Rapid Estimation of Magnitudes of Large Damaging Earthquakes in and around Japan Using Dense Seismic Stations in China

2019 ◽  
Vol 109 (6) ◽  
pp. 2545-2555
Author(s):  
Qiang Yao ◽  
Dun Wang ◽  
Lihua Fang ◽  
Jim Mori
Keyword(s):  
Source Parameters ◽  
Tohoku Earthquake ◽  
Disaster Mitigation ◽  
Limiting Factor ◽  
Origin Time ◽  
Seismic Stations ◽  
Emergency Rescue ◽  
Full Waveform ◽  
Shallow Earthquakes ◽  
Large Earthquakes

Abstract The rapid and reliable estimation of the magnitudes of large earthquakes is critical for determining the potential shaking damage and tsunami hazards. The primary challenge to rapidly and accurately estimating the magnitude of large earthquakes is the need to wait for the full waveform in order to calculate the source parameters. We used data of the M≥7.0 shallow earthquakes in Japan from 2008 to 2016, recorded at 10°–60° (regional to teleseismic distances), to establish an operational method to quickly determine their magnitudes. Our results suggest that earthquake magnitudes can be estimated accurately 6–12 min after their origin times. The only time‐limiting factor on our method is the epicentral distances to the seismic stations. For the case of the 2011 great Tohoku earthquake, the magnitude was estimated as M 8.9–9.1 at 6–12 min after the origin time. Resolutions of the results were further investigated by bootstrap and jackknife tests and subarray analysis. Therefore, we propose building a system for determining the magnitude of large earthquakes in and around Japan using real‐time seismic data in China and worldwide. This will assist in disaster mitigation immediately after a damaging earthquake, especially for the purpose of tsunami evacuation and emergency rescue.

scholarly journals Seismicity at the northeast edge of the Mexican Volcanic Belt (MVB) and activation of an undocumented fault: the Peñamiller earthquake sequence of 2010–2011, Querétaro, Mexico

2013 ◽  
Vol 13 (10) ◽  
pp. 2521-2531 ◽  
Author(s):  
A. Clemente-Chavez ◽  
A. Figueroa-Soto ◽  
F. R. Zúñiga ◽  
M. Arroyo ◽  
M. Montiel ◽  
...  
Keyword(s):  
Source Parameters ◽  
Volcanic Belt ◽  
Focal Mechanisms ◽  
Seismogenic Zone ◽  
Normal Faults ◽  
Central Mexico ◽  
Ground Acceleration ◽  
Mexican Volcanic Belt ◽  
Shallow Earthquakes ◽  
Large Earthquakes

Abstract. The town of Peñamiller in the state of Querétaro, Mexico, is located at the northeast border of the seismogenic zone known as the Mexican Volcanic Belt (MVB), which transects the central part of Mexico with an east–west orientation. In the vicinity of this town, a sequence of small earthquakes occurred during the end of 2010 and beginning of 2011. Seismicity in the continental regimen of central Mexico is not too frequent; however, it is known that there are precedents of large earthquakes (Mw magnitude greater than 6.0) occurring in this zone. Three large earthquakes have occurred in the past 100 yr: the 19 November 1912 (MS = 7.0), the 3 January 1920 (MS = 6.4), and the 29 June 1935 (MS = 6.9) earthquakes. Prior to the instrumental period, the earthquake of 11 February 1875, which took place near the city of Guadalajara, caused widespread damage. The purpose of this article is to contribute to the available seismic information of this region. This will help advance our understanding of the tectonic situation of the central Mexico MVB region. Twenty-four shallow earthquakes of the Peñamiller seismic sequence of 2011 were recorded by a temporary accelerograph network installed by the Universidad Autónoma de Querétaro (UAQ). The data were analyzed in order to determine the source locations and to estimate the source parameters. The study was carried out through an inversion process and by spectral analysis. The results show that the largest earthquake occurred on 8 February 2011 at 19:53:48.6 UTC, had a moment magnitude Mw = 3.5, and was located at latitude 21.039° and longitude −99.752°, at a depth of 5.6 km. This location is less than 7 km away in a south-east direction from downtown Peñamiller. The focal mechanisms are mostly normal faults with small lateral components. These focal mechanisms are consistent with the extensional regimen of the southern extension of the Basin and Range (BR) province. The source area of the largest event was estimated to have a radius of 0.5 km, which corresponds to a normal fault with azimuth of 174° and an almost pure dip slip. Peak ground acceleration (PGA) was close to 100 cm s−2 in the horizontal direction. Shallow earthquakes induced by crustal faulting present a potential seismic risk and hazard within the MVB, considering the population growth. Thus, the necessity to enrich seismic information in this zone is very important since the risk at most urban sites in the region might even be greater than that posed by subduction earthquakes.

scholarly journals A Methodology of Workshops to Explore Mutual Assistance Activities for Earthquake Disaster Mitigation

2021 ◽  
Vol 18 (7) ◽  
pp. 3814
Author(s):  
Kazuki Karashima ◽  
Akira Ohgai
Keyword(s):  
Disaster Management ◽  
Quantitative Evaluation ◽  
Management Plan ◽  
Suggested Method ◽  
Disaster Mitigation ◽  
Earthquake Disaster ◽  
Support Tool ◽  
Mutual Assistance ◽  
Large Earthquakes

To minimize the damage caused by large earthquakes, mutual assistance activities between residents and rescue victims (i.e., to support residents who cannot evacuate individually) are important. To enhance these activities, the technologies and methods for creating a Community Disaster Management Plan (CDMP), based on the quantitative evaluation of mutual assistance abilities, are required. However, the lack of a method for it is a key issue. This study aims to develop a methodology of workshops for making CDMPs by using the developed support tool by the authors to explore and promote mutual assistance activities. Through the demonstration and examination of a Community Disaster Management Plan on actual districts, the findings mentioned in this article were obtained. Moreover, the usability of this method is shown. In particular, this method is effective at revising CDMPs, and raising resident awareness on the importance of mutual assistance. The suggested method can also improve the lack of techniques involved in promoting mutual assistance.

Estimating the accuracy of source “parameters”

1967 ◽  
Vol 57 (3) ◽  
pp. 373-379 ◽  
Author(s):  
Helen W. Freedman
Keyword(s):  
Standard Error ◽  
Source Parameters ◽  
Seismic Source ◽  
Origin Time ◽  
Intermediate Depth ◽  
Seismic Source Parameters ◽  
Space And Time

abstract This paper suggests a method for estimating the errors accompanying estimates of seismic source parameters. While the method is a general one, the data here are from 1962 and 1963 and special attention is given to a few regions, such as the Kuriles. The overall standard error of about one-half a degree in each coordinate and four seconds in origin time are broken down and analyzed in terms of magnitude, depth, and location in space and time. The most accurately located earthquakes appear to be those of intermediate depth and magnitude in highly seismic areas. There is some indication that these errors are decreasing with time.

scholarly journals Earthquake source parameters that display the first digit phenomenon

2015 ◽  
Vol 22 (5) ◽  
pp. 625-632
Author(s):  
P. A. Toledo ◽  
S. R. Riquelme ◽  
J. A. Campos
Keyword(s):  
Seismic Moment ◽  
Waiting Times ◽  
Source Parameters ◽  
Tohoku Earthquake ◽  
Earthquake Source ◽  
Coseismic Slip ◽  
Self Organized ◽  
Earthquake Source Parameters ◽  
Self Organized Criticality

Abstract. We study the main parameters of earthquakes from the perspective of the first digit phenomenon: the nonuniform probability of the lower first digit different from 0 compared to the higher ones. We found that source parameters like coseismic slip distributions at the fault and coseismic inland displacements show first digit anomaly. We also found the tsunami runups measured after the earthquake to display the phenomenon. Other parameters found to obey first digit anomaly are related to the aftershocks: we show that seismic moment liberation and seismic waiting times also display an anomaly. We explain this finding by invoking a self-organized criticality framework. We demonstrate that critically organized automata show the first digit signature and we interpret this as a possible explanation of the behavior of the studied parameters of the Tohoku earthquake.

Reassessment of source parameters of ‘major’ southern African earthquakes

2020 ◽  
Vol 123 (1) ◽  
pp. 59-74
Author(s):  
V. Midzi ◽  
T. Pule ◽  
T. Mulabisana ◽  
B. Zulu ◽  
B. Manzunzu
Keyword(s):  
Source Parameters ◽  
Ground Truth ◽  
Velocity Model ◽  
Parametric Data ◽  
Reliable Source ◽  
Hazard And Risk ◽  
Location Algorithm ◽  
Phase Data ◽  
International Seismological Centre ◽  
Large Earthquakes

Abstract Moderate to large earthquakes within an earthquake catalogue contribute significantly to the seismic hazard and risk assessment results of any region. Thus it is prudent to ensure these events have reliable source parameters (epicentres and magnitude). The dataset of events compiled in this study contains a total of 117 instrumentally recorded events of magnitude M ≥5.0, whose parameters were obtained from the Council for Geoscience (CGS) and International Seismological Centre (ISC) databases. The events are mostly located in South Africa with a few in neighbouring countries. Parametric data made up of all available phase data and amplitudes associated with each of the earthquakes were compiled. The availability of these data enabled the earthquake epicentres and magnitude values to be recalculated using the velocity model and the local magnitude relation that are currently being used by the CGS in its analysis of national seismic data. The accuracy of the relocations was determined by producing and analysing three parameters, the azimuthal distribution of seismograph stations (GAP), root-mean-square of travel time residuals (RMS) and epicenter location error data. The analysis of these parameters showed that there was an improvement in the accuracy of the relocated events. Using the ISC location algorithm, iLOC, eight preselected events were further analysed. From this analysis, two earthquakes were found to satisfy the conditions for Ground Truth (GT595%) candidacy whilst four events satisfied the criteria for GT2090% candidacy.

scholarly journals Modeling long-term volcanic deformation at Kusatsu-Shirane and Asama volcanoes, Japan, using the GNSS coordinate time series

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Hiroshi Munekane
Keyword(s):  
Source Parameters ◽  
Tohoku Earthquake ◽  
Oblate Spheroid ◽  
Satellite System ◽  
Deformation Source ◽  
Postseismic Deformation ◽  
Tectonic Deformation ◽  
Linear Inversion ◽  
The 2011 Tohoku Earthquake

AbstractLong-term deformation of Kusatsu-Shirane and Asama volcanoes in central Japan were investigated using Global Navigation Satellite System (GNSS) measurements. Large postseismic deformation caused by the 2011 Tohoku earthquake—which obscures the long-term volcanic deformation—was effectively removed by approximating the postseismic and other recent tectonic deformation in terms of quadrature of the geographical eastings/northings. Subsequently, deformation source parameters were estimated by the Markov Chain Monte Carlo (MCMC) method and linear inversion, employing an analytical model that calculates the deformation from an arbitrary oriented prolate/oblate spheroid. The deformation source of Kusatsu-Shirane volcano was found to be a sill-like oblate spheroid located a few kilometers northwest of the Yugama crater at a depth of approximately 4 $$\text {km}$$ km , while that of Asama was also estimated to be a sill-like oblate spheroid beneath the western flank of the edifice at a depth of approximately 12 $$\text {km}$$ km , along with the previously reported shallow east–west striking dike at a depth of approximately 1 $$\text {km}$$ km . It was revealed that (1) volume changes of the Kusatsu-Shirane deformation source and the shallow deformation source of Asama were correlated with the volcanic activities of the corresponding volcanoes, and (2) the Asama deep source has been steadily losing volume, which may indicate that the volcano will experience fewer eruptions in the near future.

Characteristics of Rainfall- Groundwater Level Response in Taipei City, Taiwan

2021 ◽  
Author(s):  
Shih-Kai Chen ◽  
Yuan-Jie Lin ◽  
Yuan-Yu Lee
Keyword(s):  
Climate Change ◽  
Groundwater Level ◽  
Groundwater Table ◽  
Soil Liquefaction ◽  
Mitigation Strategies ◽  
Disaster Mitigation ◽  
Limiting Factor ◽  
Sponge City ◽  
Cumulative Rainfall ◽  
Taipei Basin

<p>The Taipei Basin, Taiwan has been densely populated and highly economically developed in recent decades. Global climate change has led to frequently flooding and drought events in recent years, formulating suitable measures to mitigate climatic disaster has become a crucial issue in this city. The sponge city concept is one of the most important options for disaster mitigation in highly urbanization areas. However, the city is also potentially threatened by soil liquefaction due to its sedimentary geology and increasing groundwater level. High groundwater level might be a key limiting factor in the promotion of sponge city. The aim of this study was to understand the relationship between rainfall and groundwater level and the impacts of cumulative rainfall, depth to groundwater table, and impervious pavement ratio on the rainfall/groundwater level response in study area. The cross-correlation function (CCF) was applied to analyze the correlation between rainfall and groundwater level data obtained from 20 observed wells and nearby rainfall gages during dry and wet seasons from 2012 to 2017. The significance groundwater recharge response can be found in 61% and 37% of the observation wells during the wet and dry seasons, respectively. Compared with the factors such as cumulative rainfall, and depth to groundwater table, the ratio of surface impervious pavement is the primary affecting factor behind the correlation between rainfall and groundwater level response. The analysis results also show the areas with shallow groundwater level, high imperious pavement ratio, and the groundwater level with no significant response to rainfall, are almost overlapped with the middle and high level liquefaction potential areas in this city. Measures such as the application of the sponge city concept to increase infiltration should be carefully reevaluated in this city. The research results can provide a reference for the future development of urban water resources management and disaster mitigation strategies under the challenge of globe climate change.</p>

Accuracy of determination of epicenter and origin time of small-magnitude earthquakes in the Indian subcontinent

1973 ◽  
Vol 63 (6-1) ◽  
pp. 1901-1912
Author(s):  
Harsh K. Gupta ◽  
Dragutin Skoko ◽  
Yasuo Satô
Keyword(s):  
Indian Subcontinent ◽  
Earth Model ◽  
Origin Time ◽  
Small Magnitude ◽  
Seismic Stations ◽  
The North ◽  
South Indian ◽  
The Monte Carlo Method ◽  
Time Determination ◽  
Seismic Networks

Abstract World seismicity maps prepared by plotting epicenters without considering their magnitude and the distribution of seismic stations may not represent true seismicity, since many earthquakes of small magnitude are not reported from regions having poor seismic networks. This situation is particularly noticeable in the Asian parts of the Alpide belt. Using the Monte Carlo method, errors of epicenter location and origin-time determination by the Indian network of seismic stations have been estimated for earthquakes in the Indian subcontinent. A simplified earth model has been used, and the calculations have been carried out for mb values of 5.0, 4.5, and 4.0. The results are compared with similar error estimations for the Romanian region where a better network of seismic stations enables location of all earthquakes of mb ≧ 4.2. This comparison shows that the errors for the central and the south Indian regions are comparable to those of Romania. However, the much larger errors in the north and northeastern regions show the necessity of establishing seismological observatories equipped with sensitive seismographs close to the foothills of the Himalayas.

Ocean-Bottom Strong-Motion Observations in the Nankai Trough by the DONET Real-Time Monitoring System

2018 ◽  
Vol 52 (3) ◽  
pp. 100-108 ◽  
Author(s):  
Takeshi Nakamura ◽  
Narumi Takahashi ◽  
Kensuke Suzuki
Keyword(s):  
Real Time ◽  
Nankai Trough ◽  
Strong Motion ◽  
Deep Ocean ◽  
Disaster Mitigation ◽  
Ocean Bottom ◽  
Source Modeling ◽  
Origin Time ◽  
Subduction Earthquakes ◽  
Sediment Layers

AbstractThe deployment of real-time permanent ocean-bottom seismic and tsunami observatories is significant for disaster mitigation and prevention during the occurrence of large subduction earthquakes near trough areas. On April 1, 2016, a moderate-sized suboceanic earthquake occurred beneath Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET) stations that were recently deployed in deep ocean-bottom areas near the Nankai Trough in southwest Japan. P-waves arrived at the ocean-bottom station within 4 s of the origin time, which was 6 and 13 s earlier than the arrival of P- and S-waves at a land station in the coastal area, respectively; this implies earlier detection of strong motion than at land stations. However, the waveforms are amplified by sediment layers and even contaminated with acceleration offsets at some stations, which would lead to overestimations during source investigations. Such amplification and offset did not occur at a borehole station connected to DONET. The amplifications caused by the sediment layers and the offset were found to have a considerable spatial variation, not only between the DONET stations and land and borehole stations but also among the DONET stations, implying that the amplitude evaluation could be unstable. Therefore, procedures for correcting or suppressing the amplification and offset problem are required for conducting waveform analyses, such as magnitude estimations and source modeling, during large subduction earthquakes.

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