The frequency and distribution of recent landslides in three montane tropical regions of Puerto Rico

Landslides are common in steep mountainous areas of Puerto Rico where mean annual rainfall and the frequency of intense storms are high. Each year, landslides cause extensive damage to property and occasionally result in loss of life. Average population density is high, 422 people/km2, and is increasing. This increase in population density is accompanied by growing stress on the natural environment and physical infrastructure. As a result, human populations are more vulnerable to landslide hazards. The Blanco, Cibuco, and Coamo study areas range in surface area from 276 to 350 km2 and represent the climatologic, geographic, and geologic conditions that typify Puerto Rico. Maps of recent landslides developed from 1:20,000-scale aerial photographs, in combination with a computerized geographic information system, were used to evaluate the frequency and distribution of shallow landslides in these areas. Several types of landslides were documented—rainfall-triggered debris flows, shallow soil slips, and slumps were most abundant. Hillslopes in the study area that have been anthropogenically modified, exceed 12° in gradient, are greater than 300 m in elevation, and face the east-northeast, are most prone to landsliding. A set of simplified matrices representing geographic conditions in the three study areas was developed and provides a basis for the estimation of the spatial controls on the frequency of landslides in Puerto Rico. This approach is an example of an analysis of the frequency of landslides that is computationally simple, and therefore, may be easily transferable to other settings.

[1]  R. Lal.  Soils of the Tropics: Properties and Appraisal , 1993 .

[2]  R L Shuster,et al.  Landslides: Analysis and Control , 1978 .

[3]  D. P. Franzmeier.  Soils and landscape evolution , 1992 .

[4]  Frederick N. Scatena,et al.  The effect of human activity on the structure and composition of a tropical forest in Puerto Rico , 1994 .

[5]  R. Birdsey,et al.  Forest Area Trends in Puerto Rico , 1987 .

[6]  T. Donnelly.  Geologic history of the Caribbean and Central America , 1989 .

[7]  Martin Haigh,et al.  Environmental correlations of landslide frequency along new highways in the Himalaya: Preliminary results , 1988 .

[8]  A. Bally,et al.  The Geology of North America: An Overview , 1989 .

[9]  Yang H. Huang,et al.  Stability analysis of earth slopes , 1983 .

[10]  V. M. Seiders.  Geologic map of the El Yunque Quadrangle, Puerto Rico , 1971 .

[11]  F. Scatena,et al.  Tropical Montane Cloud Forests , 1995, Ecological Studies.

[12]  Z. Aquino,et al.  Water resources data, Puerto Rico and the U.S. Virgin Islands Water Year 1994 , 1995 .

[13]  Herbert Riehl,et al.  Climate and weather in the tropics , 1979 .

[14]  Andrew Simon,et al.  Rainfall-threshold conditions for landslides in a humid-tropical system , 1993 .

[15]  J. Proctor.  Tropical rain forest , 1987 .

[16]  D. Varnes.  SLOPE MOVEMENT TYPES AND PROCESSES , 1978 .

[17]  H. F. Reid,et al.  The Porto Rico Earthquakes of October-November, 1918. , 1919, Bulletin of the Seismological Society of America.

[18]  J. Goldammer.  Tropical Forests in Transition , 1992, Advances in Life Sciences.

[19]  Matthew C. Larsen,et al.  How wide is a road? The association of roads and mass-wasting in a forested montane environment , 1997 .

[20]  A. J. Sánchez,et al.  Landslides Triggered by Hurricane Hugo in Eastern Puerto Rico , September 1989 , 1997 .

[21]  S. Trimble,et al.  The cow as a geomorphic agent — A critical review , 1995 .

[22]  R. E. Curtis,et al.  Water resources data, Puerto Rico and the U.S. Virgin Islands, Water Year 1990 , 1991 .

[23]  D. Keefer.  Landslides caused by earthquakes , 1984 .

[24]  R. Gierbolini.  Soil survey of mayaguez area of western puerto rico , 1975 .

[25]  Randall W. Jibson,et al.  Landslides triggered by earthquakes in the central Mississippi Valley, Tennessee and Kentucky , 1988 .

[26]  A. Lugo,et al.  METABOLISM AND EVAPOTRANSPIRATION OF SOME RAIN FOREST PLANTS AND SOIL. , 1971 .

[27]  W. Monroe.  Map showing landslides and areas of susceptibility to landsliding in Puerto Rico , 1979 .

[28]  A. Lugo,et al.  A Research Perspective on Disturbance and Recovery of a Tropical Montane Forest , 1992 .

[29]  J. Pitts,et al.  Physical adjustments in a changing landscape : the Singapore story , 1992 .

[30]  C. Klein.  The geology of North America—An overview , 1992 .

[31]  D. U. Deere,et al.  Slope Stability in Residual Soils , 1971 .

[32]  Geology of the middle Tertiary formations of Puerto Rico , 1980 .

[33]  G. Wieczorek,et al.  Preparing a Detailed Landslide-Inventory Map for Hazard Evaluation and Reduction , 1984 .

[34]  K. Terzaghi,et al.  Mechanism of Landslides , 1950 .

[35]  W. M. Gray.  Strong Association Between West African Rainfall and U.S. Landfall of Intense Hurricanes , 1990, Science.

[36]  G. Wieczorek,et al.  Landslides from the February 4, 1976, Guatemala earthquake , 1981 .

[37]  M. Larsen,et al.  Geographic relations of landslide distribution and assessment of landslide hazards in the Blanco, Cibuco, and Coamo basins, Puerto Rico , 1996 .

[38]  T. Mitchell Aide,et al.  Forest recovery in abandoned tropical pastures in Puerto Rico , 1995 .

[39]  H. Balslev,et al.  What Are TMCF?@@@Tropical Montane Cloud Forests: Proceedings of an International Symposium at San Juan, Puerto Rico 31 May-5 June 1993. , 1994 .

[40]  Randall W. Jibson,et al.  Debris flows in southern Puerto Rico , 1989 .

[41]  S. David.  Landslide distribution and earthquakes in the Bewani and Torricelli mountains, New Guinea; a statistical analysis , 1967 .

[42]  Manuel R. Guariguata,et al.  Landslide disturbance and forest regeneration in the upper Luquillo Mountains of Puerto Rico. , 1990 .

[43]  Frederick N. Scatena,et al.  Physical aspects of Hurricane Hugo in Puerto Rico , 1991 .

[44]  Russell H. Campbell,et al.  Soil slips, debris flows, and rainstorms in the Santa Monica Mountains and vicinity, southern California , 1975 .

[45]  Andrew Simon,et al.  The role of soil processes in determining mechanisms of slope failure and hillslope development in a humid-tropical forest eastern Puerto Rico , 1990 .

[46]  R. Picó,et al.  The geography of Puerto Rico , 1974 .

[47]  R. Briggs,et al.  Hydrogeologic map of Puerto Rico and adjacent islands , 1965 .

[48]  P. Reichenbach,et al.  GIS techniques and statistical models in evaluating landslide hazard , 1991 .

[49]  N. Brokaw,et al.  Earthquake-Caused Landslides: A Major Disturbance to Tropical Forests , 1979, Science.