Earthquake Area Research Articles

Assessing Earthquake Forecasting Performance Based on Annual Mobile Geomagnetic Observations in Southwest China

There have been reports about anomalies in mobile geomagnetic data before earthquakes; however, whether it can be used as an indicator for identifying potential earthquake areas was not be explored. In this study, we propose two parameters for earthquake forecasting based on annual mobile geomagnetic observation data. The spatial horizontal and three components’ changes are calculated in each year and then used to forecast moderate–large earthquakes (M ≥ 5.0) in southwest China in the subsequent period. It is found that earthquakes are more likely to occur in low H- or F-value regions. We statistically assess their forecasting performance by using Molchan’s error diagram, and the results indicate that there is considerable precursory information in the spatial H and F values. It is concluded that mobile geomagnetic observations might be useful in middle-term earthquake forecasts in the study area. We discuss the physical mechanisms of H and F values to explain their reasonability. The methodology proposed in this study could be helpful in finding out the optimal solution for annual mobile geomagnetic measurements for middle-term earthquake forecasting.

Permanent displacement estimation method based on variational mode decomposition

In the near-field area of strong earthquakes, the information recorded by a strong seismometer includes ground motion information and complex low-frequency noise. This noise results in the presence of an “extra” acceleration component in the record that is independent of ground motion, and these components are integrated into the velocity and displacement time history to cause offset. In order to solve this problem, this paper adopts a baseline correction method based on variational mode decomposition (VMD), which decomposes seismic signals into modal functions of different frequencies and then extracts the low-frequency modal functions. It is worth noting that these low-frequency modal function components contain linear trend terms, a property that allows us to perform baseline corrections efficiently. The results show that the permanent displacement obtained by this method is in good agreement with the coseismic displacement observed by GPS stations nearby. This method provides an efficient approach for estimation permanent displacement which helps revealing the focal mechanism of an earthquake.

Questioning whether there was a short-term interaction between the 6 February 2023 earthquakes and air quality parameters in Türkiye

On 6 February 2023, Türkiye was hit by two earthquakes with 7.5 (Eq2) and 7.8 (Eq1) magnitudes. In this study, the hourly ground-level air pollutant concentrations measured in the earthquake areas were examined in detail. In addition, the remote sensing retrievals of CO, NO2, SO2 and CH4 from TROPOMI instrument were also processed and investigated. The hourly mean PM2.5 and CO increased at four stations close to the epicentre several hours prior to the earthquake. The abrupt increase in CO is likely, but PM2.5 is probably related to the degassing activities in the faults. At the day of the earthquake, a significant TROPOMI NO2 increase and a different spatial distribution over the region are observed. This increase coincides with the Eq2 (20 min prior) and a distinctive spatial distribution was observed on that day, indicating this signal can be associated with the earthquake or another process affected by the earthquake. On the other hand, TROPOMI CO indicated a significantly different pattern from NO2 with lowest levels around or prior to the earthquakes, and increased levels afterwards. Limited data from TROPOMI was available for CH4 and SO2 due to meteorological conditions and data quality over the region to draw any conclusive findings. According to the results, it may be helpful to perform special Earth-based observations of NO2, CO and counts of nanoparticles in the ground-based atmosphere near fault lines in seismically active belts. In addition, anomalies can also be monitored via available satellite retrievals, especially in regions with active fault lines.

The Large (<i>M</i> ≥ 6.0) Earthquakes Seismic Precursors in the Junction Zone of the Kuril-Kamchatka and Aleutian Island Arcs

The article describes the behavior of the series of seismic precursors before the activation of 2016‒2019 in an area with a tectonically complex geodynamic environment at the boundaries of the Pacific, North American, and Eurasian lithospheric plates. In order to clarify the location of possible focal areas of future strong earthquakes, a comprehensive approach to the application of allocated precursors was considered: quiescence by parameters RTL and Z-function, variations of the slope of the recurrence graph γ and areas of seismic ruptures dS. For the first time, in relation to Kamchatka, for anomalies to parameter dS, interpreted as seismic activations, the presence of a predictive component before the onset of foreshock activation is shown by the example of an increase in its values before the events that are the strongest for the areas where their focal areas are located: the Near islands Aleutian earthquake with Mw = 7.8 on July 17, 2017 and the Uglovoye Podnyatiye earthquake on December 20, 2018, Мw = 7.3, is demonstrated. The total length of the anomalous region, currently existing and including successive stages of quiescences and foreshock activations is ~900 km, which allows for the possibility of a new strong earthquake with a magnitude exceeding all previously recorded in this area in the junction zone of three lithospheric plates.

Equipment that should be carried by a physician who goes to the earthquake region for emergency assistance during the winter season

In February 2023, two major earthquakes in Turkey affected 10 cities. We wanted to share our experience with the equipment that the first responders in the earthquake area should take with them, apart from medical supplies.The equipment required for patient care is as follows; stethoscope, trauma scissors, flashlight, and headlamp (for power outage situation), safety glasses, scrubs (spare), mask, medical gloves, regularly used drugs (such as decongestants, antibiotics, analgesics), battery, hospital ID, notepad, pen. Personal equipment that is not necessary for patient care is as follows; backpack (with name tag), power bank (to keep in touch), list of basic contact numbers, thermos (for tea and coffee), enough ready-made food to last at least three days (dry foods, energy, and protein bars, instant sachet soup, etc.), water bottle, fork, spoon, glass, garbage bag, whistle, work gloves, ear protection, sleeping bag and mat (tent if possible), personal hygiene items (soap, toothbrush, toothpaste, wet wipes, napkins).

Deprem Bölgesinden Uzaktaki Bir Hastaneye Başvuran Depremzede Hasta Profili: Sakarya İli Örneği

Objective: In our study, the effect of earthquake victims who applied to the emergency department (ED) of our hospital, despite being far from the earthquake area, on the workload and the need for additional precautions will be examined. As a result, it is aimed to create a guiding resource for future disasters.
 Materials and Methods: This study was conducted with patients who applied to Sakarya Training and Research Hospital (STRH) Emergency Department within 15 days after the Kahramanmaraş earthquake and were diagnosed as X34-Earthquake Victims according to ICD-10. 
 Results: The mean age of the 405 patients were 20.98 years, and 52.6% were female. The ratio of the admitted patients to the total number of patients was 1.62%. Regarding resource use, the laboratory was requested for 32.3%, imaging examination for 55.1%, consultation for 19%, and 353 patients were discharged from the emergency department. 
 Conclusions: Although earthquake victims may apply to the emergency departments regardless of the distance after the earthquake, this number is insufficient to require additional measures regarding the workload it creates. However, since this study is the first analysis based on distance, it should be supported by similar studies.

MONTE CARLO SIMULATION OF BARRIER-ISLAND SYSTEMS AND TSUNAMI HAZARDS

Robust characterization of the future tsunami hazard is critically important for resilient planning and engineering in coastal communities prone to tsunami inundation. The hazard from earthquake-generated tsunami waves is not only determined by the earthquake's characteristics and distance to the earthquake area, but also by the geomorphology of the nearshore and onshore areas, which can change over time. In coastal hazard assessments, a changing coastal environment is commonly taken into account by increasing the sea-level to projected values (static). However, sea-level changes and other climate-change impacts influence the entire coastal system causing morphological change (dynamic). Here, we present the modeling framework and results initially published in Weiss et al. (2022), which employs within a Monte Carlo framework the barrier island-marsh, lagoon- marsh evolution model of Lorenzo-Trueba and Mariotti (2017) and the tsunami model Geoclaw (e.g., LeVeque et al. 2011). We compare the runup of the same suite of earthquake-generated tsunamis to a barrier system for statically adjusted and dynamically adjusted sea level and bathymetry over the period from 2000 to 2100. We employ Representative Concentration Pathways 2.6 and 8.5 without and with treatment of Antarctic ice-sheet processes (e.g., Kopp et al. 2017) as different sea-level projections.

Mechanically Coupled Areas on the Plate Interface in the Kanto Region, Central Japan, Generating Great Earthquakes and Slow-Slip Events

ABSTRACT We detected the mechanically coupled areas, or high stress rate patches, on the plate interface in the Kanto region, central Japan, by analyzing the Global Navigation Satellite Systems data. The estimated patches correspond well with the focal areas of past great earthquakes and slow-slip events (Mw∼6.5) occurring every ∼5 yr. Using one of the estimated patches, we created a model of a slow-slip event as a stress release with a recurrence interval of 5 yr. This synthetic can reproduce observed features of the slow-slip events such as the slip distribution and the magnitude. We use the strain-energy magnitude Mw0 defined by the minimum strain-energy release to quantify the magnitude. This is useful to compare slow-slip events with ordinary earthquakes in terms of the strain energy release, whereas the moment magnitude does not represent the difference of the energy release in this case. The strain-energy magnitude of the slow-slip event was Mw0 4.9, which was considerably smaller than the moment magnitude, because the smaller stress drop of the slow-slip event results in a smaller strain-energy release. Furthermore, by assuming that stress has accumulated at the other patches corresponding to the source region of past earthquakes since the occurrence of the last earthquakes, we obtain a model of the stress accumulation in 2023. We then create various rupture scenarios of great earthquakes as combinations of ruptures of the different patches. When two or three of the patches release the accumulated stress simultaneously, an interplate earthquake with Mw≥7.8 can occur in the Kanto region.

Analisis Struktur Beton Bertulang Tahan Gempa Untuk Berbagai Variasi Tinggi Bangunan

Indonesia is a country prone to earthquakes because it is located at the confluence of the Pacific and Trans-Asiatic Circum. Padang is included in the 5-6 earthquake area (KDS E & F), which is an area that has the potential for an earthquake accompanied by the possibility of a tsunami., comfortable and safe against the dangers of an earthquake or tsunami. The most influential factor in the planning of high-rise building structures is the strength of the building structure itself, where this factor is closely related to the safety and resilience of the building in holding and accommodating the loads acting on the structure. Instability in the structure is a basic thing that must be avoided and considered for various types of building heights. An unstable structure when subjected to loads causes the structure to experience a greater deformation than a stable structure. One way that can be done to make the structure more stable is to combine the structure with Shear Walls. Shear wall systems can be used to withstand vertical forces such as gravity loads and horizontal/lateral forces such as earthquake and tsunami loads, thereby preventing excessive swaying of the structure. The use of shear walls is also intended so that when an earthquake and tsunami occurs, the lateral forces that affect the structure are not only resisted by the beam and column elements in the structure but are also resisted by the shear wall system. because the placement of the shear walls that are not appropriate causes the shear forces that occur in the columns and beams to be greater. The research object is multi-storey reinforced concrete buildings with variations in height of 5, 7, 10, 15 and 20 floors. Buildings 5, 7 and 10 floors are designed with an open frame system, while buildings with floors 7, 10, 15 and 20 are designed with a double system, namely open portals and shear walls as lateral load resisters. Open portals use a Special Moment Resisting Frame System (SRPMK) design, while shear walls use a Special Structural Wall System (SDSK) design. The calculated structural loads are dead loads, live loads, superimposed dead loads and earthquake loads. Building location in the city of Padang with moderate soil conditions. The strength and stiffness of structures with shear walls are higher than those without shear walls

Seismic response of high-speed railway system under actions of ground motions from deterministic physics-based simulation

In order to investigate the response of a high-speed railway bridge under seismic excitations in the near-fault area, a deterministic physics-based method is used to construct the ground motion field in the near-fault area of a scenario earthquake. A finite element model of an assumed high-speed railway system is established, which consists of a finite length CRTS III ballastless track laid on a 15-span simply-supported girder bridge. The simulated ground motions and a group of three-component as-recorded accelerograms are used to provide non-uniform and uniform excitations at bridge piers, respectively. The seismic response of the rail-track-bridge system is calculated, and the effects of using different types of seismic excitations for the seismic analysis of the high-speed railway bridge in the near-fault area are analyzed. The results show that two end piers of a multi-span simply supported girder bridge could encounter remarkably different excitations in terms of waveform and frequency content for different bridge alignments in the near-fault area. The vertical response of the railway bridge system is more sensitive to the pattern of the excitation than the longitudinal response. Considering the spatial difference of ground motions among piers could increase the difference of the rail vertical displacement between the beam joint and mid-point of span, forming a remarkable periodic vertical irregularity of the rail. Using non-uniform excitation could lead to a reduction in DPeak and APeak which is most significant for DPeak in the vertical direction.

Research on irregular plane mid story isolation structures in castor earthquake prone areas considering SSI effect

The rock composition of karst area is mainly limestone, which is easy to be eroded and dissolved by water, forming a complex and fragile tectonics. Under the action of earthquake, the instability of stratum is aggravated. The mid story isolation structure is a new type of isolation structure developed from the basic isolation structure, and irregular mid story isolation buildings are highly susceptible to adverse seismic conditions. Previous studies have mostly adopted the assumption of rigid foundations, neglecting the influence of soil on irregular structures. In order to study the seismic response of isolated structures in irregular planes in karst earthquake prone areas considering soil structure interaction, a finite element model of isolated structures in irregular planes considering soil component interaction was established, and the seismic response of the structure under rigid foundation was calculated. Soft and hard soil foundations were studied, and compared with structures without considering SSI effect. Research shows that when considering the SSI effect, the seismic response of the structure increases and the damage to the structure intensifies; When considering SSI, the seismic response of soft soil is greater than that of hard soil, and the softer the soil, the more obvious it becomes; After considering the SSI effect, the torsional effect caused by the irregularity of the plane increases; The design of building structures should fully consider the adverse effects of soil layers on the seismic response of structures under plane interlayer seismic irregularities. In the design of building structures, it is necessary to fully consider the adverse effects of irregular planes on the seismic response of the structure. This consideration is particularly important in the design of soft soil high-rise buildings in karst earthquake areas to prevent unsafe designs and consider the SSI effect in actual seismic resistance.

Evaluation of rocking seismic isolation performance of railway tall piers with different energy dissipation devices

Conventional pier top isolation measures cannot reduce the inertial force produced by railway gravity tall piers. This may damage the pier column and pile foundation during strong earthquakes. As an effective pier bottom seismic isolation structure, rocking piers have broad application prospects in railway tall pier bridges. This paper considers five energy dissipation devices (EDDs) to constrain the bottom of a free rocking pier (F-RP), namely buckling restrained braces (BRBs), yielding steel cables (YSCs), self-centering buckling restrained braces (SC-BRBs), superelastic shape memory alloy wires (SMAs), and viscous dampers (VDs). In particular, an additional “locking” structure is proposed to prevent excessive rocking of the piers and protect the EDDs. Parameter design methods are proposed for damage control and residual deformation control of piers. Nonlinear static and dynamic analyses are performed. The results show that the fixed base piers based on the ductility design suffered severe damage during strong earthquakes. The longitudinal rebar strain ratio is recommended as the damage index for the rocking pier due to large axial force fluctuations. Based on the design method proposed in this paper, the additional EDD constraints make the pier's expected damage level controllable and improve the post-earthquake predictability of the railway pier. BRBs and VDs are unfavorable to pier bottom shear forces. YSCs may produce irrecoverable residual deformation, while BRBs may have significant residual stresses. SC-BRBs and SMAs require no post-earthquake repair. SC-BRBs have more potential for application in rocking piers in high-intensity earthquake areas.

Seismic Performance of Precast Concrete Column-to-Column Joint Using the Steel Plate Hoop and Bolts Connection

The traditional precast concrete column-to-column connections are widely used in the prefabricated concrete frame structures in China. However, many studies on the column-to-column joints have demonstrated their complex forms and poor construction efficiency. To overcome these shortcomings, a new type column–column connection with steel plate hoop and bolts was designed and proposed. In order to reveal the seismic performance of this new type connection, four precast concrete columns and two cast-in-situ columns were tested by cyclic lateral loading. They were compared and analyzed from the aspects of test phenomenon, failure mode, load–displacement relationship, strength, and stiffness degradation. The results showed that the prefabricated columns with this new type connection had the same seismic performance as the cast-in-place columns. Additionally, the strain curves of longitudinal reinforcement, stirrups, and steel plate hoops were presented, and the force transmission mode of this novel connection was analyzed. The results indicated that the innovative connection had reliable force transmission mode, which can provide reference for the application of prefabricated frame structure in the earthquake area.

Recurrence and Long-Term Evaluation of Kanto Earthquakes

ABSTRACT The 1923 Taisho Kanto earthquake—an interplate event along the Sagami trough where the Philippine Sea plate subducts beneath the Kanto region—produced ground shaking, crustal deformation, landslides, and tsunamis, and caused the worst earthquake disaster in Japan. Based on seismological and geodetic data, many fault models have been proposed, extending ∼100 km from the epicenter, with a moment magnitude (Mw) of 7.8–8.2, and large slips of ∼8 m located near the epicenter and beneath the Miura Peninsula. The penultimate 1703 Genroku Kanto earthquake produced similar macroseismic effects around Sagami Bay and the Miura Peninsula, but larger coastal uplift and tsunami in the Boso Peninsula. The proposed fault models extend off the Boso Peninsula with Mw of 8.1–8.5. In 2004, the Earthquake Research Committee (ERC) classified the Kanto earthquakes as “Taisho type” and “Genroku type” with recurrence intervals of 200–400 yr and 2300 yr, respectively. In 2014, the ERC revised the long-term evaluation to a recurrence interval of 180–590 yr and a 30 yr probability of 0%–5% based on the Brownian passage time model. With the Cabinet Office, the ERC considered the source area of the maximum possible earthquake of Mw 8.6–8.7. The recent historiographical and paleoseismological studies have identified other candidates for the past Kanto earthquakes in 1495, 1433, 1293, and 878. Various combinations of these candidates give a mean recurrence interval of 210–315 yr, an aperiodicity parameter of 0.04–0.76, and a 30 yr probability of 0.0%–19%. The Cabinet Office has calculated the seismic intensity and tsunami heights of various types of Kanto earthquakes. National and local governments estimate the damage from these hazards. For the Tokyo metropolitan area, the estimated damage and occurrence probability are more significant for M ∼7 earthquakes with various types and depths, and most mitigation efforts are directed at such events.

Shaking table test and cumulative deformation evaluation analysis of a tunnel across the hauling sliding surface

AbstractTo explore the cumulative deformation effect of the dynamic response of a tunnel crossing the hauling sliding surface under earthquakes, the shaking table test was conducted in this study. Combined with the numerical calculations, this study proposed magnification of the Arias intensity (MIa) to characterize the overall local deformation damage of the tunnel lining in terms of the deformation characteristics, frequency domain, and energy. Using the time‐domain analysis method, the plastic effect coefficient (PEC) was proposed to characterize the degree of plastic deformation, and the applicability of the seismic cumulative failure effect (SCFE) was discussed. The results show that the low‐frequency component (f1 and f2 ≤ 10 Hz) and the high‐frequency component (f3 and f4 > 10 Hz) acceleration mainly cause global and local deformation of the tunnel lining. The local deformation caused by the high‐frequency wave has an important effect on the seismic damage of the lining. The physical meaning of PEC is more clearly defined than that of the residual strain, and the SCFE of the tunnel lining can also be defined. The SCFE of the tunnel lining includes the elastic deformation effect stage (<0.15g), the elastic–plastic deformation effect stage (0.15g–0.30g), and the plastic deformation effect stage (0.30g–0.40g). This study can provide valuable theoretical and technical support for the construction of traffic tunnels in high‐intensity earthquake areas.

Recurrence intervals for M > 7 Miyagi-ken-Oki earthquakes during an M ~ 9 earthquake cycle

The 2011 Tohoku-Oki great earthquake increased the difficulty of evaluating the long-term probability of seismic activity along the Japan Trench because of the unknown impact of the unprecedentedly large slip. In this study, the long-term activity of “Miyagi-ken-Oki earthquakes”, an M > 7 earthquake sequence off Miyagi Prefecture, located at the edge of the source area of the Tohoku-Oki earthquake was simulated. We conducted numerical simulations of earthquake generation cycles based on the rate- and state-dependent friction law representing the stress accumulation and release process on the plate interface. We also validated the results based on analyses of observational data, including time intervals and afterslip distributions for the previous Miyagi-ken-Oki earthquakes. The simulation results were then compared with repeating-earthquake-derived interplate slip observations over 30 years. The results showed that the spatial and temporal characteristics of aseismic slips on the plate interface near the M > 7 Miyagi-ken-Oki source were qualitatively reproduced. The time interval between the M ~ 9 earthquake and the first M > 7 earthquake is shorter than the average recurrence interval of M > 7 earthquakes during the latter stage of each M ~ 9 earthquake cycle. In contrast, the interval between the first and the second M > 7 earthquakes is the longest in each M ~ 9 earthquake cycle. The time intervals of the M > 7 earthquakes fluctuated in the early stage compared to those in the latter stage of the M ~ 9 earthquake cycle. These characteristics were associated with the extent of the locked and afterslip areas in and around the source. Hence, monitoring the spatio-temporal distribution of the slip rate in and around the source area during the preparation process of earthquakes occurring in the downdip area off Miyagi Prefecture is very important to assess whether the next M > 7 earthquake is approaching. Furthermore, earthquake cycle simulations combined with earthquake and slow slip monitoring can provide meaningful insights for long-term assessments of great interplate earthquakes.

Evolution of hydrocarbon deposits in the South Caspian Basin

Studies of the South Caspian Basin display that the Early Pliocene sediments define mainly the structural characteristic of the section in this area. The Productive Series consists of deposits accumulated during the Pliocene epoch. It is known that within the basin, the major commercial hydrocarbon accumulations are attributed to the Productive Series of the Early Pliocene and concentrated mainly in the Absheron oil and gas province, Baku archipelago and Low Kur oil and gas provinces. Studies of fluid generation are required for correct planning of geological exploration for oil and gas in these areas.
 This research work aimed to study the fluid generation processes in the South Caspian Basin by use of 3D modeling.
 The history of hydrocarbon formation was reconstructed. Fluid generation focuses were studied and the distribution areas of these focuses was clarified. The maturity of the Middle Jurassic and Low Cretaceous sediments and Maikop and Diatom deposits were assessed, the temperature regime of the Maikop and Diatom deposits were analyzed. We also evaluated the hydrocarbon fields’ and mud volcanoes’ relations to the focal areas of small-focused earthquakes.
 In the South Caspian Basin, the Middle Jurassic, Low Cretaceous, Maykop, and Diatom focuses of fluid generation were outlined and their allocation and time-spatial evolution history were researched.
 Evaluation of the maturity of Middle Jurassic and Low Cretaceous sediments, Maykop, and Diatom showed neither oil formed at the peak of oil-gas generation with maturity values Ro=0.8ff0.9 %, nor low-maturity gases of the transition zone even within the fluids of gas-condensate fields, while some oil fields had gases of abnormally high maturity of Ro=2.4ff3.09 %.
 3D modeling of paleogeotemperatures in Maykop and Diatom suites found that a) both in the western and the eastern part of the South Caspian Basin the temperature in the bottom of Maykop increases by 20 ◦C in comparison to the top of the suite; b) in the west of the trough in the middle portion of Diatom at a depth of 8000 m and in the east of the trough at 9000 m, the temperature reaches 120 ◦C.
 In the case of small-focused seismicity caused by fluid-generation processes, the latter at the phase conversions are accompanied by high energy output, decompaction, pressing-out of fluids and matters in pseudo-liquefied state into the permeable areas of the media, thus assisting the development of diapiric structures and mud volcanoes.

Seismic regime and features of geophysical fields in the epicentral area of the Andrey-Tas earthquake (seismotectonic zone of the Chersky Randge, northeast Yakutia)

This paper describes the strong Andrey-Tass earthquake (Mѡ=6.1), which occurred in 2008 on the northeastern flank of the seismotectonic zone of the Chersky Randge in the region of the interaction of the Eurasian and North American lithospheric plates. Geophysical fields were using to elucidate structural and tectonic features of the study area and their relationship with seismicity. Using data from digital maps of magnetic and gravity field anomalies, it was possible to clarify the kinematic parameters of the western end of the Ilin-Tas fault, where the epicenter of the Andrey-Tas earthquake occurred. This fault separates the Indigiro-Zyrian Trough from the Momskii Randge and Andrei Tas Locke elevations and is traced by gradient zones of transition from negative to positive ΔTa and Δg values. The main seismic shock is confining to thickening of Δg isoanomalies, which form a gravitational step, within which gravity values decrease from south to north. The entire epicentral field with aftershocks covers the western slope of the Andrei Tas Locke. The development of the seismic process during three stages was analyzed: 1963-2007 (before the event), 2008 (the event with aftershocks), 2009-2020 (after the event). We plotted the recurrence of the aftershocks of the Andrei Tas earthquake. Information obtained because of study of Andrei Tas earthquake aftershocks enables us to detail manifestations of local seismic activity.

Characteristics of Regional GPS Crustal Deformation before the 2021 Yunnan Yangbi Ms 6.4 Earthquake and Its Implications for Determining Potential Areas of Future Strong Earthquakes

The 2021 Yangbi Ms 6.4 earthquake in Yunnan, China, occurred in an area where the Global Positioning System (GPS) geodetic observations are particularly intensive. Based on a detailed retrospective analysis of the GPS observations of about 133 stations distributed in the proximately 400 km × 400 km region that contains the area affected by the earthquake., we obtain a high-resolution GPS velocity field and strain rate field and then derive the present-day slip rates of major faults in the region with the commonly used half-space elastic dislocation model and constraints from the GPS velocity field. Furthermore, by calculating the seismic moment accumulation and release and deficit rates in the main fault segments and combining with the distribution characteristics of small earthquakes, we evaluate the regional seismic risk. The results show that (1) there was a localized prominent strain accumulation rate around the seismogenic area of the impending Yangbi Ms 6.4 earthquake, although this was not the only area with a prominent strain rate in the whole region. (2) The seismogenic area of the earthquake was just located where the strain direction was deflected, which, together with the localized outstanding maximum shear strain and dilatation rates, provides us with important hints to determine the potential areas of future strong earthquakes. (3) Of all the seismogenic fault segments with relatively high potentials, judged using the elapsed time of historical earthquakes and effective strain accumulation rate, the middle section of the Weixi–Qiaohou fault has a higher earthquake risk than the southern section, the Midu–Binchuan section of the Chenghai fault has a higher risk than the Yongsheng section and the Jianchuan section of the Jianchuan–Qiaohou–Lijiang–Xiaojinhe fault has a higher risk than the Lijiang section.

Introduction of business continuity plan for small and medium-sized local construction companies and restoration activities in Japan in the event of natural disasters

In recent years, Japan has suffered significant damage due to natural disasters such as major earthquakes and flood Construction companies are expected to play an important role during natural disasters and respond quickly and restore infrastructure. The first author runs a small local construction company in Okayama, Japan. During a flood in 2011 at Okayama, the embankment restoring site turned extremely dangerous for workers. At this juncture, the first author, in the capacity of a company manager, identified the safety and administrative issues, and in 2013, the company began to implement BCP. When there was heavy flooding in Okayama in 2017, they supported the administration in recovery operations based on their BCP. The impact of BCP is to be acknowledged as the emergency operations were safer and timelier. BCP of the company has been continuously improved, and they were invited to join infrastructure recovery activities in the disaster area of Great East Japan Earthquake in 2019. The area is not the usual business region of the company, but 1,000 km away. There is a high requirement for human resources and equipment for emergency and recovery activities immediately after a disaster. Most of the construction companies are small and locally based in Japan, and several resources available at the construction site itself for initial recovery activities. It is desirable to prepare a plan so that the affected companies themselves can respond. The main tasks are the training of personnel to provide guidance and support for BCP, and the development of systems and laws that can actively support activities. By capturing accurate information on resources of local construction companies, their capability and response speed during an emergency can be improved. It is also necessary to create a system to receive support from other companies or organizations in case self-help is difficult or insufficient.