Earthquake

[dik]

== PRELIMINARY EARTHQUAKE REPORT ==

***This event has been revised.


Region: OFFSHORE MAULE, CHILE
Geographic coordinates: 35.846S, 72.718W
Magnitude: 8.8 Mw
Depth: 35 km
Universal Time (UTC): 27 Feb 2010 06:34:14
Time near the Epicenter: 27 Feb 2010 03:34:14
Local standard time in your area: 27 Feb 2010 06:34:14

Location with respect to nearby cities:
104 km (65 miles) WSW (246 degrees) of Talca, Chile
114 km (71 miles) NNE (15 degrees) of Concepcion, Chile
321 km (200 miles) SW (215 degrees) of SANTIAGO, Chile


ADDITIONAL EARTHQUAKE PARAMETERS
________________________________
event ID : US 2010tfan

This event has been reviewed by a seismologist at NEIC
For subsequent updates, maps, and technical information, see:

http://earthquake.usgs.gov/eqcenter/recenteqsww/Quakes/us2010tfan.php

or

http://earthquake.usgs.gov/

National Earthquake Information Center
U.S. Geological Survey

http://neic.usgs.gov/

 

[JAE]

Here's a Yahoo news report on it:

http://news.yahoo.com/s/ap/lt_chile_earthquake

8.8 - that is quite large I believe. very large.

 

[dik]

They've had 10 aftershocks over 5 and some over 6, since...

Dik

 

[CPENG78]

I woke up this morning to the news of such a massive earthquake. An amazing amount of energy released. It appears based on that prelimary data that in comparison, it was deeper than the Haiti earthquake.

Preliminary news footage shows various signs of liquefaction. Various buildings seemed to just have tilted on their side or floated to the surface. Entire sections of road have just lifted 3 to 4 feet in the footage I saw. Other damage includes roadway opverpasses and bridges with only the main supports standing.

 

[ishvaaag]

More...

http://www.nytimes.com/slideshow/2010/02/27/world/20100227-CHILEQUAKE_12.html

 

[msquared48]

A good description is "total devastation". Even some of the newer buildings failed - high rises - mainly due to the subsidence. Reinforcement is very evident.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Qshake]

This is one of the areas for potentially huge earthquakes. Chile, Alaska, Seattle, San Francisco and Japan are all geographical areas with the potential for exceptionally large earthquakes, i.e., greater than 8. This is, of course, due to the fault characteristics in these areas.

I'm not as well versed in the Middle Eastern and or Asian continent countries so I can't say anything about those areas, but India strikes me as a location for huge quakes too.

Here in the central US, there is potential and history but not the same fault characteristics which makes this area a bit of a anomaly.

At any rate, there is a limit to which you can engineer facilities to withstand such monterous earthquakes. That even engineered facilities failed in this quake is likely proof of that statement. Once you combine strength and ductility with good construction practice and details. And once you have a population that is educated on such hazards and post earhquake response what do you do?

I hope the death toll will stay low.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[concretemasonry]

Qshake -

India is relatively low on the probability and strength of seismic activity except for the narrow strip adjacent to the the mountains of Nepal and the far NW corner near Pakistan.

They define the activity categories (details not known) in 5 categories ranging from 1 (least active) and 5 (most active). Most of the country is in a category 1 or 2 with a portion a few category areas and a smattering of category 3. Category 4 areas are small and isolated and the very narrow strip along the northern mountains.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[dik]

There have been 20 aftershocks ranging from 5.5 to 6.9

Dik

 

[ishvaaag]

More Photos.

http://www.boston.com/bigpicture/2010/02/earthquake_in_chile.html

And I will say it once more:

The width of available support for precast or bridge beams needs be bigger.

 

[msquared48]

I also see the need for staggered tie splices at the supports too. Too many places where the exposed rebar stops in a line.

Overaqll, no comparison to the construcdtion in Haiti, but with a larger quake, the damage result was the samd, but the loss of live reduced.

Kinda emphasizes our humanitarian and social responsibilities we have as structural engineers. Very sobering.

I, for one, except for the tsunami, expect the same thing in Seattle, and very soon.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Teguci]

Not so sure additional real estate for the bearing area is the fix. I'd be happier seeing more steel used between the pier and beam. Say 2% of the contact area to be steel for high seismic areas.

 

[hokie66]

Mike,

Why wouldn't you have the same type tsunami in Seattle?

 

[msquared48]

We are well inland from the likely event, and not only would the force of the wave be deflected by the terrain of the Olympic Mountains, but the volume of water to make any surge would be also limited due to the twists and turns to get to Seattle.

It may be 30 feet on the coast, but where I am, substantially less - 5 feet or so at best I think. Just my analysis based on living her 61 years ande having seen three other area quakes of 6 or higher.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[unclesyd]

Just watched a newscast are there was a little heartening news as the reporter stated that Chili had some very stringent building codes in respect to seismic activity. He also stated that the new construction stood up very well and his Chilean official stated that for some of the damaged buildings the owners could face criminal charges if they are found to have taken some shortcuts.
The background of the news shot was newer 15 story apartment building on the ground. In another shot there were 2 tower cranes still standing over new construction.
It was also stated that very few of the earthquake resistant bridges stood up.
Lets hope some civil people and do a little evaluation as it appears the reconstruction is well underway in some areas.

PS; The day is 1.2 milliseconds shorter due to the quake.

 

[unclesyd]

No disrespect meant Chili should have been Chile.

 

[Qshake]

Agree that the bridge seats need to be larger and that restrainers would have helped several bridges in photos. It's worth noting that restrainers can be seen on one of the larger bridges in the photos but failed. It also looks like a lot of the bridge columns made it ok, but was probably due to the restrainers failing and the span falling. Had the spans not fallen the load wouldhave been transfered to the columns and it remains to be seen if they could handle that lateral load.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[msquared48]

So... Maybe there are some engineering jobs in Chile now?

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[dig1]

I've done several projects in Chile, mainly designing tall pressure vessels and towers at paper mills (in fact I am working on another now). They do have fairly stringent seismic design criteria, much of which has been improved in the past 8-10 years. Designs also have to be reviewed by a Chilean engineer experienced in seismic design. The structural engineers I have worked with on the industrial side have been very good. I am curious how the design review procedure will be afftected by what has happened.

One note, is that the bridge in picture 18 in the link in Ishvaaag's post (the one in Concepcion)that collapsed has been closed for several years (at least 6). The new bridge (where the picture was taken) seems to have held up fairly well.

"Kinda emphasizes our humanitarian and social responsibilities we have as structural engineers. Very sobering." Mike McCann --- Very well put.

Patrick

 

[Qshake]

Dig1 - thanks for the insight. I wondered what was different about the two bridges given that they are very similar in build. I reasoned that the soil couldn't be too different for being so close. I suspected one was older.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.