NATURAL HAZARDS ENVIRONMENT OF THE CARIBBEAN: …

1 RAFI FOR DISASTER OF GEOGRAPHY & GEOLOGYTHE UNIVERSITY OF THE WEST INDIES, MONAKINGSTON 7, JAMAICANOTICENOTICEPLEASE DO NOT REPRODUCE THE CONTENTS PLEASE DO NOT REPRODUCE THE CONTENTS OF THIS LECTURE WITHOUT AUTHOROF THIS LECTURE WITHOUT AUTHOR S S PERMISSIONPERMISSIONT hank YouThank YouNATURAL HAZARDS ENVIRONMENT OF THE CARIBBEAN: AN OVERVIEW OF ACTIVE PROCESSESWe present a geologic, geomorphic, and geophysical background for the management of NATURAL HAZARDS and risks NATURAL Hazard processes are an essential part of how Earth functions These processes have been shaping the planet Earth for millions of years We often pay a high price for ignoring ground rules As far as possible we must try to match land use with geological constraintsIT IS EASY TO TRY CHANGES TO HUMAN BEHAVIOUR RATHER THAN CONTROLLING NATURAL PROCESSES NATURAL disasters result from human decisions How we choose to select building sites is critical in risk exposure We must strive to meet with geology, geomorhology, and geophysics We must discover the societal value of geological maps Physical Caribbean (From: NEIC, USGS)THE CARIBBEANP hysiographyNote.

2 Distribution of land area (brown)PLATE TECTONICS AND NATURAL HAZARDS IN THE CARIBBEAN The theory of plate tectonics is a simple yet comprehensive basis to explain how Earth works and how landforms were shaped. It is an elegant concept in that the theory allows for predictions to be made which could be tested against observations. The theory of plate tectonics thus provides a platform to address a variety of anthropologic/societal concerns in a quantitative/empirical way. Characteristics of tectonic plates, especially plate boundary zones and their working is critical to our understanding of NATURAL hazard processes, for example, how are earthquakes related to plate motions and what sorts of tsunami-generating sources may be found in different types of plate TECTONIC MAP, Modified from Munich Re. The Caribbean plate provides vivid examples of why and how NATURAL hazard processes occur in the AND VOLCANIC ACTIVITY DEFINE THE PRESENT-DAY CARIBBEAN PLATEE arthquake epicentres: black dots and centres: red triangles, open-activePlate boundaries and earthquakes in the Caribbean Region From: US Geological SurveyThe Caribbean PlateModified from National Geographic MagazineLANDSLIDE TRIGGERS ARE EARTHQUAKES AND TRIGGERS ARE EARTHQUAKES AND boundary zone of Jamaica, historical tsunami generating earthquakes, and hurricane Caribbean Plate is moving east-northeastward at a rate of approximately 18-20mm/yr relative to North America.

3 The plate boundary zone in the vicinity of Jamaica is complex. Hispaniola area: Oblique convergence between the Caribbean Plate and the Bahamas Platform. Jamaica area: Transpression. Cayman area-Central America: Strike-slip and transtension. ( Map modified from Grindlay, Hearne, and Mann, 2005)Hurricane TracksRainfall (Modified from MunichRe)Rainy months: VI (June)-XII (December)Maximum 24 hr rainfall in mm:Eastern part: 200-300 Western part: 300-400 CLIMATE CHANGE (Modified from MunichRe)El Nino yearEl Nino year: Increase in tropical storms in the Pacific Basin: Increase in tropical storms in the Pacific BasinDecrease in tropical storm activity in the Atlantic BDecrease in tropical storm activity in the Atlantic BasinasinLa Nina yearLa Nina year: Increase in tropical storms in the Atlantic Basin: Increase in tropical storms in the Atlantic BasinDecrease in tropical storm activity in the Pacific BaDecrease in tropical storm activity in the Pacific BasinsinTemperature Change: 1 Temperature Change.

4 1--30C in the Atlantic30C in the AtlanticMULTIPLE NATURAL HAZARDS MAP OF THE CARIBBEAN: VIEW OF THE WORLD S LARGEST RE-INSURER MUNICH RE.(Unit for Disaster Studies Map; modified with permission from Munich Re, 2002).SUMMARY NATURAL HAZARDS ON JAMAICA TROPICAL STORMS and HURRICANES:Zone 4on Saffir Simpson Scale, 210- 249 Km/hwith an exccedance probability of 10% in 10 years (equivalent to return period of 100 years). MAXIMUM 24 HOUR RAINFALL: 300-400MM (I/M2) LANDSLIDES; FLOODING; SEDIMENT-WATER FLOODS COAST LINE: Tsunami and Storm surge hazard. EARTHQUAKES: Zone 3 Probable Maximum Intensity MMVIII with an exceedance probability of 10% in 50 years (equivalent to return period of 475 years) for medium subsoil conditions. Kingston: A large city with Mexico City Effect .EARTHQUAKES:EARTHQUAKES:Zone 3 to 4: MMI VIIIZone 3 to 4: MMI VIII--IX and above Probable maximum intensity (Modified IX and above Probable maximum intensity (Modified MercalliMercalliIntensity Scale) with an Intensity Scale) with an exceedanceexceedanceprobability of 10% in 50 probability of 10% in 50 years (equivalent to a years (equivalent to a return periodreturn period of 475 years) for medium subof 475 years) for medium sub--soil soil : Large city with Kingston: Large city with Mexico City effectMexico City effect VOLCANOES:VOLCANOES:Last eruption before 1800 AD Last eruption after 1800 AD Last eruption before 1800 AD Last eruption after 1800 AD Particularly hazardous volcanoesParticularly hazardous volcanoesTSUNAMI AND STORM SURGESTSUNAMI AND STORM SURGES.

5 Tsunami and storm surge hazardTsunami and storm surge hazard TROPICAL STORMS TRACKS: Probable maximum intensity (SS: Saffir-Simpson hurricane scale) with an exceedance probability of 10% in 10 years(equivalent to a return period of 100 years) Zone 3: SS 3 (178-209 km/hr) Windward Zone 4: SS 4 (210-249 km/hr) LeewardACTIVE PROCESSES AND LANDFORMSA MODEL OF TROPICAL MONTANE A MODEL OF TROPICAL MONTANE STREAMSSTREAMSIN JAMAICA , MORPHOLOGY OF MONTANE STREAMS ARE LARGELY CONTROLLED BY A PLENTIFUL SUPPLY OF COARSE BEDLOAD FROM LANDSLIDES( AHMAD, SCATENA, and GUPTA, 1993, 85, 157-169).A CONCEPTUAL MODEL A CONCEPTUAL MODEL (1) The drainage density is low with the tributaries joining the 1) The drainage density is low with the tributaries joining the main stream at high stream at high angles.(2) In the mountains the valleys are narrow and deep with landsl(2) In the mountains the valleys are narrow and deep with landslideide--affected slopes and affected slopes and confined stream stream channels.

6 (3) Stream gradient is high, with local rapids at rock outcrops,(3) Stream gradient is high, with local rapids at rock outcrops,or boulder and rock block or boulder and rock block (4) Valley alluvium is characterized by extremely coarse sedimen(4) Valley alluvium is characterized by extremely coarse (5) Braiding, multiple channels, and bars are found where the va(5) Braiding, multiple channels, and bars are found where the valley widens, either locally or lley widens, either locally or near the coastal plains. In meandering streams an enlargement ofnear the coastal plains. In meandering streams an enlargement ofpoint bars in in coarse point bars in in coarse sediment is common at such is common at such places.(6) The depositional forms built by sand, pebbles, cobbles, boul(6) The depositional forms built by sand, pebbles, cobbles, boulders, and rock blocks are ders, and rock blocks are related to both the passage of high magnitude floods and size anrelated to both the passage of high magnitude floods and size and age of the nearest large d age of the nearest large RIVER (AHMAD, 2003)HOPE RIVER (AHMAD, 2003)YALLAHS RIVER, MAVIS BANK (AHMAD, YALLAHS RIVER, MAVIS BANK (AHMAD, 2005)2005)

7 FAN DELTA OF YALLAHS RIVER IN FAN DELTA OF YALLAHS RIVER IN 1963, TYNDALE BISCOE PHOTO1963, TYNDALE BISCOE PHOTOJ udgment Cliff Landslide, Judgment Cliff Landslide, 16921692 Example of a debris fan created by landslides triggered by the rExample of a debris fan created by landslides triggered by the rainfall associated ainfall associated with tropical storm Dennis, June 2005; Yallahs River, Robertsfiewith tropical storm Dennis, June 2005; Yallahs River, Robertsfield, , that the sediments in debris fans tend to block the main riNote that the sediments in debris fans tend to block the main river RiverYallahs River2005 LANDSLIDE DEBRIS FANSEDIMENTS HAVE RAISED THE SEDIMENTS HAVE RAISED THE CHANNEL BY ABOUT m CHANNEL BY ABOUT m P. RIVERP. RIVERHILL SLOPES:HILL SLOPES:Example:Evolution of hillslopes in the Neogene transpressional plate boundary regime of Jamaica is strongly influenced by landslides are typical manifestations of the gravity-induced erosive processes responsible for shaping the mountains and supply sediment to build alluvial fans and fan-deltas in the HAZARDS of slope of slope instability.

8 Sediment flooding. Land degradation. Alluvial fans are not only of academic interest Alluvial fans are not only of academic interest because they offer relatively flat building they offer relatively flat building sites. Alluvial fan fan flooding. Landslide debris is an economic debris is an economic FAULT ZONE MAKES A COMPRESSIONAL BEND IN THE ZONE OF LEFT-LATERAL STRIKE-SLIP DEFORMATION NEAR JAMAICATRANSPRESSION TRANSPRESSION ON JAMAICAON JAMAICASATELLITE IMAGE OF SPUR TREE FAULT SCARP AND LANDSLIDESA lligator PondManchesterPlateauLandslidesFault ScarpLandslide Inventory of Logwood,Lititz,Sea Air,New Forrest,Alligator Pond areas in of the old landslides were re-activated following the rainfall from tropical storm Emily in July Forrest to Alligator Pond Road follows a dry river of hillslopes in Jamaica are detachment-limited(or loosening limited) that is transportational process operating on the slopes are capable of removing slope materials at a faster rate than it is produced.

9 These slopes are generally steep and are decorated with amphitheatres or landslide hollows. Photo of the Morant River faulted mountain front near Hillside, ( A Tyndale Biscoe Photo from Buisseret, 1996)Blue Mountain ridgeHillsideMorant riverlandslideMt. MucangoJACKS HILL LANDSLIDE HILL LANDSLIDE ARE RAZOR SHARP, OFTEN ONLY A COUPLE OF METERS WIDE. IN PUERTO RICO, LARSEN AND OTHERS HAVE ESTIMATED SLOPE RECESSION RATES VARYING BETWEEN TO model of the Jack s Hill area showing landslide scars (red lines) and debris fans (orange lines). (Source: Virtual Field Trip DVD-ROM produced for 5thFaculty of Pure & Applied Sciences Conference, 2005)HOPE PASTURESBARBICANLANDSLIDE AND FLOOD HAZARDS ALONG THE FAULTED MOUNTAIN FRONT IN LIGUANEA. NATURAL DRAINAGE HAS BEEN PASTURESF orsythe Line TOWNHOPE RIVERUTECHMUD TOWNSky Line TOWND rainage outletRoad facilitates runoffRetaining WallIVAN RAINFALL MUDFLOWS; SEPT.

10 2004 VTDIVTDIMUD TOWN2004 debris flowsSPATIAL DISTRIBUTION OF MAJOR KNOWN SPATIAL DISTRIBUTION OF MAJOR KNOWN LANDSLIDES ON ON THE LOCATION OF COASTAL TOWNS NOTE THE LOCATION OF COASTAL TOWNS ON ANCIENT ALLUVIAL FANS BUILT BY ON ANCIENT ALLUVIAL FANS BUILT BY LANDSLIDE FANS ( RED DOTS ) AND FLOODING HAZARD. MODIFIED MAPD ebris flows, a flow type of landslide, may create spectacular debris fans, for example the Bluefields Debris fan built following the debris flows triggered by 1979 Flood Rains. Bluefields is located on an ancient fan characterized by abandoned dry river flowpath flooding is typical of these WAS ESTABLISHED FOLLOWING THE 12 JUNE 1979 FLOOD RAINSIN WESTERN JAMAICADEBRIS FAN IN BLUEFIELDSDEBRIS FLOWST yndale Biscoe PhotoBluefields Bay, Westmorland, 12 June 1979 STRUCTURAL MAP FROM DRAPER, 1987 FAULT TRENDSMAJOR LANDSLIDE ZONES AND FAULT SCARPSLANDSLIDE ZONESWAGWATER BELTLANDSLIDE LANDFORMS COVER kmLANDSLIDE LANDFORMS COVER km22, or 3,57% OF THE AREA IN THE PARISHES OF , or 3,57% OF THE AREA IN THE PARISHES OF KINGSTON AND ST.