user: You are a structured reasoning expert tasked with solving problems step by step. 
You first think about the reasoning process in the mind and then provide the answer. The reasoning process and answer should be enclosed within <think> </think> and <answer> </answer> tags, respectively, i.e., <think> reasoning process here </think> <answer> answer here </answer>. 
Given a question and the associated knowledge graph triplets (entity, relation, entity), you are asked to answer the question with these triplets and your own knowledge. 
You can break down the original question into several sub-questions and explore the given knowledge graph to solve them step-by-step. If there are multiple possible answers, choose one as the final answer. 
After thinking, when you finally reach a conclusion, clearly state the answer within <answer> </answer> tags, i.e., <answer> answer here </answer>. 
Question: when did the san francisco earthquake occur? 
Knowledge Triplets: San Francisco, freebase.valuenotation.is_reviewed, Time zone(s)
Looking Down Sacramento Street, San Francisco, April 18, 1906, base.newsevents.photograph.photographer, Arnold Genthe
m.09yv5y4, common.webpage.topic, San Francisco
San Francisco, location.location.containedby, United States of America
1906 San Francisco earthquake, base.newsevents.photographed_event.photograph_s, Looking Down Sacramento Street, San Francisco, April 18, 1906
m.09y22fm, common.webpage.topic, San Francisco
m.0b4827b, common.webpage.topic, San Francisco
San Francisco, book.book_subject.works, 7th Heaven
m.09y204d, common.webpage.topic, San Francisco
Looking Down Sacramento Street, San Francisco, April 18, 1906, common.topic.image, San Francisco Fire Sacramento Street 1906-04-18
Jack London, event.disaster_survivor.survived_disasters, 1906 San Francisco earthquake
San Francisco, common.topic.webpage, m.0b48p4h
San Francisco, common.topic.webpage, m.09wcrgb
San Francisco, common.topic.webpage, m.09yvkr0
San Francisco, common.topic.webpage, m.09xhnkt
1906 San Francisco earthquake, common.topic.image, Post-and-Grant-Avenue
San Francisco, common.topic.webpage, m.09wmxdf
San Francisco, book.book_subject.works, Nightcrawlers
m.09wjsz8, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09ytkc6
m.09ykr7w, common.webpage.topic, San Francisco
San Francisco, location.location.events, 1906 San Francisco earthquake
San Francisco, location.location.containedby, California
m.09x44m3, common.webpage.topic, San Francisco
San Francisco, film.film.subjects, 1906 San Francisco earthquake
San Francisco, common.topic.webpage, m.0b48qmn
San Francisco, location.statistical_region.rent50_2, m.05g9fkc
1906 San Francisco earthquake, user.robert.earthquakes.earthquake.duration, 60.0
1906 San Francisco earthquake, base.schemastaging.context_name.pronunciation, g.125_nh8xf
m.0b46cf9, common.webpage.topic, San Francisco
San Francisco, book.book_subject.works, 1st to Die
San Francisco, common.topic.webpage, m.0b48ht8
Looking Down Sacramento Street, San Francisco, April 18, 1906, common.topic.article, m.025vy7q
San Francisco, location.statistical_region.population, g.12b01lp50
A Crack in the Edge of the World: America and the Great California Earthquake of 1906, common.topic.notable_for, g.1256bxdws
San Francisco, common.topic.webpage, m.09w1wgb
San Francisco, book.book_subject.works, Unbound feet
San Francisco, common.topic.webpage, m.0g_qdd6
m.09wtp55, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09y92wl
m.02_w9xr, user.robert.earthquakes.earthquake_magnitude.earthquake, 1906 San Francisco earthquake
San Francisco, common.topic.webpage, m.0b46cf9
1906 San Francisco earthquake, event.disaster.areas_affected, San Francisco
San Francisco, location.location.adjoin_s, m.02xlhq4
m.0g_qdd6, common.webpage.topic, San Francisco
m.09ydswz, common.webpage.topic, San Francisco
San Francisco, book.book_subject.works, Fade to clear
m.094t_kq, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09ytjk1
m.09wm0d1, common.webpage.topic, San Francisco
San Francisco, common.topic.subjects, http://www.sanfranciscosightseeing.com/
San Francisco, common.topic.webpage, m.09y56v7
San Francisco, common.topic.webpage, m.09y5c2z
m.0b46qyl, common.webpage.topic, San Francisco
San Francisco, location.location.adjoin_s, m.02xlhpn
San Francisco, book.book_subject.works, Blue Light
m.09xzf2y, common.webpage.topic, San Francisco
After the Ruins, 1906 and 2006: Rephotographing the San Francisco Earthquake and Fire, book.book.editions, After the ruins, 1906 and 2006 : rephotographing the San Francisco earthquake and fire
m.09y978r, common.webpage.topic, San Francisco
San Francisco, common.image.appears_in_topic_gallery, San Francisco
San Francisco, common.topic.webpage, m.09y60fg
San Francisco, common.topic.webpage, m.09y978r
Looking Down Sacramento Street, San Francisco, April 18, 1906, common.topic.notable_types, Artwork
m.09x3sv5, common.webpage.topic, San Francisco
1906 San Francisco earthquake, time.event.locations, San Francisco
San Francisco, book.book_subject.works, Sister Noon
San Francisco, common.topic.webpage, m.09x3sv5
Simon Winchester, book.author.works_written, A Crack in the Edge of the World: America and the Great California Earthquake of 1906
After the Ruins, 1906 and 2006: Rephotographing the San Francisco Earthquake and Fire, book.written_work.author, Mark Klett
The Great Earthquake and Firestorms of 1906, book.written_work.subjects, California
m.09wf1j0, common.webpage.topic, San Francisco
m.0cj8mwt, common.webpage.topic, San Francisco
San Francisco, book.book_subject.works, And the Sea Will Tell
m.09yj4m3, common.webpage.topic, San Francisco
1906 San Francisco earthquake, common.topic.notable_types, Disaster
San Francisco Fire Sacramento Street 1906-04-18, common.image.appears_in_topic_gallery, 1906 San Francisco earthquake
1906 San Francisco earthquake, user.robert.earthquakes.earthquake.magnitude, m.02_w9xr
San Francisco, location.statistical_region.population, g.12b01lp51
San Francisco, common.topic.webpage, m.09yj4m3
San Francisco, common.topic.webpage, m.0fpsk0j
m.09w6wtc, common.webpage.topic, San Francisco
San Francisco, location.statistical_region.population, m.05svk9s
San Francisco, book.book_subject.works, The Lights of Earth
Earthquake, common.topic.image, Quake epicenters 1963-98
San Francisco, film.film.film_festivals, 1985 Berlin International Film Festival
m.09xh6pb, common.webpage.topic, San Francisco
m.09ytjk1, common.webpage.topic, San Francisco
Balfour Guthrie and Co. San Francisco Office, architecture.structure.destroyed_by, Earthquake
San Francisco, book.book_subject.works, The Great Earthquake and Firestorms of 1906
San Francisco, location.statistical_region.rent50_1, m.05g9fk4
m.09w8sgp, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.0b4827b
Earthquake, architecture.destruction_method.structures_destroyed, Palace Hotel, San Francisco
m.09y9lh7, common.webpage.topic, San Francisco
m.09w8m7x, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09yxjs0
Memory-Song Painted Gold: for the Blue Yusef Lateef (1920-2013), common.topic.subjects, San Francisco
m.0b46t1y, common.webpage.topic, San Francisco
Palace Hotel, San Francisco, event.disaster_affected_structure.survived_disasters, 1906 San Francisco earthquake
San Francisco, location.statistical_region.rent50_3, m.05g9fkl
San Francisco, common.topic.webpage, m.09y228s
m.09y5d51, common.webpage.topic, San Francisco
m.0b48ht8, common.webpage.topic, San Francisco
m.09y72nh, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09y204d
San Francisco, common.topic.webpage, m.0b46s2b
San Francisco, common.topic.webpage, m.09wtp9c
After the Ruins, 1906 and 2006: Rephotographing the San Francisco Earthquake and Fire, common.topic.notable_types, Book
m.0b48p4h, common.webpage.topic, San Francisco
m.09ytkc6, common.webpage.topic, San Francisco
1906 San Francisco earthquake, event.disaster.fatalities, 3000
m.09x0gnt, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09wyt0j
San Francisco, common.topic.article, m.0d6l_
After the Ruins, 1906 and 2006: Rephotographing the San Francisco Earthquake and Fire, book.book.editions, After the Ruins, 1906 and 2006: Rephotographing the San Francisco Earthquake and Fire
A Crack in the Edge of the World: America and the Great California Earthquake of 1906, book.book.editions, A crack in the edge of the world : America and the great California earthquake of 1906
m.09wt6tt, common.webpage.topic, San Francisco
m.02kpz3y, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09x3mn3
San Francisco, common.topic.webpage, m.09wpzr3
Palace Hotel, San Francisco, event.disaster_affected_structure.destroyed_by_disaster, 1906 San Francisco earthquake
m.09wjmzw, common.webpage.topic, San Francisco
The Great Earthquake and Firestorms of 1906, book.written_work.subjects, United States of America
San Francisco, common.topic.webpage, m.09x70ns
San Francisco, location.location.adjoin_s, m.02xlhpx
m.09x5l82, common.webpage.topic, San Francisco
A Crack in the Edge of the World: America and the Great California Earthquake of 1906, common.topic.notable_types, Book
Herb Caen's San Francisco: 1976-1991, book.written_work.original_language, English Language
m.09wmxdf, common.webpage.topic, San Francisco
After the Ruins, 1906 and 2006: Rephotographing the San Francisco Earthquake and Fire, book.written_work.author, Michael Lundgren
San Francisco, book.book_subject.works, Scenarios
San Francisco, book.book_subject.works, The Barbary Coast
m.09wg_8f, common.webpage.topic, San Francisco
San Francisco, location.location.adjoin_s, m.02xlhps
San Francisco Mint (structure), event.disaster_affected_structure.survived_disasters, 1906 San Francisco earthquake
1906 San Francisco earthquake, common.topic.image, San Francisco Fire Sacramento Street 1906-04-18
San Francisco, common.topic.webpage, m.09yv5y4
m.09yvkr0, common.webpage.topic, San Francisco
m.09w6m0k, common.webpage.topic, San Francisco
San Francisco, book.book_subject.works, Bindlestiff
m.09x3hrs, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.0b48bk0
San Francisco, common.topic.webpage, m.03ll53z
San Francisco, common.topic.webpage, m.09x0gnt
San Francisco, common.topic.webpage, m.09w6m0k
A Crack in the Edge of the World: America and the Great California Earthquake of 1906, book.written_work.author, Simon Winchester
San Francisco, common.topic.webpage, m.09ylkyw
San Francisco, location.statistical_region.population, m.05tyd8s
m.09yxjs0, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09ybqp0
m.09y5c2z, common.webpage.topic, San Francisco
Herb Caen's San Francisco: 1976-1991, book.written_work.subjects, San Francisco
m.09xyfmk, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.0b48njf
San Francisco, common.topic.webpage, m.09wq6jn
San Francisco, location.statistical_region.population, m.05tyd80
m.09xhnkt, common.webpage.topic, San Francisco
After the Ruins, 1906 and 2006: Rephotographing the San Francisco Earthquake and Fire, book.written_work.subjects, Photography
San Francisco, location.statistical_region.rent50_4, m.05g9fkt
A Crack in the Edge of the World: America and the Great California Earthquake of 1906, common.topic.article, m.064g58h
San Francisco, book.book_subject.works, Dead midnight
San Francisco, common.topic.webpage, m.09w1nrz
m.09wz41k, common.webpage.topic, San Francisco
m.0h2sfwg, common.webpage.topic, San Francisco
A Crack in the Edge of the World: America and the Great California Earthquake of 1906, book.book.genre, Non-fiction
San Francisco, common.topic.webpage, m.09wpgp4
1906 San Francisco earthquake, user.avh.default_domain.ellerdale_topic.ellerdale_id, 0098-949f
San Francisco, common.topic.webpage, m.09xyfmk
San Francisco, common.topic.webpage, m.09wm0d1
San Francisco, location.statistical_region.population, m.05tyd86
San Francisco, common.topic.webpage, m.09y39v1
San Francisco, common.topic.webpage, m.09wlk8m
m.09y39v1, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09x1nxq
San Francisco, common.topic.webpage, m.09y5d51
San Francisco, location.statistical_region.population, m.05svk77
San Francisco, common.topic.webpage, m.09wg_8f
San Francisco, common.topic.webpage, m.09wjsz8
The Great Earthquake and Firestorms of 1906, common.topic.notable_types, Book
m.09y228s, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.02kpz46
San Francisco, common.topic.webpage, m.09xqp71
1906 San Francisco earthquake, book.book_subject.works, Locked Rooms
1906 San Francisco earthquake, event.disaster.surviving_structures, San Francisco Mint (structure)
Balfour Guthrie and Co. San Francisco Office, event.disaster_affected_structure.destroyed_by_disaster, 1906 San Francisco earthquake
m.09w1w0k, common.webpage.topic, San Francisco
San Francisco, book.book_subject.works, 1906
m.09w8dlz, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09yt_t_
San Francisco, common.topic.notable_for, g.1259264lw
1906 San Francisco earthquake, book.book_subject.works, After the Ruins, 1906 and 2006: Rephotographing the San Francisco Earthquake and Fire
San Francisco, common.topic.webpage, m.09wf1j0
San Francisco, common.topic.webpage, m.09y72nh
San Francisco, film.film.edited_by, Tom Held
San Francisco, location.location.adjoin_s, m.046cwy9
1906 San Francisco earthquake, event.disaster.surviving_structures, Palace Hotel, San Francisco
1906 San Francisco earthquake, user.robert.earthquakes.earthquake.nearest_location, m.02_wb57
m.09xmh4d, common.webpage.topic, San Francisco
After the Ruins, 1906 and 2006: Rephotographing the San Francisco Earthquake and Fire, common.topic.notable_for, g.1256kn6_6
San Francisco, location.location.geolocation, m.0kb8zn
m.09ybmx4, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09xzf2y
San Francisco, common.topic.webpage, m.09w1w0k
m.09wyt0j, common.webpage.topic, San Francisco
m.03ll53z, common.webpage.topic, San Francisco
m.09xjwn2, common.webpage.topic, San Francisco
1906 San Francisco earthquake, time.event.start_date, 1906-04-18T05:12:00
m.09y632v, common.webpage.topic, San Francisco
A Crack in the Edge of the World: America and the Great California Earthquake of 1906, book.book.editions, A Crack in the Edge of the World: America and the Great California Earthquake of 1906
San Francisco, common.topic.webpage, m.09y632v
San Francisco, location.location.adjoin_s, m.02xlhq8
1906 San Francisco earthquake, event.disaster.surviving_structures, Westin St. Francis
m.09xk6vh, common.webpage.topic, San Francisco
San Francisco, common.topic.article, m.022q0vq
San Francisco, book.book_subject.works, Further Tales of the City
m.09xqp71, common.webpage.topic, San Francisco
A Crack in the Edge of the World: America and the Great California Earthquake of 1906, book.written_work.subjects, 1906 San Francisco earthquake
San Francisco, location.location.adjoin_s, m.046cw9_
http://www.sanfranciscosightseeing.com/, common.topic.subject_of, San Francisco
San Francisco, book.book_subject.works, 2nd Chance
m.09y60fg, common.webpage.topic, San Francisco
San Francisco, book.book_subject.works, Savages
1906 San Francisco earthquake, event.disaster.survivors, Jack London
m.09wcrgb, common.webpage.topic, San Francisco
m.0b48bk0, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.0b6rdz3
San Francisco, location.location.adjoin_s, m.09jx37x
San Francisco, location.statistical_region.population, m.05t5j6n
1906 San Francisco earthquake, user.robert.earthquakes.earthquake.date_and_time, 1906-04-18T13:12:00Z
Herb Caen's San Francisco: 1976-1991, common.topic.notable_types, Book
San Francisco, common.topic.subject_of, San Francisco SEO
San Francisco, location.statistical_region.population, g.11bc89n96g
San Francisco, book.book_subject.works, Herb Caen's San Francisco: 1976-1991
m.09x6llg, common.webpage.topic, San Francisco
m.09wtp9c, common.webpage.topic, San Francisco
m.09wq6jn, common.webpage.topic, San Francisco
San Francisco, book.book_subject.works, The 6th Target
WWDC 2012, time.event.locations, San Francisco
m.0b46s2b, common.webpage.topic, San Francisco
San Francisco, book.book_subject.works, Address unknown
m.022q122, common.webpage.topic, San Francisco
1906 San Francisco earthquake, user.robert.earthquakes.earthquake.fault, San Andreas Fault
San Francisco, common.topic.webpage, m.09w8dlz
San Francisco, common.topic.webpage, m.0b47y72
San Francisco, common.topic.article, m.0c1pb
1906 San Francisco earthquake, common.topic.notable_for, g.1259pqvnv
San Francisco, book.book_subject.works, Oh the Glory of It All
San Francisco, common.topic.webpage, m.09y9lh7
San Francisco, common.topic.webpage, m.09y9bqs
Westin St. Francis, event.disaster_affected_structure.survived_disasters, 1906 San Francisco earthquake
m.09yp6yq, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09x6llg
m.09y948d, common.webpage.topic, San Francisco
1906 San Francisco earthquake, user.robert.earthquakes.earthquake.fatalities, m.02_w95l
San Francisco, common.topic.webpage, m.09ykksd
San Francisco, common.topic.webpage, m.09y4yjk
m.09ykksd, common.webpage.topic, San Francisco
A Crack in the Edge of the World: America and the Great California Earthquake of 1906, book.book.editions, The professor and the madman : a tale of murder, insanity, and the making of the Oxford English dictionary
m.0b48qmn, common.webpage.topic, San Francisco
San Andreas Fault, user.robert.earthquakes.seismic_fault.earthquakes, 1906 San Francisco earthquake
San Francisco, common.topic.webpage, m.09x44m3
After the Ruins, 1906 and 2006: Rephotographing the San Francisco Earthquake and Fire, book.written_work.subjects, 1906 San Francisco earthquake
San Francisco, location.statistical_region.population, m.05tyd8d
San Francisco SEO, common.topic.subjects, San Francisco
San Francisco, book.book_subject.works, 3rd Degree
San Francisco, common.topic.webpage, m.09y9t54
San Francisco, common.topic.webpage, m.09y948d
m.09x3mn3, common.webpage.topic, San Francisco
m.09wpgp4, common.webpage.topic, San Francisco
1906 San Francisco earthquake, film.film_subject.films, San Francisco
San Francisco, book.book_subject.works, Bleeders
1906 San Francisco earthquake, event.disaster.structures_destroyed, Balfour Guthrie and Co. San Francisco Office
San Francisco, location.location.partiallycontains, m.0zwsh__
1906, book.written_work.subjects, San Francisco
San Francisco, book.book_subject.works, Memory-Song Painted Gold: for the Blue Yusef Lateef (1920-2013)
Earthquake, event.disaster_type.disasters_of_this_type, 1906 San Francisco earthquake
San Francisco, common.topic.webpage, m.0h2sfwg
Looking Down Sacramento Street, San Francisco, April 18, 1906, base.newsevents.photograph.photographed_event, 1906 San Francisco earthquake
San Francisco, common.topic.webpage, m.09xk6vh
m.09y56v7, common.webpage.topic, San Francisco
m.09x70ns, common.webpage.topic, San Francisco
San Francisco, book.book_subject.works, Only in San Francisco
San Francisco, common.topic.webpage, m.022q11g
m.09w1wgb, common.webpage.topic, San Francisco
m.09wlk8m, common.webpage.topic, San Francisco
1906 San Francisco earthquake, book.book_subject.works, A Crack in the Edge of the World: America and the Great California Earthquake of 1906
m.09y9t54, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09ybmx4
San Francisco, common.topic.webpage, m.09x5l82
San Francisco, common.topic.subject_of, Robin Duke
San Francisco, common.topic.notable_for, g.1255z32m2
After the Ruins, 1906 and 2006: Rephotographing the San Francisco Earthquake and Fire, book.book.genre, Coffee table book
San Francisco, location.location.partially_contained_by, m.0wg9gvc
San Francisco Fire Sacramento Street 1906-04-18, common.image.appears_in_topic_gallery, Looking Down Sacramento Street, San Francisco, April 18, 1906
1906 San Francisco earthquake, common.topic.article, m.01f6rx
San Francisco, common.topic.webpage, m.022q122
1906 San Francisco earthquake, event.disaster.structures_destroyed, Palace Hotel, San Francisco
m.02_wb57, user.robert.earthquakes.earthquake_nearest_location.earthquake, 1906 San Francisco earthquake
Looking Down Sacramento Street, San Francisco, April 18, 1906, common.topic.notable_for, g.125cqdww9
San Francisco, common.topic.webpage, m.09xlcpd
San Francisco, common.topic.image, San Francisco
San Francisco, common.topic.webpage, m.09xmh4d
m.09y92wl, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09wt6tt
Palace Hotel, San Francisco, architecture.structure.destroyed_by, Earthquake
m.09wpzr3, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09w8m7x
m.09y9bqs, common.webpage.topic, San Francisco
m.09ychf9, common.webpage.topic, San Francisco
Earthquake, architecture.destruction_method.structures_destroyed, Balfour Guthrie and Co. San Francisco Office
San Francisco, book.book_subject.works, Tales of the City
San Francisco, common.topic.webpage, m.09xh6pb
San Francisco, base.biblioness.bibs_topic.subsumes, San Francisco
m.0b47y72, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.0b46qyl
San Francisco, common.topic.webpage, m.09x4f_j
1906 San Francisco earthquake, event.disaster.damage, m.05bvd_b
m.0b48njf, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09yb31v
San Francisco, common.topic.webpage, m.0cj8mwt
San Francisco, common.topic.webpage, m.094t_kq
San Francisco Fire Sacramento Street 1906-04-18, common.image.size, m.02c68gh
San Francisco, book.book_subject.works, Zodiac
Simon Winchester, book.author.book_editions_published, A Crack in the Edge of the World: America and the Great California Earthquake of 1906
San Francisco, location.location.adjoin_s, m.02xlhqd
Locked Rooms, book.written_work.subjects, 1906 San Francisco earthquake
m.09x1nxq, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09wtp55
San Francisco, location.location.adjoin_s, m.02xlhq0
m.09yb31v, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09w8sgp
m.0fpsk0j, common.webpage.topic, San Francisco
m.022q11g, common.webpage.topic, San Francisco
m.09ybqp0, common.webpage.topic, San Francisco
m.09ytjp2, common.webpage.topic, San Francisco
San Francisco, location.statistical_region.rent50_0, m.05g9fjy
m.0b6rdz3, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09w6wtc
San Francisco, common.topic.webpage, m.09yp6yq
San Francisco, common.topic.subject_of, Memory-Song Painted Gold: for the Blue Yusef Lateef (1920-2013)
San Francisco, book.book_subject.works, Red Zone
San Francisco, common.topic.webpage, m.09ytjp2
San Francisco, common.topic.image, San Francisco Skyline
San Francisco, common.topic.webpage, m.09y22fm
San Francisco, common.topic.webpage, m.0b46t1y
m.09ylkyw, common.webpage.topic, San Francisco
1906 San Francisco earthquake, event.disaster.type_of_disaster, Earthquake
After the Ruins, 1906 and 2006: Rephotographing the San Francisco Earthquake and Fire, common.topic.article, m.0649cq2
San Francisco, common.topic.webpage, m.09wz41k
Post-and-Grant-Avenue, common.image.appears_in_topic_gallery, 1906 San Francisco earthquake
San Francisco, common.topic.webpage, m.09ydswz
San Francisco, common.topic.webpage, m.09wjmzw
m.09y4yjk, common.webpage.topic, San Francisco
m.0bqsy6x, award.ranking.item, San Francisco
San Francisco, book.book_subject.works, The Basic Eight
m.0qymvcv, dataworld.gardening_hint.last_referenced_by, 1906 San Francisco earthquake
San Francisco, common.topic.webpage, m.02kpz3y
The Great Earthquake and Firestorms of 1906, book.written_work.subjects, San Francisco
San Francisco, common.topic.webpage, m.09xjwn2
m.02kpz46, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09ykr7w
m.09yt_t_, common.webpage.topic, San Francisco
m.09xlcpd, common.webpage.topic, San Francisco
m.09x4f_j, common.webpage.topic, San Francisco
1906 San Francisco earthquake, user.robert.earthquakes.earthquake.total_damage, m.03rtjky
m.09w1nrz, common.webpage.topic, San Francisco
San Francisco, common.topic.webpage, m.09x3hrs
San Francisco, common.topic.webpage, m.09ychf9
San Francisco, location.statistical_region.population, g.12b01th29
San Francisco, location.statistical_region.population, g.12b01xv91

Answer: 1906-04-18