Volcanic eruptions can have significant effects on crop production. Ash fall from eruptions can damage or kill crops, especially if a thick layer of ash is deposited. Certain growth stages for crops like corn, tomatoes, and squash are particularly vulnerable to ash fall. Mitigation efforts include removing ash from leaves and mixing thin layers of ash into topsoil. Other volcanic hazards like lava flows, landslides, and lahars can destroy property and infrastructure. Predicting eruptions relies on monitoring changes in factors like gas emissions, seismic activity, and surface tilting near active volcanoes. The only active volcano currently in India is located on Barren Island.

2. VOLCANIC ERUPTIONS AND
ITS EFFECTS ON CROP
PRODUCTIONS

3. VOLCANIC ERUPTIONS:
It is a natural geological hazard.
Volcanoes occur at tectonic plate boundaries and at hot spots, where molten
rock , or magma, forms and rises to the surface.
Most of the volcanoes are located at or near tectonic plate boundaries.
The temperature, pressure, and fluid content of rock play roles in the formation
of magma.

4. Classification of volcanoes
The processes and deposits dictate the morphology
of volcanoes.
Three types of volcano:
Volcanoes are classified according to their morpholog

5. Cinder Cone Volcanoes
• A cinder cone volcano is a
relatively small, volcano with
steep sides. It is where rock
and ash shoot up into the air
and fall back around the
opening.
• Materials Erupted: small pieces
of hardened lava (rock
fragments) - called cinders
– Moderately explosive
• Example: Paricutin (Mexico) .

6. Volcanoes that alternate
between periods of lava flows
(constructive phase) and
periods of explosive eruptions
(destructive phase).
Commonly called “composite
volcanoes” because they are
made up of both lava and
pyroclastic deposits.
Steep slopes, at angle of
repose or greater.
Stratovolcanoes
© Noemi Emmelheinz 2001

7. Shield volcanoes: dominated by lava
flows
• Dominated by fluid, high temperature,
low viscosity basaltic magma.
• A shield volcano is broad with gently
sloping sides and has quiet eruptions
like those in Hawaii
• Basaltic lava can also flow through
large cracks called fissures.
• Under water flood basalts are
responsible for creating much of the
new seafloor

8. Volcanic Hazards
Damage limited to the vicinity in the immediate area of the
volcano.
Lava flows
Commonly destroy property in Hawaii and Iceland.
Fatalities rare due to slow
speed of advancing lava
flow.

9. Different types of lava
Aa type of lava Pahoehoe:
Pillow lava
Blocky lava

11. Ash fall
Extensive property damage and fatalities can result
from heavy ash falls.
Significant ash in the upper atmosphere can circle
the globe in a matter of weeks.
More than 80 commercial jets have been damaged
by flying through volcanic ash clouds.

12. An ashfall 10 million years ago killed these rhinos that are preserved at Ashfall Fossil
Beds State Historic Park, Nebraska.

13. Ash fall and its effect on crops
Plantation forestry on the slopes of Mt
Etna during the 2002 eruption,
unaffected by several millimetres of
fallen ash;

14. Acid rain damage to coffee
plantation

15.  The high sulphur concentration adhered to the ash may induce copper and
cobalt deficiencies in the long term.
 Ash falls greater than 10-15 cm (4-6 in) typically result in the complete
burial of pastures and soil. the soil will become sterile
Periods when crops are most at risk
 Pea : from emergence until end of flowering.
 Squash : during the initial stages of growth and flowering.
 Tomatoes : during seed emergence and flowering stages.
 Sweetcorn : during the early stages of growth
 The most critical period for corn yields is between three weeks before
tasselling to two weeks after pollination. Even light ash falls during this
period could result in barren stalks and crop failure

16. Mitigation measures
O Remove ash from leaves.
O Where ash falls have been around 5-25
mm, clear ash from the base of trees to
prevent plant disease or death from crown
rots fostered by the contact of damp ash
with the trunk
O Mix thinner layers of ash into the topsoil.
O Where plants have been partially
defoliated, fruit should be thinned .
Applying fertilizer will also promote the
growth of new leafs

17. Red Hot Pyroclastic Cloud with Lightning
Chile, South America

18. Lahars can be the most devastating outcome of many
volcanoes.
Water and debris rushed down the slopes, picking up more
debris along the way.
The lahar killed 28,700 people
and destroyed over 5,000
structures in the Amero
A 5 metre wall of water and
debris slammed into the
town of Amero, 72 km from
the volcano

19. Landslides
Landslides can be generated when a volcano collapses during
an eruption.
During the Mt. St. Helens eruption 2.3 km3 of debris slid down
the mountain at speeds up to 240 km/hr.
The slide traveled over 24 km and left a 45 m deep deposit.
350,000 years ago Mt. Shasta experienced a similar eruption and
landslide that was 20 times greater than that of Mt. St. Helens.

20. Gas emissions

21. Lake Nyos 10 days after the 1986
eruption
Gas concentrations in the soil in some
areas near the mountain are high
enough to kill trees and small animals.

22. Approximately 260,000 people have been killed by
volcanoes in historic times…most by a handful of individual
eruptions.

23. Prediction of Volcanic Eruptions
Identify volcanoes and the frequency and style of their
eruptions (a geological problem).
Long Term Prediction
Establish the level of risk based on historic and geologic
record.
Preparing hazard maps
VDAP is the only rapid-response volcano crisis team in the
world

24. Short-term prediction
Gas emissions: rates of emission and type of gas
changes in some volcanoes
Earthquakes: generated as the magma moves up
Seismicity and geochemistry are two of the technics for monitoring
active volcanoes

25. Surface tilting: recognition of changes in the land surface
due to building pressure in the conduit.
A surface bulge appeared on Mt. St. Helens prior to its
eruption.
April 26 May 2
April 8, 1980

26. A combination of approaches is likely the key to short-term prediction.

27. Recent volcanic eruption in world Barren Island – Active Volcano in India
The only active volcano in India is located in
Barren Island. The volcano erupted twice in
recent past, once in 1991 and again in 1994-95,
Bárdarbunga
During 27 August 2014

28. M. Jyostna Kiranmai
TAM-2013-02
Dept. of Agronomy