The oldest formation in El Salvador from the Jurassic period is found around Metapan, a metropolis in the northern portion of El Salvador, while the youngest at San Salvador is from Holocene period ( after 0.011 Ma ) . The geology of El Salvador can be outlined as follows: The formation spreading over both the south coastal part and cragged part North of San Salvador ( Morazan group ) are from the Holocene period, and they were formed during the Oligocene to the Miocene period. The in-between part of the state consists of the Balsamo group formations from the Pleistocene period. Volcanic and pyrogenic stones are distributed countrywide in El Salvador. Basalts, andesites, rhyolites, lavas and pyroclastic stones are found in mosaic.
Alliviums are found spread merely along the southern portion of the coastal part. Granites and Limestones are found isolated in a little part at the northwest terminal of the state.El Salvador is situated in an intertropical Convergence zone ( ITCZ ) , with a high seismal topographic terrain prone to hurricanes, temblors, Landslides and vent eruption, ( USGS 2004 ) .
In November 1998, Hurricane Mitch, ( fig.4 ) killed 240 people, displaced 85,000 bing the state about $ 388 million in harm. On January 13th and so on February 13th 2001, a series of temblors and associated landslides killed 1159 people, destroyed 300,000 places, bing the state about $ 1.6 billion in amendss, ( fig.6 ) ( Crone, et Al ) doing it the 5th largest temblor in 50years. The last temblor before this 1 was the upper crustal event that struck San Salvador in October in 1986, go forthing 1500 dead and causing amendss equivalent to 31 % of GDP in the same twelvemonth.
Similar to these temblors are the destructive temblors that occurred in 1951 and 1965. Besides in 1917 there was an eruption of the San Salvador vent in which lava covered portion of the northern zone, making a Crater Lake inside the Boqueron when it evaporated and a clinker cone appeared, making a unsmooth country that remains unpeopled boulder clay day of the month ( fig.5 ) .FIGURE 4.Satellite image of Hurricane Mitch, ( http//osei.noaa.
gov/Events/Tropical/Atlantic/1998/Mitch_10/TRCmitch299B_G8.jpg ) .File: Boquer & A ; Atilde ; ?n crater.
jpgFIGURE 5: Boqueron crater with Boqueroncito cinder cone visible at the underside ( hypertext transfer protocol: //upload.wikipedia.org/wikipedia/commons/3/36/Boquer % C3 % B3n_Crater.
jpg ) .hypertext transfer protocol: //upload.wikimedia.org/wikipedia/commons/7/73/ElSalvadorslide.jpgFIGURE 6: Landslide caused by temblor in 2001 ( hypertext transfer protocol: //en.wikipedia.org/wiki/2001_EL_Salvador_earthquakes ) .
Vents have been kinder in recent old ages, although landslides triggered in loose sedimentations on their inclines have had a awful impact. Landslides are the consequences from Hurricanes and temblors. The mudslide triggered on the inclines of the San Salvador vent ( fig.3 ) by heavy rainfall in September 1982 buried 500 people and go forthing 2400 homeless ( fig.6 ) , ( CEPRODE,2000 ) .
On October 1st 2005, the vent Santa Ana ( Ilamatopec ) ( fig.8 ) erupted. Due to early warnings by the SNET ( Servicio Nacional de Estudios Territoriales ) which was charged with the duty of extenuating natural jeopardies through jeopardy word picture, monitoring, and sensitisation ( Rose et Al, 2004 ) , evacuated the locals through the Civil Protection Service minimising the extent of harm. The undermentioned twenty-four hours October 2nd Hurricane Stan struck the country doing a Lahar that swept from the upper wings of the vent, travelled seven kilometers, killing two people and destroyed several places in its way which so terminated in Lake Coatepeque ( fig.3 ) . There are three big metropoliss in El Salvador, each located on the wings of possible active vents ( San Salvador, Santa Ana and San Miguel ) ( fig.8 ) , masquerading as beautiful lakes, but has one time devastated El Salvador four times in the past 56,000 old ages, ( Dull, 2004 ) and besides in the Centre of El Salvador is Ilopango Caldera ( fig.
8 ) which is another active vent, ( Mann et al ) . Most of these vents are likely to be active once more.
Due to the extended volcanic activities pyroclastic flows have blanketed the part with important thickness of ignimbrites. The northern mountain of El Salvador is believed to be at the border of the Central America Highland, associated with the Chortis Block ( Rogers 2002 ) . There appears to hold been three tectonic events that have had the greatest consequence on the morphology and construction of the northern mountain scope of El Salvador.The first and oldest event was the in-between Miocene silicic ignimbrite outburst which lasted approximately 10 million old ages ; and ended suddenly 10 M.A. B.
P. This extrusive event deposited up to 2 kilometres of ash on the southern boundary lines of the Chortis Block ( fig.9 ) , ( Rogers 2002 ) .hypertext transfer protocol: //www.harcourtschool.com/activity/pompeii/images/subductionS.jpgFIGURE 7: An illustration of Cocos and Caribbean Plates Passing under each other, ( Lyon-Caen, et Al ) .
hypertext transfer protocol: //www.geo.mtu.edu/volcanoes/central_america/el_salvador/elsalvvolcs.gifFIGURE 8: Location of major metropoliss and important quaternate vents in El Salvador, ( hypertext transfer protocol: //geo.mtu.edu/volcanoes/central_america/el_salvador/ )FIGURE 9: An Illustration demoing the geological formations of the northern mountains of El Salvador ( Modified from Lyon-Caen, et Al ) .
The 2nd event was the North-South extension of the part sometime after the deposition of the Miocene aged ignimbrite ( fig.9 ) . This extensional event may hold been the consequence of extraneous subduction of the Cocos home base underneath the Caribbean home base ( fig.
7 ) and therefore doing a series of east to west swerving arrest grabens ( Mann 2006 ) .The 3rd event was the east-west extension of the Central America Highlands. This was caused by activity along the left-lateral Motagua translational mistake in Guatemala. This extension is believed to be responsible for the development of the upper Rio Lempa watershed for the North-South system of mistakes, and the associated north-south trending drainages that are the locations for many of the Landslides in the part and the Landslides.Since the formation of the Central America Range, the western part has been continuously widening, organizing terrain dominated by north-southwest running horsts and grabens. This is most likely the consequence of the distal effects of the left sidelong strike-slip gesture of the Motagua mistake on the Caribbean home base ( Rogers 2002 ) . Many other big grabens have been formed in the Sula graben in western Honduras ( fig.
10 ) . The headwaters of the Rio Lempa, location near the boundary lines between El Salvador, Honduras and Guatemala is besides within a graben. This graben runs through Honduras and terminates in El Salvador. Smaller mistakes can be observed running paralle to the larger graben throughout the part.
These are believed to hold formed under the same emphasis conditions.FIGURE 10: Map of Northern Central America demoing regional extension in the signifier grabens due to distal emphasis from the North America and Caribbean Plate gesture ( Modified from Lyon-Caen, et Al ) .The jobs posed by temblors and Landslides are the uninterrupted eroding of the route that wraps around the scarp of the landslide and other agricultural utilizations and besides the deficiency of equal fixs and beef uping of harm edifices an issue non addressed by codification.
Features of Storm-Induced Landslides
In comparing to the other three states where pos-hurricane Landslide surveies are being conducted, the impact of Landslides in El Salvador was modest and geographically limited. The abundant rainfall associated with the storm did do tonss of Landslides in assorted parts of the state, but overall, the impact of these Landslides was far less serious than human losingss and harm caused by deluging in El Salvador. In parts of Honduras, Nicaragua, and Guatemala, Landslides denuded about full inclines in some drainage basins ( Harp et al, 2002 ; Bucknam et Al, Cannon et Al, 2001 ) , in contrast, in El Salvador, the Landslides were widely scattered, and although they did do serious jobs locally, they did non make a major national catastrophe.Virtually all of the Hurricane Mitch Landslides in El Salvador were shallow failures that involved the down slope motion of chiefly unconsolidated surficial stuffs that are the merchandise of deep tropical weathering.
Most of the Landslides moved down incline as by and large consistent multitudes and stopped at the base of a steep incline, but many of these multitudes became internally fragmented by the clip they stopped traveling. In some instances, the deposit in these Landslides contained adequate H2O to go more unstable and germinate into dust flows, ( Crone, et Al ) .Debris flow can be really detrimental and lifelessly because they travel quickly and can flux down the comparatively low-gradient inclines of watercourses and vales. In add-on to Landslides caused by Hurricane, this includes both complex Landslides that have seemingly been inactive for a long clip and persistently active Landslide composite. Most of the inactive Landslides have distinct, but rounded caput scarps hummocky topography and most appear to be earth slides and Earth flows. Some involve big volumes of stuff and are deep-rooted failures that include the unconsolidated surface dirt and implicit in bedrock. These pre-Mitch Landslides include both translational and rational Landslides.
The most outstanding active, pre-hurricane Landslide is the El Zomopera Landslide ( fig.11 ) , near the Honduran boundary line ; a big retrograde earth-slide debris-flow.When Hurricane Mitch destroyed important wellness and conveyance substructure in El Salvador in 1998 ( fig.4 ) , the wellness sector was set back by decennaries, ( World Bank ) . The Climatic state of affairs created black impact where vulnerable populations faced:DiseasesMore Extreme WeatherWorsening Agricultural OutputsDamage To Primary Industries and FisheriesNatural CatastrophesWater Shortage.
FIGURE 11: Position of the nor’-east of the upper portion of El Zompope Landslides,( hypertext transfer protocol: //landslides.usgs.gov/research/other/centralamerica.
In the last decennary, the comparative deficiency of conjunct attempts in jeopardies extenuation probably reflects the badness of more immediate demanding jobs such as H2O quality, sanitation, assorted wellness issues, etc. The combined consequence of Mitch and the 2001 temblors, nevertheless, has had an impact. In response to these, the Salvadorian authorities has taken the bold measure in the past two old ages to set up a new authorities bureau Servicio Nacional de Estudios Territoriales ( SNET ) in the Ministerio de Ambiente and Recursos Naturales ( Lopez, et Al ) . The new ministry purposes to cover with the extenuation of natural jeopardies, and it will seek to consolidate and beef up substructure. Work on jeopardies word picture involves proficient facets such as monitoring of temblors, vents, meteorology/hydrology and inclines. But instruction of the populace about hazard is severely needed. Geosciences instruction in Salvador is minimum ; the lone university grade plan in the state is one in natural philosophies with an option in geophysical sciences and preparation in earthquake-resistant structural design is besides limited.
The people of E cubic decimeter Salvador lived in an highly active geological scene and are exposed to multiple types of geological jeopardies. Destructive Landslides, inundations, hurricanes, temblors and volcanic eruptions are natural events that can non be prevented. They have occurred in the yesteryear, and similar events will surely happen in the hereafter. With equal planning and progress readying, the damaging effects of these destructive events can be moderated.Sing the one million millions of dollars in losingss that occurred in El Salvador since 1998, stairss to cut down future losingss are cost-efficient investings. The development of Landslide susceptibleness maps, inundation and debris-flow flood maps, and seismal and volcanic jeopardies maps will supply public functionaries with valuable tools to assist steer future development and to assist place countries where bing development is exposed to natural jeopardies.
Hurricanes Mitch and the two lay waste toing temblors have created a new consciousness in El Salvador of the demand to fix in progress instead respond after a catastrophe occurs. Scientific information such as the stock list contained in this study can be utile in planning and readying can salvage the lives of Salvadorians and minimise the adversities that consequences from destructive natural events such as Hurricane Mitch and Strong temblors.
I recommend that the International Community, the World Bank, International Donors and the United Nations should supply scientific, proficient and fiscal aid to back up the constitution of international Centre for the survey of regional and sub-regional establishments and webs devoted to turn toing the jobs caused by natural catastrophes chiefly those associated with utmost conditions events and temblors. I encourage international joint observation, research and the airing of scientific cognition for effectual catastrophe and hazard decrease of sudden-impact catastrophe ( e.g. storms, temblors, volcanic eruptions ) and slow-onset catastrophes ( e.g.
sea degree rise ) and guarantee broad airing of warning.