Below is another re****t on the intensity / magnitude of the earthquake
from Japanese resarches.
China Quake Delivered Seismic One-Two Punch
****no Yuasa in Tokyo
Associated Press
May 15, 2008
The fault line that caused this week's devastating earthquake in China
probably buckled in two stages, and the hardness of the terrain
contributed to the wide reach of the damage, Japanese scientists said
Thursday.
The magnitude 7.9 quake on Monday struck in Sichuan Province but
rattled buildings as far away as Beijing, Shanghai, and Thailand. (See
photos of the earthquake's destruction.)
The quake has affected ten million people and may have killed as many
as 50,000, according to a revised death toll estimate released by the
Chinese government today.
Yuji Yagi, a seismologist at Tsukuba University, said data show the
155-mile (250-kilometer) Longmenshan Fault tore in two sections.
The first section ripped about 7 yards (6.4 meters). The second
sheared 4 yards (4.6 meters).
(Related: "Pandas, Tourists Safe After China Quake; Local Towns
Leveled" [May 14, 2008].)
But it wasn't the two stages that made the quake so damaging. The
shallowness of the epicenter=97only ten miles (ten kilometers)
underground=97contributed most to the temblor's destructive power, Yagi
said.
"The damage was very severe because the quake's epicenter was shallow
and the quake occurred in densely populated areas," Yagi said.
The other distingui****ng factor to the quake was the firmness of the
terrain in central China, which allowed seismic waves to travel large
distances without losing their power, Tokyo University seismologist
Teruyuki Kato said.
Kato contrasted the hardness of the land in China with that in Japan,
where patches of soft terrain can often blunt the reach of
earthquakes.
"The strata are very hard in the quake-hit region, and that allowed
the seismic waves to travel far, while their strength remained
intact," he said.
Japan is one of the world's most quake-prone nations, and media there
have focused on the possible role of shoddy construction methods in
the large death toll in the China quake.
Japan's most destructive quake in recent times was the magnitude 7.3
temblor in the western city of Kobe, which killed more than 6,400
people in January 1995.
Yagi calculated that the energy level of the China quake was 30 times
that of the one that struck Kobe.
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