Inverting travel times with a triplication

1982 ◽  
Vol 72 (6A) ◽  
pp. 2147-2170
Author(s):  
Hans S. Jarosch
Keyword(s):  
Body Wave ◽  
P Wave ◽  
Inversion Method ◽  
Linear Inversion ◽  
Time Curve ◽  
Wave Travel ◽  
Data Points ◽  
A New Technique ◽  
The Right ◽  
Lunar Core

abstract A new technique has been developed to overcome difficulties which arise when body-wave data in the form of T-delta is reduced to the tau-p form in the presence of cusps. The technique uses sophisticated constrained spline fits to allow for constraints on the derivatives and thus eliminates the possibility of points of inflexion occurring as well as making sure that the curvature is in the right direction. Having arrived at a good fit to the T-delta data with a single spline, the tau-p curve can be derived which has taken the cusp properly into consideration. The tau-p curve is then inverted with a new linear inversion method, which again takes into consideration whether a particular point lies on a prograde or retrograde branch. The technique is applied to the lunar seismic data, where at least one triplication is presumed to occur for the P-wave travel-time curve. It is shown that the present analysis is not accurate enough to address itself to the problem of a possible lunar core, since there are insufficient data points for events close to the antipode of the center of the lunar network.

Travel times and amplitudes of S waves from nuclear explosions in Nevada

1969 ◽  
Vol 59 (1) ◽  
pp. 385-398 ◽  
Author(s):  
Otto W. Nuttli
Keyword(s):  
Stress Field ◽  
Body Wave ◽  
P Wave ◽  
Travel Times ◽  
S Wave ◽  
Low Velocity ◽  
Time Curve ◽  
Regional Stress ◽  
S Waves ◽  
Regional Stress Field

Abstract The underground Nevada explosions HALF-BEAK and GREELEY were unique in creating relatively large amplitude and long-period body S waves which could be detected at teleseismic distances. Observations of the travel times of these S waves provide a surface focus travel-time curve which in its major features is similar to a curve calculated from the upper mantle velocity model of Ibrahim and Nuttli (1967). This model includes a low-velocity channel at a depth of 150 to 200 km and regions of rapidly increasing velocity beginning at depths of 400 and 750 km. Observations of the S wave amplitudes suggest that a discontinuous increase in velocity occurs at 400 km, whereas at 750 km the velocity is continuous but the velocity gradient discontinuous. Body wave magnitudes calculated from S amplitudes are 5.3 ± 0.2 for GREELEY and 4.9 ± 0.2 for HALF-BEAK. These are about one unit less than body wave magnitudes from P amplitudes as reported by others. The shape and orientation of the radiation pattern of SH for both explosions are consistent with the Rayleigh and P-wave amplitude distribution of BILBY as given by Toksoz and Clermont (1967). This suggests that the regional stress field is the same at all three sites, and that the direction of cracking as well as the strain energy release in the elastic zone outside the cavity is determined by the regional stress field.

The identification and interpretation of upper mantle travel-time branches from measurements of dT/dΔ made on data recorded at the Yellowknife seismic array

1978 ◽  
Vol 15 (2) ◽  
pp. 227-236 ◽  
Author(s):  
A. Ram ◽  
R. F. Mereu ◽  
D. H. Weichert
Keyword(s):  
Travel Time ◽  
Upper Mantle ◽  
Body Wave ◽  
Processing Technique ◽  
The Body ◽  
Seismic Array ◽  
P Wave ◽  
Time Curve ◽  
Transition Zones ◽  
Short Period

There is broad agreement among various seismological studies that the upper mantle has two regions where very high positive velocity gradients or transition zones exist. In most cases, the presence of these zones implies that two major triplications are likely to exist in the body-wave travel-time curve for distances less than 30°. Because of the difficulties in observing and identifying later arrivals belonging to the various travel-time branches, the inversion of the seismic data is often very difficult. In this paper an adaptive processing technique was employed to examine the variations in slowness that occur along the first 36 s of the short-period P-wave trains recorded at the Yellowknife medium aperture seismic array. Over 100 earthquakes from the Alaska Peninsula and California regions were selected. From the California results we were able to clearly observe the 12–13 s/deg slowness branch as a later arrival out to distances as great as 26°. Other later arrival branches as well as cusps associated with the 400 and 650 km discontinuities were not well defined even though the cross-over point as determined from slowness measurements on first arrivals were clearly located. An inversion of the data showed that the '650 km' transition zone occurred at a much shallower depth west of the array compared to the corresponding region to the south.

scholarly journals Identifikasi Lapisan Akuifer Menggunakan Metode Seismik Refraksi di Desa Jatimulyo, Kecamatan Jati Agung, Kabupaten Lampung Selatan

2020 ◽  
Vol 6 (2) ◽  
pp. 91-100
Author(s):  
Rhahmi Adni Pesma ◽  
Mokhammad Puput Erlangga ◽  
Intan Adiani Putri ◽  
Risky Martin Antosia ◽  
Ruhul Firdaus ◽  
...  
Keyword(s):  
Seismic Refraction ◽  
P Wave ◽  
Distribution Data ◽  
Saturated Sand ◽  
Saturated Clay ◽  
Refraction Method ◽  
Wave Travel ◽  
Seismic Refraction Method ◽  
The Right ◽  
Measurement Line

An initial subsurface survey to predict the aquifer is important to avoid the unprospect drill location and getting groundwater with the right discharge. In this study, prediction of the aquifer was carried out using the seismic refraction method in Jatimulyo Village, Jati Agung District, South Lampung Regency. The data was collected on October 6, 2019 using the SUMMIT X One seismic tool with 24 Geophones. The first break data from p-wave travel time is processed and interpreted using the Hagiwara method. Interpretation results show that there are three layers of subsurface lithology in the study area. The weathering layer was found at 2 m to 3.5 m depth with average velocity of 360 m/s. The second layer is dry sand with a velocity of 890 m/s at a depth of 2 m to 8 m. The third layer with a 2300 m/s velocity is a mixture of clay rock and saturated sand at depths of more than 8 m. As a comparison there is resistivity distribution data on the same measurement line in the study area. The overall interpretation shows that at a depth of 12 m with saturated clay sedimentary rock as a prospect of aquifer in this study area.

scholarly journals Imaging the subsurface using induced seismicity and ambient noise: 3-D tomographic Monte Carlo joint inversion of earthquake body wave traveltimes and surface wave dispersion

2020 ◽  
Vol 222 (3) ◽  
pp. 1639-1655
Author(s):  
Xin Zhang ◽  
Corinna Roy ◽  
Andrew Curtis ◽  
Andy Nowacki ◽  
Brian Baptie
Keyword(s):  
Surface Wave ◽  
Ambient Noise ◽  
Velocity Structure ◽  
Joint Inversion ◽  
Body Wave ◽  
Source Parameters ◽  
Wave Dispersion ◽  
Inversion Method ◽  
Surface Wave Dispersion ◽  
Wave Data

SUMMARY Seismic body wave traveltime tomography and surface wave dispersion tomography have been used widely to characterize earthquakes and to study the subsurface structure of the Earth. Since these types of problem are often significantly non-linear and have non-unique solutions, Markov chain Monte Carlo methods have been used to find probabilistic solutions. Body and surface wave data are usually inverted separately to produce independent velocity models. However, body wave tomography is generally sensitive to structure around the subvolume in which earthquakes occur and produces limited resolution in the shallower Earth, whereas surface wave tomography is often sensitive to shallower structure. To better estimate subsurface properties, we therefore jointly invert for the seismic velocity structure and earthquake locations using body and surface wave data simultaneously. We apply the new joint inversion method to a mining site in the United Kingdom at which induced seismicity occurred and was recorded on a small local network of stations, and where ambient noise recordings are available from the same stations. The ambient noise is processed to obtain inter-receiver surface wave dispersion measurements which are inverted jointly with body wave arrival times from local earthquakes. The results show that by using both types of data, the earthquake source parameters and the velocity structure can be better constrained than in independent inversions. To further understand and interpret the results, we conduct synthetic tests to compare the results from body wave inversion and joint inversion. The results show that trade-offs between source parameters and velocities appear to bias results if only body wave data are used, but this issue is largely resolved by using the joint inversion method. Thus the use of ambient seismic noise and our fully non-linear inversion provides a valuable, improved method to image the subsurface velocity and seismicity.

scholarly journals Coughing as a potentially effective induction method of atrial tachycardia: a case report

2020 ◽  
Author(s):  
Reina Tonegawa-Kuji ◽  
Kenichiro Yamagata ◽  
Kengo Kusano
Keyword(s):  
Pulmonary Vein ◽  
Atrial Tachycardia ◽  
Superior Vena ◽  
Vena Cava ◽  
P Wave ◽  
Induction Method ◽  
Voluntary Cough ◽  
Wave Morphology ◽  
The Right

Abstract Background  Cough-induced atrial tachycardia (AT) is extremely rare and its electrical origin remains largely unknown. Atrial tachycardias triggered by pharyngeal stimulation, such as swallowing or speech, appears to be more common and the majority of them originate from the superior vena cava or right superior pulmonary vein (PV). Only one case of swallow-triggered AT with right inferior pulmonary vein (RIPV) origin has been reported to date. Case summary  We present a case of a 41-year-old man with recurring episodes of AT in the daytime. He underwent electrophysiology study without sedation. Atrial tachycardia was not observed when the patient entered the examination room and could not be induced with conventional induction procedures. By having the patient cough periodically on purpose, transient AT with P-wave morphology similar to the clinical AT was consistently induced. Activation mapping of the AT revealed a centrifugal pattern with the earliest activity localized inside the RIPV. After successful radiofrequency isolation of the right PV, AT was no longer inducible. Discussion  In the rare case of cough-induced AT originating from the RIPV, the proximity of the inferior right ganglionated plexi (GP) suggests the role of GP in triggering tachycardia. This is the first report that demonstrates voluntary cough was used to induce AT. In such cases that induction of AT is difficult using conventional methods, having the patient cough may be an effective induction method that is easy to attempt.

scholarly journals Surgical treatment for common hepatic aneurysm. Original one-step technique

Open Medicine ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 898-904
Author(s):  
Bruno Amato ◽  
Renato Patrone ◽  
Gennaro Quarto ◽  
Rita Compagna ◽  
Roberto Cirocchi ◽  
...  
Keyword(s):  
Surgical Treatment ◽  
Hepatic Artery ◽  
Distal Part ◽  
Intraoperative Ultrasound ◽  
Section Area ◽  
One Step ◽  
A New Technique ◽  
Open Surgical Treatment ◽  
The Right ◽  
Vascular Stapler

AbstractIntroductionHepatic artery aneurysms are rare, and their treatment represents a challenge for the surgeons.Materials and methodsA new technique is presented for common hepatic artery (CHA) aneurysm: it requires minimal vascular surgical dissection and only one linear vascular stapler is applied at the bottom of aneurysm. Aneurysm exclusion is easily obtained, which allowed retrograde thrombosis. Liver blood supply is ensured to the right and left hepatic artery, through the gastroduodenal artery, and can be previously monitored, with temporary clamping of the section area, by visual control, enzyme evaluation and intraoperative ultrasound examination. We reported an open surgical treatment, with simultaneous removal of hepatic and adrenal metastases, secondary to colon cancer.ResultsThe duration of vascular surgery was 30 min and did not involve complications. Postoperative controls confirmed the efficacy of the procedure.DiscussionThis original technique can be added to the various open and endovascular techniques so far described for the treatment of a CHA aneurysm. It is advisable as open surgery, mostly in case of associated pathologies.ConclusionsThe authors believe that this “one shot” technique by vascular staple of the distal part of CHA is minimally invasive and effective to obtain the exclusion of the aneurysm.

scholarly journals Teleseismic P-wave travel time and amplitude anomalies observed in Hokkaido region, Japan.

1990 ◽  
Vol 38 (2) ◽  
pp. 163-177 ◽  
Author(s):  
Ichiro Nakanishi ◽  
Yoshinobu Motoya
Keyword(s):  
Travel Time ◽  
P Wave ◽  
Wave Travel

Aftershocks of the February 21, 1973 Point Mugu, California earthquake

1976 ◽  
Vol 66 (6) ◽  
pp. 1931-1952
Author(s):  
Donald J. Stierman ◽  
William L. Ellsworth
Keyword(s):  
Fault Zone ◽  
Main Shock ◽  
Fault Plane ◽  
Body Wave ◽  
P Wave ◽  
Fault System ◽  
Wave Radiation ◽  
Fault Plane Solutions ◽  
Complex Deformation ◽  
Transverse Ranges

abstract The ML 6.0 Point Mugu, California earthquake of February 21, 1973 and its aftershocks occurred within the complex fault system that bounds the southern front of the Transverse Ranges province of southern California. P-wave fault plane solutions for 51 events include reverse, strike slip and normal faulting mechanisms, indicating complex deformation within the 10-km broad fault zone. Hypocenters of 141 aftershocks fail to delineate any single fault plane clearly associated with the main shock rupture. Most aftershocks cluster in a region 5 km in diameter centered 5 km from the main shock hypocenter and well beyond the extent of fault rupture estimated from analysis of body-wave radiation. Strain release within the imbricate fault zone was controlled by slip on preexisting planes of weakness under the influence of a NE-SW compressive stress.

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