Earthquakes (Seismic Destruction)

Earthquakes, also called temblors, can be so tremendously destructive, it’s hard to imagine they occur by the thousands every day around the world, usually in the form of small tremors.

Some 80 percent of all the planet’s earthquakes occur along the rim of the Pacific Ocean, called the “Ring of Fire” because of the preponderance of volcanic activity there as well. Most earthquakes occur at fault zones, where tectonic plates—giant rock slabs that make up the Earth’s upper layer—collide or slide against each other. These impacts are usually gradual and unnoticeable on the surface; however, immense stress can build up between plates. When this stress is released quickly, it sends massive vibrations, called seismic waves, often hundreds of miles through the rock and up to the surface. Other quakes can occur far from faults zones when plates are stretched or squeezed.

Scientists assign a magnitude rating to earthquakes based on the strength and duration of their seismic waves. A quake measuring 3 to 5 is considered minor or light; 5 to 7 is moderate to strong; 7 to 8 is major; and 8 or more is great.

On average, a magnitude 8 quake strikes somewhere every year and some 10,000 people die in earthquakes annually. Collapsing buildings claim by far the majority of lives, but the destruction is often compounded by mud slides, fires, floods, or tsunamis. Smaller temblors that usually occur in the days following a large earthquake can complicate rescue efforts and cause further death and destruction.

Loss of life can be avoided through emergency planning, education, and the construction of buildings that sway rather than break under the stress of an earthquake.

Japan earthquake

The 2011 earthquake off the Pacific coast of Tohoku, also known as the 2011 Tohoku earthquake, or the Great East Japan Earthquake, (Japanese: “Eastern Japan Great Earthquake Disaster” was a magnitude9.0 (M_w) undersea megathrust earthquake off the coast of Japan that occurred at 14:46 JST (05:46 UTC) on Friday, 11 March 2011,with the epicenter approximately 70 kilometres (43 mi) east of the Oshika Peninsula of Tōhoku and the hypocenter at an underwater depth of approximately 32 km (20 mi). It was the most powerful known earthquake ever to have hit Japan, and one of the five most powerful earthquakes in the world overall since modern record-keeping began in 1900. The earthquake triggered powerful tsunami waves, which reached heights of up to 40.5 metres (133 ft) in Miyako in Tōhoku’s Iwate Prefecture, and which in the Sendai area travelled up to 10 km (6 mi) inland. In addition to loss of life and destruction of infrastructure, the tsunami caused a number of nuclear accidents, primarily the ongoing level 7 meltdowns at three reactors in the Fukushima I Nuclear Power Plant complex, and the associated evacuation zones affecting hundreds of thousands of residents.

1990 Luzon earthquake

The Luzon earthquake occurred on Monday, July 16, 1990, at 4:26 PM local time in the Philippines. The densely populated island of Luzon was struck by an earthquake with a 7.8 M_s (surface-wave magnitude). The earthquake produced a 125 km-long ground rupture that stretched from Dingalan, Aurora to Cuyapo, Nueva Ecija as a result of strike-slip movements along the Philippine Fault and the Digdig Fault within the Philippine Fault System. The earthquake epicenter was placed at 15° 42’ N and 121° 7’ E near the town of Rizal, Nueva Ecija, northeast of Cabanatuan City.

An estimated 1,621 people were killed in the earthquake, most of the fatalities located in Central Luzon and the Cordillera region.

Impact

The earthquake caused damage within in an area of about 20,000 square kilometers, stretching from the mountains of the Cordillera Administrative Region and through the Central Luzon region. The earthquake was strongly felt in Metropolitan Manila, Destroying many buildings and leading to panic and stampedes and ultimately three deaths in the National Capital Region, one of the lowest fatalities recorded in the wake of the tremor. The Southern Tagalog (nowadays Regions 4A and 4B) and Bicol Regions also felt the quake, but with low casualty figures.

Baguio City, Benguet

The popular tourist destination of Baguio City, situated over 5000 feet above sea level, was among the areas hardest hit by the Luzon earthquake. The earthquake caused 28 collapsed buildings, including hotels, factories, government and university buildings, as well as many private homes and establishments. The quake destroyed electric, water and communication lines in the city. The main vehicular route to Baguio, Kennon Road, as well as other access routes to the mountain city were shut down due to landslides, and it took three days before enough landslide debris was cleared to allow access by road to the stricken city. Baguio City was isolated from the rest of the Philippines for the first 48 hours after the quake. Damage at Loakan Airport rendered access to the city by air limited through helicopters. American & Philippine Air Force C-130s did evacuate many residents from this airport. Many city residents, as well as patients confined in hospital buildings damaged by the quake were forced to stay inside tents set up in public places, such as in Burnham Park, or in the streets. Looting of department stores in the city was reported. Among the first rescuers to arrive at the devastated city were miners from Benguet Corporation, who focused on rescue efforts at the collapsed Hotel Nevada. Teams sent by the Philippine government and by foreign governments and agencies likewise participated in the rescue and retrieval operations in Baguio City. One of the more prominent buildings destroyed was the Hyatt Terraces Hotel where at least eighty hotel employees and guests were killed. However, three hotel employees were pulled out alive after having been buried under the rubble for nearly two weeks, and after international rescue teams had abandoned the site convinced there were no more survivors.Luisa Mallorca and Arnel Calabia were extricated from the rubble 11 days after the quake, while hotel cook Pedrito Dy was recovered alive 14 days following the earthquake. All three survived in part by drinking their own urine and in Dy’s case, rainwater. At that time, Dy’s 14-day ordeal was cited as a world record for entombment underneath rubble.

The United States Agency for International Development was sponsoring a seminar at the Hotel Nevada when the tremor struck, causing the hotel to collapse. 27 of the seminar participants, including one American USAID official were killed in the quake. Among those who were pulled out alive from the ruins of the hotel was future Presidential candidate Sonia Roco, wife of politician Raul Roco, who was pulled out from the rubble by miners after 36 hours.