MEXICO CITY (Reuters) -- A powerful earthquake that struck
                  southern Mexico this week damaged the important pre-Hispanic ruins of
                  Monte Alban, and other archaeological sites in the state of
                  Oaxaca, an official said on Saturday.

                  Samira Hernandez of the National Anthropology and History Institute
                  (INAH) in the state capital, Oaxaca City, said that 18 buildings in the
                  ancient Zapotec city of Monte Alban suffered moderate or partial damage
                  after Thursday's temblor.

                  "According to preliminary reports, 18 buildings were damaged partially or
                  moderately, some walls collapsed and stucco fell off," Hernandez told
                  Reuters.

                  Measuring 7.5 on the open-ended Richter scale -- in the same league as a
                  quake earlier this month in Taiwan that killed 2,000 and a temblor in Turkey
                  in August in which 15,000 died -- the earthquake could have wrought
                  severe devastation in built-up areas.

                  But it struck near the sparsely populated Pacific coast of Oaxaca and
                  originated deep below the ground, minimizing its impact. At the latest count,
                  the death toll stood at 19.

                  Founded in around 600 B.C. and abandoned around 1,300 years later,
                  Monte Alban looms over the Oaxaca valley from its vantage point on a high
                  hill outside the state capital.

                  With tombs found to be full of gold, silver and jade jewelry, the 25 square
                  mile (40 square km) site ranks as one of Mexico's premier archaeological
                  treasures.

                  Its temples, palaces and pyramids, some displaying Olmec influences from
                  the eastern states of Tabasco and Veracruz, were decorated with intricate
                  frescoes of what have variously been taken to be dancers, prisoners of war
                  or even the ceremonies of a bizarre sex cult.

                  Monte Alban became world known after the discovery, verified in 1932 by
                  Mexican anthropologists, of Tomb 7, a spectacular burial chamber filled with
                  treasures and ornaments in quantities rarely matched through the
                  Mesoamerican world.

                  Hernandez said a group of experts from Mexico City was inspecting the
                  ruins on Saturday and the site had been closed to tourists because of the
                  dangers of falling debris.

                  She said another precious archaeological site, Mitla, 25 miles (40 km)
                  southeast of Oaxaca City, also suffered some damage when the quake tore
                  through the state. But it appeared to have been spared the worst and was
                  open to tourists.