Free Republic
Browse · Search
News/Activism
Topics · Post Article

To: winoneforthegipper
That is fascinating...

On the Channe 7 show after the quake...they talked to a manager that was on the 46th floor of a downtown Los Angeles building and he said it was very intense....rocked the elevators and cracks in the stairwell...rocked the building also. They evacuated the building going down the stairs...

Seems like this quake was too distant to cause that much action.

Building had special designed stuff for earthquakes also....

Don't have anymore detail than that.

733 posted on 04/04/2010 10:42:12 PM PDT by Ernest_at_the_Beach ( Support Geert Wilders)
[ Post Reply | Private Reply | To 708 | View Replies ]


To: Ernest_at_the_Beach; Steve Van Doorn; Quix
EATB, there are many signs that support this being an unusual shake, for sure.

Here is the USGS summary.

Tectonic Summary
The magnitude 7.2 northern Baja California earthquake of Sunday April 4th 2010, occurred approximately 40 miles south of the Mexico-USA border at shallow depth along the principal plate boundary between the North American and Pacific plates. This is an area with a high level of historical seismicity, and also it has recently been seismically active, though this is the largest event to strike in this area since 1892. Today's earthquake appears to have been larger than the M 6.9 earthquake in 1940 or any of the early 20th century events (e.g., 1915 and 1934) in this region of northern Baja California.

At the latitude of the earthquake, the Pacific plate moves northwest with respect to the North America plate at about 45 mm/y. The principal plate boundary in northern Baja California consists of a series of northwest-trending strike-slip (transform) faults that are separated by pull-apart basins. The faults are distinct from, but parallel to, strands of the San Andreas fault system. The April 4 main-shock occurred along a strike-slip segment of the plate boundary that coincides with the southeastern part of the Laguna Salada fault. Although the location and focal-mechanism of the earthquake are consistent with the shock having occurred on this fault, we do not yet have surface rupture or other confirmation. Aftershocks appear to extend in both directions along this fault system from the epicenter of today's event. The aftershock zone extends from the northern tip of the Gulf of California to the Mexico-USA border.

Earthquakes having magnitudes as high as 7 have been historically recorded from the section of the Pacific/North American plate boundary on which the 4 April 2010 earthquake occurred. The 1892 earthquake occurred along the Laguna Salada fault system, but significantly farther northwest than today's event epicenter. The 1940 Imperial Valley earthquake approached magnitude 7, though it occurred farther to the north and on the Imperial fault. Both the 1892 and 1940 earthquakes were associated with extensive surface faulting. An event of M 7.0 or 7.1 occurred in this region in 1915, and then a M 7.0 to 7.2 in 1934 broke the Cerro Prieto fault with up to several meters of surface slip.

In the vicinity of the 4 April 2010 earthquake, there are several active faults and it has not yet been determined specifically which fault the earthquake occurred on. Within the transition from the ridge-transform boundary in the Gulf of California to the continental transform boundary in the Salton Trough, faulting is complex. Most of the major active faults are northwest-southeast oriented right-lateral strike-slip faults that are common in mechanism to the San Andreas fault and parallel Elsinore and San Jacinto faults, that run north of the Mexico-USA border

http://earthquake.usgs.gov/earthquakes/recenteqsus/Quakes/ci14607652.php#summary

If this was indeed a supershear event, it occurred in the best area possible. The main force of such would have been expended in the deserts of northern mexico. Plus side scientists have been drooling to study such an event, if this is one.

Good Stuff. Quix, right now California is quaking so much I have no idea what to make of it.

755 posted on 04/05/2010 6:08:55 AM PDT by winoneforthegipper ("If you can't ride two horses at once, you probably shouldn't be in the circus" - SP)
[ Post Reply | Private Reply | To 733 | View Replies ]

Free Republic
Browse · Search
News/Activism
Topics · Post Article


FreeRepublic, LLC, PO BOX 9771, FRESNO, CA 93794
FreeRepublic.com is powered by software copyright 2000-2008 John Robinson