scholarly journals Processing and Communication Delays in EWS: On the Performance of the Earthcloud Prototype

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Martin Klapez ◽  
Carlo Augusto Grazia ◽  
Maurizio Casoni ◽  
Simone Zennaro ◽  
Matteo Cozzani
Keyword(s):  
Seismic Waves ◽  
Warning System ◽  
Sensor Nodes ◽  
Communication Delays ◽  
Alert System ◽  
P Waves ◽  
Earthquake Early Warning System ◽  
S Waves ◽  
First Results ◽  
Initial Results

A Seismic Alert System (SAS), also called Earthquake Warning System (EWS) or Earthquake Early Warning System (EEW or EEWS), represents one of the most important measures that can be taken to prevent and minimize earthquake damage. These systems are mainly used to detect P-waves and the faster seismic waves and to subsequently trigger an alarm about the incoming S-waves, the slower and most dangerous seismic waves. In some cases, distributed systems are also able to alert some locations before the impending P-waves strike them. This paper presents Earthcloud, a cloud-based SAS that aims to provide all the former capabilities while retaining financial accessibility. Earthcloud first results, generated from four months of data acquisition, are compared with those coming from other systems. In particular, the paper focuses on processing and communication delays, showing how the Earthcloud new detection strategy may minimize delays. Although a thorough test campaign with more sensor nodes is needed to assess performance reliably, especially for highly dense urban scenarios, initial results are promising, with total latencies for Earthcloud always kept under the 1-second mark, despite being at the expense of solid magnitude estimation.

Ground Motion Estimation Using Front Site Wave Form Data Based on RVM for Earthquake Early Warning

2015 ◽  
Vol 10 (4) ◽  
pp. 667-677
Author(s):  
Yincheng Yang ◽  
◽  
Masato Motosaka ◽  
Keyword(s):  
Ground Motion ◽  
Early Warning ◽  
Warning System ◽  
Earthquake Early Warning ◽  
Peak Ground Velocity ◽  
Wave Form ◽  
Source Information ◽  
Ground Acceleration ◽  
P Waves ◽  
Earthquake Early Warning System

The use of the earthquake early warning system (EEWS), one of the most useful emergency response tools, requires that the accuracy of real-time ground motion prediction (GMP) be enhanced. This requires that waveform information at observation points along earthquake wave propagation paths (hereafter, front-site waveform information) be used effectively. To enhance the combined reliability of different systems, such as on-site and local/regional warning, we present a GMP method using front-site waveform information by applying a relevant vector machine (RVM). We present methodology and application examples for a case study estimating peak ground acceleration (PGA) and peak ground velocity (PGV) for earthquakes in the Miyagi-Ken Oki subduction zone. With no knowledge of source information, front site waveforms have been used to predict ground motion at target sites. Five input variables – earthquake PGA, PGD, pulse rise time, average period and theVpmax/Amaxratio – have been used for the first 4 to 6 seconds of P-waves in training a regression model. We found that RVM is a useful tool for the prediction of peak ground motion.

scholarly journals Converted‐wave seismic exploration: Applications

Geophysics ◽  
2003 ◽  
Vol 68 (1) ◽  
pp. 40-57 ◽  
Author(s):  
Robert R. Stewart ◽  
James E. Gaiser ◽  
R. James Brown ◽  
Don C. Lawton
Keyword(s):  
Seismic Waves ◽  
Seismic Exploration ◽  
Fracture Density ◽  
Converted Wave ◽  
P Waves ◽  
Near Surface ◽  
S Waves ◽  
Subsurface Fluid ◽  
Processing Techniques ◽  
Gas Bearing

Converted seismic waves (specifically, downgoing P‐waves that convert on reflection to upcoming S‐waves are increasingly being used to explore for subsurface targets. Rapid advancements in both land and marine multicomponent acquisition and processing techniques have led to numerous applications for P‐S surveys. Uses that have arisen include structural imaging (e.g., “seeing” through gas‐bearing sediments, improved fault definition, enhanced near‐surface resolution), lithologic estimation (e.g., sand versus shale content, porosity), anisotropy analysis (e.g., fracture density and orientation), subsurface fluid description, and reservoir monitoring. Further applications of P‐S data and analysis of other more complicated converted modes are developing.

A new instrument in earthquake early warning system by detection and modeling of prompt gravity signals

2020 ◽  
Author(s):  
Kevin Juhel ◽  
Jean-Paul Montagner ◽  
Jean-Paul Ampuero ◽  
Matteo Barsuglia ◽  
Pascal Bernard ◽  
...  
Keyword(s):  
Early Warning ◽  
Seismic Noise ◽  
Seismic Waves ◽  
Matched Filter ◽  
Accurate Determination ◽  
Warning System ◽  
Tohoku Earthquake ◽  
Earthquake Early Warning ◽  
Earthquake Early Warning System ◽  
New Instrument

<p>The recent finding of prompt elastogravity signals (PEGS) before the arrival of P-waves, associated with the M9.1 2011 Tohoku earthquake (Montagner et al., Nat. Comm., 2016; Vallée et al., Science, 2017) and a few earthquakes of magnitude larger than 8.5  (Vallée and Juhel, JGR, 2019) opens the new field of speed-of-light seismology.  The systematic detection of PEGS on real-time might help saving a few seconds before the arrival of destructive seismic waves and to obtain an accurate determination of the magnitude of the earthquake at the end of rupture. So the potential application to earthquake early warning is obvious.</p><p>However, the use of classical broadband seismometers for detecting PEGS has severe limitations for detecting earthquakes of magnitude smaller than 8.5: first of all, the background seismic noise and second of all, the partial cancellation of the gravitational perturbation by the inertial induced acceleration recorded by seismometers (Heaton, Nature Comm., 2017). Two different approaches can be explored for detecting for earthquakes of magnitude smaller than 8.5. Either, by using a dense array of broadband seismometers  (more than 100 receivers) or by designing completely new instruments such as gravity strainmeters. These new detectors must be able to measure the difference in gravity acceleration between two masses, making this instrument isolated from the seismic noise. A sensitivity of 10<sup>-15 </sup>Hz<sup>-1/2</sup> at 0.1 Hz is required for detecting earthquakes of M>7 (Juhel et al., JGR, 2019) and the technology developed by the gravitational wave physicists can be used for reaching such a sensitivity. The simulation of the expected gravity strain signals based on analytical model of gravity perturbations associated with a network-based matched filter approach show that a network of 3 gravity strainmeters might make it possible to reach such a challenging goal. Gravity strainmeters could therefore open new ways to investigate the first seconds of the earthquake rupture, speed up the estimate of earthquake magnitude, enhance tsunami warning systems and  complement other EEWS in the future.</p><p> </p><p> </p>

4. Seismic waves

2018 ◽  
pp. 53-61
Author(s):  
Mike Goldsmith
Keyword(s):  
Seismic Wave ◽  
Rayleigh Waves ◽  
Seismic Waves ◽  
Shear Waves ◽  
Free Vibrations ◽  
Love Waves ◽  
Sound Waves ◽  
P Waves ◽  
Tectonic Plates ◽  
S Waves

Sound waves travel very easily underground, often for many thousands of kilometres. These are usually referred to as a kind of seismic wave and are most often triggered by earthquakes, which result from a sudden slip of tectonic plates, down to about 700 kilometres below the Earth’s surface. ‘Seismic waves’ describes the four types of seismic wave generated by earthquakes: P-waves (primary waves), S-waves (shear waves), Love waves (usually the most powerful and destructive of seismic waves), and Rayleigh waves, which are created when P and S waves reach the Earth’s surface together, combining to form undulating ground rolls. Free vibrations and star waves are also described.

scholarly journals Estimation of Earthquake Early Warning Parameters for Eastern Gulf of Corinth and Western Attica Region (Greece). First Results

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5084
Author(s):  
Filippos Vallianatos ◽  
Andreas Karakonstantis ◽  
Nikolaos Sakelariou
Keyword(s):  
Early Warning ◽  
Warning System ◽  
Seismic Signal ◽  
Earthquake Early Warning ◽  
Initial Portion ◽  
P Waves ◽  
Peak Displacement ◽  
Earthquake Early Warning System ◽  
Gulf Of Corinth ◽  
Seismic Risk Management

The main goal of an Earthquake Early Warning System (EEWS) is to alert before the arrival of damaging waves using the first seismic arrival as a proxy, thus becoming an important operational tool for real-time seismic risk management on a short timescale. EEWSs are based on the use of scaling relations between parameters measured on the initial portion of the seismic signal after the arrival of the first wave. To explore the plausibility of EEWSs around the Eastern Gulf of Corinth and Western Attica, amplitude and frequency-based parameters, such as peak displacement (Pd), the integral of squared velocity (IV 2) and the characteristic period (τc), were analyzed. All parameters were estimated directly from the initial 3 s, 4 s, and 5 s signal windows (tw) after the P arrival. While further study is required on the behavior of the proxy quantities, we propose that the IV 2 parameter and the peak amplitudes of the first seconds of the P waves present significant stability and introduce the possibility of a future on-site EEWS for areas affected by earthquakes located in the Eastern Gulf of Corinth and Western Attica. Parameters related to regional-based EEWS need to be further evaluated.

Nonlinear Rheology at Shallow Depths with Reference to the 2016 Kumamoto Earthquakes

2019 ◽  
Vol 109 (6) ◽  
pp. 2674-2690 ◽  
Author(s):  
Norman H. Sleep ◽  
Nori Nakata
Keyword(s):  
Seismic Waves ◽  
Inelastic Strain ◽  
P Wave ◽  
Seismic Velocities ◽  
P Waves ◽  
S Waves ◽  
Shallow Subsurface ◽  
Horizontal Acceleration ◽  
Normal Traction ◽  
Uppermost Layer

Abstract Strong S waves produce dynamic stresses, which bring the shallow subsurface into nonlinear inelastic failure. We examine implications of nonlinear viscous flow, which may be appropriate for shallow muddy soil, and contrast them with those of Coulomb friction within a shallow reverberating uppermost layer with low‐seismic velocities. Waves refract into essentially vertical paths at the shallow layers and produce tractions on horizontal planes. The Coulomb ratio of shear traction to lithostatic stress for S waves equals the resolved horizontal acceleration normalized to the acceleration of gravity. The ratio of dynamic vertical normal traction to lithostatic stresses is the vertical normalized acceleration from P waves. The predicted viscous inelastic strain rate in muddy soil begins at low normalized accelerations and then increases mildly and nonlinearly with increasing normalized acceleration. Failure is unaffected when P waves decrease the vertical normal traction. Seismic waves recorded at KiK‐net station KMMH16 for the 2016 Kumamoto mainshock and strong foreshock show these effects. Inelastic deformation commences at a normalized horizontal acceleration of ∼0.25 and reduces S‐ and P‐wave velocities within the uppermost ∼15  m reverberating layer. Normalized horizontal accelerations and the Coulomb stress ratio reach ∼1.25. Strong S waves arrived even when strong P waves produced vertical tension on horizontal planes. In contrast, inelastic Coulomb failure commences at a normalized horizontal acceleration equal to the effective coefficient of friction; rapid inelastic strain precludes even higher accelerations. Furthermore, horizontal planes should fail from the stresses of strong S waves during the tensional cycle of strong P waves.

scholarly journals Remote Detection of the Electric Field Change Induced at the Seismic Wave Front from the Start of Fault Rupturing

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Yukio Fujinawa ◽  
Kozo Takahashi ◽  
Yoichi Noda ◽  
Hiroshi Iitaka ◽  
Shinobu Yazaki
Keyword(s):  
Electric Field ◽  
Seismic Waves ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Warning System ◽  
Wave Mode ◽  
P Wave ◽  
Remote Detection ◽  
Electrokinetic Effect ◽  
Earthquake Early Warning System

Seismic waves are generally observed through the measurement of undulating elastic ground motion. We report the remote detection of the Earth's electric field variations almost simultaneously with the start of fault rupturing at about 100 km from the fault region using a special electric measurement. The rare but repeated detection indicates that the phenomenon is real. The characteristic time of diffusion is almost instantaneous, that is, less than 1 second to travel 100 km, more than ten times faster than ordinary seismic P wave propagation. We suggest that the measured electric field changes are produced by the electrokinetic effect through increased pore water pressure of the seismic pulse. It is also suggested that the long range propagation is due to the surface wave mode confined near the interface of the different conductivity. The length scale of the finite strength of the electric field is 16 km, 160 km for electric conductivity of 0.01, 0.001, Sm−1, respectively. This phenomenon suggests a new seismic sensing method and a new earthquake early warning system providing more seconds of lead time.

Corner frequencies of P and S waves and models of earthquake sources

1973 ◽  
Vol 63 (6-1) ◽  
pp. 2091-2104 ◽  
Author(s):  
Peter Molnar ◽  
Brian E. Tucker ◽  
James N. Brune
Keyword(s):  
Seismic Waves ◽  
Wave Spectra ◽  
S Wave ◽  
P Waves ◽  
S Waves ◽  
Earthquake Sources ◽  
Dislocation Models ◽  
San Fernando

Abstract P- and S-wave spectra of 144 aftershocks 12≦M≦412 of the February 9, 1971 San Fernando earthquake corroborate previous work showing that the corner frequencies for P waves in general are greater than those for S waves. This observation is consistent not only with models that treat earthquakes as volume sources, but also with physically reasonable dislocation models for which (1) the source is approximately equidimensional, (2) both the duration of slip at each point on the fault and the time for the ruptured area to develop are not long compared with the time for seismic waves to cross the ruptured area, and (3) much of the source radiates essentially simultaneously. There may be other physically reasonable dislocation models compatible with the observations. Savage's calculations indicate that models that involve propagating dislocations on long thin faults are not adequate for describing most moderate and small earthquakes studied.

scholarly journals Development of Earthquake Early Warning System Using ADXL335 Accelerometer

2018 ◽  
Author(s):  
Yoga Priyana ◽  
Folkes E. Laumal ◽  
Emir E. Husni
Keyword(s):  
Early Warning ◽  
Early Warning System ◽  
Seismic Waves ◽  
Human Life ◽  
Warning System ◽  
Earthquake Early Warning ◽  
P Wave ◽  
Earthquake Early Warning System ◽  
Wave Data ◽  
Seismic Sensors

Indonesia is an archipelago located at three earthquake belts. This condition cause an earthquake can occur anytime and threaten human life. A quick and accurate early warning system by using the seismic wave data processing is required so, the number of victims affected by the earthquake can be shortened. Here, ADXL335 accelerometers are used as seismic sensors with an Arduino minimum system. The results show that when the first earthquake’s vibration occurs, P wave data detected by the ADXL335 sensor is successfully buffered, calibrated, transmitted and displayed on the server. When there are errors on the transmission, server will request for retransmission. The alarm of the earthquake early warning system will be activated if there are at least three sensors from different locations successfully transmit P wave data with the same scale. This is needed to prevent fake seismic waves.

Sign in / Sign up

Export Citation Format

Share Document