrect near-source velocity structure and (2) errors in the surface-wave mechanisms due to inadequate propagation path corrections.

scholarly journals ML:M0 as a regional seismic discriminant

1993 ◽  
Vol 83 (4) ◽  
pp. 1167-1183 ◽  
Author(s):  
Bradley B. Woods ◽  
Sharon Kedar ◽  
Donald V. Helmberger
Keyword(s):  
Surface Waves ◽  
Seismic Moment ◽  
Body Wave ◽  
Detection Threshold ◽  
Data Set ◽  
Waveform Data ◽  
Long Period ◽  
Source Type ◽  
Short Period ◽  
Source Excitation

Abstract The mb:MS ratio determined by teleseismic observations has proven to be an effective discriminant, for explosive sources tend to be significantly richer in short-period energy than are earthquakes. Unfortunately, this method is limited by the detection threshold of teleseismic surface waves. However, recent advances in instrumentation allowing low amplitude surface wave measurements coupled with new analytical techniques make it feasible to use regional waveform data to determine the long-period source excitation level of low magnitude events. We propose using the ratio of ML (local magnitude) to M0 (scalar seismic moment) as an analogous regional discriminant. We applied this criterion to a data set of 299 earthquakes and 178 explosions and found that this ratio seems to be diagnostic of source type. For a given M0, the ML of an explosion is more than 0.5 magnitude units larger than that of an earthquake. This separation of populations with respect to source type can be attributed to the fact that ML is a short-period (1 Hz) energy measurement, whereas seismic moment is determined from long-period body wave phases (period &gt; 4 s) and surface waves (10 to 40 sec). Using regional stations with sources 200 to 600 km away, the effective threshold for magnitude measurements for this discriminant is found to be ML = 3.1 for earthquakes and ML = 3.6 for explosions. This method does require the determination of regional crustal models and path calibrations from master events or by other means.

Source Parameters of Large Australian Intracontinental Earthquakes

1988 ◽  
Vol 59 (4) ◽  
pp. 315-315
Author(s):  
Robert McCaffrey ◽  
Joanne Fredrich
Keyword(s):  
Continental Margin ◽  
Source Parameters ◽  
Strike Slip ◽  
Thrust Faulting ◽  
Long Period ◽  
The Past ◽  
Preliminary Examination ◽  
Short Period ◽  
Australian Continent ◽  
Large Earthquakes

Abstract We have examined the largest earthquakes in the Australian continent over the past 20 years by modeling their teleseismic long-period P and SH and short-period P waveforms. Eight earthquakes beneath the continent show thrust faulting at depths shallower than 10 km. Three (1, 2, 4 below) produced surface faulting and their waveforms indicate centroid depths of 3 km or less. The P-axes in the southwestern half of the continent have easterly trends. Preliminary examination of the 3 large earthquakes near Tennant Creek on 22 January, 1988, (7–9) indicate thrusting at less than 10 km depth, but with N-trending P-axes. The largest event (9), at 12:06 GMT, had a seismic moment of roughly 1019 Nm, which makes it comparable in size to the 1968 Meckering event (1). One event (6) beneath the continental margin indicates strike-slip at 26 km depth.

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