SECONDARY FAULTING: II. GEOLOGICAL ASPECTS

1966 ◽  
Vol 3 (2) ◽  
pp. 175-190 ◽  
Author(s):  
M. A. Chinnery
Keyword(s):  
Shear Stress ◽  
Shear Zone ◽  
Direct Result ◽  
End Effect ◽  
The Past ◽  
Fault Systems ◽  
San Andreas ◽  
Transcurrent Fault ◽  
Secondary Fault

A secondary fault is defined as a fracture which arises as a direct result of movement on a master transcurrent fault. Some previous approaches to the study of secondary faulting are discussed, and fallacies in the arguments of McKinstry (1953) and Moody and Hill (1956) are pointed out. The effect of movement on a fault is to reduce the initial shear stress everywhere except in the vicinity of the ends of the fault, where it causes complex additional stresses (see first paper in this series on the theoretical aspects of secondary faulting). Thus it is proposed that secondary faulting is an end effect of a master shear movement, and on this basis six major modes of secondary faulting, labelled types A to F, are described. The usefulness of these results in the analysis of fault systems is illustrated by applying them to the Alpine, San Andreas, and Mac Donald faults. In each case it is possible to predict or explain the curvature, location, and sense of the secondary faults in the area. In addition, the development of the master fault may be traced by locating the ends of the shear zone at various times in the past.

scholarly journals Joint earthquake ruptures of the San Andreas and San Jacinto faults, California, USA

Geology ◽  
2021 ◽  
Author(s):  
Alba M. Rodriguez Padilla ◽  
Michael E. Oskin ◽  
Thomas K. Rockwell ◽  
Irina Delusina ◽  
Drake M. Singleton
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Ground Shaking ◽  
Physical Conditions ◽  
The Past ◽  
San Andreas ◽  
Earthquake Ruptures ◽  
Future Events ◽  
Secondary Fault ◽  
Strong Ground

Large, multi-fault earthquakes increase the threat of strong ground shaking and reshape the probability of future events across a system of faults. Fault junctions act as conditional barriers, or earthquake gates, that stop most earthquakes but permit junction-spanning events when stress conditions are favorable. Constraining the physical conditions that favor multi-fault earthquakes requires information on the frequency of isolated events versus events that activate faults through the junction. Measuring this frequency is challenging because dating uncertainties limit correlation of paleoseismic events at different faults, requiring a direct approach to measuring rupture through an earthquake gate. We show through documentation and finite-element modeling of secondary fault slip that co-rupture of the San Andreas and San Jacinto faults (California, USA) through the Cajon Pass earthquake gate occurred at least three times in the past 2000 yr, most recently in the historic 1812 CE earthquake. Our models show that gate-breaching events taper steeply and halt abruptly as they transfer slip between faults. Comparison to independent chronologies shows that 20%–23% of earthquakes on the San Andreas and the San Jacinto faults are co-ruptures through Cajon Pass.

scholarly journals The earthquake of 1 January 1837 in Southern Lebanon and N orthern Israel

1997 ◽  
Vol 40 (4) ◽  
Author(s):  
N. N. Ambraseys
Keyword(s):  
Middle East ◽  
20Th Century ◽  
Dead Sea ◽  
Transform Fault ◽  
Earthquake Catalogues ◽  
Dead Sea Transform ◽  
The Past ◽  
Fault Systems ◽  
Heavy Damage

All of our 20th-century information for the Levant Fracture and Dead Sea transform fault systems is for a qui- escent period in the seismicity. This is apparent when we consider earlier events which show that infi.equent earthquakes have occurred in the past along this system, an important consideration for the assessment of haz- ard and tectonics of the Middle East. One of these events was the earthquake of 1837 which caused heavy damage in Northem Israel and Southem Lebanon. This earthquake was a much larger event than earthquake catalogues indicate. We reckon it was a shallow, probably multiple event of magnitude greater than 7.0.

scholarly journals Displacement on the San Andreas fault subsequent to the 1966 Parkfield earthquake

1968 ◽  
Vol 58 (6) ◽  
pp. 1955-1973
Author(s):  
Stewart W. Smith ◽  
Max Wyss
Keyword(s):  
Shear Stress ◽  
Ground Motion ◽  
San Andreas Fault ◽  
High Rate ◽  
Aftershock Activity ◽  
Fault Surface ◽  
San Andreas ◽  
Parkfield Earthquake ◽  
Fault Displacement ◽  
Displacement Measurements

ABSTRACT Immediately following the 1966 Parkfield earthquake a continuing program of fault displacement measurements was undertaken, and several types of instruments were installed in the fault zone to monitor ground motion. In the year subsequent to the earthquake a maximum of at least 20 cm of displacement occurred on a 30 km section of the San Andreas fault, which far exceeded the surficial displacement at the time of the earthquake. The rate of displacement decreased logarithmically during this period in a manner similar to that of the decrease in aftershock activity. After the initial high rate of activity it could be seen that most of the displacement was occurring in 4–6 day epochs of rapid creep following local aftershocks. The variation of fault displacement along the surface trace was measured and shown to be consistent with a vertidal fault surface 44 km long and 14 km deep, along which a shear stress of 2.4 bars was relieved.

Performance Assessment of the Lead User Idea-Generation Process for New Product Development

2002 ◽  
Vol 48 (8) ◽  
pp. 1042-1059 ◽  
Author(s):  
Gary L. Lilien ◽  
Pamela D. Morrison ◽  
Kathleen Searls ◽  
Mary Sonnack ◽  
Eric von Hippel
Keyword(s):  
New Product Development ◽  
Idea Generation ◽  
New Product ◽  
Major Product ◽  
Product Line ◽  
Direct Result ◽  
Target Market ◽  
Generation Process ◽  
The Past ◽  
Lead User

Traditional idea generation techniques based on customer input usually collect information on new product needs from a random or typical set of customers. The “lead user process” takes a different approach. It collects information about both needs and solutions from users at the leading edges of the target market, as well as from users in other markets that face similar problems in a more extreme form. This paper reports on a natural experiment conducted within the 3M Company on the effect of the lead user (LU) idea-generation process relative to more traditional methods. 3M is known for its innovation capabilities— and we find that the LU process appears to improve upon those capabilities. Annual sales of LU product ideas generated by the average LU project at 3M are conservatively projected to be $146 million after five years—more than eight times higher than forecast sales for the average contemporaneously conducted “traditional” project. Each funded LU project is projected to create a new major product line for a 3M division. As a direct result, divisions funding LU project ideas are projecting their highest rate of major product line generation in the past 50 years.

Cracked Shaft Detection Using the Unbalance Excitation Technique

1995 ◽  
Author(s):  
Farokh H. Kavarana ◽  
R. Gordon Kirk
Keyword(s):  
Crack Detection ◽  
Direct Result ◽  
Response Characteristics ◽  
The Past ◽  
Promising Tool ◽  
Complete Test ◽  
Vibration Signature ◽  
Complete Failure ◽  
Cracked Shafts ◽  
Cracked Shaft

Abstract The ever-growing interest of the modern rotordynamicist in the early detection of rotor cracks in turbomachinery has been the direct result of multiple catastrophic experiences that industry has faced in recent times due to cracked rotors. The complete failure of the rotor due to crack propagation is easily recognized as one of the most serious modes of plant failure. Even though the past decade has witnessed some laudable attempts that have been moderately successful in detecting cracked rotors, this aspect has not received the attention it warrants. A complete test rig has been designed and constructed for experimental research on the response characteristics of cracked rotors, the results of which will permit increased confidence in detecting the presence of rotor cracks in turbomachinery. The rig is capable of testing cracked shafts under the effect of lateral and coupled lateral/torsional vibrations. Conventional vibration signature analysis has been employed for the purpose of crack detection. This paper presents the details of the rig capabilities and results from the unbalance excitation technique applied for crack detection. The response of a cracked shaft differs markedly from that of an uncracked shaft when subjected to a known unbalance. This paper shows that unbalance excitation is a promising tool for cracked shaft detection.

Microearthquake activity following the Parkfield, California earthquake of June, 1966

1969 ◽  
Vol 59 (2) ◽  
pp. 603-613
Author(s):  
Thomas J. Fitch
Keyword(s):  
Main Shock ◽  
High Sensitivity ◽  
Amplitude Distribution ◽  
B Value ◽  
Epicentral Area ◽  
San Andreas ◽  
Recording Station ◽  
Parkfield Earthquake ◽  
Secondary Aftershock ◽  
Secondary Fault

abstract A high sensitivity microearthquake recording station was established 10 km from the epicenter of the magnitude 5.5 Parkfield earthquake of June 28, 1966. Beginning 43 hours after the main shock, an hourly average of 22 microaftershocks was recorded for a period of 13 days. Events with magnitudes roughly equivalent to a Richter magnitude of −1.5 were recorded. The amplitude distribution suggests that there was a smaller percentage of small shocks in the Parkfield microaftershock series than has commonly been reported for Japanese and other California aftershock series. b values between 0.8 and 0.9 are commonly reported while the average b value for the Parkfield microaftershock series was 0.59. The distribution of S-P times for the microaftershocks is consistent with the epicentral area defined in other studies as a strip approximately 5 km wide astride a 35 km long trace of the San Andreas fault; however, some evidence suggests that the microaftershock activity extends beyond the zone defined by the larger aftershocks. The spatial distribution of microearthquake activity is shown to be strongly non-uniform within the aftershock zone. The microaftershocks, in general, did not cluster in time about the larger aftershocks (M > 2.0). Of 24 aftershocks with M greater than or equal to 2.0, only one event gave strong evidence of triggering a secondary aftershock series. Assuming that secondary foreshock and/or aftershock series imply the creation or reactivation of a secondary fault, one is led to the conclusion that secondary faulting was a rare occurrence in the Parkfield aftershock zone.

scholarly journals Erebus Glacier Tongue, Mcmurdo Sound, Antarctica

1974 ◽  
Vol 13 (67) ◽  
pp. 27-35 ◽  
Author(s):  
G. Holdsworth
Keyword(s):  
Shear Stress ◽  
Strain Rate ◽  
Shear Strain ◽  
Longitudinal Strain ◽  
Strain Rates ◽  
Shear Strain Rate ◽  
Mcmurdo Sound ◽  
Glacier Tongue ◽  
The Past ◽  
Image Position

Examination of the past and present behaviour of the Erebus Glacier tongue over the last 60 years indicates that a major calving from the tongue appears to be imminent. Calculations of the regime of the tongue indicate that bottom melt rates may exceed 1 m a−1. By successive mapping of the ice tongue between the years 1947 and 1970, longitudinal strain-rates were determined using the change in distance between a set of 15 teeth, which are a prominent marginal feature of the tongue. Assuming a flow law for ice of the form where τ is the effective shear stress and is the effective shear strain-rate, values of the exponent n = 3 and B = 1 × 108 N m−2 are determined. These are in fair agreement with published values.

Choosing Surgery: Identifying Factors Leading to Increased General Surgery Matriculation Rate

2017 ◽  
Vol 83 (3) ◽  
pp. 290-295 ◽  
Author(s):  
David T. Pointer ◽  
Matthew D. Freeman ◽  
James R. Korndorffer ◽  
Peter C. Meade ◽  
Bernard M. Jaffe ◽  
...  
Keyword(s):  
General Surgery ◽  
Role Models ◽  
Medical Student Education ◽  
Direct Result ◽  
Factors Affecting ◽  
The Past ◽  
Education Experience ◽  
Surgical Career ◽  
Core Rotation ◽  
Question Survey

Tulane graduates have, over the past six years, chosen general surgical residency at a rate above the national average (mean 9.6% vs 6.6%). With much of the recent career choice research focusing on disincentives and declining general surgery applicants, we sought to identify factors that positively influenced our students’ decision to pursue general surgery. A 50-question survey was developed and distributed to graduates who matched into a general surgery between the years 2006 and 2014. The survey evaluated demographics, exposure to surgery, and factors affecting interest in a surgical career. We achieved a 54 per cent (61/112) response rate. Only 43 per cent considered a surgical career before medical school matriculation. Fifty-nine per cent had strongly considered a career other than surgery. Sixty-two per cent chose to pursue surgery during or immediately after their surgery clerkship. The most important factors cited for choosing general surgery were perceived career enjoyment of residents and faculty, resident/faculty relationship, and mentorship. Surgery residents and faculty were viewed as role models by 72 and 77 per cent of responders, respectively. This study demonstrated almost half of those choosing a surgical career did so as a direct result of the core rotation experience. We believe that structuring the medical student education experience to optimize the interaction of students, residents, and faculty produces a positive environment encouraging students to choose a general surgery career.

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