трехмерная скоростная модель среды в районе карымского

Êîìïëåêñíûå ñåéñìîëîãè÷åñêèå è ãåîôèçè÷åñêèå èññëåäîâàíèÿ Êàì÷àòêè
ÓÄÊ 550.34
ÒÐÅÕÌÅÐÍÀß ÑÊÎÐÎÑÒÍÀß ÌÎÄÅËÜ ÑÐÅÄÛ Â ÐÀÉÎÍÅ
ÊÀÐÛÌÑÊÎÃÎ ÂÓËÊÀÍÈ×ÅÑÊÎÃÎ ÖÅÍÒÐÀ
ÏÎ ÄÀÍÍÛÌ ÐÅÃÈÎÍÀËÜÍÎÉ ÑÅÉÑÌÈ×ÍÎÑÒÈ
Ë. Á. Ñëàâèíà1, Í. Á. Ïèâîâàðîâà1, Â. È. Ëåâèíà2
Èíñòèòóò ôèçèêè Çåìëè ÐÀÍ, ã. Ìîñêâà
Êàì÷àòñêàÿ îïûòíî-ìåòîäè÷åñêàÿ ñåéñìîëîãè÷åñêàÿ ïàðòèÿ Ãåîôèçè÷åñêîé ñëóæáû ÐÀÍ,
ã. Ïåòðîïàâëîâñê-Êàì÷àòñêèé
1
2
Àííîòàöèÿ. Ðàáîòà ïîñâÿùåíà ïîñòðîåíèþ ñêîðîñòíûõ ìîäåëåé Ð- è S-âîëí â
êîðå è âåðõíåé ìàíòèè ðàéîíà Êàðûìñêîãî âóëêàíè÷åñêîãî öåíòðà íà Êàì÷àòêå.
Ðàñ÷åò ïðîâîäèëñÿ íà îñíîâå ñåéñìîëîãè÷åñêèõ äàííûõ ðåãèîíàëüíîé ñåòè
ñåéñìè÷åñêèõ ñòàíöèé ïî äàííûì çà 1996ã.  ÿíâàðå 1996ã. â ýòîì ðàéîíå íàáëþäàëèñü îäíîâðåìåííî ìîùíûå âóëêàíè÷åñêèå è ñåéñìè÷åñêèå ñîáûòèÿ.
Ïðèâåäåíû ðåçóëüòàòû ðàñ÷åòà ñêîðîñòíûõ ìîäåëåé â âåðòèêàëüíîé ïëîñêîñòè
âäîëü ìàãìîïðîâîäÿùåãî ðàçëîìà. Âûÿâëåíû íåêîòîðûå îñîáåííîñòè äèíàìèêè
ñêîðîñòíûõ ïîëåé â ïðîñòðàíñòâå è âðåìåíè â ïåðèîä ðàçâèòèÿ âóëêàíè÷åñêîãî
è ñåéñìè÷åñêîãî ïðîöåññîâ.
THREE-DIMENSIONAL VELOCITY MODEL IN THE REGION OF
KARYMSKY VOLCANIC CENTRE ON THE BASIS OF REGIONAL
SEISMICITY DATA
L. B. Slavina1, N. B. Pivovarova1, B. I. Levina2
2
Institute of Physics of the Earth of Russian Academy of Sciences, Moscow
Kamchatkan Experimental and Methodical Seismological Department, Geophysical Service, RAS,
Petropavlovsk-Kamchatsky
1
Abstract. The study is devoted to construction of velocity models of P and S waves in the
crust and upper mantle in the region of Karymsky volcanic centre in Kamchatka. The
calculations were done on the basis of seismological data of the regional network of seismic
stations in 1996. In January of 1996 large seismic and volcanoes events were observed in
this region simultaneously. The results of calculations of velocity models in the vertical
plane along the magma-conducting fault are presented. Some peculiarities of the dynamics
of the velocity fields in space and time in the period of development of volcanic and
seismic processes are discovered.
Ââåäåíèå
1 ÿíâàðÿ 1996ã. â ðàéîíå Êàðûìñêîãî âóëêàíè÷åñêîãî öåíòðà, íà ñóøå ïðîèçîøëî
ñèëüíîå (Ì=7.0) êîðîâîå, òåêòîíè÷åñêîå çåìëåòðÿñåíèå, ñîïðîâîæäàâøååñÿ ìíîãî÷èñëåííûìè àôòåðøîêàìè.  ýòîò æå ïåðèîä â ýòîì ðàéîíå íà÷àëîñü íåîáû÷íîå âóëêàíè÷åñêîå èçâåðæåíèå. Âóëêàíè÷åñêàÿ àêòèâíîñòü ïðîÿâèëàñü íå òîëüêî íà ñàìîì
âóëêàíå Êàðûìñêèé, íî òàêæå è íà ñåâåðå Êàðûìñêîãî îçåðà â êàëüäåðå Àêàäåìèè Íàóê,
377
Ë.Á. Ñëàâèíà, Í.Á. Ïèâîâàðîâà è äð.
êîòîðàÿ îáðàçîâàëàñü 28-48 òûñ. ëåò íàçàä [1, 10]. Ïðåäûäóùèå èçâåðæåíèÿ ïðîèñõîäèëè
â ãîëîöåíîâîå âðåìÿ è ïðèóðî÷åíû áûëè ê òîìó æå ìàãìîïðîâîäÿùåìó ðàçëîìó ñóáìåðèäèîíàëüíîãî ïðîñòèðàíèÿ, êîòîðûé ïðîõîäèò ÷åðåç âóëêàíû Äâîð, Êàðûìñêèé,
êîíóñ Ëàãåðíûé, îç. Êàðûìñêîå, êàëüäåðà Àêàäåìèè Íàóê. Ïî ñîñòàâó èçâåðæåíèå
1996ã. îòâå÷àåò áàçàëüòàì, ò.å. ýòî ÷åòâåðòûé èìïóëüñ ïîäà÷è áàçàëüòîâîãî ìàòåðèàëà
ïî òîìó æå ìàãìîïðîâîäÿùåìó ðàçëîìó [1]. Âñå ýòè ñîáûòèÿ ñîïðîâîæäàëèñü ìíîãî÷èñëåííûìè ñëàáûìè çåìëåòðÿñåíèÿìè íà ãëóáèíàõ äî 65 êì. Ñåéñìè÷åñêàÿ àêòèâíîñòü
â ýòîì ðàéîíå íå çàòóõàëà åùå íåñêîëüêî ìåñÿöåâ [2].
Ïîëó÷åííûå Êàì÷àòñêîé îïûòíî-ìåòîäè÷åñêîé ñåéñìîëîãè÷åñêîé ïàðòèåé ÃÑ ÐÀÍ
(ÊÎÌÑÏ) óíèêàëüíûå ñåéñìè÷åñêèå äàííûå ïîçâîëèëè àâòîðàì ïîñòàâèòü è ðåøèòü
çàäà÷ó îïðåäåëåíèÿ ñêîðîñòíîé ìîäåëè ñðåäû ïî äàííûì ñåéñìè÷åñêèõ P- è S- âîëí
íà ðàçëè÷íûõ ýòàïàõ ðàçâèòèÿ ðàññìàòðèâàåìûõ ñåéñìè÷åñêèõ è âóëêàíè÷åñêèõ ïðîöåññîâ.
Îïèñàíèå èñõîäíûõ äàííûõ
 äàííîé ðàáîòå èñïîëüçîâàíû ñåéñìîëîãè÷åñêèå äàííûå, âêëþ÷àþùèå ïàðàìåòðû
ãèïîöåíòðîâ ëîêàëüíûõ çåìëåòðÿñåíèé è âðåìåíà ïðîáåãà P- è S-âîëí äî ðÿäà
ðåãèîíàëüíûõ ñòàíöèé Êàì÷àòêè. Îáðàáîòêà çåìëåòðÿñåíèé ïðîèçâîäèëàñü â Êàì÷àòñêîé Îïûòíî ìåòîäè÷åñêîé Ñåéñìîëîãè÷åñêîé Ïàðòèè (ÊÎÌÑÏ) Ãåîôèçè÷åñêîé
ñëóæáû ÐÀÍ íà îñíîâàíèè ïðîñòîé îäíîìåðíîé ìîäåëè ñðåäû ñ ó÷åòîì ñòàíöèîííûõ
ïîïðàâîê. Êàòàëîã ñîñòàâëÿëñÿ ïî äàííûì ñåòåé ðàäèîòåëåìåòðè÷åñêèõ ñòàíöèé
ÊÎÌÑÏ. Ïàðà-ìåòðû ãèïîöåíòðîâ îïðåäåëÿëèñü ïî ïðîãðàììå Þ.Þ. Ìåëüíèêîâà
[5]. Âðåìÿ â î÷àãå ðàññ÷èòûâàåòñÿ ïî ãðàôèêó Âàäàòè, íî íå óñòàíàâëèâàëñÿ åãî
ôèêñèðîâàííûé íàêëîí. Äëÿ êàæäîãî çåìëåòðÿñåíèÿ ðàññ÷èòûâàëèñü ãðàíè÷íûå
çíà÷åíèÿ VP/VS, ò.å. êîðèäîð çíà÷åíèé. Äëÿ ðàññòîÿíèé 0 – 500 êì è ãëóáèí 0 – 200
êì èñïîëüçîâàëñÿ ãîäîãðàô È.Ï.Êóçèíà [4].
Áîëüøîå êîëè÷åñòâî çàðåãèñòðèðîâàííûõ ìåñòíûõ çåìëåòðÿñåíèé ïîçâîëèëî, â õîäå
èññëåäîâàíèÿ, ðàññìîòðåòü äàííûå òðåõ âðåìåííûõ èíòåðâàëîâ:
- 1 ÿíâàðÿ 1996 ã.- ïîñëå 22 ÷àñîâ ìåñòíîãî âðåìåíè, ò. å. ïîñëå çåìëåòðÿñåíèÿ
ñ Ì=7.0;
- 2 ÿíâàðÿ 1996ã. - íà÷àëî èçâåðæåíèÿ â êàëüäåðå Àêàäåìèè Íàóê;
- ïåðèîä 3 ÿíâàðÿ – 20 ôåâðàëÿ 1996ã. – ïðîäîëæåíèå èçâåðæåíèÿ âóëêàíà Êàðûìñêèé, ïðîäîëæàâøååñÿ äëèòåëüíîå âðåìÿ.
 ðàñ÷åòå èñïîëüçîâàëèñü äàííûå 5-8 áëèæàéøèõ ñåéñìîñòàíöèé, ê ñîæàëåíèþ,
äàííûå ñàìîé áëèçêîé ñòàíöèÿ KRY íå ìîãëè áûòü èñïîëüçîâàíû â íà÷àëå èññëåäóåìîãî ïåðèîäà. Ïîýòîìó ñêîðîñòü â âåðõíåì ñëîå êîðû îïðåäåëÿëàñü ìåíåå óâåðåííî.
Íà ðèñ. 1. ïðèâåäåíû ñõåìà èçó÷àåìîãî ðàéîíà, óêàçàíû áëèæàéøèå ñåéñìîñòàíöèè.
Ïðè ðàñ÷åòå ñêîðîñòè èçó÷àåìàÿ îáëàñòü ñîñòàâëÿëà ïðèáëèçèòåëüíî ïðÿìîóãîëüíèê â ãîðèçîíòàëüíîé ïëîñêîñòè ñ ðàçìåðàìè: 30´50 êì, êîëè÷åñòâî ëó÷åé ñòàíöèÿî÷àã, ïîïàäàþùèõ â îòäåëüíûé âðåìåííîé èíòåðâàë ñîñòàâëÿëî 700-1200 øòóê.
Êðàòêàÿ èíôîðìàöèÿ î ìåòîäèêå ðàñ÷åòà
Àâòîðàìè áûëà ðàçðàáîòàíà îðèãèíàëüíàÿ ìåòîäèêà âîññòàíîâëåíèÿ ïîëåé ñêîðîñòåé ñåéñìè÷åñêèõ âîëí â çîíàõ êîíöåíòðàöèè î÷àãîâ çåìëåòðÿñåíèé ïî ñåéñìîëîãè÷åñêèì äàííûì [6], êîòîðàÿ ïðèìåíÿëàñü äëÿ îöåíêè ñêîðîñòíîãî ïîëÿ ïðîäîëüíûõ
âîëí â îòäåëüíûõ ñåéñìîàêòèâíûõ ðàéîíàõ [8]. Â ïîñëåäíèå ãîäû ýòà ìåòîäèêà áûëà
ìîäèôèöèðîâàíà, ÷òî ïîçâîëèëî ñíÿòü ðÿä êðèòè÷åñêèõ çàìå÷àíèé è óëó÷øèòü êà÷åñòâî
ïîëó÷àåìûõ ñêîðîñòíûõ ïîëåé [7].
 îñíîâó ðàññìàòðèâàåìîé ìåòîäèêè ðàñ÷åòà ñêîðîñòè ïðîäîëüíûõ è ïîïåðå÷íûõ
âîëí â òðåõìåðíîé ñðåäå ïîëîæåí ïðèíöèï âçàèìíîñòè âîëíîâûõ ïîëåé. Èñïîëüçîâàíèå
ýòîãî ïðèíöèïà ïîçâîëÿåò ðàññìàòðèâàòü ìíîæåñòâî âðåìåí ïåðâûõ âñòóïëåíèé
ñåéñìè÷åñêîé âîëíû îò äîñòàòî÷íî ñëàáûõ çåìëåòðÿñåíèé íà íåêîòîðîé ñåéñìè÷åñêîé
378
Òðåõìåðíàÿ ñêîðîñòíàÿ ìîäåëü ñðåäû â ðàéîíå Êàðûìñêîãî âóëêàíè÷åñêîãî öåíòðà
Ðèñ. 1. Ñõåìà ðàñïîëîæåíèÿ îáëàñòè èññëåäîâàíèÿ. Êàðòà ýïèöåíòðîâ çåìëåòðÿñåíèé
Êàðûìñêîãî âóëêàíè÷åñêîãî öåíòðà â 1996 ã. (KS>8).
1 – ýíåðãåòè÷åñêèé êëàññ KS (ïî Ñ.À. Ôåäîòîâó); 2 – ýïèöåíòð Êàðûìñêîãî çåìëåòðÿñåíèÿ 1 ÿíâàðÿ â 9h57m45.8s (MS=7.0); 3 – ýïèöåíòðû ôîðøîêîâûõ çåìëåòðÿñåíèé; 4 – ñåéñìè÷åñêàÿ ñòàíöèÿ Êàðûìñêàÿ; 5 - äåéñòâóþùèå âóëêàíû; 6 – ãëóáèííûé ìàãìîïîäâîäÿùèé ðàçëîì.
Fig. 1. The scheme of location of the investigated area.
The map of the epicentres of Karymsky volcanic centre in 1996 (KS>8). 1 – energetic class KS (by S.A.
Fedotov); 2 – epicentre of Karymsky earthquake on January 1, 1996, at 9h57m45.8s (MS=7.0); 3 –
epicentres of foreshock earthquakes; 4 – seismic station Karymsky; 5 – active volcanoes; 6 – deep
magma-supplying fault.
379
Ë.Á. Ñëàâèíà, Í.Á. Ïèâîâàðîâà è äð.
ñòàíöèè êàê âðåìåíà ïðîáåãà îáðàòíîé âîëíû îò ýòîé ñåéñìè÷åñêîé ñòàíöèè äî ðàçëè÷íûõ òî÷åê òðåõìåðíîãî ïðîñòðàíñòâà. Àëãîðèòì ïîçâîëÿåò ðàññ÷èòûâàòü ïîëîæåíèå
ôðîíòà ñåéñìè÷åñêîé âîëíû è ñêîðîñòü åãî ïåðåìåùåíèÿ, åñëè çàäàíû âðåìåíà ïðîáåãà P- èëè S-âîëí îò ñåðèè î÷àãîâ, ðàñïîëîæåííûõ â íåêîòîðîé ôèêñèðîâàííîé îáëàñòè,
äî êîíêðåòíîé ñòàíöèè.
Ïðè ïîñòðîåíèè ôðîíòà â îáëàñòè G èñïîëüçóþòñÿ ïðîñòûå ïîâåðõíîñòè, àïïðîêñèìèðóþùèå ôîðìó ôðîíòà, íàïðèìåð ïëîñêîñòü èëè ñôåðà. Äëÿ ñëó÷àÿ àïïðîêñèìàöèè ôðîíòà âîëíû ïëîñêîñòüþ âðåìåíà ïåðâûõ âñòóïëåíèé ìîæíî çàïèñàòü â âèäå:
tij=t0j+Aj(xi–x0)+Bj(yi–y0)+Cj(zi–z0)
Çàäà÷à îïðåäåëåíèÿ ñêîðîñòè, ò.å. êîýôôèöèåíòîâ Aj, Bj, Cj ñâîäèòñÿ ê ðåøåíèþ
íåñîâìåñòíîé ñèñòåìû óðàâíåíèé
t0j+Aj(xi–x0)+Bj(yi–y0)+Cj(zi–z0)=tij, i=1, …n
Ýòî òèïè÷íàÿ íåêîððåêòíàÿ çàäà÷à, êîòîðàÿ ìîæåò áûòü ðåøåíà ñ ïîìîùüþ ââåäåíèÿ ñòàáèëèçèðóþùåãî ôóíêöèîíàëà. Ïðè ýòîì â çàäà÷å ïîÿâëÿåòñÿ ïàðàìåòð ðåãóëÿðèçàöèè ±, âûáîð êîòîðîãî äîëæåí áûòü îáîñíîâàí ñ ïîìîùüþ äîïîëíèòåëüíûõ ìîäåëüíûõ ðàñ÷åòîâ. Áîëåå ïîëíî îñîáåííîñòè ìåòîäèêè èçëîæåíû â ðàáîòàõ [6-8].
Îòìåòèì, ÷òî õîðîøåå çàïîëíåíèå ðàññìàòðèâàåìîé îáëàñòè î÷àãàìè çåìëåòðÿñåíèé äàåò âîçìîæíîñòü èññëåäîâàòü ðàçëè÷èå ñêîðîñòåé ðàñïðîñòðàíåíèÿ ñåéñìè÷åñêèõ
ïðîäîëüíûõ âîëí â ðàçëè÷íûõ íàïðàâëåíèÿõ. Âîçìîæíî, ïðè õîðîøåì íàáîðå äàííûõ
óäàñòñÿ âûÿâèòü àíèçîòðîïèþ ñêîðîñòåé ðàñïðîñòðàíåíèÿ ñåéñìè÷åñêèõ âîëí. Äëÿ
ýòîãî ñëåäóåò ðàññìîòðåòü ïîëÿ ñêîðîñòåé, óñðåäíÿÿ ñêîðîñòè â òî÷êå òîëüêî äëÿ ñòàíöèé
ñ áëèçêèõ íàïðàâëåíèé.
Ðàññìàòðèâàåìàÿ ìåòîäèêà ÿâëÿåòñÿ äèôôåðåíöèàëüíîé, â àëãîðèòìå èñïîëüçóþòñÿ òîëüêî ðàçíîñòè ýêñïåðèìåíòàëüíûõ âðåìåí îò äâóõ î÷àãîâ èç îáëàñòè G. Ðàçìåðû
îáëàñòè G âûáèðàþòñÿ äîñòàòî÷íî ìàëûìè ïî ñðàâíåíèþ ñ ðàññòîÿíèåì äî ñòàíöèè,
÷òîáû ìîæíî áûëî ñ÷èòàòü, ÷òî âîëíû èç áëèçêèõ òî÷åê Ì0 è Mi âíå îáëàñòè G ïðîõîäÿò ïðèáëèçèòåëüíî îäèíàêîâûé ïóòü. Òåì ñàìûì èñêëþ÷àåòñÿ âëèÿíèå îñîáåííîñòåé ñòðîåíèÿ êîðû ïîä ñòàíöèåé, íàëè÷èå ñèñòåìàòè÷åñêîé îøèáêè âî âðåìåíàõ è
êîîðäèíàòàõ î÷àãîâ.
Áîëüøîå çíà÷åíèå äëÿ êà÷åñòâà ðåçóëüòàòîâ ðàñ÷åòà èìååò ðàâíîìåðíîå çàïîëíåíèå
îáëàñòè óñðåäíåíèÿ î÷àãàìè çåìëåòðÿñåíèé. Äëÿ ðàññìàòðèâàåìîãî ðåãèîíà áûëî
ïðîâåäåíî ñïåöèàëüíîå èññëåäîâàíèå òî÷íîñòè âîññòàíîâëåíèÿ ñêîðîñòè, â êîòîðîì
ðàñïîëîæåíèå òî÷åê áûëî ðåàëüíûì, à âðåìåíà ïðîáåãà ðàññ÷èòûâàëèñü â òðåõñëîéíîé
ñðåäå ñ ââåäåíèåì ñëó÷àéíûõ îøèáîê. Ðåçóëüòàòû ðàñ÷åòîâ ïðèâåäåíû â ðàáîòå [7].
Ðàñ÷åòû áûëè ïðîâåäåíû íåçàâèñèìî ïî äàííûì Ð- è S-âîëí, ýòî âîçìîæíî, òàê
êàê ïðè îïðåäåëåíèè âðåìåíè â î÷àãå íå ôèêñèðîâàëñÿ óãîë íàêëîíà ãðàôèêà Âàäàòè.
 õîäå ðàñ÷åòîâ áûëà ââåäåíà ëîêàëüíàÿ äåêàðòîâàÿ ñèñòåìà êîîðäèíàò. Íàïðàâëåíèå
îñè OY ïàðàëëåëüíî íàïðàâëåíèþ ìàãìîïðîâîäÿùåãî ðàçëîìà. Ïîëó÷åííûå çíà÷åíèÿ
ñêîðîñòåé â îòäåëüíûõ òî÷êàõ, ðàñïîëîæåííûõ õàîòè÷íî â òðåõìåðíîé îáëàñòè, ïðèõîäèòñÿ ñãëàæèâàòü äëÿ ïîñòðîåíèÿ èçîëèíèé.  ðàáîòå [9] ïðèâåäåíû êàðòû – ñðåçû
ïîëåé ñêîðîñòåé Ð- è S-âîëí, ïîñòðîåííûå â ãîðèçîíòàëüíûõ ïëîñêîñòÿõ. Â äàííîé
ðàáîòå ïðèâîäÿòñÿ ðåçóëüòàòû óñðåäíåíèÿ ïîëÿ ñêîðîñòåé â âåðòèêàëüíûõ ïëîñêîñòÿõ
â íàïðàâëåíèè Þãî-Çàïàä - Ñåâåðî-Âîñòîê (Õ=const). Ïðè ýòîì ïðè ïîñòðîåíèè
èçîëèíèé ó÷àñòâîâàëè òî÷êè ñ êîîðäèíàòàìè ±10 êì îò âûáðàííîé ïëîñêîñòè ñå÷åíèÿ.
Íà âñåõ ðèñóíêàõ ñëåâà ðàñïîëîæåíà þæíàÿ ÷àñòü ñå÷åíèÿ, ñïðàâà – ñåâåðíàÿ.
380
Z, km
0
Z, km
Z, km
Z, km
0
10
8.5
20
7.5
6.5
30
Vs km/s
10
381
4.5
50
115
105
a
95
85
60
75 115
Y, km
3.5
105
95
b
85
75
Y, km
1.93
5.0
4.4
20
1.83
3.8
30
1.73
3.2
5.5
40
Vp/Vs
40
1.63
2.6
50
1.53
2.0
60
115
-- 1
105
95
c
85
75
Y, km
115
105
95
d
85
75
Y, km
Ðèñ. 2. Âåðòèêàëüíûå ñå÷åíèÿ þãî-çàïàä – ñåâåðî-âîñòîê ïî äàííûì 1 ÿíâàðÿ 1996 ã.:
à – ðàñïðåäåëåíèå òî÷åê, â êîòîðûõ áûëà îïðåäåëåíà ñêîðîñòü; b – ñêîðîñòíîå ïîëå Vp; c – ñêîðîñòíîå ïîëå Vs; 㠖 îòíîøåíèå Vp/
Vs. 1 – Ýïèöåíòð 01.01.96 Ì=7.0, 2 – êàëüäåðà ÀÍ.
Fig. 2. Vertical sections south-west – north-east by the data of January 1, 1996:
a – distribution of the points were the velocity was determined; b – velocity field Vp; c – velocity field Vs; d – field of the relation Vp/Vs: 1–
epicenter 01.01.96 Ì = 7.0, 2– caldera RAN.
Òðåõìåðíàÿ ñêîðîñòíàÿ ìîäåëü ñðåäû â ðàéîíå Êàðûìñêîãî âóëêàíè÷åñêîãî öåíòðà
Vp km/s
Ë.Á. Ñëàâèíà, Í.Á. Ïèâîâàðîâà è äð.
382
Ðèñ. 3. Âåðòèêàëüíûå ñå÷åíèÿ þãî-çàïàä – ñåâåðî-âîñòîê ïî äàííûì 2 ÿíâàðÿ 1996 ã.:
à – ðàñïðåäåëåíèå òî÷åê, â êîòîðûõ áûëà îïðåäåëåíà ñêîðîñòü; b – ñêîðîñòíîå ïîëå Vp; c – ñêîðîñòíîå ïîëå Vs; d – îòíîøåíèå Vp/
Vs. 1 – Ýïèöåíòð 01.01.96 Ì=7.0, 2 – êàëüäåðà ÀÍ.
Fig. 3. Vertical sections south-west – north-east by the data of January 2, 1996:
a – distribution of the points were the velocity was determined; b – velocity field Vp; c – velocity field Vs; d – field of the relation Vp/Vs.
Z, km
Z, km
0
Z, km
0
Vp êì/ñ
10
Vs êì/ñ
20
30
383
40
50
20
30
6.5
5.5
40
40
50
3.5
115 110 105 100
à
95
90
85
80
Y, km
115
110
105
b
100
95
90
85
80
Y, km
1.98
5.0
20
4.7
4.4
4.1
30
3.8
3.5
3.2
40
-- 1
110
105
100
c
95
90
85
50
2.3
80
Y, km
-- 2
1.88
1.83
1.78
1.68
1.63
2.6
2.0
115
1.93
1.73
2.9
4.5
50
10
5.3
7.5
30
Vp/Vs
10
8.5
20
0
115 110 105 100 95
d
90
85
1.58
1.53
80
Y, km
Ðèñ. 4. Âåðòèêàëüíûå ñå÷åíèÿ þãî-çàïàä – ñåâåðî-âîñòîê ïî äàííûì 3 ÿíâàðÿ – 20 ôåâðàëÿ 1996 ã.:
à – ðàñïðåäåëåíèå òî÷åê, â êîòîðûõ áûëà îïðåäåëåíà ñêîðîñòü; b – ñêîðîñòíîå ïîëå Vp; c – ñêîðîñòíîå ïîëå Vs; d – îòíîøåíèå
Vp/Vs. 1 – Ýïèöåíòð 01.01.96 Ì=7.0, 2 – êàëüäåðà ÀÍ.
Fig. 4. Vertical sections south-west – north-east by the data of January 3 – February 20, 1996:
a – distribution of the points were the velocity was determined; b – velocity field V p; c – velocity field Vs; d – field of the relation Vp/Vs.
Òðåõìåðíàÿ ñêîðîñòíàÿ ìîäåëü ñðåäû â ðàéîíå Êàðûìñêîãî âóëêàíè÷åñêîãî öåíòðà
10
0
Z, km
Ë.Á. Ñëàâèíà, Í.Á. Ïèâîâàðîâà è äð.
Ðåçóëüòàòû ðàñ÷åòà ïîëåé ñêîðîñòåé
Íà ðèñóíêàõ 2-4 ïðèâåäåíû ðåçóëüòàòû ðàñ÷åòà äëÿ òðåõ âðåìåííûõ èíòåðâàëîâ.
Íà êàæäîì ðèñóíêå äàíû: ðàñïðåäåëåíèå î÷àãîâ, â êîòîðûõ áûëà ðàññ÷èòàíà ñêîðîñòü,
èçîëèíèè ñêîðîñòåé Ð- è S-âîëí è îòíîøåíèå VP/VS . Ïîñëåäíÿÿ âåëè÷èíà VP/VS âíà÷àëå ðàññ÷èòûâàëàñü äëÿ êàæäîé òî÷êè, à ïîòîì ñãëàæèâàëàñü è ñòðîèëèñü åå èçîëèíèè.
Íà âñåõ ðèñóíêàõ âèäíî, ÷òî çàïîëíåíèå òî÷åê âûáðàííîé ïëîñêîñòè íåðàâíîìåðíî, ïîýòîìó èçîëèíèè íå áûëè ïîñòðîåíû òàì, ãäå íåò èñõîäíûõ äàííûõ. Êðîìå òîãî,
çàìåòíî, ÷òî â öåëîì èçìåí÷èâîñòü ïîëåé Ð-âîëí áîëåå âûðàæåííàÿ, ÷åì ïîëåé S-âîëí.
Íåñèíõðîííàÿ èçìåíÿåìîñòü Ð- è S-âîëí ïðèâîäèò ê çàìåòíîìó èçìåíåíèþ îòíîøåíèÿ VP/VS â îáëàñòè, ãäå áûëè ðàññ÷èòàíû ñêîðîñòè.
Ñðàâíèâàÿ ïîëÿ èçîëèíèé ïî äàííûì 1 ÿíâàðÿ (ðèñ. 2) è 2 ÿíâàðÿ (ðèñ. 3), ìîæíî
îòìåòèòü, ÷òî â îáîèõ ñëó÷àÿõ íà êàðòàõ Ð-âîëí çàìåòíî îïóñêàíèå (ïîíèæåíèå)
èçîëèíèè VP=6.5 êì/ñ äî ãëóáèíû 35 êì (1 ÿíâàðÿ) è äî ãëóáèíû 25 êì (2 ÿíâàðÿ).
Ïðè ýòîì ýòî îïóñêàíèå èçîëèíèè ðàñïîëàãàåòñÿ 1 ÿíâàðÿ ïîä ãèïîöåíòðîì ãëàâíîãî
òîë÷êà, à 2 ÿíâàðÿ îáëàñòü ïîíèæåíèÿ ñêîðîñòè ñäâèíóëàñü íà ñåâåð â ñòîðîíó êàëüäåðû Àêàäåìèè íàóê. Íà ðèñ. 4 òàêîå ïîíèæåíèå èçîëèíèè VP=6.5 êì/ñ ïðàêòè÷åñêè
èñ÷åçëî. Ïîäîáíîå ïîâåäåíèå ñêîðîñòåé Ð- è S-âîëí íà ãëóáèíàõ 10 - 25 êì îòðàçèëîñü
íà êàðòå VP/VS àíîìàëüíî íèçêèìè çíà÷åíèÿìè âåëè÷èíû VP/VS.
Íà âñåõ òðåõ ðèñóíêàõ çàìåòåí ïîäúåì èçîëèíèé âûñîêèõ çíà÷åíèé ñêîðîñòåé,
ðàâíûõ VP³7.5 êì/ñ. Ïðè÷åì, èçîëèíèè ñêîðîñòè èñïûòûâàþò ïîäúåì â íàïðàâëåíèè
ñ þãà íà ñåâåð. Òàê èçîëèíèÿ ñêîðîñòè VP=7.5 êì/ñ ïîäíèìàåòñÿ äî 35 êì 1 è 2
ÿíâàðÿ. Ïîõîæàÿ ñèòóàöèÿ íàáëþäàåòñÿ è íà ïîëå èçîëèíèé VS=4.34 êì/ñ, ïîýòîìó â
ïîëå VP/VS â îáëàñòè áîëüøèõ ãëóáèí àíîìàëèé íåò. Îäíàêî, íà ðèñ. 4 ïî äàííûì 3
ÿíâàðÿ – 20 ôåâðàëÿ, íà ãëóáèíå îêîëî 40 êì âèäíà îáëàñòü àíîìàëüíî âûñîêèõ
çíà÷åíèé VP/VS, ÷òî îáóñëîâëåíî áîëåå íèçêèìè ñêîðîñòÿìè S-âîëí â ýòîé îáëàñòè.
 èòîãå, ìîæíî íàáëþäàòü çíà÷èòåëüíîå óâåëè÷åíèå ãðàäèåíòà ñêîðîñòåé Ð-âîëí
íà ãëóáèíàõ 25 – 45 êì.
Çàêëþ÷åíèå
Ñåéñìîëîãè÷åñêèå äàííûå ðåãèîíàëüíîé ñåòè Êàì÷àòêè, ïîëó÷åííûå è îáðàáîòàííûå ÊÎÌÑÏ ÃÑ ÐÀÍ, ÿâëÿþòñÿ õîðîøåé îñíîâîé äëÿ ïîñòðîåíèÿ ñêîðîñòíûõ ìîäåëåé
Ð - è S-âîëí. Ïðèìåíåíèå ìåòîäà îáðàùåííîé âîëíû äëÿ îáðàáîòêè ñåéñìîëîãè÷åñêèõ
äàííûõ ñëàáûõ êîìïàêòíî ðàñïîëîæåííûõ çåìëåòðÿñåíèé ïîçâîëèëî ïîëó÷èòü ëîêàëüíûå
ñêîðîñòíûå ìîäåëè, ïðîñëåäèòü çà äèíàìèêîé èõ èçìåíåíèÿ âî âðåìåíè è ïðîñòðàíñòâå.
Ïî äàííûì ðàñ÷åòîâ ìîæíî ñäåëàòü âûâîä, ÷òî âî âðåìÿ ïðîòåêàþùèõ âóëêàíè÷åñêèõ
ïðîöåññîâ, ïðîèñõîäèò èçìåíåíèå ñêîðîñòíîãî ïîëÿ ñåéñìè÷åñêèõ âîëí, ïîÿâëÿþòñÿ
îáëàñòè ïîâûøåííûõ ãðàäèåíòîâ ñêîðîñòåé.
Ïîëó÷åííûå âåðòèêàëüíûå, îäíîìåðíûå ñêîðîñòíûå ðàçðåçû Vp(z) è Vs(z) ìîãóò
áûòü èñïîëüçîâàíû â ñåéñìè÷åñêîé ñëóæáå äëÿ óòî÷íåíèÿ ïàðàìåòðîâ ãèïîöåíòðîâ
çåìëåòðÿñåíèé â ðàéîíå Êàðûìñêîãî âóëêàíè÷åñêîãî öåíòðà.
Ñïèñîê ëèòåðàòóðû
1. Áðàéöåâà Î.À. Ôðåàòîìàãìàòè÷åñêîå èçâåðæåíèå â îçåðå Êàðûìñêîå (âîñòî÷íàÿ Êàì÷àòêà) 650014 Ñ ëåò íàçàä è èìïóëüñû ïîäà÷è áàçàëüòîâîãî âåùåñòâà â
ðàéîíå Êàðûìñêîãî âóëêàíà â ãîëîöåíå // Âóëêàíîëîãèÿ è ñåéñìîëîãèÿ. 1997.
¹ 5. ñ.138 -144.
2. Ãîðäååâ Å.È., Äðîçíèí Ä.Â., Êàñàõàðà Ì., Ëåâèíà Â.È. è äð. Ñåéñìè÷åñêèå
ÿâëåíèÿ, ñâÿçàííûå ñ èçâåðæåíèåì âóëêàíîâ â Êàðûìñêîì âóëêàíè÷åñêîì öåíòðå
â 1996 ã. // Âóëêàíîëîãèÿ è ñåéñìîëîãèÿ. 1998. ¹ 2. ñ. 28-48.
384
Òðåõìåðíàÿ ñêîðîñòíàÿ ìîäåëü ñðåäû â ðàéîíå Êàðûìñêîãî âóëêàíè÷åñêîãî öåíòðà
3. Ãóñåâ À.À. Îïðåäåëåíèå ãèïîöåíòðîâ áëèçêèõ çåìëåòðÿñåíèé Êàì÷àòêè íà ÝÂÌ //
Âóëêàíîëîãèÿ è ñåéñìîëîãèÿ. 1979. .¹ 1. ñ. 74-81.
4. Êóçèí È.Ï. Ôîêàëüíàÿ çîíà è ñòðîåíèå âåðõíåé ìàíòèè â ðàéîíå Âîñòî÷íîé
Êàì÷àòêè. Ì. Íàóêà, 1994. 132 ñ.
5. Ìåëüíèêîâ Þ.Þ. Ïàêåò ïðîãðàìì äëÿ îïðåäåëåíèÿ êîîðäèíàò ãèïîöåíòðîâ
çåìëåòðÿñåíèé Êàì÷àòêè íà ÝÂÌ // Âóëêàíîëîãèÿ è ñåéñìîëîãèÿ. 1990. ¹ 5.
c. 103-112.
6. Ïèâîâàðîâà Í.Á., Ñëàâèíà Ë.Á. Ìåòîäèêà ðàñ÷åòà è èññëåäîâàíèå óñòîé÷èâîñòè
òðåõìåðíûõ ïîëåé ñêîðîñòåé ïðîäîëüíûõ âîëí (íà ïðèìåðå Êàì÷àòêè) // Ôèçèêà Çåìëè. 1981. ¹ 12, ñ 19-27.
7. Ïèâîâàðîâà Í.Á, Ïèâîâàðîâ Â.Ã. Ìåòîäè÷åñêèå àñïåêòû àëãîðèòìà âîññòàíîâëåíèÿ òðåõìåðíîé ñêîðîñòíîé ñðåäû // Ýëåêòðîííûé æóðíàë «Âåñòíèê îòäåëåíèÿ
íàóê î Çåìëå». 2003. ¹ 1(21).
8. Ñëàâèíà Ë.Á., Ãàðàãàø È.À., Ãîðåëü÷èê Â.È. è äð. Ñêîðîñòíîå ñòðîåíèå è
íàïðÿæåííî-äåôîðìèðîâàííîå ñîñòîÿíèå çåìíîé êîðû â ðàéîíå Êëþ÷åâñêîé
ãðóïïû âóëêàíîâ Êàì÷àòêè // Âóëêàíîëîãèÿ è ñåéñìîëîãèÿ. 2001. ¹ 1. ñ. 49-59.
9. Ñëàâèíà Ë.Á., Ïèâîâàðîâà Í.Á., Ëåâèíà Â.È. Ñêîðîñòíîå ñòðîåíèå â ðàéîíå
Êàðûìñêîãî âóëêàíè÷åñêîãî öåíòðà íà Êàì÷àòêå // Ýëåêòðîííûé æóðíàë «Âåñòíèê îòäåëåíèÿ íàóê î Çåìëå». 2003. ¹ 1(21).
10. Ôåäîòîâ Ñ.À. Îá èçâåðæåíèÿõ â êàëüäåðå Àêàäåìèè Íàóê è Êàðûìñêîãî âóëêàíà
íà Êàì÷àòêå â 1996 ã., èõ èçó÷åíèè è ìåõàíèçìå // Âóëêàíîëîãèÿ è Ñåéñìîëîãèÿ.
1997. ¹ 5. ñ. 3-37.
11. Hole. J.A. at al. Three-dimensional P and S wave structure of Redoubt Volcano, Alaska.
J. Geophys. Res., 1996, v. 101, p. 8111-8128.
12. Slavina L.B., Pivovarova N.B. Three – dimensional velocity models of focal zones and
refinement of hypocenter parameters // Phys. îf the Earth and Planet. Inter., 1992, v.
75, p. 77-88.
385