Magnitude 7.2 earthquake rattles Mexico

MEXICO CITY - A powerful earthquake struck Mexico on Friday, shaking buildings in the capital and sending people running out into the street, although there were no early reports of major damage.

The magnitude 7.2 quake was centered in the southwestern state of Guerrero, close to the Pacific beach resort of Acapulco, the U.S. Geological Survey (USGS) said.

Some residents of the capital ran outdoors in their pajamas after the quake. Electricity was cut off in parts of the city and some residents said paintings fell off the walls and small parts of masonry crumbled inside apartment buildings.

Luis Felipe Puente, head of the Mexican government's emergency services, said there were no immediate reports of damage and the U.S. Pacific Warning Center said it did not expect the quake to trigger a destructive tsunami.

Nevertheless, residents of the capital were shaken by the quake, one of the biggest to hit Mexico in several years.

"I had to hold on to a tree, like a drunk," said Pedro Hernandez, 68, a doorman working in central Mexico City.

The USGS said the quake was centered some 37 km (23 miles) north of the municipality of Tecpan de Galeana in Guerrero. It was relatively shallow, at a depth of about 24 km (15 miles).

Emergency services in Guerrero, which is frequently struck by earthquakes, said there were no immediate reports of major damage, but that checks were still being made.

An employee of the Fairmont hotel in Acapulco, said the situation was calm and that guests had returned to the building.

"The structure is fine," the woman, who identified herself only as Ana, said by telephone.

Cesar Sanchez, 24, a student living in Guerrero's capital Chilpancingo said he got a big shock when the tremors began.

"I was in bed, and some things fell that have never fallen. The dogs outside were barking and barking," Sanchez said.

A devastating 8.1-magnitude earthquake in 1985 killed thousands of people in Mexico City. In March 2012, a 7.4 magnitude quake hit Mexico but did not cause major damage.

Saudi Arabia to build world's tallest tower that will reach one kilometer into the sky

(CNN) -- Dubai -- long champion of all things biggest, longest and most expensive -- will soon have some competition from neighboring Saudi Arabia.

Dubai's iconic Burj  Khalifa -- the world's tallest building -- could be stripped of its Guinness title if Saudi Arabia succeeds in its plans to construct the even larger Kingdom Tower in Jeddah -- a prospect looking more likely as work begins next week, according to Construction Weekly.

For buildings of this stature, wind load could also put stress on the structure. To battle this, the design of the structure will change every few floors.

It is expected construction of the tower will require 5.7 million square-feet of concrete and 80,000 tons of steel.

Consultants Advanced Construction Technology Services (ACTS) have recently announced testing materials to build the 3,280-feet (one kilometer) skyscraper (the Burj Khalifa, by comparison, stands at a meeker 2,716-feet, or 827 meters).

The Kingdom Tower, estimated to cost $1.23 billion, would have 200 floors and overlook the Red Sea. Building it will require about 5.7 million square-feet of concrete, and 80,000 tons of steel, according to the Saudi Gazette.

There are plans for a 98-feet sky terrace on the 157th floor. When completed, it will be the highest terrace in the world.

The structure will overlook the Red Sea -- posing additional challenges to the building process. It's particularly important that the foundations -- 200 feet deep -- won't be affected by saltwater from the ocean.

Building a structure that tall, particularly on the coast, where salt water could potentially damage it, is no easy feat. The foundations, which will be 200 feet (60 meters) deep, need to be able to withstand the saltwater of the nearby ocean. As a result, ACTS will test the strength of different concretes.

Wind load is another issue for buildings of this magnitude. To counter this challenge, the tower will change shape regularly.

"Because it changes shape every few floors, the wind loads go round the building and won't be as extreme as on a really solid block," Gordon Gill explained to Construction Weekly. Gill is a partner at Adrian Smith + Gordon Gill Architecture, the design architects for the project.

Delivering the concrete to higher floors will also be a challenge. Possibly, engineers could use similar methods to those employed when building the Burj Khalifa; six million cubic feet of concrete were pushed through a single pump, usually at night to ensure the temperatures were low enough to ensure it would set.

Though ambitious, building the Kingdom Tower should be feasible, according to Dr. Sang Dae Kim, the director of the Council on Tall Buildings.

"At this point in time we can build a tower that is one kilometer, maybe two kilometers. Any higher than that and we will have to do a lot of homework," he told Construction Weekly.