Observed amplitude changes and seismic activity prior to two recent earthquakes in the Himachal Himalayas, India

1984 ◽  
Vol 104 (3-4) ◽  
pp. 375-386 ◽  
Author(s):  
Amit Das Gupta
Keyword(s):  
Seismic Activity ◽  
Recent Earthquakes

Transforms are forever

2021 ◽  
Author(s):  
Paola Vannucchi ◽  
David Iacopini ◽  
Jason P. Morgan
Keyword(s):  
Fluid Flow ◽  
Seismic Activity ◽  
Plate Tectonics ◽  
Driving Forces ◽  
Permanent Deformation ◽  
Oceanic Lithosphere ◽  
Ocean Floor ◽  
Spreading Center ◽  
Transform Faults ◽  
Recent Earthquakes

<p>According to Plate Tectonics, fracture zones (FZs) are born at Transform Faults (TFs), which leave behind "inactive" FZs traces as scars on the seafloor that reflect their initial use as one side of a strike-slip transform fault. FZs were originally thought to "heal" as the oceanic lithosphere cooled and strengthened with time. However, the occurrence of recent earthquakes reveals that FZs can be associated with significant seismic activity (for example during the recent Mw 8.6 2012 EQ offshore Sumatra and Mw 7.9 2018 EQ offshore SE Kodiak), and also with permanent deformation that occurs well after passage through the TF.</p><p>The TF at the spreading center is known to be accompanied by the formation of the transform valley which exposes serpentinized peridotite to the ocean floor. Valley relief itself can drive fluid flow that promotes continued serpentinization, and also cooling- and volume-change-linked stress variations. Off-axis seismicity suggests that FZs remain weaker that neighbouring oceanic lithosphere. The transform valley relief in general persists as a fracture zone valley that itself can continue to be a major drive of fluid flow even in the “healed” oceanic lithosphere. After reviewing evidence for FZ activity on (normal) ocean floor we will focus on the long-lived impact of FZs at continental margins. Offshore/onshore evidence of ongoing deformation at FZs is observed through seismic activity at both the western Brazilian and eastern Ghana-Côte d’Ivoire ends of the Romanche FZ. The western Brazil end is also characterized by recent folding and faulting, both offshore across the FZ, and onshore co-linearly with FZ extensions into the continent. Seismic activity in continental Brazil is focused where the FZ intersects the continental margin. This activity suggests that FZs remain as permanent weak lithospheric heterogeneities that are able to store elastic strain.</p><p>The reasons why FZs remain active are still poorly understood. Possible causes include i) effects of serpentinization that occurs both in the TF and in the FZ through hydrothermal fluid/mantle interaction, ii) thermal stress, iii) changing tectonic stresses related to plate driving forces.</p>

scholarly journals Oklahoma’s recent earthquakes and saltwater disposal

2015 ◽  
Vol 1 (5) ◽  
pp. e1500195 ◽  
Author(s):  
F. Rall Walsh ◽  
Mark D. Zoback
Keyword(s):  
Pore Water ◽  
Seismic Activity ◽  
Produced Water ◽  
Active Faults ◽  
Crystalline Basement ◽  
The Public ◽  
The Past ◽  
Basement Faults ◽  
Recent Earthquakes

Over the past 5 years, parts of Oklahoma have experienced marked increases in the number of small- to moderate-sized earthquakes. In three study areas that encompass the vast majority of the recent seismicity, we show that the increases in seismicity follow 5- to 10-fold increases in the rates of saltwater disposal. Adjacent areas where there has been relatively little saltwater disposal have had comparatively few recent earthquakes. In the areas of seismic activity, the saltwater disposal principally comes from “produced” water, saline pore water that is coproduced with oil and then injected into deeper sedimentary formations. These formations appear to be in hydraulic communication with potentially active faults in crystalline basement, where nearly all the earthquakes are occurring. Although most of the recent earthquakes have posed little danger to the public, the possibility of triggering damaging earthquakes on potentially active basement faults cannot be discounted.

scholarly journals Recent seismic activity at Cephalonia island (Greece): a study through candidate electromagnetic precursors in terms of nonlinear dynamics

2015 ◽  
Vol 2 (6) ◽  
pp. 1587-1629 ◽  
Author(s):  
S. M. Potirakis ◽  
Y. Contoyiannis ◽  
N. S. Melis ◽  
J. Kopanas ◽  
G. Antonopoulos ◽  
...  
Keyword(s):  
Seismic Activity ◽  
The West ◽  
Linear Processes ◽  
Hazard Zoning ◽  
Natural Time ◽  
Electromagnetic Emissions ◽  
Critical Characteristics ◽  
Recent Earthquakes ◽  
Electromagnetic Precursors ◽  
Critical Process

Abstract. The preparation process of two recent earthquakes (EQs) occurred in Cephalonia (Kefalonia) island, Greece, (38.22° N, 20.53° E), 26 January 2014, Mw =6.0, depth =21 km, and (38.25° N, 20.39° E), 3 February 2014, Mw =5.9, depth =10 km, respectively, is studied in terms of the critical dynamics revealed in observables of the involved non-linear processes. Specifically, we show, by means of the method of critical fluctuations (MCF), that signatures of critical, as well as tricritical, dynamics were embedded in the fracture-induced electromagnetic emissions (EME) recorded by two stations in locations near the epicenters of these two EQs. It is worth noting that both, the MHz EME recorded by the telemetric stations on the island of Cephalonia and the neighboring island of Zante (Zakynthos), reached simultaneously critical condition a few days before the occurrence of each earthquake. The critical characteristics embedded in the EME signals were further verified using the natural time (NT) method. Moreover, we show, in terms of the NT method, that the foreshock seismic activity also presented critical characteristics before each one of these events. Importantly, the revealed critical process seems to be focused on the area corresponding to the west Cephalonia zone, following the seismotectonic and hazard zoning of the Ionian Islands area near Cephalonia.

scholarly journals Special issue: Evaluation of the potential for large earthquakes in regions of present day low seismic activity in Europe

2001 ◽  
Vol 80 (3-4) ◽  
pp. 67-68
Keyword(s):  
Seismic Activity ◽  
Historical Sources ◽  
Local Effects ◽  
Epicentral Area ◽  
Issue Evaluation ◽  
Time Period ◽  
Recent Earthquakes ◽  
Different Origins ◽  
Large Earthquakes

Studies of long-term seismic activity in any region of the world require the longest historical perspective as possible. In most of the regions of Europe, before the XIIIth and the XIVth centuries, historical sources allow to establish a catalogue of felt earthquakes but the available data give very few information to estimate local intensities and epicentres.Thus, the knowledge of the seismic activity begins really at this epoch and covers a time period of less than 700 years. From that time, sources from different origins. (chronicles, annotations, parish registers, account registers,…) give us more details on local effects and allow reliable estimation of damages and perceptibility area of the earthquakes. It is then possible to determine the probable epicentral area of the strongest earthquakes and also to estimate their magnitude by comparison with recent earthquakes for which the magnitude has been instrumentally determined.

The Intervention of Earthen Heritage in Seismic Areas and the Conservation Charters

2010 ◽  
Vol 133-134 ◽  
pp. 727-734 ◽  
Author(s):  
Julio Vargas Neumann ◽  
Marcial Blondet ◽  
Carlos Iwaki
Keyword(s):  
Seismic Activity ◽  
Construction Materials ◽  
Structural Response ◽  
Stone Masonry ◽  
Natural Phenomena ◽  
Architectural Heritage ◽  
Unique Case ◽  
Catholic University ◽  
Reinforced Earth ◽  
Recent Earthquakes

Earthquakes are recurring natural phenomena that cause cumulative damage to earth constructions that can lead to their collapse. The discovery of earthen architectural heritage in Peru, has led to the re-exposure of adobe buildings, increasing their vulnerability to seismic activity. How can we prevent protect them from further damage their loss and? Due to their gradual and progressive destruction, earth constructions located in seismic areas constitute a critical and unique case. The structural response of stone masonry joined with mud mortar depends on the weakest of their construction materials: earth. This paper presents the criteria for structural conservation of earthen architectural heritage and tools for seismic-resistant reinforcement developed by field experts during the last 25 years. The concepts of reinforced earth and liquid mud injection, developed by the Pontifical Catholic University of Peru (PUCP) with support from the Getty Conservation Institute (GCI), are also included in this work. The article also analyzes recent cases of the re-intervention of earth monuments initially restored during the last century and re-destroyed by more recent earthquakes; offers solutions to this situation, ranging from the safest and friendliest to the most aggressive ones. Finally, I concludes expressing the urgent need to reassess the conservation criteria accepted by the International Charters ratified by ICOMOS and UNESCO regarding earthen architectural heritage located in seismic areas.

scholarly journals Recent seismic activity at Cephalonia (Greece): a study through candidate electromagnetic precursors in terms of non-linear dynamics

2016 ◽  
Vol 23 (4) ◽  
pp. 223-240 ◽  
Author(s):  
Stelios M. Potirakis ◽  
Yiannis Contoyiannis ◽  
Nikolaos S. Melis ◽  
John Kopanas ◽  
George Antonopoulos ◽  
...  
Keyword(s):  
Seismic Activity ◽  
Linear Processes ◽  
Hazard Zoning ◽  
Natural Time ◽  
Non Linear ◽  
Electromagnetic Emissions ◽  
Critical Characteristics ◽  
Recent Earthquakes ◽  
Neighbouring Island ◽  
Electromagnetic Precursors

Abstract. The preparation process of two recent earthquakes (EQs) that occurred in Cephalonia (Kefalonia), Greece, ((38.22° N, 20.53° E), 26 January 2014, Mw = 6.0, depth  ∼  20 km) and ((38.25° N, 20.39° E), 3 February 2014, Mw = 5.9, depth  ∼  10 km), respectively, is studied in terms of the critical dynamics revealed in observables of the involved non-linear processes. Specifically, we show, by means of the method of critical fluctuations (MCF), that signatures of critical, as well as tricritical, dynamics were embedded in the fracture-induced electromagnetic emissions (EMEs) recorded by two stations in locations near the epicentres of these two EQs. It is worth noting that both the MHz EMEs recorded by the telemetric stations on the island of Cephalonia and the neighbouring island of Zante (Zakynthos) reached a simultaneously critical condition a few days before the occurrence of each earthquake. The critical characteristics embedded in the EME signals were further verified using the natural time (NT) method. Moreover, we show, in terms of the NT method, that the foreshock seismic activity also presented critical characteristics before each event. Importantly, the revealed critical process seems to be focused on the area corresponding to the western Cephalonia zone, following the seismotectonic and hazard zoning of the Ionian Islands area near Cephalonia.

Failure Analysis Of Buried Gas Pipelines Crossing Seismic Faults

2020 ◽  
Vol 3 (2) ◽  
pp. 781-790
Author(s):  
M. Rizwan Akram ◽  
Ali Yesilyurt ◽  
A.Can. Zulfikar ◽  
F. Göktepe
Keyword(s):  
Ground Deformation ◽  
Warning System ◽  
Strike Slip ◽  
Gas Pipelines ◽  
Steel Pipes ◽  
Seismic Fault ◽  
Fault Parameters ◽  
Dip Angle ◽  
Permanent Ground Deformation ◽  
Recent Earthquakes

Research on buried gas pipelines (BGPs) has taken an important consideration due to their failures in recent earthquakes. In permanent ground deformation (PGD) hazards, seismic faults are considered as one of the major causes of BGPs failure due to accumulation of impermissible tensile strains. In current research, four steel pipes such as X-42, X-52, X-60, and X-70 grades crossing through strike-slip, normal and reverse seismic faults have been investigated. Firstly, failure of BGPs due to change in soil-pipe parameters have been analyzed. Later, effects of seismic fault parameters such as change in dip angle and angle between pipe and fault plane are evaluated. Additionally, effects due to changing pipe class levels are also examined. The results of current study reveal that BGPs can resist until earthquake moment magnitude of 7.0 but fails above this limit under the assumed geotechnical properties of current study. In addition, strike-slip fault can trigger early damage in BGPs than normal and reverse faults. In the last stage, an early warning system is proposed based on the current procedure. 

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