Publications

We have produced probabilistic seismic hazard maps of Haiti for peak ground acceleration and response spectral accelerations that include the hazard from the major crustal faults, subduction zones, and background earthquakes. The hazard from the Enriquillo-Plantain Garden, Septentrional, and Matheux-Neiba fault zones was estimated using fault slip rates determined from GPS measurements...

The 2009 NEHRP Provisions modified the definition of horizontal ground motion from the geometric mean of spectral accelerations for two components to the peak response of a single lumped mass oscillator regardless of direction. These maximum-direction (MD) ground motions operate under the assumption that the dynamic properties of the structure (e.g., stiffness, strength) are identical in...

Since the launch of the USGS’s Prompt Assessment of Global Earthquakes for Response (PAGER) system in fall of 2007, the time needed for the U.S. Geological Survey (USGS) to determine and comprehend the scope of any major earthquake disaster anywhere in the world has been dramatically reduced to less than 30 min. PAGER alerts consist of estimated shaking hazard from the ShakeMap system...

Previous approaches used to determine the rates of different earthquakes on a fault have made assumptions regarding segmentation, have been difficult to document and reproduce, and have lacked the ability to satisfy all available data constraints. We present a relatively objective and reproducible inverse methodology for determining the rate of different ruptures on a fault or fault...

The influence of noise in strong-motion records is most problematic at low and high frequencies where the signal to noise ratio is commonly low compared to that in the mid-spectrum. The impact of low-frequency noise (5 Hz) on computed pseudo-absolute response spectral accelerations (PSAs). In contrast to the case of low-frequency noise our analysis shows that filtering to remove high...

Following a damaging earthquake, “business interruption” (BI)—reduced production of goods and services—begins and continues long after the ground shaking stops. Economic resilience reduces BI losses by making the best use of the resources available at a given point in time (static resilience) or by speeding recovery through repair and reconstruction (dynamic resilience), in contrast to...

Damage to fault-zone rocks during fault slip results in the formation of a channel of low seismic-wave velocities. Within such channels guided seismic waves, denoted by Fg, can propagate. Here we show with core samples, well logs and Fg-waves that such a channel is crossed by the SAFOD (San Andreas Fault Observatory at Depth) borehole at a depth of 2.7 km near Parkfield, California, USA...

The largest historical earthquake in the northern Great Plains occurred on 16 May 1909. Our analysis of intensity assignments places the earthquake location (48.81° N, 105.38° W) close to the Montana–Saskatchewan border with an intensity magnitude MI of 5.3–5.4. Observations from two seismic observatories in Europe give an average Ms value of 5.3. The 1909 earthquake is near an alignment...

No abstract available.

Strong aftershocks following major earthquakes present significant challenges for infrastructure recovery as well as for emergency rescue efforts. A tragic instance of this is the 22 February 2011 Mw 6.3 Christchurch aftershock in New Zealand, which caused more than 100 deaths while the 2010 Mw 7.1 Canterbury mainshock did not cause a single fatality (Figure 1). Therefore, substantial...

Cross correlation of ambient seismic noise is known to result in time series from which station-station travel-time measurements can be made. Part of the reason that these cross-correlation travel-time measurements are reliable is that there exists a theoretical framework that quantifies how these travel times depend on the features of the ambient noise. However, corresponding...

No abstract available.