Crustal Activity Research Articles

Process Analysis of Toppling Failure on Anti-dip Rock Slopes Under Seismic Load in Southwest China

Due to complex geological structures and strong crustal activity, geological disasters occur frequently in the upper reaches of the Yalong River, Southwest China. Toppling failure on anti-dip rock slopes is a common phenomenon; in particular, after the Wenchuan earthquake in 2008, numerous landslides caused by toppling deformation occurred in reservoir areas, seriously threatening the construction and operation of large-scale water conservancy projects and hydropower projects. Taking three typical toppling slopes in the basin as research objects, the dynamic behaviour, failure evolution, and failure plane location of toppling failure under seismic waves were investigated by shaking table tests and UDEC simulations. The test results indicated that slope angle and stratum dip angle were both inversely proportional to the stability of the slope in the tested ranges. The failure evolution of toppling on anti-dip rock slopes could be divided into four stages: (1) the development stage of tensile cracks in the strata; (2) the formative stage of tensile cracks at the crest of the slope; (3) the formative stage of toppling zones; and (4) the failure stage. Two equations were proposed to reveal the relationships between the surface peak ground acceleration and the horizontal depth of the failure plane and displacement of the slope surface. The propagation and coalescence of discontinuous cross joint in the slope and the entire failure evolution simulated by the UDEC damage model agreed well with the shaking table test results.

The Thermal and Dynamic Process of Core → Mantle → Crust and the Metallogenesis of Guojiadian Mantle Branch in Northwestern Jiaodong

The Jiaodong gold mineral province, with an overall endowment estimated as >3000 t, located at the eastern segment of the North China Craton (NCC), ranks as the greatest source of Au in China. The structural evolution, magmatic activity and metallogenesis during the Mesozoic played important roles in the large scale regional gold, silver and polymetallic mineralization in this area; among them, the intensive activation of fault structures is the most important factor for metallogenesis. This study takes the regional deep faults as main thread to discuss the controlling role of faults in large scale metallogenesis. The Jiaojia fault and Sanshandao faults in the northwest margin of the Guojiadian mantle branch not only are dominant migration channels for hydrothermal fluid but are very important favorable spaces for ore-forming and ore-hosting during the formation of world-class super large gold deposits in this area. The deep metallogenic process can be summarized as involving intensive Earth’s core, mantle and crust activity → magmatism → uplifting of metamorphic complex → detachment of cover rocks → formation of mantle branch → penetration of hydrothermal fluid along deep faults → concentration of metallogenic materials → formation of super large deposits.

Seismological Structures and Crustal Activities at Plate Boundaries:Approach from Active-Source Seismic Survey

Seismological Structures and Crustal Activities at Plate Boundaries:Approach from Active-Source Seismic Survey

Timings of early crustal activity in southern highlands of Mars: Periods of crustal stretching and shortening

Extensional and compressional structures are globally abundant on Mars. Distribution of these structures and their ages constrain the crustal stress state and tectonic evolution of the planet. Here in this paper, we report on our investigation over the distribution of the tectonic structures and timings of the associated stress fields from the Noachis-Sabaea region. Thereafter, we hypothesize possible origins in relation to the internal/external processes through detailed morphostructural mapping. In doing so, we have extracted the absolute model ages of these linear tectonic structures using crater size-frequency distribution measurements, buffered crater counting in particular. The estimated ages indicate that the tectonic structures are younger than the mega impacts events (especially Hellas) and instead they reveal two dominant phases of interior dynamics prevailing on the southern highlands, firstly the extensional phase terminating around 3.8 Ga forming grabens and then compressional phase around 3.5–3.6 Ga producing wrinkle ridges and lobate scarps. These derived absolute model ages of the grabens exhibit the age ca. 100 Ma younger than the previously documented end of the global extensional phase. The following compressional activity corresponds to the peak of global contraction period in Early Hesperian. Therefore, we conclude that the planet wide heat loss mechanism, involving crustal stretching coupled with gravitationally driven relaxation (i.e., lithospheric mobility) resulted in the extensional structures around Late Noachian (around 3.8 Ga). Lately cooling related global contraction generated compressional stress ensuing shortening of the upper crust of the southern highlands at the Early Hesperian period (around 3.5–3.6 Ga).

Using salt tectonic structures as proxies to reveal post-rift crustal tectonics: The example of the Eastern Sardinian margin (Western Tyrrhenian Sea)

Abstract The METYSS project (Messinian Event in the Tyrrhenian from Seismic Study) is based on high-resolution seismic data acquired along the Eastern Sardinian margin, Western Tyrrhenian Sea. The main aim is to study the Messinian Salinity Crisis (MSC) in the Western Tyrrhenian Basin, but we also investigated the thinning processes of the continental crust and the timing of crustal vertical movements across this backarc domain. Our first results shown that rifting ended before the MSC, but that crustal activity persisted long after the end of the rifting. This has been particularly observed on the proximal margin, the East-Sardinia Basin, where the Mobile Unit (MU, mobile Messinian salt) is thin or absent. In this study, we examined the distal margin, the Cornaglia Terrace, where the MU accumulated during the MSC and acted as a decollement, thus potentially decoupling the basement from the sedimentary cover. Our observations provide evidence for lateral flow and gravity gliding of the salt and its brittle sedimentary overburden along local basement slopes generated by the post-MSC tilting of some basement blocks formerly generated during the rifting. We also investigated an intriguing wedge-shaped body of MU located in a narrow N-S half graben bounded to the west by a major, east-dipping, crustal normal fault. Classically, one could think that this salt wedge is related to the syn-tectonics deposition of the MU, but we propose an original scenario, in which the post-rift vertical motion of the major fault has been cushioned by lateral flow of an initially tabular salt layer, leaving the supra-salt series apparently unaffected by the crustal motions of the basement. We tested this scenario by comparing natural data and physical (analogue) modelling data. Our results reveal that salt tectonics provides a powerful tool to understand the deep crustal tectonics of the margin and to constrain the timing of vertical motions in the Western Tyrrhenian Basin, results that can be applied to rifted salt-bearing margins worldwide.

Current Status of Postseismic Deformation Following the 2011 Tohoku-Oki Earthquake

Postseismic deformation following the 2011 Tohoku-Oki earthquake has been observed by the Global Navigation Satellite System (GNSS) Earth Observation Network System (GEONET) and the Seafloor Geodetic Observation (SGO) over the past six and half years. Observed deformation at onshore sites exceeds 140 cm horizontally, there is uplift of 50 cm, and deformation tends eastward. However, offshore sites reveal complex patterns ranging from near-zero deformation in the northern part of Iwate-Oki, to westward in the southern part of Iwate-Oki, Miyagi-Oki, and the northern part of Fukushima-Oki regions, and eastward in the southern part of Fukushima-Oki and Ibaraki-Oki regions, respectively. The vertical deformation pattern is more complex than the horizontal. Offshore sites demonstrate subsidence but a large uplift is observed onshore along the Pacific coast. Subsidence is only observed along the Pacific coast in the northern part of Iwate, where there are variations in uplift or subsidence patterns. Many previous 2011 Tohoku-Oki event studies have used a primary model that considers only the afterslip effect. However, westward displacements observed by the SGO highlight the importance of viscoelastic relaxation, even during short-term deformation. It is thus considered that studies on postseismic deformation following the 2011 Tohoku-Oki earthquake should adopt a combined afterslip and viscoelastic model. Postseismic deformation following this event is estimated to continue for more than a few decades; therefore, assessing this effect is crucial for interpreting crustal deformation in Japan. Information on the status of interplate coupling or slip is also vital when assessing earthquake occurrence probability. The continued observation of postseismic deformation and careful monitoring of temporal and spatial changes in interplate coupling or slip will mitigate hazards from successive large megathrust earthquakes and improve understanding of crustal activity in Japan.

Present-day crustal deformation characteristics of the southeastern Tibetan Plateau and surrounding areas by using GPS analysis

The southeastern Tibetan Plateau and surrounding areas comprise a typical tectonic belt in mainland China, characterized by a complex geological background and intense tectonic activity. We study present-day crustal deformation characteristics of this region based on GPS data for the periods 1999–2007 and 2009–2011. We first analyze the variations in crustal motion and strain rate, and then discuss the 3D crustal motion and local sub-block activities, as well as the correlation between the intensity of crustal activity and the strain rate distribution. Finally, we explain the present-day geodynamic characteristics of the region. Our results indicate that the entire region shows overall clockwise motion with respect to the stable Eurasian Plate. The tectonic boundary belts between this region and the South China Block display significant compressional strain, accompanied by associated extensional strain. Relatively high maximum shear strain and the transition zones of the significant plane strain gradients are also mainly concentrated along the Ganzi–Yushu–Xianshuihe, Anninghe–Zemuhe–Xiaojiang, Lijiang–Xiaojinhe, and Red River faults, as well as the western and southern Yunnan Province. 3D crustal velocities further reflect significant differences in tectonic activity between different structural belts. We conclude that the regions showing higher shear strain and the transition zones of the significant plane strain gradients correspond to the areas with frequent earthquakes. According to the crustal deformation and strain characteristics, we infer that the present-day geodynamic setting of the region is related to the ongoing India–Eurasia collision and the associated resistance of the stable Alashan, Ordos, and South China blocks, resulting in the extrusion of the southeastern Tibetan Plateau crustal material with an overall clockwise flow around the Eastern Himalayas and significant compressional strain along the tectonic boundary belts. Furthermore, notable compressional strain and enhanced sub-block motions occurred around the Longmenshan fault area following the Wenchuan earthquake.

Phreatic eruptions and deformation of Ioto Island (Iwo-jima), Japan, triggered by deep magma injection

On Ioto Island (Iwo-jima), 44 phreatic eruptions have been recorded since 1889, when people began to settle there. Four of these eruptions, after the beginning of continuous observation by seismometers in 1976, were accompanied by intense seismic activity and rapid crustal deformation beforehand. Other eruptions on Ioto were without obvious crustal activities. In this paper, we discuss the mechanisms of phreatic eruptions on Ioto. Regular geodetic surveys and continuous GNSS observations show that Ioto intermittently uplifts at an abnormally high rate. All of the four eruptions accompanied by the precursors took place during intermittent uplifts. The crustal deformation before and after one of these eruptions revealed that a sill-like deformation source in the shallow part of Motoyama rapidly inflated before and deflated after the beginning of the eruption. From the results of a seismic array and a borehole survey, it is estimated that there is a layer of lava at a depth of about 100–200 m, and there is a tuff layer about 200–500 m beneath it. The eruptions accompanied by the precursors probably occurred due to abrupt boiling of hot water in hydrothermal reservoirs in the tuff layer, sealed by the lava layer and triggered by intermittent uplift. For the eruptions without precursors, the hydrothermal systems are weakly sealed by clay or probably occurred on the same principle as a geyser because phreatic eruptions had occurred beforehand and hydrostatic pressure is applied to the hydrothermal reservoirs.

Vertical Gravimeter Array Observations and Their Performance in Groundwater‐Level Monitoring

AbstractThe gravitational effects of the atmosphere and subsurface water are significant obstacles to observing gravity variations on the sub‐μGal (1 μGal = 10 nm/s2) scale. The goal of this study is to detect changes in gravity that are caused by mass redistributions deep underground related to seismological phenomena by reducing environmental gravity effects using multiple gravimeters belowground and aboveground, which we term a “vertical gravimeter array.” Based on an evaluation of the responses to atmospheric effects and rainfall events identified in observations made with individual relative gravimeters, the vertical gravimeter array succeeds in stacking the target signals from deep underground and in reducing errors due to rainfall or free groundwater and atmospheric effects. To enable accurate interpretation, we introduce a physical approach that is based on attraction and loading deformation effects for atmospheric reduction using state‐of‐the‐art gridded weather data products. Changes in the water levels of confined groundwater can be regarded as a signal from deep underground, and a response coefficient of approximately −15 μGal/m was obtained. In addition, the response coefficient of the free groundwater level was determined to be approximately 5 μGal/m. Such array observations are expected to contribute to monitoring crustal activity and hydrological studies.

A reassessment of the anomalous geomagnetic diurnal variation two months prior to the 2011 Tohoku earthquake, Japan (Mw 9.0)

This study reassesses the claim of an anomalous geomagnetic diurnal variation two months prior to and northwest of the eventual epicenter of the 2011 Tohoku earthquake, Japan (Mw 9.0). Instead of discussing the ratios of geomagnetic diurnal variation ranges at observation and reference stations, which previous studies have analyzed, the ranges themselves are examined in the present work. For the reassessment, the technique to identify the range of typical variations is improved, leading to more appropriate values of the geomagnetic diurnal variation range than those obtained by previous studies. The variations that were deemed anomalous by previous authors can be explained by coupling of the ranges of three components of the geomagnetic diurnal variation; this coupling effect was not discussed in previous studies. The cause of the high ratio was a combination of low-amplitude quiet-day diurnal solar variations in the geomagnetic field in winter, day-to-day variations, and a weak magnetic disturbance during the period. It is therefore not strictly correct that the observed variations were anomalous and, as such, they cannot be unambiguously related to seismo-magnetic phenomena due to crustal activity prior to the megathrust earthquake. In addition, due to issues with the statistical treatment of samples in previous studies, a more appropriate statistical discussion of the matter is presented.

FRB 121102: A Starquake-induced Repeater?

Abstract Since its initial discovery, the fast radio burst (FRB) FRB 121102 has been found to be repeating with millisecond-duration pulses. Very recently, 14 new bursts were detected by the Green Bank Telescope during its continuous monitoring observations. In this paper, we show that the burst energy distribution has a power-law form which is very similar to the Gutenberg–Richter law of earthquakes. In addition, the distribution of burst waiting time can be described as a Poissonian or Gaussian distribution, which is consistent with earthquakes, while the aftershock sequence exhibits some local correlations. These findings suggest that the repeating FRB pulses may originate from the starquakes of a pulsar. Noting that the soft gamma-ray repeaters (SGRs) also exhibit such distributions, the FRB could be powered by some starquake mechanisms associated with the SGRs, including the crustal activity of a magnetar or solidification-induced stress of a newborn strangeon star. These conjectures could be tested with more repeating samples.

Generic identification and classification of morphostructures in the Noachis-Sabaea region, southern highlands of Mars

ABSTRACTThe Noachis-Sabaea region in the southern highlands preserves some of the oldest Martian crust. It records deformation by both endogenic and exogenic processes. This deformation includes giant impacts and their impact stresses, which could have resulted in both the reactivation and modification of pre-impact tectonic structures, in addition to impact-generated tectonic structures. There are also widespread extensional and compressional tectonic structures, which were formed due to endogenic processes. We have produced the first detailed morphostructural map of the Noachis-Sabaea region, which details the characteristics and spatial arrangements of structures in the region, forms the basis for making inferences about Noachian-Hesperian crustal activity, and provides information for further studies regarding the reconstruction of the evolutional history of the region.

Lithospheric thermal evolution and dynamic mechanism of destruction of the North China Craton

The dynamic mechanism for destruction of the North China Craton (NCC) has been extensively discussed. Numerical simulation is used in this paper to discuss the effect of mantle upward throughflow (MUT) on the lithospheric heat flux of the NCC. Our results yield a three-stage destruction of the NCC lithosphere as a consequence of MUT variation. (1) In Late Paleozoic, the elevation of MUT, which was probably caused by southward and northward subduction of the paleo-Asian and paleo-Tethyan oceans, respectively, became a prelude to the NCC destruction. The geological consequences include a limited decrease of the lithospheric thickness, an increase of heat flux, and a gradual enhancement of the crustal activity. But the tectonic attribute of the NCC maintained a stable craton. (2) During Late Jurassic-Early Cretaceous, the initial velocity of the MUT became much faster probably in response to subduction of the Pacific Ocean; the conductive heat flux at the base of the NCC lithosphere gradually increased from west to east; and the lithospheric thickness was significantly decreased. During this stage, the heat flux distribution was characterized by zonation and partition, with nearly horizontal layering in the lithosphere and vertical layering in the underlying asthenosphere. Continuous destruction of the NCC lithosphere was associated with the intense tectono-magmatic activity. (3) From Late Cretaceous to Paleogene, the velocity of MUT became slower due to the retreat of the subducting Pacific slab; the conductive heat flux at the base of lithosphere was increased from west to east; the distribution of heat flux was no longer layered. The crust of the western NCC is relatively hotter than the mantle, so-called as a ‘hot crust but cold mantle’ structure. At the eastern NCC, the crust and the mantle characterized by a ‘cold crust but hot mantle.’ The western NCC (e.g., the Ordos Basin) had a tectonically stable crust with low thermal gradients in the lithosphere; whereas the eastern NCC was active with a hot lithosphere. The numerical results show that the MUT is the main driving force for the NCC destruction, whereas the complex interaction of surrounding plates lit a fuse for the lithospheric thinning.

Metabolic activity duration can be effectively predicted from macroclimatic data for biological soil crust habitats across Europe

Biological soil crusts (BSC) perform several important environmental functions such as soil erosion prevention, soil nutrient enrichment through photosynthesis and nitrogen fixation, and are receiving growing interest due to their importance in some changing habitats with soils under degradation risk. Primary producers within BSC (cyanobacteria, lichens, algae and bryophytes) are all poikilohydric and active only when wet, meaning that knowledge of the period of metabolic activity is essential to understand growth and adaptation to environment. Finding links with macroclimatic factors would allow not only prediction of activity but also the effects of any climate change over these communities. Metabolic activity and microclimate of BSC at four sites across Europe with different soils from semi-arid (Almeria, SE Spain) to alpine (Austria) was monitored during one year using a chlorophyll fluorometer. Local climatic data were also recorded. Mean monthly activity of crust within each site were strongly linked irrespective of crust type whilst, using the data from all sites, highly significant linear relationships (mean monthly values) were found for activity with incident light, air temperature and air relative humidity, and a nonlinear response to rainfall saturating at about 40mm per month. Air relative humidity and air temperature were the best predictors of metabolic activity duration. The links observed are all highly significant allowing climate data to be used to model activity and to gain inferences about the effects of climate change over BSC communities, soil structure and fertility. Linear relationships mean that small changes in the environment will not produce massive alterations in activity. BSC also appear to behave as a single functional group, which is helpful when proposing general management policies for soil ecosystems protection.

Crustal strain fields in the surrounding areas of the Ordos Block, central China, estimated by the least-squares collocation technique

The Ordos Block and its surrounding areas play a special role in the kinetic pattern of current tectonic deformation in mainland China (East Asia). In order to better understand the recent crustal deformation and geodynamics of this region, we use GPS velocities and employ the least-squares collocation (LSC) technique to estimate the distribution of the crustal strain rate fields. We calculate the principal components of strains, such as the maximum shear strains, the plane strain gradients and the principal axes of strains. The strain fields obtained in this paper can well portray crustal deformation in the region. Our results show that the relatively higher maximum shearing strain rates are mainly distributed over region surrounding the Ordos Block, indicating these periphery areas have intense crustal activities. Indeed, these periphery areas encompass major active tectonic belts (e.g., the western edge of the Qilian Fold System, the northeastern margin of the Tibetan Plateau and the Taihang Mountain) and active grabens (e.g., Yinchuan, Hetao, Shanxi and Weihe Grabens). Significant plane strain gradients concentrated over the periphery areas of the Ordos Block, indicating that these areas have more intense crustal activity and are more prone to earthquakes. The principle strain rates also show the strain rates for the periphery of the Ordos Block are higher than other regions. The highest strain rates are along the southwestern side of the Ordos Block, indicating that the eastward extrusion dynamics from the Tibetan Plateau may still be the main cause of tectonic deformation in this region. The extensional strains are present in most parts of the Yinchuan, Hetao and Shanxi Grabens. Finally, the characteristics of the strain fields predicted by the LSC technique are discussed, and some interesting tectonic deformation information can be found through further comparison with the strain results predicted by other methods The detailed results and findings obtained in this paper, could further help us better understand the recent active deformation and geodynamics in the surrounding areas of the Ordos Block.

Elastic Invariants Observed by Borehole Stress and Strain Meters, and the Reliability of the Instruments

An earthquake cannot be observed near the hypocenter as it occurs at a significant depth underground. Accordingly, an earthquake is observed on the surface of the earth, where signals of the earthquake will be disturbed by artificial noises and other factors. Therefore, it is difficult to detect weak signals, including precursory movements. A possible solution to such problems lies in installing a monitoring instrument in the deep bedrock where S/N ratio is improved much better. Based on such an idea, we have been developing a multicomponent borehole instrument (a comprehensive crustal activity observation instrument) that is capable of observing crustal activity at significant depths for predicting earthquakes. This instrument can be equipped with highly sensitive stress meters, strain meters, tilt meters, seismographs, accelerometers, thermometers, and declinometers, and it is capable of observing multiple components of various types of signals. The stress meters were recently developed and can observe both stress and strain as reported in a previous paper about development of stress meters.

Thermal inactivation kinetics of β-galactosidase during bread baking.

In this study, β-galactosidase was utilized as a model enzyme to investigate the mechanism of enzyme inactivation during bread baking. Thermal inactivation of β-galactosidase was investigated in a wheat flour/water system at varying temperature-moisture content combinations, and in bread during baking at 175 or 205°C. In the wheat flour/water system, the thermostability of β-galactosidase increased with decreased moisture content, and a kinetic model was accurately fitted to the corresponding inactivation data (R2=0.99). Interestingly, the residual enzyme activity in the bread crust (about 30%) was hundredfold higher than that in the crumb (about 0.3%) after baking, despite the higher temperature in the crust throughout baking. This result suggested that the reduced moisture content in the crust increased the thermostability of the enzyme. Subsequently, the kinetic model reasonably predicted the enzyme inactivation in the crumb using the same parameters derived from the wheat flour/water system. However, the model predicted a lower residual enzyme activity in the crust compared with the experimental result, which indicated that the structure of the crust may influence the enzyme inactivation mechanism during baking. The results reported can provide a quantitative understanding of the thermal inactivation kinetics of enzyme during baking, which is essential to better retain enzymatic activity in bakery products supplemented with heat-sensitive enzymes.

Synchronous changes in the seismicity rate and ocean-bottom hydrostatic pressures along the Nankai trough: A possible slow slip event detected by the Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET)

We detected long-term hydrostatic pressure changes at ocean-bottom stations of the Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET) along the Nankai trough, off southwestern Japan. We detected these changes after removing the contributions of ocean mass variations and sensor drift from the records. In addition, we detected a decrease in the background seismicity rate of a nearby earthquake cluster that was synchronous with the hydrostatic pressure changes. We interpreted these observed hydrostatic pressure changes to reflect vertical deformation of the ocean floor of 3–8cm, and we consider the cause of the seafloor crustal deformation to be a slow slip event (SSE) beneath the stations. Because the pressure changes were observed at stations with distances less than 20km to each other, we inferred that the SSE occurred in the shallow part of the sedimentary wedge, such as on a splay fault system. The synchronous observation of an SSE and a seismicity rate change suggests that both were triggered by a change in the regional stress that may be associated with stress accumulation and release processes occurring along the Nankai trough. These data show that continuous and careful monitoring of crustal activities by DONET stations provides an effective way to detect seismic and geodetic signals related to the occurrence of megathrust or other types of large earthquakes.

Central Compact Objects in Kes 79 and RCW 103 as ‘Hidden’ Magnetars with Crustal Activity

AbstractWe propose that observations of ‘hidden’ magnetars in central compact objects can be used to probe crustal activity of neutron stars with large internal magnetic fields. Estimates based on calculations by Perna & Pons, Pons & Rea and Kaminker et al. suggest that central compact objects, which are proposed to be ‘hidden’ magnetars, must demonstrate flux variations on the time scale of months–years. However, the most prominent candidate for the ‘hidden’ magnetars — CXO J1852.6+0040 in Kes 79 — shows constant (within error bars) flux. This can be interpreted by lower variable crustal activity than in typical magnetars. Alternatively, CXO J1852.6+0040 can be in a high state of variable activity during the whole period of observations. Then we consider the source 1E161348 − 5055 in RCW103 as another candidate. Employing a simple 2D-modelling we argue that properties of the source can be explained by the crustal activity of the magnetar type. Thus, this object may be supplemented for the three known candidates for the ‘hidden’ magnetars among central compact objects discussed in literature.

Comparative Study of Global Seismicity on the Hot Engine Belt and the Cooling Seismic Belt—Improvement on Research Ideas of Earthquake Prediction

The study in this paper analyzes and compares the distribution on the global engine active seismic zone and cooling seismic belt basing on the ANSS earthquake catalog from Northern California Earthquake Data Center. An idea of the seismogenesis and earthquake prediction research is achieved by showing the stratigraphic structure in the hot engine belt. The results show that the main engine and its seismic cones are the global seismic activity area, as well as the subject of global geological disaster. Based on the conjecture of other stratum structure, the energy of crustal strong earthquake and volcano activities probably originates from the deep upper mantle. It is suggested that the research on earthquake and volcano prediction should focus on the monitor and analysis on the sub-crustal earthquake activities.