Seismic Intensity Estimation through Questionnaire Survey and Collapse Rates of Various Building Types in the 2003 Bam, Iran, Earthquake

2007 ◽  
Vol 23 (4) ◽  
pp. 841-865 ◽  
Author(s):  
Tetsuo Tobita ◽  
Masakatsu Miyajima ◽  
Abdolhossein Fallahi ◽  
Reza Alaghebandian ◽  
Mohanmad Reza Ghayamghamian
Keyword(s):  
Questionnaire Survey ◽  
Spectral Ratio ◽  
Peak Frequency ◽  
Seismic Intensity ◽  
Observation Point ◽  
Japan Meteorological Agency ◽  
Epicentral Area ◽  
Reinforced Masonry ◽  
Large Earthquakes ◽  
Microtremor Measurements

Seismic intensity in the epicentral area of the 2003 Bam, Iran earthquake is estimated using a questionnaire survey conducted two months after the earthquake. The estimated average seismic intensity on the Japan Meteorological Agency (JMA) scale is 6.1 (VIII to IX in the MMI scale). The peak frequency of the horizontal-to-vertical spectral ratio derived from microtremor measurements conducted during reconnaissance is also compared with the seismic intensity. Collapse rates for various structure types, such as adobe, unreinforced/reinforced masonry, steel-frame, and reinforced concrete, are obtained by counting the number of demolished buildings within an area of about 50-m radius around an observation point. Results show large differences in collapse rates between unreinforced and reinforced masonry, and suggest the upper limit of seismic intensity that unreinforced masonry can sustain. This fact can be utilized for an initial damage assessment within affected areas after large earthquakes.

Emergency Response to Sediment-Related Disasters Caused by Large Earthquakes in Japan - the Case of the Iwate-Miyagi Nairiku Earthquake in 2008 -

2010 ◽  
Vol 5 (3) ◽  
pp. 315-323 ◽  
Author(s):  
Shin’ya Katsura ◽  
◽  
Yoko Tomita ◽  
Nobutomo Osanai ◽  
Chiaki Inaba ◽  
...  
Keyword(s):  
Emergency Response ◽  
Slope Failure ◽  
Central Government ◽  
Seismic Intensity ◽  
Japan Meteorological Agency ◽  
Mountainous Area ◽  
Slope Failures ◽  
Landslide Dams ◽  
Large Earthquakes ◽  
Emergency Measures

Learning the lessons to be taught by large earthquakes of the past is one key to solving the problems of sediment-related disasters of the future, including slope failures, deep-seated landslides, and landslide dam (natural barriers formed by landslides). Our case subject is the Iwate-Miyagi Nairiku Earthquake in 2008 and the emergency response to disasters of Japan’s central government and other organizations. The earthquake occurred on 14th June 2008 and had a JMA (Japan Meteorological Agency) magnitude of 7.2 and a maximum seismic intensity of 6 upper on the JMA seismic intensity scale. The hypocenter in a mountainous area underlain by thick volcanic ejecta triggered over 3,000 slope failures, deep-seated landslides, and debris flows. The earthquake created 15 landslide dams which were expected to cause serious damage downstream if dams collapsed. Emergency measures taken included channel excavation and pumping of landslide dams. Moreover, emergency checking of potential danger sites immediately after the earthquake found 20 sites requiring emergency measures. The relationship between seismic intensity and sites of slope failure and deep-seated landslide showed that seismic intensity exceeding 5 upper caused such disasters and required emergency checking.

New Japanese Guidelines for the Information of the Prospect of Seismic Activity After Large Earthquakes and Their Applications

2017 ◽  
Vol 12 (6) ◽  
pp. 1109-1116
Author(s):  
Noriko Kamaya ◽  
Kiyoshi Takeda ◽  
Tetsuo Hashimoto ◽  
◽  
Keyword(s):  
Seismic Activity ◽  
Seismic Intensity ◽  
Aftershock Sequence ◽  
Lessons Learned ◽  
Japan Meteorological Agency ◽  
Aftershock Activity ◽  
Research Committee ◽  
New Guidelines ◽  
Large Earthquakes ◽  
Strong Ground

The Kumamoto Prefecture suffered an earthquake of MJMA6.5 on April 14, 2016 at 21:26 (Japan Standard Time). A seismic intensity of 7, on the Japan Meteorological Agency (JMA) seismic intensity scale, was observed, which, by definition, is the maximum possible value. After 18 hours of the earthquake, the JMA issued a prospect for aftershock activity, where the probability of aftershocks with a seismic intensity of 6 Lower (6-) or greater, was 20% within three days following 16:00 JST on April 15, 2016. Ten hours post the issuance of the prospect, at 01:25 on April 16, a larger earthquake of MJMA7.3, with a maximum JMA seismic intensity of 7, occurred in the same region as the MJMA6.5 event, triggering many distant earthquakes. As this seismic occurrence did not follow a mainshock-aftershock sequence, the JMA discontinued the issuance of prospective aftershock activity. With lessons learned from this occurrence sequence, the Earthquake Research Committee of Japan (ERC), including JMA, seismologists and social scientists, have formulated new guidelines for the assessment of successive seismic activity, in order to enhance the understanding of strong ground motions after large earthquakes. The five main points of the guidelines are as follows: (1) alert to a similar strong ground motion, (2) highlighting previous examples of successive large events, (3) consideration of all active source faults, (4) quantitative forecasting of aftershocks a week after the event, and (5) not using the term “aftershock” in information issued by the JMA for disaster prevention. The JMA has commenced the implementation of these new guidelines, effective August 2016.

scholarly journals A geophone-based and low-cost data acquisition and analysis system designed for microtremor measurements

2020 ◽  
Vol 9 (2) ◽  
pp. 365-373
Author(s):  
Ozkan Kafadar
Keyword(s):  
Data Acquisition ◽  
Dynamic Range ◽  
Low Cost ◽  
Noise Analysis ◽  
Internal Noise ◽  
Spectral Ratio ◽  
Peak Frequency ◽  
Integrated System ◽  
Open Hardware ◽  
Microtremor Measurements

Abstract. The commercial data acquisition instruments designed for three-component microtremor measurements are usually very expensive devices. In this paper, a low-cost, computer-aided, and geophone-based system designed to record, monitor, and analyze three-component microtremor data is presented. This proposed system is not a simple data acquisition system. It is also an integrated system developed to interpret the microtremor data using the horizontal-to-vertical spectral ratio (H ∕ V) method without any external software. Therefore, the H ∕ V peak frequency and amplitude can be easily estimated using this system. The proposed system has several features such as a 200 Hz sampling frequency, approximately 72 dB dynamic range, text data format, and data analysis tools. This system consists of a graphical user interface developed by using the .NET Framework 4.5.2 and external hardware that includes signal conditioning circuits, voltage converter circuit, external analog-to-digital converter, and Arduino Uno board. The proposed system uses low-cost vertical and horizontal geophones with a 4.5 Hz natural frequency to measure three-component microtremor data. The developed software undertakes many tasks such as communication between the external hardware and computer, transferring, monitoring, and recording the seismic data to the computer, and interpretation of the recorded data using the Nakamura method. Channel consistency and internal noise measurement tests were performed to demonstrate the accuracy and precision of the proposed system. The proposed system was compared to a commercial triaxial digital seismograph, and satisfactory results were obtained. The developed system is a completely open-source and open-hardware system and can be easily used in academic studies conducted by researchers and university students who are interested in seismic ambient noise analysis.

The Extended Integrated Particle Filter Method (IPFx) as a High-Performance Earthquake Early Warning System

2021 ◽  
Author(s):  
Masumi Yamada ◽  
Koji Tamaribuchi ◽  
Stephen Wu
Keyword(s):  
Particle Filter ◽  
Early Warning ◽  
Seismic Intensity ◽  
Earthquake Early Warning ◽  
Japan Meteorological Agency ◽  
Estimation Accuracy ◽  
Filter Method ◽  
Source Estimation ◽  
Single Station ◽  
Seismic Networks

ABSTRACT An earthquake early warning (EEW) system rapidly analyzes seismic data to report the occurrence of an earthquake before strong shaking is felt at a site. In Japan, the integrated particle filter (IPF) method, a new source-estimation algorithm, was recently incorporated into the EEW system to improve the source-estimation accuracy during active seismicity. The problem of the current IPF method is that it uses the trigger information computed at each station in a specific format as the input and is therefore applicable to only limited seismic networks. This study proposes the extended IPF (IPFx) method to deal with continuous waveforms and merge all Japanese real-time seismic networks into a single framework. The new source determination algorithm processes seismic waveforms in two stages. The first stage (single-station processing) extracts trigger and amplitude information from continuous waveforms. The second stage (network processing) accumulates information from multiple stations and estimates the location and magnitude of ongoing earthquakes based on Bayesian inference. In 10 months of continuous online experiments, the IPFx method showed good performance in detecting earthquakes with maximum seismic intensity ≥3 in the Japan Meteorological Agency (JMA) catalog. By merging multiple seismic networks into a single EEW system, the warning time of the current EEW system can be improved further. The IPFx method provides accurate shaking estimation even at the beginning of event detection and achieves seismic intensity error <0.25  s after detecting an event. This method correctly avoided two major false alarms on 5 January 2018 and 30 July 2020. The IPFx method offers the potential of expanding the JMA IPF method to global seismic networks.

Continuity of Earthquake and Tsunami Monitoring by Japan Meteorological Agency under Critical Conditions

2020 ◽  
Vol 92 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Noriko Kamaya ◽  
Mitsuyuki Hoshiba ◽  
Akio Katsumata ◽  
Keiji Doi
Keyword(s):  
Natural Disasters ◽  
Satellite Communication ◽  
Full Range ◽  
Volcanic Eruptions ◽  
Weather Conditions ◽  
Seismic Intensity ◽  
Japan Meteorological Agency ◽  
Critical Conditions ◽  
Governmental Organization ◽  
Other Information

Abstract The Japan Meteorological Agency (JMA) is a governmental organization that has responsibilities for mitigation of natural disasters. JMA issues warnings and information about natural disasters, in addition to daily weather forecasts. When an earthquake occurs, JMA analyzes seismic data to issue an earthquake early warning and to warn of possible tsunamis when a tsunami is expected to strike coastal areas of Japan. During tsunami warning in effect, JMA monitors tsunami meters and updates the warning. JMA also provides several types of macroseismic information. To fulfill these responsibilities, JMA collects data from 4400 seismic intensity meters, 1800 seismometers, 400 tsunami meters, and 39 strainmeters. Monitoring must be continued even under difficult situations such as times following great earthquakes, volcanic eruptions, severe weather conditions, and pandemics. JMA has dual operations centers located in Tokyo and Osaka. When one loses functionality due to a disaster or infection, the other continues 24/7 operations including warnings and issuing other information. Disastrous situations often cause power and communication failures and insufficient numbers of technical specialists. Following the 2011 Tohoku-oki earthquake, JMA enhanced power and communication capabilities by adding large capacity batteries at each station and satellite communication links. During the coronavirus disease 2019 (COVID-19) pandemic, JMA has taken several measures to prevent technical specialists’ infection to continue the full range of functions for issuing of warnings and conveying needed information.

scholarly journals Intensity Reassessment of the 2017 Pohang Earthquake Mw = 5.4 (South Korea) Using ESI-07 Scale

Geosciences ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 471
Author(s):  
Sambit Prasanajit Naik ◽  
Ohsang Gwon ◽  
Sabina Porfido ◽  
Kiwoong Park ◽  
Kwangmin Jin ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Environmental Effects ◽  
Land Use Planning ◽  
Korean Peninsula ◽  
Agricultural Land ◽  
Seismic Intensity ◽  
Substantial Contribution ◽  
Intensity Scale ◽  
Small Magnitude ◽  
Epicentral Area

The earthquake environmental effects (EEEs) around the epicentral area of the Pohang earthquake (Mw-5.4) that occurred on 15 November 2017 have been collected and classified using the Environmental Seismic Intensity Scale (ESI-07 scale) proposed by the International Union for Quaternary Research (INQUA) focus group. The shallow-focus 15 November Pohang earthquake did not produce any surface rupture, but caused extensive secondary environmental effects and damage to life-line structures. This earthquake was one of the most damaging earthquakes during the instrumental seismic era of the Korean Peninsula. The EEEs included extensive liquefaction, ground cracks, ground settlement, localized rockfall, and variation of the water table. The main objective of this paper was to carry forward a comparative assessment of the Pohang earthquake’s intensity based on traditional macroseismic scales and the ESI-07 scale. With that objective, this study will also make a substantial contribution to any future revision of the ESI-07 scale, which mostly comprises case studies from Europe and South America. The comparison of the ESI-07 scale with traditional intensity scales similar to the intensity scale used by the Korean Meteorological Administration for the epicentral areas showed 1–2-degree differences in intensity. Moreover, the ESI scale provided a clearer picture of the intensity around the epicentral area, which is mostly agricultural land with a lack of urban units or buildings. This study urges the integration of the traditional and ESI-07 scale for such small magnitude earthquakes in the Korean Peninsula as well as around the world in future. This will predict seismic intensity more precisely and hence provide a more-effective seismic hazard estimation, particularly in areas of low seismic activity. The present study will also provide a useful and reliable tool for the seismic hazard assessment of similar earthquakes around the study area and land-use planning at a local scale considering the secondary effects.

Practical Site-Specific Earthquake Early Warning Application

2009 ◽  
Vol 4 (4) ◽  
pp. 579-587 ◽  
Author(s):  
Katsuhisa Kanda ◽  
◽  
Tadashi Nasu ◽  
Masamitsu Miyamura
Keyword(s):  
Early Warning ◽  
Estimation Error ◽  
Seismic Intensity ◽  
Earthquake Early Warning ◽  
P Wave ◽  
Japan Meteorological Agency ◽  
Estimation Accuracy ◽  
Intensity Estimation ◽  
Site Specific ◽  
Wide Range

Real-time hazard mitigation we have developed using earthquake early warning (EEW) (1) enhances seismic intensity estimation accuracy and (2) extends the interval between when an EEW is issued and when strong tremors arrive. We accomplished the first point (enhancing seismic intensity estimation) by reducing estimation error to less than that commonly used based on an attenuation relationship and soil amplification factor by considering source-location and wave propagation path differences based on site-specific empiricism. We accomplished the second point (shortening the time between warnings and when tremors arrive) using a high-speed, reliable communication network for receiving EEW information from the Japan Meteorological Agency (JMA) and quickly transmitting warning signals to users. In areas close to quake epicenters, however, warnings may not arrive before the arrival of strong ground motions. The on-site warning system we developed uses P-wave pickup sensors that detect P-wave arrival at a site and predict seismic intensity of subsequent S-waves. We confirmed the on-site warning prototype’s feasibility based on numerical simulation and observation. We also developed an integration server for combining on-site warnings with JMA information to be applied to earthquakes over a wide range of distances. We installed a practical prototype at a construction site near the 2008 Iwate-Miyagi Inland Earthquake epicenter to measure its aftershocks because JMA EEW information was too late to use against the main shock. We obtained good aftershock results, confirming the prototype’s applicability and accuracy. Integration server combination logic was developed for manufacturing sites requiring highly robust, reliable control.

The 2018 Hokkaido Eastern Iburi Earthquake and its Aftermath

2019 ◽  
Vol 14 (Scientific Communication) ◽  
pp. sc20190112 ◽  
Author(s):  
Hiroaki Takahashi ◽  
Reo Kimura ◽  
◽  
Keyword(s):  
Urban Areas ◽  
Seismic Intensity ◽  
Soil Liquefaction ◽  
Japan Meteorological Agency ◽  
Economic Damage ◽  
Economic Activities ◽  
Crust And Upper Mantle ◽  
Power Outage ◽  
System A ◽  
Upper Mantle Structure

The central Hokkaido, Northern Japan, was struck by an earthquake of M6.7 on September 6, 2018. Its deep hypocenter of 37 km might result of a complex crust and upper mantle structure in Hidaka arc-arc collision system. A seismic intensity of 7 on the Japan Meteorological Agency (JMA) scale was observed at Atsuma Town. About 90% of the casualties were due to the multiple earthquake-induced landslides in Atsuma Town, and a significant number of houses in the urban areas of Sapporo were damaged due to soil liquefaction. Destruction of electric power facilities near the epicenter caused a long-term power outage in approximately 2,950,000 houses in Hokkaido. The widespread blackout caused secondary damages to utilities, civil life, and economic activities in the region. The number of refugees from this incident was approximately 13,111 in maximum, and the economic damage also increased further as a result of the electric blackout. The Hokkaido Prefectural Government immediately applied the Disaster Relief Act on that accrual day. On September 28, 2018, the National Government certified the event as the Designated Disaster of Extreme Severity.

An experimental investigation of factors influencing compressional‐ and shear‐wave velocities and attenuations in tight gas sandstones

Geophysics ◽  
1994 ◽  
Vol 59 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Azra N. Tutuncu ◽  
Augusto L. Podio ◽  
Mukul M. Sharma
Keyword(s):  
Shear Wave ◽  
Correlation Method ◽  
Clay Content ◽  
Spectral Ratio ◽  
Peak Frequency ◽  
Ratio Method ◽  
Tight Gas ◽  
S Waves ◽  
Amplitude Spectra ◽  
Tight Gas Sandstones

Results are presented for compressional and shear velocities and attenuations in fully brine‐saturated tight gas cores with porosities from 3 to 11.9 percent and clay contents from 1 to 38 percent. The influence of porosity, clay content, frequency, and stress on velocities and attenuations were examined using the amplitude spectra of P‐ and S‐waves in the frequency domain. Attenuations of samples were obtained using the spectral ratio method. For a few selected samples the attenuations were also measured using the length correlation method and these results were compared with the spectral ratio results. In tight gas sandstones, the attenuations obtained were 2 to 5 times greater than the attenuation obtained for Berea sandstone. In general, the presence of clay softens the rock grain contacts causing smaller values of compressional ([Formula: see text] and shear ([Formula: see text]) velocities as the clay content increases. However, the [Formula: see text] ratio was found to increase with clay content. Compressional‐and shear‐wave amplitude spectra exhibited a shift in peak frequency toward lower frequencies for samples with higher clay content when compared to clean samples. Velocities and attenuations were found to be frequency dependent, but the positive slope of both compressional and shear attenuations indicate that scattering starts to dominate at the lower frequency end of the ultrasonic measurements. Both [Formula: see text] and [Formula: see text] increased while both compressional and shear attenuations decreased when stress was increased.

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