Earthquakes Of Similar Magnitude Research Articles

Instant prediction of earthquake casualties for early rescue planning: A joint Poisson mixed modeling approach

Reasonable and timely prediction of the number of earthquake casualties is crucial to reduce the risk of severe earthquake casualties. Good real-time predictions help government decision makers make informed emergency rescue decision in a timely manner. To provide timely predictions of casualties for an early rescue planning, we only consider factors available to government agencies early on. These factors include earthquake magnitude, aftershocks, population density, depth of epicenter, time of earthquake and location of epicenter. Casualties caused by earthquakes of similar magnitude often vary greatly from region to region; however, the types of death, serious injury and minor injury, associated with each earthquake are highly correlated. Therefore, we consider a joint Poisson mixed model for death, serious injury and minor injury, in which earthquake-specific random effects can help capture the uncertainty between earthquakes and characterize the positive correlation between the three types of casualties. Furthermore, we have applied this method to analyze the casualty data in two very different regions. The first one is Yunnan province which is a region of frequent earthquakes in China, and the other is Indonesia, a country with frequent earthquakes. In both cases, our method provided good estimates for the numbers of death, serious injury and minor injury simultaneously. In addition, the predicted random effects associated with our method not only help identify anomalous earthquake casualties, but also provide a basis for probabilistic prediction of severe casualties.

Characteristics of strong ground motion attenuation in the 2019 Mw 5.8 Changning earthquake, Sichuan, China

A moderate magnitude earthquake with Mw 5.8 occurred on June 17, 2019, in Changning County, Sichuan Province, China, causing 13 deaths, 226 injuries, and serious engineering damage. This earthquake induced heavier damage than earthquakes of similar magnitude. To explain this phenomenon in terms of ground motion characteristics, based on 58 sets of strong ground motions in this earthquake, the peak ground acceleration (PGA), peak ground velocity (PGV), acceleration response spectra (Sa), duration, and Arias intensity are analyzed. The results show that the PGA, PGV, and Sa are larger than the predicted values from some global ground motion models. The between-event residuals reveal that the source effects on the intermediate-period and long-period ground motions are stronger than those on short-period ground motions. Comparison of Arias intensity attenuation with the global models indicates that the energy of ground motions of the Changning earthquake is larger than those of earthquakes with the same magnitude.

Coseismic landslides triggered by the 8th August 2017 Ms 7.0 Jiuzhaigou earthquake (Sichuan, China): factors controlling their spatial distribution and implications for the seismogenic blind fault identification

On 8th August 2017, a magnitude Ms 7.0 earthquake struck the County of Jiuzhaigou, in Sichuan Province, China. It was the third Ms ≥ 7.0 earthquake in the Longmenshan area in the last decade, after the 2008 Ms 8.0 Wenchuan earthquake and the 2013 Ms 7.0 Lushan earthquake. The event did not produce any evident surface rupture but triggered significant mass wasting. Based on a large set of pre- and post-earthquake high-resolution satellite images (SPOT-5, Gaofen-1 and Gaofen-2) as well as on 0.2-m-resolution UAV photographs, a polygon-based interpretation of the coseismic landslides was carried out. In total, 1883 landslides were identified, covering an area of 8.11 km2, with an estimated total volume in the order of 25–30 × 106 m3. The total landslide area was lower than that produced by other earthquakes of similar magnitude with strike-slip motion, possibly because of the limited surface rupture. The spatial distribution of the landslides was correlated statistically to a number of seismic, terrain and geological factors, to evaluate the landslide susceptibility at regional scale and to identify the most typical characteristics of the coseismic failures. The landslides, mainly small-scale rockfalls and rock/debris slides, occurred mostly along two NE-SW-oriented valleys near the epicentre. Comparatively, high landslide density was found at locations where the landform evolves from upper, broad valleys to lower, deep-cut gorges. The spatial distribution of the coseismic landslides did not seem correlated to the location of any known active faults. On the contrary, it revealed that a previously-unknown blind fault segment—which is possibly the north-western extension of the Huya fault—is the plausible seismogenic fault. This finding is consistent with what hypothesised on the basis of field observations and ground displacements.

Earthquakes can be Predicted

The aim of this research is to discover a reliable and scientific precursor that is theoretically able to predict all earthquakes, within specified parameters, within a few days, in this case within two days, of the earthquakes - this is more efficient than having a prediction window of months or years. This method has accurately predicted 14 out of 15 earthquakes within specified parameters of location, magnitude and depth, with no false predictions-this is a success rate of 93%. Deviations in the times for a simple pendulum to complete 30 oscillations were analysed and these deviations were used to make earthquake predictions. This is related to plate motion and changes in ‘g’. The parameters of earthquakes predicted include those that occurred in north-eastern Colombia, of magnitude M 4.0 and higher, and depth 100 km or more. Also included in the predictions are earthquakes of similar magnitude, originating at depths of 25 km and more in Antigua and Barbuda, Montserrat and Guadeloupe. Another parameter is that for an earthquake to be accurately predicted it must not occur within 24 hours of the previous one. These earthquakes were predicted within two days of their occurrences. In addition to predicting earthquakes, the data supports the rebound theory, since deviations in times for 30 oscillations return to zero within a day or two after an earthquake-this allows for calculations of rebound velocities. The data also shows that there is a net transfer of lithospheric matter away from the observation point at St. Augustine, Trinidad. This method can be applied anywhere on earth-it is simple to set up, inexpensive, scientific and reliable.

Tectonic setting and general features of coseismic rupture of the 25 April, 2015 <italic>M</italic><sub>w</sub> 7.8 Gorkha, Nepal earthquake

An earthquake of M w 7.8 occurred on 25 April, 2015 in Nepal Himalaya, with a focal mechanism of low-angle thrust, determined unanimously by multiple research agencies. More than 100 aftershocks occurred thus far, including strong ones with magnitude larger than M s7.0, triggered normal-mechanism swarms hundreds of kilometers northeast of the epicenter in Tibet. The mainshock, located in central Himalayan orogenic belt and within the seismic gap between the ruptured zones of the 1934 Bihar M w~8.1 and 1505 Lo Mustang M w~8.2 earthquakes, is the largest one on the Main Himalaya Thrust since 1950 Assam M w~8.4 earthquake. To help a better understanding of the earthquake, we provide in this paper a review on the tectonic setting and geometry of the Himalayan fault system, large historical earthquakes and their rupture areas, pattern of modern microseismicity, general models of seismic cycle in the Nepal Himalaya, and spatial pattern of surface deformation resulted from interseismic loading and coseismic slip. Combining the overall features of coseismic rupture of the mainshock from teleseismic finite fault solutions, we comment on this earthquake regarding to its relationship with the characteristic (typical topography-building) Himalayan events, the comparison with the 2008 Wenchuan M w 7.9 earthquake of similar magnitude, the general condition for low-angle thrust-type rupture reaching surface, and its implication to regional seismic hazard.

Estimation of the 2010 Mentawai tsunami earthquake rupture process from joint inversion of teleseismic and strong ground motion data

Joint inversion of teleseismic body-wave data and strong ground motion waveforms was applied to determine the rupture process of the 2010 Mentawai earthquake. To obtain stable solutions, smoothing and non-negative constraints were introduced. A total of 33 teleseismic stations and 5 strong ground motion stations supplied data. The teleseismic and strong ground motion data were separately windowed for 150 s and 250 s and band-pass filtered with frequencies of 0.001–1.0 Hz and 0.005–0.5 Hz, respectively. The finite-fault model was established with length and width of 190 km and 70 km, and the initial seismic source parameters were set by referring to centroid moment tensor (CMT) solutions. Joint inversion results indicate that the focal mechanism of this earthquake is thrust fault type, and the strike, dip, and rake angles are generally in accordance with CMT results. The seismic moment was determined as 5.814 × 1020 Nm (Mw7.8) and source duration was about 102 s, which is greater than those of other earthquakes of similar magnitude. The rupture nucleated near the hypocenter and then propagated along the strike direction to the northwest, with a maximum slip of 3.9 m. Large uncertainties regarding the amount of slip retrieved using different inversion methods still exist; however, the conclusion that the majority of slip occurred far from the islands at very shallow depths was found to be robust. The 2010 Mentawai earthquake was categorized as a tsunami earthquake because of the long rupture duration and the generation of a tsunami much larger than was expected for an earthquake of its magnitude.

A seismic story told by turbidites

Sediment deposits off the coast of Washington and Oregon reveal periodic tsunami and earthquakes of similar magnitude to the ones that struck Japan's Tohoku ... Sediment deposits off the coast of Washington and Oregon reveal periodic tsunami and earthquakes of similar magnitude to the ones that struck Japan's Tohoku ...

Gauging the societal impacts of natural disasters using a capability approach

There is a widely acknowledged need for a single composite index that provides a comprehensive picture of the societal impact of disasters. A composite index combines and logically organizes important information policy-makers need to allocate resources for the recovery from natural disasters; it can also inform hazard mitigation strategies. This paper develops a Disaster Impact Index (DII) to gauge the societal impact of disasters on the basis of the changes in individuals' capabilities. The DII can be interpreted as the disaster impact per capita. Capabilities are dimensions of individual well-being and refer to the genuine opportunities individuals have to achieve valuable states and activities (such as being adequately nourished or being mobile). After discussing the steps required to construct the DII, this article computes and compares the DIIs for two earthquakes of similar magnitude in two societies at different levels of development and of two disasters (earthquake and wind storm) in the same society.

The great New Madrid, Missouri (U.S.A.) Earthquake of 1811–1812

The series of earthquakes that occurred along the New Madrid Fault System in 1811 and 1812 probably was as large as any earthquakes that ever occurred in eastern North America. The magnitude of each of the four major shocks exceeded M2 = 8.4, and the effects of these shocks were felt with a Modified Mercalli Intensity V or greater over approximately 2.5 million km2. Because the epicenters were located in a sparsely settled region of the American frontier, there was little loss of life or damage. However, eyewitness accounts of those who lived through the shocks have provided striking accounts of the high levels of ground motion the region experienced. Thus, the historical record gives engineering geologists a good indication of the catastrophic damage that could result if earthquakes of similar magnitude would occur today.

The San Salvador Earthquake of October 10, 1986—Processed Strong Motion Data

Strong-motion records were recovered from nine accelerographs at seven stations of the El Salvador Geotechnical Investigation Center Strong Motion Network following the damaging 5.4 Ms San Salvador earthquake of October 10, 1986. The sites were all within 6 km of the epicenter; peak horizontal accelerations at ground level ranged from 0.32 to 0.72 g. The duration of strong shaking was about 3 seconds at most sites. One 10-story concrete building was instrumented with recorders at the basement, second floor, and roof level. The maximum accelerations recorded at this building were 0.47 g at the basement, 0.69 g at the second floor, and 0.91 g at the roof. Eight of the accelerograms were digitized and processed. A maximum horizontal velocity of 80 cm/s was obtained for a station 4 km from the epicenter. Peak velocity for the other stations ranged from 26 to 75 cm/s. The maximum horizontal displacements ranged from 5 to 18 cm. The San Salvador records and spectra are compared to other close-in observations such as the Station 2 record from the ML 5.6 Parkfield earthquake of 1966. The San Salvador records share many features with the Parkfield record. In general, the peak accelerations recorded at many of the stations are larger than previously recorded values at close-in distances from earthquakes of similar magnitude.

Earthquakes in continental Antarctica

No earthquake had been definitely located in the interior of the Antarctic continent before that in Dronning Maud Land, which occurred on 1982 November 4, and was found by the “search” procedure of the International Seismological Centre. A further earthquake of similar magnitude ( Mb 4.4) has now been located about 200 km inland from the coast of Wilkes Land, near 69°S, 123°E. The second event occurred on 1983 September 20, and was also found by the ISC search procedure, from readings at four Antarctic seismograph stations, and six farther afield. Reflected phases suggest that the focus of this earthquake is in the upper few kilometres of rock beneath the ice cap. Two later earthquakes occurred on 1984 May 19 about 400 km west of the event of 1983 September 20. They had magnitudes ( Mb) of 5.0 and 4.6, and were large enough to be located by the US National Earthquake Information Service.

Two historical North Wales earthquakes — A macroseismic comparison

Two earthquakes of similar magnitude and location, but historically separated by 37 years, are compared using macroseismic data, largely relying on contemporary newspaper reports of felt effects. These are the North Wales earthquakes of 1903 June 19 and 1940 December 12, of magnitude 4.8 and 4.7 M L. The epicentral intensities are also similar: 6 and 5–6 MSK. There are, however, great differences in the amount of data on these two earthquakes. It is found that some of these differences relate to non- seismological factors such as changes in newspapers and historical context, and others to such factors as event time and interests of contemporary investigators. It is concluded that attention to the limitations of data sources is an important component of macroseismic revaluations of historical earthquakes. Despite differences in reporting it is still possible to assess adequately the maeroseismic parameters of these two earthquakes.

Health implications of the Tumaco earthquake, Colombia, 1979

A retrospective study of the effects of the Tumaco earthquake of 1979 shows a smaller number of deaths and injuries than in earthquakes of similar magnitude that have occurred elsewhere, which is probably related to the type of building. Most of the deaths were caused by a tsunami. Proportionally the mortality was higher in the 0 to 4 age group. Among the injured, most of the lesions were minor. Morbidity was higher in the over 45 years age group, and lower among the “under‐fives.” There was an evident need for a simple “disaster medical record card.” Coordination among the different relief agencies could have been better.

Field-seismic investigation of the August 1975 Oroville, California, earthquake sequence

Several thousand aftershocks of the August 1, 1975 Oroville, California, earthquake ( M L = 5.7 ) were recorded by an 8-station field-seismic network. Focal coordinates of 104 of these events were fitted by least-squares to a plane striking N07°W and dipping 59°W; the strike (but not the dip) of this plane is in good agreement with that (N09°W) obtained from a fault-plane solution for a large foreshock 8 sec before the main shock, and it agrees fairly well with the trend (N15°W) of structural lineaments in the vicinity of Lake Oroville. The surface trace of the plane of foci passes through the Oroville Dam, as well as through surface cracking 12 km south of the dam. The main shock occurred 7 years after the filling of Lake Oroville, but only a month after the most rapid filling since 1968. The rate of aftershock occurrence during the first month decayed approximately as 1/t. Event duration was measured for more than 2,000 aftershocks during August and September; average log-duration, taken over samples of 100 events, decreased gradually during this period. Close-in spectra obtained from strong-motion recordings of several of the larger aftershocks have corner frequencies that are quite high compared to other western U.S. earthquakes of similar magnitude. The Oroville earthquakes had several features in common with another Sierra Nevada earthquake sequence, near Truckee, California, in September, 1966.

Seismic design considerations for gravity retaining structures

Major earthquakes have been observed to damage marginal wharf gravity retaining structures or walls throughout the world, and earthquakes of similar magnitude occur quite often in Canada. These earthquakes generally take place in the British Columbia coastal areas, the St. Lawrence Valley, Baffin Island, and the Yukon Territory. Elsewhere, normally designed marginal retaining structures should have adequate factors of safety to withstand anticipated seismic loads. However, in earthquake-prone areas it is recommended that most marginal retaining structures be designed using the seismic coefficient method. While not all aspects of the suggested seismic design procedure are developed, detail is provided on seismic exposure at the site, earth pressures due to earthquake conditions, and recommended factors of safety for short-term conditions. Design aspects of a more specific geotechnical nature (soils investigation, liquefaction, remedial measures, tsunamis, and backfill specifications) are indicated.