EARTHQUAKES T recent earthquakes in Taiwan, Turkey, and India tragically demonstrate the abruptness with which earthquakes occur and the devastation that often accompanies them. Scientists, emergency officials, and the public are greatly interested in earthquakes-sudden fractures in Earth's crust followed by ground shaking-and have Seismologists have never directly observed rupture in Earth's i...

In November 2013, a series of earthquakes began along a mapped ancient fault system near Azle, Texas. Here we assess whether it is plausible that human activity caused these earthquakes. Analysis of both lake and groundwater variations near Azle shows that no significant stress changes were associated with the shallow water table before or during the earthquake sequence. In contrast, pore-press...

Earthquake sources represent dynamic rupture within rocky materials at depth and often can be modeled as propagating shear slip controlled by friction laws. These laws provide boundary conditions on fault planes embedded in elastic media. Recent developments in observation networks, laboratory experiments, and methods of data analysis have expanded our knowledge of the physics of earthquakes. N...

The observation of foreshocks preceding large earthquakes and the suggestion that foreshocks have specific properties that may be used to distinguish them from other earthquakes have raised the hope that large earthquakes may be predictable. Among proposed anomalous properties are the larger proportion than normal of large versus small foreshocks, the power law acceleration of seismicity rate a...

Recent parallel development of improved quantitative methods to analyze intensity distributions for historical earthquakes and of web-based systems for collecting intensity data for modern earthquakes provides an opportunity to reconsider not only important individual historical earthquakes but also the overall characterization of intensity distributions for historical events. The focus of this...

In large earthquakes, damaging ground motions may occur at large epicentral distances. Because of the relatively slow speed of seismic waves, it is possible to construct a system to provide short-term warning (as much as several tens of seconds) of imminent strong ground motions from major earthquakes. Automated safety responses could be triggered by users after receiving estimates of the arriv...

The central United States has undergone a dramatic increase in seismicity over the past 6 years (Fig. 1), rising from an average of 24M ≥3 earthquakes per year in the years 1973–2008 to an average of 193M ≥3 earthquakes in 2009–2014, with 688 occurring in 2014 alone. Multiple damaging earthquakes have occurred during this increase including the 2011M 5.6 Prague, Oklahoma, earthquake; the 2011 M...

[1] We find that slow seismic events have smaller fault slips compared to ordinary earthquakes with similar dimensions. For ordinary earthquakes, the ratio of slip to fault length is largely consistent, yet the physical controls on this ratio are unknown. Recently discovered slow slip or creep events in which faults move quasi-statically over periods of days to years shed new light on this old ...

Multi sensor data available through remote sensing satellites provide information about changes in the state of the oceans, land and atmosphere. Recent studies have shown anomalous changes in oceans, land, atmospheric and ionospheric parameters prior to earthquakes events. This paper introduces an innovative data mining technique to identify precursory signals associated with earthquakes. The p...

Over the past 5 years, parts of Oklahoma have experienced marked increases in the number of small- to moderate-sized earthquakes. In three study areas that encompass the vast majority of the recent seismicity, we show that the increases in seismicity follow 5- to 10-fold increases in the rates of saltwater disposal. Adjacent areas where there has been relatively little saltwater disposal have h...