1 GLACIERS IN CHILE´S HIGH MOUNTAIN MINE EXPLORATIONS AND PROJECTS. The author thanks CODELCO- Chile’s Andina Division for permission to use data that was for it generated. Cedomir Marangunic Geoestudios

WHY GLACIERS MUST BE CONSIDERED AS EARLY AS BASIC EXPLORATION STAGES? BECAUSE: They are common in high mountain terrain. They are becoming “untouchables”, as well as their surroundings. They may pose serious hazards and risks.  Over 3,700 “white” glaciers.  Over 2,000 rock glaciers. CHILE’s GLACIER INVENTORY, so far: Estrecho glacier

ROCK GLACIER: Accumulation and ablation forms different from “white” glaciers. Pedregoso rock glacier Monolito rock glacier Trench at the surface of a rock glacier flowing from upper right to lower left. About 1,4 m thick rock debris covers the ice-core containing interspersed rock fragments. Flow

RECENT INCREASE OF REGULATIONS RELATING TO CHILE’s GLACIERS:  Since 2005: 3 proposals of laws to prohibit affecting glaciers. None approved, so far.  2008, November: changes to Environmental Impact Evaluation System regulations. A study must be produced when glaciers may be affected.  2009, April: National Environment Commission “Policy for Protection and Conservation of Glaciers“. Definition of glacier: any perennial ice mass, regardless of size and form. Even small snow-fields are now considered glaciers.  2010, January: message from President to Congress: Changes to Chile’s Constitution: “Waters are public national resources… glaciers included”. Message not yet discussed.

GLACIER RELATED HAZARDS AND RISKS Main hazards:  CATASTROPHIC SLIDE : large and sudden, of most of a glacier, affecting whole valleys.  GLOF phenomena (Glacier Lake Outburst Flood).  LAHARS : dense currents because of debris load, related to fast melting of glaciers on erupting volcanic cones.  SURGES : fast glacier advances, and related secondary effects (i.e. damming valleys).  TOPPLING of an ice mass from steep glacier terminus.

1980 APAREJO GLACIER SUDDEN CATASTROPHIC SLIDE: m 3 EMPTY GLACIER CIRQUE

HOW CAN MINE EXPLORATIONS AND PROJECTS AFFECT GLACIERS? By direct contact: excavations, dumps, cavities, roads, others. Changes in the glacier surface: most common by deposition of anthropic dust. Changes in the local topography altering patterns of: wind, snow, avalanches, insolation, etc. Changes in the drainage patterns: entering or issuing from glaciers, sub-glacial. Induced ground accelerations (blastings). Changes in the local micro-climate.

EFFECT OF DUST ON SNOW/ICE SURFACES increases of ablation rate on the surface of firn-snow artificially dusted with various concentrations of mainly (85%) silt size particles (21-60 m).

ABLATION RATES: Virgin site: 1.7 g/cm 2 -day Test site, 3.5 g/m 2 of compound: 2.7 g/cm 2 -day (59% increase) AERIAL DUSTING WITH A SMOKE-BLACK BASED COMPOUND, APRIL 1969: Coton Glacier. To increase ablation and river runoff. THE APPLICATION COST WAS LESS THAN THE VALUE OF GENERATED WATER. IMPORTANT INTERVENTIONS OF GLACIERS IN CHILE:  1969, Coton glacier dusted (ENDESA and Univ. of Chile).  , Andina’s open pit excavates rock glaciers.  Since: other mines and projects affect glaciers.

TO EVALUATE A PROJECT IMPACTS ON GLACIERS: 1)Define a PRELIMINARY PROJECT INFLUENCE AREA : 15 km radius from all explorations and project works, and above the contour line which is 500 m below lowest limit of known glaciers in region. 2)Identify and INVENTORY ALL GLACIERS within preliminary influence area. 3)Make a PRELIMINARY EVALUATION OF LIKELY IMPACTS on glaciers (be conservative). 4)Make BASE LINE STUDIES of presumedly impacted glaciers, and dust dispersion models. 5)IDENTIFY REALLY IMPACTED GLACIERS and effects. 6)CHANGE DESIGNS to prevent impacts; or/and PLAN FOR MITIGATIONS AND COMPENSATIONS. 7)Produce a GLACIER’s CONTROL AND MONITORING PLAN for the duration of project.

1.GENERAL DESCRIPTION: + temperature of the ice mass, & stratigraphy (mainly in rock glaciers). 2.ICE/SNOW (MASS) BALANCE: at surface and base. 3.HEAT BALANCE: at surface and base. 4.WATER BALANCE: precipitation data, evaporation, discharge, infiltration, intra- glacier phreatic levels, etc. 5.VELOCITIES OF MOVEMENT AND STRESSES: surface movement, basal sliding, surface strain conditions. 6.THICKNESS: from geophysical or electromagnetic data, and bore-hole. 7.GENERAL STABILITY: geotechnical stability analysis methods, and glacier bed material. 8.BIODIVERSITY: within the glacier and its surroundings. 9.VARIATIONS: Recent and Quaternary (or Holocene – last glaciation). CONTENT OF A GLACIER’S BASE LINE:

TO AVOID AFFECTING GLACIERS: SUPRESS DUST. RELOCATE INFRASTRUCTURE AND DEPOSITS. IF UNAVOIDABLE: MITIGATE AND COMPENSATE WITH GLACIER MANAGEMENT TECHNIQUES: Relocation of ice masses to dedicated and protected deposits, and control of ice losses in the process. Artificial reduction of surface ablation. Artificial increase of surface snow accumulation. Generating a new glacier (new technology – being tested).

A RELOCATED-ICE DEPOSIT: BETTER BEHAVIOUR THAN ON AN ICE-CORED ROCK GLACIER DURING  The pickup stands on a 32,000 tons ice deposit, 16 m deep, 2,400 m 2 surface area, covered with 1 m of “inert” rock-debris.  The deposit rests on a 1 m thick “inert” rock-debris layer.  Temperature sensors in post-deposition drill-holes, and ablation stakes anchored at the base.  No “hot spots” developed.  Less than 1% of ice mass lost during relocation.  ACHIEVEMENT: Ice melting rate is lower (half) than on ice-cored rock glacier.

A NEW MINI-ROCK GLACIER TO LAST OVER 2 CENTURIES. Results of summer summer 2010 surface elevation reduction of a relocated and protected, 32,000 tons, 16 m thick ice deposit.

GENERATING A NEW GLACIER: initial avalanche-snow accumulation area, to be developed in 2011, diverting into it avalanches using earth trench-wall systems. THANK YOU TRANSFORMING A SNOW FIELD INTO GLACIER: increasing snow accumulation with a snow-fence.