[1] We estimate the spatial variation of the seismic parameter t* using teleseismic (epicentral distance = 30 –85 ) P wave spectra of about 200 deep (focal depths > 200 km) earthquakes recorded by 378 broadband seismometers in the United States and Canada. Relative P wave spectral ratios up to 1 Hz for about 63,000 station pairs with high signal-to-noise ratio and impulsive P waveforms are inve...

Travel times of 11,612 Pn arrivals collected from 7675 earthquakes are inverted to image the uppermost mantle velocity and anisotropy structure beneath the southern half of the Iberian Peninsula and surrounding regions. Pn phases are routinely identified and picked for epicentral distances from 200 to 1200 km. The method used in this study allows simultaneous imaging of variations of Pn velocit...

A sequence of earthquakes occurred in 2008 in the Meruoca granitic pluton, located in the northwestern part of the Borborema Province, NE Brazil. A seismological study defined the seismic activity occurring along the seismically-defined Riacho Fundo fault, a 081° striking, 8 km deep structure. The objective of this study was to analyze the correlation between this seismic activity and geologica...

[1] Using a model of a complex fault system, we examine the initiation, propagation, and termination of ruptures and their relationship to fault geometry and shaking hazard. We find concentrations of epicenters near fault step overs and ends; concentrations of terminations near fault ends; and persistent propagation directivity effects. Taking advantage of long sequences of dynamic events, we d...

A downhole seismometer at 900-m depth and a temporary network of surface stations were deployed to use rays from local microearthquakes to study the upper and middle crust beneath the Long Valley caldera. The downhole seismograms show S waves with high apparent amplitudes from earthquakes located 2-20 km to the south of the downhole seismometer. In contrast, S waves from earthquakes located in ...

We constrain SH and P wave velocity structures in the upper mantle beneath southern Africa, using triplicated phases recorded in the epicentral distance range of 11°–28° for one shallow event. We then explore thermal and compositional models appropriate for explaining the inferred seismic structures in the region. Both SH and P wave data suggest presence of a low velocity zone with velocity red...

S U M M A R Y We perform a systematic survey of triggered deep ‘non-volcanic’ tremor beneath the Central Range (CR) in Taiwan for 45 teleseismic earthquakes from 1998 to 2009 with Mw ≥ 7.5 and epicentral distance≥1000 km to the broad-band station TPUB. Triggered tremors are visually identified as bursts of high-frequency (2–8 Hz), non-impulsive and long-duration seismic energy that are coherent...

Ionospheric perturbations in plasma parameters have been observed before large earthquakes, but the correlation between different parameters has been less studied in previous research. The present study is focused on the relationship between electron density (Ne) and temperature (Te) observed by the DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) satellite ...

We quantify changes in gravity that have occurred over the past 15 years at 14 points between latitudes 42.5°S and 44°S in the South Island of New Zealand. Ten of the points form two transects across the Southern Alps and four lie in the epicentral region of the 2010 Canterbury earthquakes. At each location gravity was measured using an absolute gravimeter (FG5–111) with a nominal accuracy of 1...

All the available data from historic time has been collected for earthquakes of magnitude 5 and above occurring in around India an epicentral map beer. prepared.
 
 Earthquake recurrence curve Himalayan seismic region a few places special interest. viz., Chatra,Dehra Dun. Delhi Sonepat have drawn. It found that slope diagrams is nearly same all cases. does not vary with change area. o...