pure and applied geophysics最新文献

The tsunami generated by the 29 July (30 July locally) M_w 8.8 Kamchatka-Kuril earthquake produced significant runup in both the far- and nearfield. Along the southeastern coast of Kamchatka and North Kuril Islands, for a distance of at least 550 km proximal to the rupture, runups reached at least 2–3 m, typically 5–10 m, with maximum runups of 10–16 m over a 100-km stretch of Kamchatka (centered on Vestnik Bay) and also on Paramushir Island. Via a range of methods, we tabulated more than 550 runup (vertical) and inundation (horizontal) tsunami measurements from Shipunsky Peninsula on Kamchatka to Mussel Bay on Onekotan Island. We employed several means of tsunami measurement. The most comprehensive data are from post-tsunami aerial photography along the coast via helicopter, with subsequent application of 2-m Arctic DEM to determine elevations. Instrumental tsunami measurements were made on the islands of Paramushir, Shumshu, Atlasova and Onekotan. Expeditionary studies of the tsunami's effects were also conducted on the coast of Avachinsky Bay near Petropavlovsk-Kamchatsky. Continuous lines of maximum inundation were mapped for many coastal areas based on the aerial survey data. Additional points of runup and inundation can be generated from these lines. Long inundation distances for the 2025 tsunami are usually in cases of tsunami penetration up low river valleys. There are several examples of high tsunami runup up steep coastal slopes and narrow stream valleys, typically 15–18 m with an outlier of 33 m. In cases where that runup was unusually high (relative to other nearby elevations), we label the elevation the tsunami reached “splash” and interpret these as small-scale features representing complex, often high frequency, dynamics of the tsunami that scientists may not always be able to numerically recreate using the data to compare to models.

This paper addresses the controversial open question of tidal triggering seismic activity. Two situations illustrate our methodology, the Fani Maoré volcano seismic catalog (Mayotte) and the seismic catalog of Vrancea area (Romania). We apply the HiCum stacking which accepts irregularly sampled time series, directly applicable to seismic databases. It has been tested on synthetic random catalogs showing its neutrality. For the Fani Maoré volcano, the seismic catalogues are divided in two sub-catalogues corresponding to 6-month periods around the solstices. HiCum is used to evaluate the amplitude and phase of the different tidal components present in the seismic catalogue. Two very interesting signals are present in volcano-tectonic and low-frequency seismic events at P1 and K1 periods. The two waves show a phase opposition between June and December solstices. P1 and K1_S correspond to the main declinational waves of the Sun. The amplitude modulation of the sum of this pair of waves corresponds to the product of a carrier wave at (K1 + P1)/2 frequency i.e. the diurnal period S1, and a beat frequency at (K1-P1)/2, corresponding to the tropical year. The S1 and S2 signals are also very clearly present with identical phases for the two sub-periods. It demonstrates the tidal Solar influence in the triggering of seismic events in the Fani-Maore seismic catalogue. We select the RomPlus catalogue of the National Institute of the Earth Physics, Bucharest to analyse Tidal modulation applied to seismic data in the Vrancea area. The HiCum method is applied, on the sequence of events, into a sliding time window of 365 days shifted by 30 days, to determine the amplitude and the phase of the two main semidiurnal tides M2 and S2. The phase obtained is used to resolve the variations of the Schuster test p_s and the permutation test p_p—values. Our analysis confirms the presence of tidal influences induced by earth tides in intermediate seismic activity through specific characteristics of the variation of the statistical coefficients p_S and p_P near a medium, intermediate or strong earthquake. The analysis in 3D moving windows of the spatial distribution of the statistical coefficient p allowed us to introduce the concept of “statistical tomography of a seismic area using earth tides”.

Annual deformation signals recorded by vault-housed extensometers remain poorly understood despite their prevalence in crustal dynamics research. Many observatories in mainland China report pronounced annual strain variations, yet their physical origin has rarely been quantified. Here this study systematically analyzes data from the Kuancheng Geodynamic Observatory (KGO), North China, to test whether annual air temperature variations drive these signals. Using a half-space thermoelastic model overlain by a thin unconsolidated layer, we show that the observed annual temperature cycle (amplitude 16.8 °C) can generate thermoelastic strains on the order of 10⁻⁷ at 30 m depth. Modeled amplitudes and phases agree closely with observed North–South and East–West strain components, strongly indicating that temperature-induced thermoelastic deformation is the primary source of annual strain at KGO. These findings provide a quantitative framework for interpreting annual signals in China’s extensometer network and highlight the need to separate temperature-driven annual strain variations from potential earthquake precursor signals.

On January 15, 2022 the great volcanic explosion at the Hunga-Tonga–Hunga-Hua’apai Island in the South Pacific sent atmospheric Lamb waves (A_n) around the Earth in all directions. The Lamb wave (A_1) caused clearly observable disturbances on barometers, seismic sensors, and also gravimeters. We show these disturbances on barometers (with a peak-to-peak amplitude of 2.3 hPa) and the superconducting gravimeters (SG) iOSG-023 and OSG-056 at the stations J9 and BFO (57 km to the east), respectively. We subsequently model these disturbances in gravity using very simple physics-based models. It turns out that the inertial accelerations due to ground displacement by the pressure loading are very important in this case as already shown by Imanishi (Earth Planets Space 74:54, 2022 https://doi.org/10.1186/s40623-022-01615-4) for the SG in Matsushiro, Japan. This inertial effect is almost twice as large at J9 than at BFO, while the pressure pulses have about equal amplitudes. This must with high probability be blamed to the higher deformability of the upper layers of the crust at J9 with soft fluvial sediments on the top compared to BFO where granites and gneisses make up the rocks near the surface.

This research investigates how lateral near-surface inhomogeneity affects three-dimensional (3D) electrical resistivity tomography (ERT) in terms of resolution and resolvability for Dipole–Dipole, Wenner-Schlumberger, and Joint arrays. Data from an archaeological site in Iraq, along with synthetic models, are used to evaluate the ability of these arrays in resolving underground-buried structures. The presence of lateral near-surface inhomogeneity (characterized by High-Low–High resistivity values) in the upper layer significantly impacts the measured apparent resistivity data. It tends to reduce the resolution and resolvability of the arrays and increase misfit error ratios, which can lead to serious interpretation issues for the 3D resistivity maps. This can lead to partial identification of underground structures. Under these conditions, both Dipole–Dipole and Joint arrays produce similar images, with a slight advantage to Dipole–Dipole as it provides the best resolution. Joint array exhibits a slight reduction in resolution, despite having higher data coverage and quality. Wenner-Schlumberger array provides the poorest resolution. When the upper layer is dominated only by high resistivity values, the resolution and resolvability of these arrays are significantly improved.

During open-pit mining, the geotechnical strength and geological structure of the slope are rather complicated. Varying geological structures and rock mass strengths can lead to diverse failure modes of slopes. Particularly, fault-containing geological structures can exert a pivotal influence on the slope stability and ultimately affect the safe production of open-pit mines. This paper focuses on the K5-K6-K7 convex slope formed from the top to the bottom in the eastern mining area of Kangcheng Stone Mine. Through similarity simulation, the failure modes and deformation characteristics of the convex slope under two conditions, namely with and without a fault tectonic alteration zone, were analyzed. Furthermore, the results of similarity simulation experiments were verified with the aid of FLAC^3D based on the strength reduction method. The key findings are as follows: (1) The failure mode of the K5-K6-K7 slope and similar convex slopes in Kangcheng Stone Mine is overall arc-shaped sliding. The horizontal displacement of the convex slope surface mainly occurs on both sides of the convex surface. (2) The displacement process of the slope can be divided into three stages. In Stage I, i.e., the stable deformation stage, the displacement is relatively mild, accompanied by the emergence of small cracks. In Stage II, i.e., the local failure stage, the displacement changes increasingly noticeably, and small cracks keep expanding into large ones in the upper left, upper middle, and lower middle parts of the slope. Besides, these cracks penetrate the inner part of the slope, ultimately inducing plastic failure and slope sliding. In Stage III, i.e., the failure stage, the deformation and displacement continue at an accelerated rate. Moreover, cracks extend from the upper part to the bottom of the slope and penetrate the inner part of the slope, resulting in damage and sliding. At this time, the displacement distance reaches the maximum. (3) Due to its low strength, the rock mass in the FTA zone exerts a relatively strong influence on the intact surrounding rock mass. During slope failure, the displacement is mainly concentrated on the midline of the convex slope ridge and in the upper part on both sides are relatively large. The stability of the slope with a FTA zone is 0.067 less than that of the slope without a FTA zone, as calculated by the strength reduction method.

Two heavy rainfall episodes occurred during 12–16 May 2022 and 14–18 June 2022 over the southern districts of Assam, namely Dima Hasao, Cachar, Hailakandi, and Karimganj in the northeast region of India (NER). These episodes resulted in two consecutive catastrophic flood events, causing large-scale infrastructure damage and enormous losses of property and human life. Analysis of vertically integrated moisture flux convergence (VIMFC), Vorticity-Budget, vertical motion, and Iso-surface of wind have been carried out to look into the driving mechanism of two heavy rainfall episodes. A sharp rise (> 1 × 10^–5 kg m⁻² s⁻¹) in district-averaged VIMFC at 1000–700 hPa levels was observed between 2100 UTC on 13 May and 0600 UTC on 14 May, with a peak value of 3.05 × 10^–5 kg m⁻² s⁻¹ at 0000 UTC on 14 May over Dima Hasao district during the first episode. During the second episode, an increase in district-averaged VIMFC at 1000–700 hPa levels was noted from 0000 to 0600 UTC on 18 June, peaking at 6.88 × 10^–5 kg m⁻² s⁻¹ at 0600 UTC over Cachar district. These observations indicate that the high VIMFC over the study area was primarily due to the convergence of lower-level southwesterlies from the Bay of Bengal. Common factors for both episodes include strong moisture transport from the Bay of Bengal via southwesterly winds, resulting in increased VIMFC at lower levels. Furthermore, vertical velocity was positive and more pronounced during these episodes. Vorticity budget analysis shows that during both the episodes, the horizontal advection term and convergence term contributed positively at lower levels, while the vertical advection term contributed positively between low and mid-levels. This suggests that the transport of low-level vorticity to upper and middle levels fueled deep convection, which contributed to the heavy rainfall and subsequent flooding.