Publications

What’s the best way to get alerted about the occurrence and potential impact of an earthquake? The answer to that question has changed dramatically of late, in part due to improvements in earthquake science, and in part by the implementation of new research in the delivery of earthquake information

We present a new finite-element technique for calculating dynamic 3-D spontaneous rupture on an earthquake fault, which can reduce the required computational resources by a factor of six or more, without loss of accuracy. The grid-doubling technique employs small cells in a thin layer surrounding the fault. The remainder of the modelling volume is filled with larger cells, typically two...

Rotational motions generated by large earthquakes in the far field have been successfully measured, and observations agree well with the classical elasticity theory. However, recent rotational measurements in the near field of earthquakes in Japan and in Taiwan indicate that rotational ground motions are 10 to 100 times larger than expected from the classical elasticity theory. The near...

Deep tremor under Shikoku, Japan, consists primarily, and perhaps entirely, of swarms of low-frequency earthquakes (LFEs) that occur as shear slip on the plate interface. Although tremor is observed at other plate boundaries, the lack of cataloged low-frequency earthquakes has precluded a similar conclusion about tremor in those locales. We use a network autocorrelation approach to...

We determine the finite-fault slip distribution of the 2001 Kunlun earthquake (Ms = 8.1) by inverting teleseismic waveforms, as constrained by geological and remote sensing field observations. The spatial slip distribution along the 400-km-long fault was divided into five segments in accordance with geological observations. Forward modelling of regional surface waves was performed to...

Most digital accelerograph recordings are plagued by long-period drifts, best seen in the velocity and displacement time series obtained from integration of the acceleration time series. These drifts often result in velocity values that are nonzero near the end of the record. This is clearly unphysical and can lead to inaccurate estimates of peak ground displacement and long-period...

A volcanic earthquake with Mw 5.6 occurred beneath the Bárdarbunga caldera in Iceland on 29 September 1996. This earthquake is one of a decade-long sequence of events at Bárdarbunga with non-double-couple mechanisms in the Global Centroid Moment Tensor catalog. Fortunately, it was recorded well by the regional-scale Iceland Hotspot Project seismic experiment. We investigated the event...

Developed herein is a new peak ground acceleration (PGA)-based predictive model for 5% damped pseudospectral acceleration (SA) ordinates of free-field horizontal component of ground motion from shallow-crustal earthquakes. The predictive model of ground motion spectral shape (i.e., normalized spectrum) is generated as a continuous function of few parameters. The proposed model eliminates...

The shallow seismic velocity structure of the Kunlun fault zone (KLFZ) was jointly deduced from seismic refraction profiling and the records of trapped waves that were excited by five explosions. The data were collected after the 2001 Kunlun Ms8.1 earthquake in the northern Tibetan Plateau. Seismic phases for the in-line record sections (26 records up to a distance of 15 km) along the...

Space geodesy now provides quantitative maps of the surface velocity field within tectonically active regions, supplying constraints on the spatial distribution of deformation, the forces that drive it, and the brittle and ductile properties of continental lithosphere. Deformation is usefully described as relative motions among elastic blocks and is block-like because major faults are...

In 1999, the eastern coastline of the Marmara region (Turkey) witnessed increased seismic activity on the North Anatolian fault (NAF) system with two damaging earthquakes (M 7.4 Kocaeli and M 7.2 D??zce) that occurred almost three months apart. These events have reduced stress on the western segment of the NAF where it continues under the Marmara Sea. The undersea fault segments have...