Nealtican lava flow field, Popocatépetl volcano: A window to the past and
Boulder, Colo., USA: The Popocatépetl volcano, located southeast of Mexico
City, stands as the second highest peak in Mexico and is considered to be
one of the potentially most dangerous volcanoes in the world, given its
record of highly explosive eruptions over the last 23,000 years.
Scientists have been studying the record of past eruptions from
Popocatépetl to better understand possible future eruption scenarios and to
mitigate potential risks. A new study published 25 February in GSA Bulletin took a
focused look at one of the largest lava flows from Popocatépetl—the
Nealtican lava flow—to evaluate its emplacement mechanisms and assess
future volcanic hazards.
Researchers studied the lava flow in its entirety by mapping units of the
lava flow, analyzing its forms and features, and performing chemical and
mineral analyses of the rocks.
“All of this work helps us to reconstruct the eruptive history of this flow
and to determine exactly what the basic characteristics were for this
eruption to occur,” said Israel Ramírez-Uribe, the lead author of this
study. “It’s important to study these phenomena so that we can better
anticipate future scenarios and mitigate the risks.”
Co-author Dr. Claus Siebe said, “We can determine the areas that have been
affected by past eruptions and then speculate on areas that may be affected
in the future. And if these areas are inhabited by people, we can tell
whether they might suffer the consequences of an eruption in the future.”
The Nealtican lava flow covers an area of ~70 km2 to the east of
Popocatépetl and was formed shortly after a highly explosive eruption known
as the Lorenzo Pumice, which is dated between 350–50 BCE. From examining
the layers of volcanic material, the Nealtican lava flow likely erupted
only months to years after the explosive Lorenzo Pumice eruption.
Unlike the oozing, low-viscosity lava flows we often see from volcanoes in
Hawaii, researchers determined that the Nealtican lava flows would have had
a much higher viscosity, traveling at a rate of only 1–33 meters per day.
Based on reconstructed eruption rates, it likely took ~35 years for the
whole Nealtican lava field to be emplaced.
While a lava flow moving this slowly would not pose a direct risk for loss
of human life, it would fully destroy existing structures and permanently
render agricultural areas useless.
The Nealtican lava flows and the preceding explosive Lorenzo Pumice
eruption would have significantly impacted pre-Hispanic settlements,
burying villages under volcanic material and causing an exodus of the local
population. Part of the pre-Hispanic Tetimpa settlement is currently buried
under ash and 30–100 m of lava, but the full impact of the eruption on
settlements closer to the volcano isn’t known.
“The archeological site of Tetimpa seems to be the outskirts of settlements
that are buried under tens of meters of lava flows, so the main
archeological material is still lying under the lavas and won’t be easy to
access.” said Siebe.
Notably, the rise and fall of large Mesoamerican cities like Teotihuacán
and Cholula coincide with the last major explosive eruptions from
Popocatépetl. The population exodus and subsequent relocation as a result
of the volcanic eruptions may have led to the rise of these important
cities in central Mexico.
If Popocatépetl produced a lava flow today similar to the extent of the
Nealtican lava field, it could severely damage the infrastructure of
existing towns in the vicinity of the volcano and displace local residents,
as it has in the past.
The millions of residents in the vicinity of Popocatépetl should be
prepared and aware of these volcanic hazards, as it is not a question of if
the volcano will erupt, but when.
“This volcano is an active volcano, and we don’t know when it will have a
high magnitude eruption again, but it will certainly have one, and we
should be ready for that,” said Siebe.
Ramírez-Uribe noted that “we must work with the communities at risk and try
to explain volcanic hazards and their effects not only from a technical
perspective, but also considering the socio-cultural aspects, religious
beliefs, and the worldview of inhabitants.”
The Late Holocene Nealtican lava-flow field, Popocatépetl volcano:
Emplacement dynamics and future hazards
by Israel Ramírez-Uribe, Claus Siebe, Magdalena Oryaëlle Chevrel, Dolors
Ferres, and Sergio Salinas
Author contact: email@example.com
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