Types of Heart Disease

Types of Heart Disease

Phenomena Of Earthquakes

The phenomena of earthquakes differ greatly in accordance with the number, duration, and intensity of the shocks, and with the distance of the place of observation from that of the origin of the disturbance. One of the greatest of modern earthquakes is that of northern India of 1897, which is well summed up in the official report.

"On the afternoon of June 12,1897, there burst upon the western portion of Assam an earthquake which, for violence and extent, has not been surpassed by any of which we have historic record. Lasting about .two and one-half minutes, it had not ceased at Shillong before an area of 150,000 square miles had been laid in Tuins, all means of communication interrupted, the hills rent and cast down in landslips, and the plains fissured and riddled with vents, from which sand and water poured out in most astounding quantities; and ten minutes had not elapsed from the time when Shillong was laid in ruins before about one and three-quarter million square miles had felt a shock, which was everywhere recognized as one quite out of the common." (R. D. Oldham).

Fig. 6. - Earthquake fissure in limestone, Arizona. (U. S. G. S).

A great earthquake usually begins suddenly and without warning. A rumbling sound, quickly becoming a loud roar, accompanies or slightly precedes the movement of the ground, which is at first a trembling, then a shaking, and finally a rapid swaying, wriggling motion, describing a figure 8, which is extremely destructive and overthrows the buildings affected, and even in the open country it is impossible to keep one's feet. The surface of the ground has been repeatedly observed to rise in low, very swiftly moving waves, somewhat like those on the surface of water, upon the crests of which the soil opens in cracks, closing again in the wave-troughs. When the earth-waves traverse a forested region, the trees sway violently from side to side, like a field of ripe grain in the breeze. In the details of movement earthquakes differ greatly from one another; sudden and extremely violent vertical shocks may come from below, or the surface may writhe and twist in every direction, instead of rolling in waves; there may be only a single shock, or many successive ones.

Lisbon, Portugal, November 1, 1755

Magnitude: 8.6; 60,000 people killed.

Most of Lisbon's 250,000 inhabitants were at church for All Saints' Day when the first quake struck at 9:40 a.m. on November 1, 1755. It was followed by an even more powerful tremor, which sent buildings toppling down on the terrified populace. Huge waves generated by the quake crashed over the quays, drowning thousands and causing widespread damage. Fire raged through what was left of the city, burning for three days. Other countries also experienced a great deal of destruction in the Lisbon quake and associated tsunamis. For instance, approximately 10,000 people died in Morocco alone.

San Francisco, California, April 18, 1906

Magnitude 8.3; 700 people killed.

Most of San Francisco lay in ruins after movement along 270 miles (430 kilometers) of California's San Andreas fault generated an 8.3 earthquake. However, it was the post-quake fire, which swept through the city that caused most of the damage.

Kansu, China, December 16, 1920

Magnitude 8.5; 200,000 people killed.

The Kansu region had been earthquake-free for 280 years before this disastrous quake struck. A great deal of the damage was due largely to poor soil conditions throughout the province with intense shock waves causing violent undulations of surface clay and several landslips. An area 280 miles by 95 miles (450km by 150km) was severely affected by landscape deformation. Ten cities suffered widespread destruction and heavy casualties.

Tokyo-Yokohama, Japan, September 1, 1923

Magnitude 8.3; 143,000 people killed.

The 1923 earthquake was one of Japan's worst natural disasters. The ground shook for five minutes as the Sagami Bay Fault ruptured. Thousands of buildings collapsed and a tsunami measuring 36 feet (11 meters) struck the coast. Most destructive of all were the resulting fires. A massive firestorm swept through Tokyo, destroying two thirds of the city's remaining buildings and burning thousands. A commemoration service is held annually in Tokyo on the anniversary of the catastrophic event.

Agadir, Morocco, January 13, 1960

Magnitude 5.9; 12,500 people killed.
Although smaller in size seismically than other historical earthquakes, the 1960 Agadir quake still caused tremendous damage. Occuring directly under the town of Agadir, Morocco, it reduced the town to ruins in seconds. Thousands of people were buried beneath the vast piles of rubble. Destruction was so wide-spread that rebuilding was considered out of the question, and the area was abandoned.

Tangshan, China, July 27, 1976

Magnitude 8.0; 255,000 people killed.
This is probably the greatest death toll from an earthquake in the last four centuries, and the second greatest in recorded history. An additional 800,000 people were reported injured. Damage extended as far as Beijing, but was particularly extensive in the Tangshan area.

Mexico City, Mexico September 19, 1985

Magnitude 8.1; 9,500 people killed.
Felt by almost 20 million people, this devastating earthquake injured nearly 30,000 people and left more than 100,000 people homeless. Severe damage was caused in parts of Mexico City, as well as several central Mexico states. In Mexico City, 412 buildings collapsed and another 3,124 were seriously damaged. A large percentage of the buildings that were damaged in Mexico City were between 8 and 18 stories high, indicating resonance effects due to the soft soils under the city.

Armenia, USSR, December 7, 1988

Magnitude 6.8; 25,000 people killed.
About 19,000 people were injured and 500,000 left homeless in the Leninakan-Spitak-Kirovakan area of northern Armenia, USSR. More than 20 towns and 342 villages were affected, 58 of them destroyed completely. Spitak was almost totally destroyed, and one-quarter of the housing units in Leninakan were destroyed or damaged.

Northridge (Los Angeles), California, January 17, 1994

Magnitude 6.8; 60 people killed.
In addition to killing 60 people, this early morning quake injured more than 7,000 people and left 20,000 homeless. More than 40,000 buildings were damaged in Los Angeles, Ventura, Orange, and San Bernardino counties. Damages were estimated to be in the range of $20 billion (U.S.)

Kobe, Japan, January 16, 1995

Magnitude 6.8; 5,530 people killed.
The Great Kobe Quake as it is called, killed 5,530 people, injured another 37,000. There was extensive damage in the Kobe area and on the island of Awajishima with more than 200,000 buildings damaged or destroyed. Total damages were estimated at US$100 billion.

Gölcük,Turkey, August 17, 1999

Magnitude 7.6; 17,000+ people killed.
More than 17,000 people were killed in this massive earthquake and many more were left homeless since many buildings were uninhabitable. Thousands of families in the region have been living in tent cities in fields since the quake.

Nanaou, Taiwan, September 20, 1999

Magnitude 7.6; 2,200+ people killed.
This 1999 quake killed more than 2,200 people and left several thousands more homeless. Thousands of families in the region have been living in tent cities in fields.

The 1990 Baguio City Earthquake

Looking back, it was exactly 4:26 p.m. on Monday, 16 July 1990, that a killer earthquake unexpectedly hit and extensively devastated the City of Baguio. As reported, the powerful temblor measured 7.7 in the open-ended Richter scale and lasted for 45 seconds. It was said to be the most destructive earthquake on record within the Cordillera Region. There were numerous aftershocks that followed and the strongest, which occured at 3:15 a.m. of July 18, lasted for eight seconds ... and measured 5.3 on the Richer scale.

Fearing for their lives, many of Baguio's 120,000 people slept outdoors on Monday night. The city suffered the most in terms of destruction to properties and numerous deaths. Many commercial and government buildings, hotels, inns, and residences were heavily damaged. The death toll continued to rise as rescuers pulled more bodies from the rubbles. It was estimated that as many as 1,000 people were trapped and killed in damaged buildings.

The five-star Hyatt Terraces Plaza sustained the worst damage when its terraced front collapsed onto the lobby area, killing about 50 people. The Baguio Park Hotel along Harrison Road was a total wreck. The luxurious Nevada Hotel which is located right across from the main gate of Camp John Hay was ripped in half by the quake, leaving a huge gash in the middle of the structure. The Saint Vincent Catholic Church along Naguilian Road was spared by the strong quake, however a portion of its retaining wall and parking area was damaged and collapsed to the road below. The church, which has withstood typhoons, bombings during the 2nd World War, and other disasters, suffered only minor damage.

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