the eruption Flashcards
what source do we have for the eruption?
PLiny’s letter to Tacitus provided only first hand account, which has since been proven with analysis by Sigurosson of the volcanic deposit at P.
why were ppl of Vesuvian unprepared for the eruption?
although new Vesuvius was volcano, didn’t know it was active as no record of precious eruption c.1200BC and no awareness of association between seismic activity and eruptions
what happened on Feb AD62?
massive earthquake
destruction to P, H, Nuceria
what did Seneca and Tacitus say about earthquake?
“i have just heard that P… has just been laid low by an earthquake which also disturbed all adjacent districts” -Seneca
earthquake “ largely demolished the populous Campanian town of P” - Tacitus
what was Nero doing at time of AD62 earthquake?
Nero performing at Odeon
what are the 2 phases of the eruption?
‘plinian’ phase - lasted bout 18 hours and produced rain of pumice
‘Pelean’ phase or nuee ardente devastating pyroclastic surges and flow
what happened in the plinian phase?
cloud column of toxic gas, ash and debris from volcano, basalt and lapilli (pumice stone) rose 20-30km. as Pliny the younger stated, resembled an ‘umbrella pine’
what explosion was heard on the morning 24 August AD79?
phreatomagmatic explosion showered fine ash over sides of mountain
when was the eruption?
24 august, AD79
how much of P was covered in layer of pumice by first phase?
2.8m think layer
what was the reaction of people of H in first phase?
estimated 5000 inhabitants escaped by early sign by boat (lack of it), others gathered on beach and vaulted boat houses (100 bodies found) on harbour front waiting for rescue
reaction of first phase in P?
10 000 inhabitants fled during 1st phrase - absence of horses and other animals for transport
at house of Meanders, cart packed with wine jars left behind
but family pets left behind e.g. dog with chain still attached to neck .
what may have impeded the people’s escape from first phase?
although create distance between volcano, increasing fallout, darkness and constant earth tremors at night may have impeded their escape with 48 bodies found outside town wall in direction of Harbour.
What happened to those waiting inside?
rising layer of ash and pumice trapped them inside.
394 victims found in layers of pumice at P, most inside home
to those venturing outside?
died from falling masonry e.e. temple of isis priests as crossing triangular forum, columns toppled over them.
what hit the towns on 25 August AD79?
hit by 6 surges (volcanic ash and superheated gases) and flows (larger fragments of volcanic material following topography of town made fluid like by high temp.)
what happened in second stage at H?
first surge blasted through town with force of hurricane.
e.g. women body crushed skull and pelvis found.
how did most victims die in second stage?
die of asphyxiation or thermal shock (bodies baked by intense heat) within two mins of surge.
struck down by projectiles and entombed by flow
what bodies was found in 1980-82?
discovered bodies in vaulted chambers of sea wall at H. Found body in natural position indicating death was instantaneous, incinerated by temp around 500 degrees.
what was the second surge at H like?
hotter and more powerful, responsible for widespread destruction of buildings
What did these two surges do?
both surges completely destroyed and covered H, failed to reach P stopping at Opolontis and Boscoreale
What happened with surge 3-6 at H?
grey pumice fell again and eruptive columns rose, collapse turning into surges and flows. these added volcanic debris to H, hidden under 20m of hardened volcanic material
WHat was different at H than P?
less pumice/ash fell and slow moving lava gave time for most ppl to escape
What happened by pyroclastic phase at P?
not hit by surge 1 or2 but hit by S3-6, ppl killed by asphyxiation or thermal shock
What happened with Surge 3 at P?
swept against city north wall demolishing parts of it, more grey pumice fell before more surges.
buildings interrupted various flows, hence layers of debris dense in countryside than inhabited areas.
S6 at P?
most severe, covering P with 90-110cm of material and knocking down all walls above layers of pumice from 1 phase that hit P.
Where were most bodies in layers of ash from surges and where? in P.
650 bodies found in open areas and streets or near city gate.
What did the fine ash left by surge allow for in P?
casts of body that reveal fine details
PLiny the younger description of S6:
“everything appeared change, covered by thick later of ashes like an abundant snowfall”
conclusion, what happened to P and H?
both devastated by pyroclastic surge/flow, not just pumice and ash in P and mudslides in H
TOtal number of fatalities unknown
The eruption P: when?
24 August AD79
The eruption P: according to pliny, what did it look like?
a pine tree shaped coloumns of super heated gases, ash and lapilli/pumice
The eruption P: what happened?
violent tremors - many ppl fled. Some remained in city
The eruption P: rate of air fall deposits fell
at approx 12-15cm per hour
The eruption P: wht phase was fatal?
hot gas avalanches mixed with other debris (second stage)
The eruption P: what probs accounted for most of death?
gaseous surges
The eruption P: how much ash covered?
4m thick mantle of ash
things grow on it and disappear
The eruption at H: why would the experience be diff from P?
due to wind direction (town was upwind of Mt Vesuvius) and topographical location.
The eruption H: what was it spared?
the fall of ash and lapilli, but surge of gas and ash rolled down upon city.
The eruption H: what did the super hot volcanic debris and mud do?
carbonised many wooden and organic materials, hardened into rock like consistency. it then flowed into sea.
within how many hours did both cities decimate/disappear?
18 hours
what could the Roman residents see and smell?
according to dio cassius, could see and smell the clouds of ash
what made recovery/excavation ineffective?
winter rain hardned ash and pumice
what did the cities disappear under?
soil and grass and cities on top
how much ash was covered in H?
13m covered in more debris than P
after eruption, what happened to the 2 cities
eruption spanning 2 days, bureied under 4-6m of ash and pumice for 1500 years.
only rediscoered in 1599 by accident
value of P?
today, is a world heritage site (most popular arch. site due to preservation) and very popular tourist desitination
