Ionospheric perturbations by natural geophysical activity, such as volcanic eruptions and earthquakes, have been studied since the great Alaskan earthquake in 1964. Measurements made from the ground show a variation of the critical frequency of the ionosphere layers before and after the shock. In this paper, we present an experimental investigation of the electron density variations around the ...

The manner in which an earthquake rupture propagates across a fault reflects both the initial properties of the fault and the dynamical stresses produced by the rupture. We quantify the propagation of an earthquake rupture using the second moments of the earthquake space–time distribution. In particular, the second moments provide a simple way to differentiate between approximately bilateral an...

We report horizontal sliding of the kilometre-scale geologic block under the Aso hot springs (Uchinomaki area) caused by vibrations from the 2016 Kumamoto earthquake (Mw 7.0). Direct borehole observations demonstrate the sliding along the horizontal geological formation at ~50 m depth, which is where the shallowest hydrothermal reservoir developed. Owing to >1 m northwest movement of the geolog...

Received 3 March 2009; revised 13 October 2009; accepted 30 October 2009; published 9 April 2010. [1] Electric and magnetic fields in the (10–1.0) Hz band were monitored at two sites adjacent to the San Andreas Fault near Parkfield and Hollister, California, from 1995 to 2007. A data window (2002–2005), enclosing the 28 September 2004 M6 Parkfield earthquake, was analyzed to determine if anomal...

This paper introduces the application of seismic wave method in earthquake prediction and early estimation. The advantages of the seismic wave method over the traditional earthquake prediction method are demonstrated. An example is presented in this study to show the accuracy and efficiency of using the seismic wave method in predicting a medium-sized earthquake swarm occurred in Wencheng, Zhej...

Geochemical monitoring of groundwater and soil gas emission pointed out precursor and/or coseismic anomalies of noble gases associated with earthquakes, but there was lack of plausible physico-chemical basis. A laboratory experiment of rock fracturing and noble gas emission was conducted, but there is no quantitative connection between the laboratory results and observation in field. We report ...

[1] Knowledge of frictional resistance along faults is important for understanding the mechanics of earthquakes and faulting. The clearest in situ measure of fault friction potentially comes from temperature measurements in boreholes crossing fault zones within a few years of rupture. However, large temperature signals from frictional heating on faults have not been observed. Unambiguously inte...

Several recent studies have presented evidence that significant induced earthquakes occurred in a number of oil-producing regions during the early and mid-twentieth century related to either production or wastewater injection. We consider whether the 21 July 1952 Mw 7.5 Kern County earthquake might have been induced by production in the Wheeler Ridge oil field. The mainshock, which was not prec...

introduction natural hazards as recurring phenomenon have always existed in human life and will in the future, too. nowadays natural hazards occur throughout the world, but their impacts have been increasing and are generally much greater in developing countries than in developed ones. earthquake is a kind of natural hazard that has the most damages for humankind. earthquakes pose inevitable ri...

We describe a large-scale simulation of the seismic wave propagation from the 2011 Tohoku-Oki earthquake. We combine structure models for topography, sediments, crust and subducting plates to construct a 3D structure model for the northeastern Japan area. Then we simulate the near-field wave propagation by using a FDTD method which is accelerated by the use of multi-GPUs (Graphics Processing Un...