Source Parameters of Some Friuli Earthquakes (1976–1977) from Strong Motion Data

1987 ◽  
pp. 85-97
Author(s):  
G. Natale ◽  
R. Madariaga ◽  
R. Scarpa ◽  
A. Zollo
1989 ◽  
Vol 79 (2) ◽  
pp. 500-514 ◽  
Author(s):  
Allison L. Bent ◽  
Donald V. Helmberger ◽  
Richard J. Stead ◽  
Phyllis Ho-Liu

Abstract Long-period body-wave data recorded at teleseismic distances and strong-motion data at Pasadena for the Superstition Hills earthquakes of 24 November 1987 are modeled to obtain the source parameters. We will refer to the event that occurred at 0153 UT as EQ1 and the event at 1316 UT as EQ2. At all distances the first earthquake appears to be a simple left-lateral strike-slip event on a fault striking NE. It is a relatively deep event with a source depth of 10 km. It has a teleseismic moment of 2.7 ×1025 dyne cm. The second and more complex event was modeled in two ways: by using EQ1 as the Green's function and by using a more traditional forward modeling technique to create synthetic seismograms. The first method indicated that EQ2 was a double event with both subevents similar, but not identical to EQ1 and separated by about 7.5 sec. From the synthetic seismogram study we obtained a strike of 305° for the first subevent and 320° for the second. Both have dips of 80° and rakes of 175°. The first subevent has a moment of 3.6 ×1025 which is half that of the second. We obtain depths of at least 6 km. The teleseismic data indicate a preferred subevent separation of 30 km with the second almost due south of the first, but the error bounds are substantial. This would suggest that the subevents occurred on conjugate faults. The strong-motion data at PAS, however, imply a much smaller source separation, with the sources probably produced by asperities.


Author(s):  
Hernando Tavera ◽  
Bertrand Delouis ◽  
Arturo Mercado ◽  
David Portugal

Abstract The Loreto earthquake of 26 May 2019 occurred below the extreme northeast part of Peru at a depth of 140 km within the subducting Nazca plate at a distance of 700 km from the trench Peru–Chile. The orientation of the seismic source was obtained from waveform inversion in the near field using velocity and strong-motion data. The rupture occurred in normal faulting corresponding to a tensional process with T axis oriented in east–west direction similar to the direction of convergence between the Nazca and South America plates. The analysis of the strong-motion data shows that the levels of ground shaking are very heterogeneous with values greater than 50 Gal up to distances of 300 km; the maximum recorded acceleration of 122 Gal at a distance of 100 km from the epicenter. The Loreto earthquake is classified as a large extensional event in the descending Nazca slab in the transition from flat-slab geometry to greater dip.


2016 ◽  
Vol 83 (2) ◽  
pp. 867-883 ◽  
Author(s):  
A. Joshi ◽  
Monu Tomer ◽  
Sohan Lal ◽  
Sumer Chopra ◽  
Sandeep Singh ◽  
...  

1988 ◽  
Author(s):  
Kenneth W. Campbell ◽  
Sylvester Theodore Algermissen

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