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Japanese seismologist Yuji Yagi at the University of Tsukuba said that the earthquake occurred in two stages: "The 155-mile Longmenshan Fault tore in two sections, the first one ripping about seven yards, followed by a second one that sheared four yards." His data also showed that the earthquake lasted about two minutes and released 30 times the energy of the Great Hanshin earthquake of 1995 in Japan, which killed over 6,000 people. He pointed out that the shallowness of the epicenter and the density of population greatly increased the severity of the earthquake. Teruyuki Kato, a seismologist at the University of Tokyo, said that the seismic waves of the quake traveled a long distance without losing their power because of the firmness of the terrain in central China. According to reports from Chengdu, the capital of Sichuan province, the earthquake tremors lasted for "about two or three minutes".

Besides the population density, what else contributed to the severity of the quake?
Answer: shallowness of the epicenter
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Historically, AC motors were used for single or double speed elevator machines on the grounds of cost and lower usage applications where car speed and passenger comfort were less of an issue, but for higher speed, larger capacity elevators, the need for infinitely variable speed control over the traction machine becomes an issue. Therefore, DC machines powered by an AC/DC motor generator were the preferred solution. The MG set also typically powered the relay controller of the elevator, which has the added advantage of electrically isolating the elevators from the rest of a building's electrical system, thus eliminating the transient power spikes in the building's electrical supply caused by the motors starting and stopping (causing lighting to dim every time the elevators are used for example), as well as interference to other electrical equipment caused by the arcing of the relay contactors in the control system.

Throughout history, what type of engines were used for elevator machines?
Answer: AC motors
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Laird writes that Altan Khan abolished the native Mongol practices of shamanism and blood sacrifice, while the Mongol princes and subjects were coerced by Altan to convert to Gelug Buddhismor face execution if they persisted in their shamanistic ways. Committed to their religious leader, Mongol princes began requesting the Dalai Lama to bestow titles on them, which demonstrated "the unique fusion of religious and political power" wielded by the Dalai Lama, as Laird writes. Kolmas states that the spiritual and secular Mongol-Tibetan alliance of the 13th century was renewed by this alliance constructed by Altan Khan and Sonam Gyatso. Van Praag writes that this restored the original Mongol patronage of a Tibetan lama and "to this day, Mongolians are among the most devout followers of the Gelugpa and the Dalai Lama." Angela F. Howard writes that this unique relationship not only provided the Dalai Lama and Panchen Lama with religious and political authority in Tibet, but that Altan Khan gained "enormous power among the entire Mongol population."

Who did Altan Khan persuade to convert to Gelug Buddhism?
Answer:
the Mongol princes and subjects