Casualties and Damage
Based on our personal observations in the field, the two towns mentioned above (El Porvenir and
Rolando Rodriguez) were completely destroyed beyond recognition. About 2,000 people lived
there. We do not know how many people survived, probably only a few. We saw many cadavers
and dead livestock lying on the overbank and burnt for sanitary reasons. We do not know who
was responsible for these sanitary measures because we have not yet received the official report
in this regard. Many other smaller hamlets, isolated residences, and farms were destroyed.
Future hazard potential
The disaster of October 30, 1998 was produced by the coincidence of two discrete events, an
avalanche and extraordinarily heavy rains. Neither of these alone would have produced such
extensive damage to the surrounding area. In this respect it should also be noted that the towns of
El Porvenir and Rolando Rodriguez were only established a few decades ago in an area of high
geologic risk. To reduce the risk for new settlements near volcanoes, a comprehensive geologic
hazard study should be made.
In the absence of another episode of heavy rainfall, the deposit seems to be stable. In fact, there
is little mud or silt within the deposits at higher elevations to facilitate remobilization. However,
the conditions near the summit that favored the rockslide avalanche still exist. An altered and
fractured dacite occurs on steep slopes at a high elevation. Destabilizing events, such as an
earthquake or torrential rains, could produce another avalanche in an adjacent area. The
probability of such an extreme avalanche seems remote. However, an assessment of the
associated hazards and risks should be undertaken.
There have been press reports concerning a new eruption of Cerro Negro Volcano, southeast of
Casita. A report by Julio Alvarez Garcia (INETER) on November 10, 1998 and observations
made by two of our group (MFS and CS) during a short visit on Friday, November 13 have
determined that this report is false. Apparently the most recent lava flows of 1995 contained
enough heat to produce small steam clouds which were mistaken for a new lava flow.
Information contacts:
Michael F. Sheridan, SUNY at Buffalo (mfs@acsu.buffalo.edu)
Claus Siebe, UNAM, Mexico (csiebe@tonatiuh.igeofcu.unam.mx)
Christophe Bonnard, EPFL Lausanne, Switzerland (christophe.bonnard@epfl.ch)
Wilfried Strauch, INETER, Nicaragua (wil@ibw.com.ni)
Martha Navarro, INETER, Nicaragua (ineter@ibw.com.ni)
Jorge Cruz Calero, INETER, Nicaragua (ineter@ibw.com.ni)
Nelson Buitrago Trujillo, INETER, Nicaragua (ineter@ibw.com.ni) |
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