The Relationship between the Damage Rate of High Voltage Electrical Equipment and Instrumental Seismic Intensity

Wenchuan earthquake that occurred in China in 2008 caused severe damage to a large number of electric substations. In this paper, Kriging interpolation method was used to calculate the impact area of the instrumental seismic intensity in Wenchuan earthquake, and to compare the intensities based on strong motion observation against the instrumental seismic intensities at locations where the observation data is available. The instrumental seismic intensities were calculated for the Wenchuan Earthquake at substations in the national power grid with voltage of 110kV or higher in areas of Mianyang, Deyang, Guangyuan and Chengdu. The cumulative Gaussian distribution function was then used to fit the relationship of the curves of the damage probabilities of high-voltage electrical equipment such as transformers, voltage mutual inductors, current mutual inductors, circuit breakers, isolating switches and lightning arrester with their instrumental seismic intensities. The damage probability density distribution curve of high-voltage electrical equipment based on the instrumental seismic intensities was obtained. The results showed that: (1) In the lower seismic intensity region, the mean instrumental seismic intensity was in good agreement with the traditional seismic intensity, but there was noticeable dispersion; in regions of intensity IX and above, the instrumental intensity was lower than the seismic intensity, but there was a lower degree of dispersion. (2) Among high-voltage electrical equipment, the transformers were most vulnerable to damage and they had some damage even under lower instrumental intensity. More damage would be produced when the instrumental intensity reached VIII or above; the second most vulnerable equipment was the circuit breaker, and the damage was most likely to occur when the instrument intensity was IX or above . (3) The damage rate curves of lightning arresters, current mutual inductors, voltage mutual inductors and isolating switches were relatively close to each other and the damage probability was the highest when the instrumental intensity was about X.

Seismology at School in Nepal: a network and program for education and citizen seismology

<p>Nepal, located above the convergent India-Eurasia plate boundary, has repeatedly experienced devastating earthquakes. During the 2015 magnitude 7.8 Gorkha earthquake, an often-reported experience was that people were not aware of the threatening seismic hazard and have insufficient level of preparedness. An important source of the problem is that earthquake-related topics are not part of the school curriculum. Earthquake education reaching a broad group of the population early in their lives is therefore strongly needed.</p><p>We established an initiative in Nepal to introduce seismology in schools, with focus on education and citizen seismology. We have prepared educational materials adapted to the Nepali school system, which we distributed and also share on our program’s website: . In selected schools, we also installed a low-cost seismometer to record seismicity and to allow learning-by-doing classroom activities. Our approach was very well received and we hope it will help making earthquake-safe communities across Nepal.</p><p>The seismic sensor installed in schools is a Raspberry Shake 1D (RS1D), selected based on performance in laboratory tests and adequacy to field conditions. At a test site in Switzerland we were able to record magnitude 1.0 events up to 50 km distance with a RS1D. In Nepal, 22 such seismometers installed in schools create the Nepal School Seismology Network providing online data openly. The seismometer in each school allows students to be informed of earthquakes, visualize the respective waveforms, and estimate distance and magnitude of the event. For significant local and regional events, we provide record sections and network instrumental intensity maps on our program’s website.</p><p>In 6 months of network operation, more than 194 local and teleseismic earthquakes of M≥4 have been recorded. From a local and a global catalogue, complemented with our own visual identifications, we provide an earthquake wave detectability graph in distance—magnitude space. Based on our observations, we calibrate a new magnitude equation for Nepal, related to the epicentral distance <em>D[km]</em> and to the observed peak ground velocity <em>PGV[µm/s]</em>. The calibration is done to best fit local catalogue magnitudes, and we will present the updated parameters at the conference.</p>

Toward a Unified Near-Field Intensity Map of the 2015 Mw 7.8 Gorkha, Nepal, Earthquake

We develop a unified near-field shaking intensity map for the 25 April 2015 Mw 7.8 Gorkha, Nepal, earthquake by synthesizing intensities derived from macroseismic effects that were determined by independent groups using a variety of approaches. Independent assessments by different groups are generally consistent, with minor differences that are likely due in large part to differences in spatial sampling. Throughout most of the near-field region, European Macroseismic Scale (EMS-98) intensities were generally close to 7 EMS. In the Kathmandu Valley, intensities were somewhat higher (6.5–7.5) along the periphery of the valley and in the adjacent foothills than in the central valley, where they were ≈6. The results are consistent with instrumental intensity values estimated from available data using a published relationship between peak ground acceleration (PGA) and intensity. Using this relationship to convert intensities to PGA, we estimate strong-motion PGA de-amplification factors of ≈0.7 in the central Kathmandu Valley, with amplification of ≈1.6 in adjacent foothills. The results support the conclusion that the Kathmandu Valley experienced a pervasively nonlinear response during the Gorkha main shock.

Study on Instrumental Intensity Using Wenchuan Earthquake Records

This paper invesigates the peak ground acceleration (PGA) and peak ground velocity (PGV) regression equations as well as the PGA or PGV middle values in Chinese seismic intensity scale 2008 (the CSIS 2008), using the Wenchuan earthquake records of China with the full seismic information. Based on the analytical results, the PGA-V method is proposed to assess the instrumental intensity which combines both PGA and PGV. Besides, a problem is raised to further verify and modify the middle values of PGA or PGV for the seismic intensity VI and VII in the CSIS 2008.

Comparative Analysis of Two Methods for Instrumental Intensity Estimations using the Database Accumulated during Recent Large Earthquakes in Japan

A database containing records from nine large earthquakes in Japan, obtained by K-NET and KIK-net strong motion stations, was used for the analysis of two techniques for the estimation of instrumental seismic intensity from accelerograms. The first technique is the standard method for JMA intensity evaluation from filtered three-component accelerograms. The second technique is the so-called FAS-intensity, which was developed for MM and MSK scales and which is based on the correlation between levels of the Fourier Amplitude spectrum (FAS) and observed intensity. The relation between these two types of instrumental intensities ( JMAI and spectral MMI) may be described by linear function for intensities larger than JMAI 3.5–4 and MMI 5.0–5.5, but large discrepancy arises at small intensities. The variation is most probably caused by differences in the spectral content of the ground motions, since the JMAI calculation is sensitive to the spectral amplitude within a narrow frequency band around 0.5 Hz.