Seismic Radiation From Simple Models of Earthquakes

We review some basic features of shear wave generation and energy balance for a 2D anti plane rupture. We first study the energy balance for a flat fault, and for a fault that contains a single localized kink. We determine an exact expression for the partition between strain energy flow released from the elastic medium surrounding the fault, radiated energy flow and energy release rate. This balance depends only on the rupture speed and the residual stress intensity factor. When the fault contains a kink, the energy available for fracture is reduced so that the rupture speed is reduced. When rupture speed changes abruptly, the radiated energy flow also changes abruptly. As rupture propagates across the kink, a shear wave is emitted that has a displacement spectral content that decreases like ω^(-2) at high frequencies. We then use spectral elements to model the propagation of an antiplane crack with a slip-weakening friction law. Since the rupture front in this case has a finite length scale, the wave emitted by the kink is smoothed at very high frequencies but its general behavior is similar to that predicted by the simple sharp crack model. A model of a crack that has several kinks and wanders around a mean rupture directions, shows that kinks reduce the rupture speed along the average rupture direction of the fault. Contrary to flat fault models, a fault with kinks produces high frequency waves that are emitted every time the rupture front turns at a kink. Finally, we discuss the applicability of the present results to a 3D rupture model

Study of the fracture process of Al Hoceima earthquake (24/02/2004, Mw=6.2) from regional and teleseismic data.

We studied the source time function (STF) and rupture process of the 2004 Alhoceima, Morocco earthquake of Mw = 6.2 using teleseismic and regional broad-band data. From regional broad-band data, STF function was determined using three large after- shocks as empirical Green functions. We inverted of body wave forms at teleseismic distances using an extended source model with rupture velocity between 2.5-3.0 km and using as preliminary orientation the fault plane solution derived from 126 P-wave polarities. Results show a complex bilateral rupture formed by four shallow subevents (2-8 km) with a maximum seismic moment release during the first seconds (more than 80% of a total of 1.8x1018 Nm) and time duration of 8-10 s. The focal mechanism shows a strike slip motion with a normal component. Nodal planes strike on NNE- SSW and WNW-ESE direction with horizontal pressure axes in NNW-SSE direction. The rupture propagated mainly towards the North. This propagation is in agreement with the damages caused in the epicentral region. The larger aftershocks have been relocated using a master event method. Comparisson of these results with those ob- tained for the 1994 earthquake shown similar behaviour: complex rupture process and, apparently, no relation of the 1994 nor the 2004 shocks with the Nekor fault, the most important geological feature in the area. The stress pattern derived from focal mech- anisms of 1994 and 2004 are in agreement with the regional stress pattern, horizontal compression in NNW-SSE and horizontal extension in E-W direction in the Alboran Sea

Corrective treatment and anatomic considerations for laparoscopic cholecystectomy injuries

BACKGROUND: Complete reports of biliary and vascular injuries after laparoscopic cholecystectomy are rare. STUDY DESIGN: Fifteen patients with complex laparoscopic cholecystectomy injuries underwent corrective operations. The injuries consisted of 14 bile duct injuries and one large laceration of a cirrhotic liver. Five of the bile duct injuries were accompanied by inadvertent occlusion of the right hepatic artery, and one was further complicated by portal vein occlusion. One hepatic artery occlusion and one portal vein occlusion were successfully reconstructed. Two patients with arterial occlusion required right hepatic lobectomy. Corrective biliary operations consisted of common hepaticojejunostomy (seven cases), right and left hepaticojejunostomies (one case), right anterior and left hepaticojejunostomies (two cases), right hepaticojejunostomy (one case), right posterior hepaticojejunostomy (one case), and left hepaticojejunostomy after right lobectomy (two cases). RESULTS: Except for a patient with a severe laceration of a cirrhotic liver who died as a result of hepatic failure, the remaining 14 patients are alive and well with normal hepatic function tests at six and 37 months after corrective operations. CONCLUSIONS: A knowledge of anatomy is critical to the prevention of injuries to the hepatobiliary tree and related structures during laparoscopic cholecystectomy

Modelling the tsunami free oscillations in the Marquesas (French Polynesia)

The tsunami resonance inside basins (closed or semi-enclosed) depends on the period of the incident waves, reflection and energy dissipation, characteristics of the boundary and the geometry of the basin.When waves continuously enter the basin, they caus

Hepatic artery pseudoaneurysm ligation after orthotopic liver transplantation-a report of 7 cases

Pseudoaneurysm (PA) is a rare but life-threatening complication of liver transplantation. The authors present their experience on 7 patients treated by ligation of a post-OLT PA. Hepatic artery ligation or embolization was performed from 10 to 70 days after liver transplantation. Of the seven patients, four survived, one developed a biliary stricture, treated by percutaneous ballon dilatation, two died of a complication not related to treatment, and one died of multiple organ failure. © 1992 by Williams & Wilkins