Earthquake Of December Research Articles

Global earthquakes in the 2022 second half according to the GS RAS

Information is provided on the seismicity of the Earth at the level of mb≥6.0 in the 2022 second half, as well as on 66 earthquakes felt on the territory of the Russian Federation according to the to the Alert Service of the Geophysical Survey RAS. For the 15 most severe earthquakes, information messages were published within one or two days after their implementation, the parameters of the mechanisms of foci were calculated and given. During the period under review, the strongest earthquake on the globe with MS=7.8 (Mw=7.7) occurred on September 19 in the state of Michoacan, Mexico. The greatest human casualties and material damage were caused by a catastrophic earthquake with MS=5.3 (Mw=5.6), which occurred on November 21 on the island of Java, Indonesia. Because of the earthquake, 318 people were killing and more than 7,700 people were injured. On the territory of Russia, the strongest earthquake was on September 20 with MS=6.0 (Mw=6.1) in the area of the Commander Islands. The earthquake of December 8 with mb=5.6 (Mw=5.5), which occurred on the territory of the Republic of Dagestan, was felt with the greatest intensity of concussions (6 points) in the settlements of Russia. The seismic energy released on the globe for the 2022 second half (9.1⋅1016 J) increased after its minimum over the past 13 years (2010–2022), observed in the 2022 first half (2.76⋅1016 J), however, remained below the average value for 2010–2022 (2.31⋅1017 J).

An explosive component in a December 2020 Milan earthquake suggests outgassing of deeply recycled carbon

Carbon dragged at sub-arc depths and sequestered in the asthenospheric upper mantle during cold subduction is potentially released after millions of years during the breakup of continental plates. However, it is unclear whether these deep-carbon reservoirs can be locally remobilized on shorter-term timescales. Here we reveal the fate of carbon released during cold subduction by analyzing an anomalously deep earthquake in December 2020 in the lithospheric mantle beneath Milan (Italy), above a deep-carbon reservoir previously imaged in the mantle wedge by geophysical methods. We show that the earthquake source moment tensor includes a major explosive component that we ascribe to carbon-rich melt/fluid migration along upper-mantle shear zones and rapid release of about 17,000 tons of carbon dioxide when ascending melts exit the carbonate stability field. Our results underline the importance of carbon-rich melts at active continental margins for emission budgets and suggest their potential episodic contributions to atmospheric carbon dioxide.

The assessment and strengthening proposal of building structure after the Pidie Jaya earthquake in December 2016

A case study of the steel–concrete composite structure in the Pidie Jaya Regency Multipurpose Hall, which experienced substantial permanent lateral deformation due to the effect of an earthquake, is presented in this study. Therefore, it is important to assess the response of the structure to earthquake load and propose strengthening strategies to make the buildings useful again. The purpose was to evaluate the causes of large deformations and the behavior of the structure in resisting earthquake loads. The building structure model used in this study is a space frame with two-column base support conditions, which are fixed and hinged supports, after which a nonlinear time history analysis was conducted. The time history analysis was conducted using five ground motion acceleration data recorded during earthquakes to determine the deformation, and it was found that the large structure’s permanent deformation was due to the small structure stiffness in the direction of the deformation due to the use of only one column row in front of the building. Moreover, hinged support was observed to have caused a greater deformation than fixed support but was found not to be the main cause of large permanent deformation of the structure. The building structure was further strengthened by adding four columns while the oblique columns remained in a sloping condition. Meanwhile, the response spectrum analysis showed the strengthening structure was able to withstand earthquake loads with less deformation than the required standard.

Parameters of the Rupture Planes of the Spitak Focal Zone Constructed by Averaged Aftershock Mechanisms

The focal mechanisms of aftershocks of the focal zone of the Spitak earthquake of December 7, 1988, have been constructed. The method of averaged mechanisms is applied using data from the international seismological center. Along the boundaries of active faults of the study area, four blocks are distinguished with pairs of compressive tension forces different in directions. The prevailing types of movements in the foci of the Spitak earthquake aftershocks are revealed. It is shown that the prevailing uplift type of movement in the aftershock foci changes from the rupture of the Spitak earthquake in the northern and southeastern direction to the predominant shear type. Solutions of the averaged mechanisms for the selected blocks, the parameters of faults, the angles of incidence and strike, and the types of movements are obtained. It is shown that the nodal planes reflect tectonically active faults.

Infrasound signals from earthquakes of December 5, 2014 in the water area of lake Hovsgol, Northern Mongolia

A comprehensive analysis of waveforms of seismic and infrasonic vibrations from the earthquake that occurred on December 5, 2014, in the water area of Lake Hovsgol was performed. The analysis showed that the infrasonic signal recorded at the Tory station (Geophysical Observatory of the Institute of Solar-Terrestrial Physics, Russian Academy of Sciences) was formed by the sources of three generation types: local, secondary, and epicentral. The obtained results allow us to propose the model of epicentral infrasonic signal generation by flexural waves from an elastic ice membrane on the surface of Lake Hovsgol.

Infrasonic Signals from Earthquakes of December 5, 2014, in the Water Area of Lake Hovsgol, Northern Mongolia

Infrasonic Signals from Earthquakes of December 5, 2014, in the Water Area of Lake Hovsgol, Northern Mongolia

Earthquake Monitoring Using Variometric GPS Data Processing

Variometric Approach for Standalone Engine Displacement Analysis (VADASE) is a technique used in seismology purposes using GPS measurements. VADASE is used to determine the small displacement from the earthquake. The VADASE L1 solution is using the klobuchar ionospheric model. In this study VADASE was used in earthquakes with magnitudes> 7 to> 9 righter scales. In the scale of the earthquake category> 9 used Indian Ocean earthquake of December 26, 2016 with the strength of 9.1 SR by using the closest SAMP station and the Japanese Tohoku earthquake of March 11, 2011 with a power of 9.1 SR using 4 different stations namely MIZU, KMSV, TSK2 and Knii . The earthquake category with a scale of> 8 SR is the offshore earthquake Bio Bio, Chile on February 27, 2010 with a power of 8.8 SR using 2 stations namely ANTC and SANT, the Bengkulu Indonesia earthquake on 12 September 2007 with a power of 8.4 SR using the SAMP station, an illaper earthquake, chile September 16 2015 with 8.3 SR using SANT station, and Tres Piscos earthquake Mexico on September 8, 2017 with a power of 8.2 SR using IENG station. Earthquake with a strength of> 7 SR, namely the amberlay-New Zealand earthquake on November 13, 2016 with a strength of 7.8 SR using MRLL and WGTN stations, Puerto quello-chile earthquake on December 25, 2016 with a strength of 7.6 SR using COYQ station, Java sea earthquake -Indonesia on 8 August 2007 with 7.5 SR power using BAKO station and ayula mexico earthquake on 19 september 2017 with 7.1 SR power using INEG station. From the results of VADASE, the farthest distance from the epicenter to the observation station is 1100 km (INEG station) and the closest distance is 95 km (BAKO station). The highest speed is 0.12 m / s after 5 minutes from the earthquake in the earthquake Offshore Bio Bio-Chile 2010 uses the SANT station and the lowest speed is 0.006 m / s after 10 minutes from the earthquake in the 2007 Bengkulu earthquake using the SAMP station. Whereas in the other earthquakes was the 2011 Tohoku earthquake with a speed of 0.06 m / s after 1 minute using MIZU station, the amberley-New Zealand earthquake 2016 with a speed of 0.015 m / s after 1 minute using the MRLI satellite, Puerto quelloearthquake Chile 2016 with a speed of 0.025 m / s after 40 minutes using the COYQ satellite.

Once More about Deep Caucasus Earthquakes

The upper crustal location of the foci of the Spitak earthquake of December 7, 1988, and its aftershocks is proved. It is demonstrated that the seismological network in Armenia and Georgia allowed unequivocal focal depth identification based on the kinematic data. The waveforms of all the Spitak earthquakes are typical of sources in the upper crust. It is noted that up to now, mantle earthquakes in the Caucasus have only been revealed in the Terek–Sunzha depression.

Ring-Shaped Seismicity Structures in the Areas of Sarez and Nurek Water Reservoirs (Tajikistan): Lithosphere Adaptation to Additional Loading

Seismicity characteristics in the areas of Sarez Lake and the Nurek water reservoir are studied. Ring-shaped seismicity structures in two depth ranges (0–33 and 34–70 km) formed prior to the Pamir earthquake of December 7, 2015 (M w = 7.2). Seismicity rings cross each other near the Usoi Dam, which formed after the strong earthquake in 1911 and led to the formation of Sarez Lake, and near the epicenter of the Pamir earthquake. In addition, three out of the four strongest events (М ≥ 6.0) recorded in the Pamir region at depths of more than 70 km since 1950 have occurred near Sarez Lake. An aggregate of the data allows us to conclude that the Pamir earthquake, despite its very large energy, refers to events related to induced seismicity. Ring-shaped seismicity structures in two depth ranges also formed in the Nurek water reservoir area. It is supposed that the formation of ring-shaped structures is related to the self-organization processes of a geological system, which result in the ascent of deep-seated fluids. In this respect, the lithosphere is gradually adapting to the additional load related to the filling of the water reservoir. The difference between Nurek Dam (and many other hydroelectric power stations as well) and Usoi Dam is the permanent vibration in the former case due to water falling from a height of more than 200 m. Such an effect can lead to gradual stress dissipation, resulting in the occurrence of much weaker events when compared to the Pamir earthquake of December 7, 2015, in the areas of artificial water reservoirs.

Contributions of Resilience to Mental Health in Chinese Secondary School Students at Different Disaster Stress Levels

A key feature of positive education is its focus on factors that can help students flourish. In the current study, we examined the role of resilience in promoting optimal mental health of Chinese secondary school students who suffered the 2008 Wenchuan earthquake, China. In the earthquake central region, 518 participants recruited in November 2008 about 6 months and 473 participants recruited 1 year after the earthquake, were assumed to have the highest and mid-level disaster stress levels, respectively. 602 participants from areas unaffected by the earthquake in December 2008 were assumed to have the lowest stress level. Participants' mental health and resilience were assessed by the clinical scales of the Cross-cultural (Chinese) Personality Assessment Inventory for Adolescents and the Resilience Scale for Chinese Adolescents, respectively. Higher stress level participants reported significantly lower resilience and higher mental health problems. Negative correlations between resilience and mental health problems were confirmed across the three groups. Only supportive power resilience showed significant predictions on mental health problems in the two earthquake groups. The implications on mental health counseling and positive education in Chinese secondary school students were discussed.

Increased seismicity in Kansas

Most people, including those who live there, regard Kansas as a seismically quiet place. Until a couple of years ago, hardly anyone I met from Kansas had felt an earthquake that had originated within the state. That all changed about 18 months ago. In the fall of 2013, the state experienced several events, reported by the U. S. Geological Survey (USGS) and Oklahoma Geological Survey (OGS), including a magnitude 4.2 earthquake in December 2013. In 2014, the USGS National Earthquake Information Center reported more than 100 events with epicenters inside Kansas. The largest was a magnitude 4.9 in November 2014.

Andaman-Sumatra island arc: III. Time evolution of seismogenic activation of the arc since the beginning of the 21st century

The spatiotemporal evolution of the intense burst in seismogenesis within the Andaman-Sumatra island arc in 2000–2010 is analyzed. The onset of seismogenic activation was marked by two strong (MS ∼ 7.9, MS ∼ 7.8) quakes that occurred in the lithosphere of the South Sumatra region on June 4, 2000 and by the strongest (MW = 7.3) earthquake of July 25, 2004 that took place in the lower part of the focal zone. These seismic events were the foreshocks of the main episode of seismogenic activation of the island arc—the catastrophic earthquake of December 26, 2004, with its source near the northern coast of Sumatra. The large shocks (MS ∼ 7.7–8.4) that occurred from March 28, 2005 to October 25, 2010 between the source of the Sumatran earthquake and epicentral zone of the foreshocks of June 4, 2000, are the aftershocks of the Sumatran event. The spatiotemporal evolution of seismogenic activation of the Andaman-Sumatra island arc at the beginning of the 21st century is compared to the seismogenic activation of the Kuril-Kamchatka arc in the middle of the 20th century. The positions, geological conditions, and focal parameters of the strongest Sumatran earthquakes of 2000–2010 are determined. The interpretation of the sources relies on the (1) complex analysis of all the manifestations of the earthquakes of 2000–2010 and (2) the established regularities of the occurrence of the earthquakes in the island arcs. The sources of the earthquakes of 2005–2010 are the steep longitudinal (trending along the arc) reverse faults of a backthrust type, which have a bedding depth of about a few dozen kilometers. The reverse-fault sources of the earthquakes of March 28, 2005, September 12, 2007 (11:10 UT), and October 10, 2010 are located in the zone of the Outer Range, and the earthquakes of September 12, 2007 (23:49 UT) fall in the Mentawai Trough. The strike-slip reverse fault, which cuts the island arc, is likely to be the focal mechanism of the earthquake of June 4, 2000. The sources of the events of March 28, 2005 and September 12, 2007 did not coincide with the sources of the historical devastating earthquakes of 1861 and 1833, respectively. The system of seismic sources in the form of a series of subparallel arc-parallel steep reverse faults off the western coast of Sumatra is similar to the system of seismic sources in the Kuril-Kamchatka island arc.

The 2004 Sumatra Earthquake and Tsunami: Lessons Learned in Subduction Zone Science and Emergency Management for the Cascadia Subduction Zone

The 26 December 2004, Mw 9.3 Sumatra earthquake and tsunami was a pivotal turning point in our awareness of the dangers posed by subduction zone earthquakes and tsunamis. This earthquake was the world’s largest in 40 years, and it produced the world’s deadliest tsunami. This earthquake ruptured a subduction zone that has many similarities to the Cascadia Subduction Zone. In this article, I summarize lessons learned from this tragedy, and make comparisons with potential rupture characteristics, slip distribution, deformation patterns, and aftershock patterns for Cascadia using theoretical modeling and interseismic observations. Both subduction zones are approximately 1,100–1,300 km in length. Both have similar convergence rates and represent oblique subduction. Slip along the subduction fault during the 26 December earthquake is estimated at 15–25 m, similar to values estimated for Cascadia. The width of the rupture, ~80–150 km estimated from modeling seismic and geodetic data, is similar to the width of the “locked and transition zone” estimated for Cascadia. Coseismic subsidence of up to 2 m along the Sumatra coast is also similar to that predicted for parts of northern Cascadia, based on paleoseismic evidence. In addition to scientific lessons learned, the 2004 tsunami provided many critical lessons for emergency management and preparedness. As a result of that tragedy, a number of preparedness initiatives are now underway to promote awareness of earthquake and tsunami hazards along the west coast of North America, and plans are underway to develop prototype tsunami and earthquake warning systems along Cascadia. Lessons learned from the great Sumatra earthquake and tsunami tragedy, both through scientific studies and through public education initiatives, will help to reduce losses during future earthquakes in Cascadia and other subduction zones of the world.

海洋観測フロートによって観測された大規模海底地震の震源近傍における音速プロファイルの変化

The Tohoku region Pacific Ocean earthquake that occurred on March 11, 2011, resulted in extensive damage in a vast area ranging from the Tohoku to Kanto. However, at the time of the earthquake, no research vessel was confirmed to be investigating marine life in the seas adjacent to epicenter area, so physical data like water temperature and salinity, as well as ocean sound speed data required for the echo sounder, could not be acquired. Therefore, in this study, we compute the sound speed profile from the Argo system data(water temperature, salinity, pressure) that was being deployed near the area of the epicenter both before and after the earthquake, and attempt to detect the change in the sound speed field. In addition, the Tohoku region Pacific Ocean earthquake and the Sumatra earthquake in December 2004, which were accompanied by a giant tsunami, were also investigated. Results showed that in the main temperature front between the central thermocline and deep-sea isothermal layer, water temperature did not change very much. However, we confirmed the tendency for the underwater sound speed to suddenly increase dramatically after an earthquake.

Some properties of low-frequency seismic noise

The low-frequency seismic noise recorded by the broadband IRIS stations in 1994–2012 is studied in the period range of 40 to 360 s. It is shown that for samples of a few months in length, the power spectra of noise at stations spaced apart a few thousand kilometers and operating in different meteorological and seismotectonic conditions are overall similar, which indicates that the sources of the noise are global. At the same time, the slope of the spectra changes with the increase in the period in the subintervals of 40–90, 120–200, and 200–360 s, which points to the difference of the sources generating the seismic noise. The amplitude of the noise at the stations located a few thousand km apart from the Sumatra earthquake of December 26, 2004, M = 9.2, and from the Tohoku earthquake of March 11, 2011, M = 9.0, increased after these events. This indicates the global character of the aftermath of these seismic catastrophes. After the Kronotskoe earthquake of December 5, 1997, which was weaker (M = 7.9), the noise grew only at the PET station located within 300 km of the epicenter. According to the records at the PET station, this earthquake was preceded by the increased noise level observed in 1994–1997. After 1999, the seismic noise declined and remained low up to the end of the studied interval with a duration of 14 years. Our results show that the low-frequency seismic noise generated by the sources in the atmosphere of the Earth is contributed by the processes taking place in the lithosphere.

The Tuva earthquakes of December 27, 2011, M L = 6.7, and February 26, 2012, M L = 6.8, and their aftershocks

The Tuva earthquakes of December 27, 2011, M L = 6.7, and February 26, 2012, M L = 6.8, and their aftershocks

Main challenges on community-based approaches in earthquake risk reduction: Case study of Tehran, Iran

During the recent years and especially after the destructive Bam Earthquake in December 2003, the importance of public awareness and community-based activities for disaster risk mitigation and management have been revealed more clearly to Iran׳s authorities. In this regard, several national policies have been prepared and some activities were carried out by governmental and non-governmental organizations for improving the public awareness and participation in earthquake risk reduction programs from local to national levels. In this paper, these activities have been partly addressed. In addition, the results of a pilot study carried out in three districts of Tehran are presented and discussed in order to evaluate the current situation of public awareness as well as the willingness of Tehran residents to participate in risk mitigation activities. After providing the necessary training and preparing disaster maps, the results of this study showed that communities found novel ways to improve their capabilities for reducing the impacts of potential earthquakes and responding to their effects. Understanding the physical and technical shortages of community-based organizations in Tehran in the field of disaster preparedness and management was another outcome of this research.

Estimation of the 3-D velocity structure of the Sorachi–Yezo and Oshima Belts in the western part of Hokkaido, Japan

We adopted the seismic tomography technique to refine the three-dimensional velocity structure model of the western part of Hokkaido, Japan. Using the P-wave first arrival data listed by Japan Meteorological Agency from 2002 to 2005, we could estimate a 3-D inhomogeneous velocity structure model with a low velocity at a depth of 14 km beneath Asahikawa. The crustal structure near Sapporo was characterized by lateral velocity change toward the southern seaside. The low-velocity zone near Urakawa, proposed by previous research, was also clarified. In general, the present model showed lower-velocity values for most of the crustal layers in the area concerned. The results of this study were affected by less number of higher magnitude events (M ≥ 0.5) in the central part of the area of interest. However, the perturbation results for comparatively shallow layers (6–50 km) were good in resolution. It was found that the source region of the Rumoi–Nanbu earthquake of December 14, 2004 was characterized by a low-velocity zone, located between high velocity zones. Such an inhomogeneous crustal structure might play an important role in the relatively high seismic activity in the Rumoi–Nanbu earthquake source region.

Media velocity model and macroseismic effect: The Spitak earthquake of December 7, 1988

Relationship between the intensity of seismic shaking on the surface and the velocity structure of the medium at large depth is studied. The Spitak earthquake of December 7, 1988 is chosen as an object of study. A method to correlate the intensity of shaking in the localities to the geophysical parameters specified in the nodes of regular spatial grid is proposed. Formalized definition of anomalous intensity is suggested; it takes into account the distribution of distances from the localities with given intensity degrees to the hypocenter or to the nearest segment of the surface fault. It is found that the seismic wave velocities at a depth of 1 km are higher (up to 0.2–0.6 km/s) under the localities with anomalously high intensity. No any certain regularity is found in deeper layers.

Aftershock sequences of two great Sumatran earthquakes of 2004 and 2005 and simulation of the minor tsunami generated on September 12, 2007 in the Indian Ocean and its effect

We present the seismic energy, strain energy, frequency–magnitude relation (b-value) and decay rate of aftershocks (p-value) for the aftershock sequences of the Andaman–Sumatra earthquakes of December 26, 2004 (M w 9.3) and March 28, 2005 (M w 8.7). The energy released in aftershocks of 2004 and 2005 earthquake was 0.135 and 0.365% of the energy of the respective mainshocks, while the strain release in aftershocks was 39 and 71% for the two earthquakes, respectively. The b-value and p-value indicate normal value of about 1. All these parameters are in normal range and indicate normal stress patterns and mechanical properties of the medium. Only the strain release in aftershocks was considerable. The fourth largest earthquake in this region since 2004 occurred in September 2007 off the southern coast of Island of Sumatra, generating a relatively minor tsunami as indicated by sea level gauges. The maximum wave amplitude as registered by the Padang, tide gauge, north of the earthquake epicenter was about 60 cm. TUNAMI-N2 model was used to investigate ability of the model to capture the minor tsunami and its effect on the eastern Indian Coast. A close comparison of the observed and simulated tsunami generation, propagation and wave height at tide gauge locations showed that the model was able to capture the minor tsunami phases. The directivity map shows that the maximum tsunami energy was in the southwest direction from the strike of the fault. Since the path of the tsunami for Indian coastlines is oblique, there were no impacts along the Indian coastlines except near the coast of epicentral region.